Online EPC Course

How to use the Manual

This manual contains much of the technical information you will need during your training and assessment for the Domestic Energy Assessor (DEA) qualification. However, we may provide supplementary guidance as required in the form of additional handouts. Additional information may also be provided from time to time by other means, such as by email. It is advisable to add any supplements to the manual binder because once you are qualified it will be up to you to maintain your knowledge of the latest conventions. The energy assessment industry is a fast developing one and changes are inevitable and regular. It is strongly recommended that you read more widely than this manual on some technical areas such as, for example, building construction. While the basics are covered here, you may wish to continue to increase your understanding of residential construction technology in order that you feel competent to inspect the full range of residential property. A current reading list supplied in Appendix 2 at the end of this manual. Becoming qualified is not just a matter of learning the technical aspects of RDSAP. There are other aspects to consider such as understanding the regulatory framework within which DEAs operate. This manual can be interactive, and in fact, we have deliberately made space available for you to scribble away–so please feel free to make whatever notes, reminders or diagrams you need to within the pages. Just make sure that your notes are legible and technically correct as the manual will be a useful point of reference, not just during training, but also for information in the future. There are often times when it is useful to confirm your instincts with a quick check in the manual. The manual is divided into a number of clearly laid out Sections relating to major subject areas, e.g. heating or construction. Within each Section there are sub-sections containing subjects that are referred to in the contents page, for ease of location.

History of energy rating 

Energy rating of buildings is not new and it has long been known that as much as 27% of our total CO2 emissions come from our homes. SAP is used to produce energy ratings for new homes.

RDSAP 

The Reduced Data SAP (RDSAP) is the government approved survey system used to produce the Energy Performance Certificates (EPCs) required by 2002 European Energy Performance of Buildings Directive (EPBD), which came into force in 2006. The EPBD seeks to reduce the amount of CO2 which is emitted as a result of heating, lighting and providing hot water to UK homes, many of which have remained poorly insulated. With certain exceptions an Energy Performance Certificate (EPC) is required whenever a residential property is sold or let and is currently valid for 10 years. The EPC gives prospective buyers and tenants up-front information about the energy efficiency and running costs of the property they are considering occupying. The rating system that the EPC illustrates means that they can compare one property against another before choosing and, it is hoped that landlords and vendors would feel some pressure to upgrade their properties to make them more marketable and thereby some progress could be made in reducing the levels of CO2 emissions. The physical RDSAP survey of a home required to produce an EPC is a non-invasive inspection. The DEA is not required to lift carpets to see the floors or to drill holes in the walls to see the insulation and is therefore limited in what they can see of the property. There may be some reliance on documentary evidence instead. RDSAP produces an EPC that, on its front page, shows an eye-catching and easy-to-read graphical illustration of the energy performance of the property similar to the labels displayed on white goods

The EPC

 The page 1 of the EPC shows the energy efficiency rating graph which illustrates the current rating (on the graph above of 49 or band E) and the potential rating (above of 75 or band C) that the property could achieve if the recommendations contained in the report were implemented.

The graph starts at 1 in the red bar and extends to 100 in the dark green and represents the cost to the occupant of heating, lighting and hot water for the property. A low number in the red is an inefficient property and a high number in the green is an extremely efficient one. It is possible for a property to score above 100 but this is extremely rare and would normally involve exporting energy gained from a renewable energy system. It means that the cost of the energy consumption of the property is more than met by the ‗income‘ obtained from exporting surplus energy.

On the front page the EPC will also provide an indication of the costs of providing heating, hot water and lighting to the property over a three year period along with a clear indication of the financial incentive to implementing the recommendations, i.e. the savings that could be made. 

It is important to note that these costs will not necessarily correlate with the occupant‘s billing history because RDSAP uses ‗standard occupancy‘ assumptions that may not reflect actual occupancy of the property. 

Standard occupancy

Standard occupancy is an important concept in energy rating because, in order to provide a means by which readers of an EPC can compare one property with another, a level playing field must first be achieved. 

For example, you might inspect a five-bedroom house occupied by a single person whose running costs are lower than if the property were occupied by a family of five people. Conversely, you might encounter a large family inhabiting a very small flat and who use a lot of hot water and considerable heat. The RDSAP rating ignores the occupants and their behavioural patterns, focusing instead on the dwelling itself; its fabric, heating, lighting, etc. RDSAP works by measuring the annual cost of maintaining an acceptable temperature regime in a dwelling. The assumption is that an acceptable regime would be achieved by heating the property to 21 degrees Celsius in the lounge and 18 degrees Celsius in other habitable rooms for 9 hours per week day and 16 hours at weekends. The calculation uses the size of the property to estimate a suitable average number of occupants and hence the hot water requirements for that number of occupants. This method is sometimes referred to as an ‗asset rating‘.

Recommendations 

The subject of recommendations is dealt with in more depth in Section nine of this manual. The EPC presents the reader with recommendations for improving the fabric of the building, the heating, lighting and other areas. The top three recommendations are shown on the first page of the report (see below). There is also a first reference to the Green Deal in this section.

The improvements suggested help to prioritise the different ways of saving energy, illustrated over a three year period. RDSAP Manual March 2012 Some improvements make obvious economic sense, and others are really only realistic considerations when a particular item requires replacing. Loft insulation and hot water cylinder insulation, for example, are obvious improvements, as they are cheap to purchase, can be easy to install, and often save enough energy to produce real savings in less than a year. On the other hand, double-glazing and a replacement central heating boiler are examples of improvements that cost far more, and this means that they often will not be replaced unless there is the need, i.e. a broken boiler or rotting/leaking window frames are present. The idea is to present the homeowner with enough information to help them decide on the best value for money when investing in energy efficiency. The recommendations report offers an independent comparison of the options–for example: installing new double-glazing (often only adding 2-4 SAP points) with a new boiler and controls (which could easily add in excess of 10 SAP points). The running costs associated with the ratings can also help the consumer to identify the best ways to target their money to reduce fuel bills. Energy efficiency measures do make sense—for cost and comfort. A typical 1960s house could have its fuel bills reduced by £200 per year for an expenditure of about £500–an effective rate of return of 40%– tax-free and inflation proof. Warmer, less draughty properties are generally more comfortable to live in and may command higher prices when sold or rented. Furthermore, our understanding of the ill effects of carbon dioxide and other pollutants on our environment should be reason enough to act.

Other information on the EPC

Page 2 of the EPC also contains basic details of the property‘s construction, levels of insulation, heating system, hot water system, lighting and other features and these are given an easily interpreted star-rating, depending on how efficient they are deemed to be. It is important that DEAs record these elements accurately during their inspection. Page 2 also shows details of any low and zero carbon technologies present.

Page 3 (detail above) contains the full set of recommendations and an indicative cost for each, together with suggested savings per year. The green ticks suggest the measure could be applicable for Green Deal funding and the orange tick suggests partial Green Deal funding.

Page 4 of the EPC (detail above) shows the environmental impact rating graph which illustrates carbon emissions associated with the property, expressed in tonnes of carbon dioxide produced per year.

Page 5 of the EPC (detail above) shows the details of any Green Deal charge associated with the property, including details of the installed measures, in this case loft insulation and double glazing, their monthly costs and savings, balance to repay and the interest rate charged.

Survey of the property Data collection 

Consider for a moment what it is that you are actually doing when assessing the energy performance of a property. An input of heat is needed to replace the heat lost through the envelope of the dwelling. Some of this comes from natural solar input or is generated by the occupants, but most of it has to be supplied by the heating systems. So the DEA collects information on those characteristics of the dwelling which influence the heat loss; as well as the characteristics of the heating system. While learning the process of inspection you can follow a survey form which will prompt you with the data items you need to record while at the property. Take care not to miss anything at the property as doing so may mean you are forced to return again later. When completing the survey forms, make your entries clear and if you do not use a section strike a line through it to show that you have not simply forgotten to complete it. For example, if there are no extensions strike a line through the section of the form that relates to extensions. RDSAP Manual March 2012 Your site notes or survey forms are very important, firstly as a vital part of the training and assessment process, but also (once you are qualified) as part of the auditing process that DEAs are subject to by all accreditation schemes. You are obliged to maintain your site notes for a period of no less than 15 years. It is perfectly possible that you could be challenged on your findings long after the EPC was completed and your notes must be good enough to defend your position in this event. You will collect information on the building, the age, construction and insulation present in the dwelling, together with information about the heating and hot water systems and any renewable energy systems. Your survey forms should provide supporting evidence to back up any decisions you make. For example, it is not good enough simply to state that the property was built in 1980. You must provide sufficient evidence to allow an auditor (or other reader of your notes) to be confident in your decision. Did you see the deeds and photograph them? Did the planning office provide a date? Did you rely on stylistic clues and if so what were they? 

The thermal envelope 

In order to calculate the heat loss of the property, the software needs to know the area of the walls, the external wall thicknesses, the floor areas, and the roof area (assumed to be the same as the floor area) together with details of any insulation present. The assessor measures these areas as well as the room height and the length of the heat loss walls. The subject of property measurement is covered in detail later in this manual. Results of thousands of previous energy surveys allow the software to accurately estimate the area of the windows for a property of any type and age without the need to actually measure the windows, in most cases. It is necessary that the assessor follows the conventions so that all DEA end up with the same result.

U–values

DEAs using RDSAP are not required to calculate U-values, but some understanding of them is important because the option of entering U values directly to the software is available if the assessor is presented with documentary evidence that fully supports the U values entered. U-values are numbers with units of W/m2K (Watts per metres squared Kelvin), e.g. 0.35 W/m2K. The U-values tell us the rate of heat loss of a wall, window, floor, etc. A built element with a larger U-value will have a higher rate of heat loss, so the built element will ‗leak‘ heat more quickly. The heat loss through the fabric of the building depends upon the construction method; material and thickness of each part of the envelope; and upon the area of that part. By collecting descriptions of the building age and construction, the energy rating software can assign a suitable rate of heat loss and U-value to each built element of roof, wall, floor etc. It can do this because the U-values are usually characterised by the building procedures of the period and (since 1966) by the energy design standards demanded by successive upgrades of modern Building Regulations. However, what the software needs to know is whether any changes to the insulation standards have occurred since the property was constructed. So for instance, a house built during the period of 1976–82 has an assumed wall U-value of 1.0. If the wall has had cavity wall insulation fitted the improved U–value falls to 0.40, a reduction of 60%. Such an insulation upgrade will substantially improve the EPC rating. RDSAP age bands are considered in Section Four of this manual.

Heating systems 

The annual cost of providing heating (including water heating) to a home depends upon the amount of energy required to maintain the set standard of comfort, after allowing for the heat losses, the efficiency of conversion of energy to useable heat, the quantity of fuel needed to provide the energy, and the price of fuel. It will also be reduced or ‗offset‘ by the presence of any renewable energy system. Information is needed on the type of the primary heating system; details of the primary heat source (e.g. the central heating boiler); the fuel used (including for electricity–the tariff, i.e. on-peak or off-peak); the use made of secondary space heating systems; the type of water heating system; the type of hot water storage, if any; as well as types of controls and renewable energy systems incorporated in the space and water heating systems. Heating is considered in more detail later in this manual.

How does the software use the data? The software process.

When the DEA enters data into the software, it then uses the input data, combined with its built-in defaults, to carry out the calculations. The output of this calculation is the predicted running cost for the home under standard. The predicted running cost is then divided by the floor area of the home and this figure is then converted into an energy efficiency rating and an environmental impact rating, somewhere on the A to G scale. The calculation is then used to estimate the savings from installing energy efficiency improvements, so that the energy advice report can make recommendations for improving the home–and give a predicted potential rating if they were to be carried out. 

The Landmark Register

The report is produced, reviewed by you and finalised when you are happy that its content can be finalised. Once finalised you cannot later change the report or its content. Once you are qualified, your EPCs will automatically be lodged on the Landmark Register where all EPCs are stored. During training and assessment you will not be able to lodge reports and do not have to worry about creating a ‗real‘ EPC for a property. You are able to practice with the software as much as you need to. RDSAP Manual March 2012 3. Section three | RDSAP software To Produce EPCs you need to use one of the softwares provided by different accreditation schemes. All softwares use same conventions and methodology. While training you will have access to a training account which will allow you to use most of the features of EPC online but will stop short of allowing you to produce ‗real‘ EPCs. You are able to practice with the software without fear of actually creating an EPC for a property. The software that you will use at this stage is essentially the same as the ‗live‘ software that you will use once qualified. 

Purpose of EPC

Marketed sale: This option should be used for EPCs required for marketed sales. (known as single survey in Scotland)

Non-marketed sale: This option should be used for ‗Right to buy‘ or sales that are not advertised. For example the sale of a house by one family member to another. 

Rental (social): This option should be used for dwellings owned by social landlords; this could be local authorities or housing associations.

 Rental (private): This option should be used for rental EPCs from the private sector. Institutions such as universities will fall into this category.

Not sale or rental: This option should be used if the EPC regulations do not require and EPC for the dwelling, for example, if a homeowner wanted an EPC just to see how energy efficient their dwelling is.

There is a field on this page that asks if the report is ‗created from existing data‘. This refers to the practice of cloning, whereby data is used from previous EPCs. This practice is outside of the scope of this manual and requires additional training. Further information may be gained by contacting NES. Consequently that field and the next, which asks for a reference number, should be left blank.

General details

Here you are required to enter some fairly self-explanatory information about the property such as the detachment, the number of storeys and the number of extensions. You will be asked whether you measured internally or externally. 

Internal or external measurements 

The measurements required are: 

The floor area

The exposed perimeter

Room height on each storey

Exposed perimeter includes the wall between the dwelling and an unheated garage or a separated conservatory and, in the case of a flat or maisonette, the wall between the dwelling and an unheated corridor. Internal dimensions are permissible in all cases. When using external measurements for a dwelling joined onto another dwelling (semi-detached and terraced houses) the measurement is to the mid-point of the party wall. Flats and maisonettes are usually measured internally. Whichever is chosen the same basis must be used for all parts of the dwelling. Room heights are always measured internally within the room, from carpet level to ceiling. The software automatically makes an allowance for the thickness of intermediate floors.

Integral or adjoining unheated garages (a heated garage is defined as one which contains fixed heat emitters linked to a main/central heating system).

Stores, coal sheds or other external (thermally separated) unheated spaces.

Thermally separated conservatories.

Unheated, thermally separated porches.

Terrain type 

The terrain type must be recorded for every survey. This allows the software to assume an average wind speed for the area. The average wind speed is used in the calculation of the benefit of a micro wind turbine. Even if a wind turbine is not present the terrain type must be recorded to enable the software to assess whether a recommendation for a wind turbine is viable. See the table for the choices and note that unless you are in a city centre location, suburban is the most common choice. Dense urban City centres with mostly closely spaced building of four storeys or higher Suburban Towns or village situations with other buildings well spaced Rural Open country with occasional houses and trees

Mains gas available

If there is a gas meter at the property or a mains gas appliance then you need to record that mains gas is available. The fact that there is a gas supplied to other properties in the street does not mean that mains gas is available to the property you are inspecting. 

Number of rooms and habitable rooms

The software asks for the number of habitable rooms and whether any of these are unheated.

 Habitable rooms include any living room, si Excluded from the room count are any rooms used solely as a kitchen; utility room; bathroom; cloakroom; en-suite accommodation and similar; any hallway; stairs or landing; and also any room not having a window.

sitting room, dining room, RDSAP Manual March 2012 bedroom, study and similar; and also a non-separated conservatory.

A kitchen/diner having a discrete seating area also counts as a habitable room.

A non-separated conservatory adds to the habitable room count if it has an internal quality door between it and the dwelling. 

For open plan dwellings count all spaces thermally connected to the main living area (e.g. a living/dining room) as one room.

For a kitchen to be a kitchen/diner it must have space for a table and 4 chairs. 

A lounge/dining room where the door was temporarily removed (i.e. architrave and hinges still there) is two habitable rooms. 

A lounge/dining room with the door permanently removed (hinge holes filled etc) is one habitable room. 

Flats and Maisonettes

Note that flats are dealt with in more depth in Section Four

Semi-exposed elements 

This page asks for details of the flat or maisonette you are entering and will simply not apply if you are dealing with a house. If you are entering a flat you will need to enter the flat type; that is whether it is a basement, a ground floor, mid floor or top floor flat. You will also be asked to enter the flat‘s position in the block. If it is a first floor flat, the floor position will be 1 and the software helps you by providing the choices. Under ‗semi-exposed elements‘ the software asks if there is a corridor and, if so, what type and what length. A more detailed explanation of this and some examples is contained within Section Four of this manual.

Age and roofs Unknown or as built

Depending on the element, you will have the option of entering the insulation as being ‗as-built‘ or ‗unknown‘. Using either will mean that the software defaults to the insulation depth that apply according to the date you have entered for the property‘s (or extension‘s) date of build. However, with ‗unknown‘ there will not be a recommendation for further insulation. (Take for example a roof in a 1900 terraced house, over the page.) If you are unable to access the loft you might enter that the loft insulation is ‗unknown‘. The software will assume the roof is insulated as it would have been when new (in 1900 that would be none) and there will then not be a recommendation for increasing the insulation. This is because the roof has not been assessed for its suitability; there might be a condensation problem or there might already be 300 mm of insulation. This does illustrate why it is so important for the DEA to make every effort to inspect the roof space where possible. Choosing ‗as-built‘ for a wall for example, means the wall is as it was when built. For a 2007 house ‗cavity walls as-built‘ means the walls are built to 2007 Building Regulations and will therefore be insulated.

Property age

Property age is extremely important to the software. The property age is required for the software to select the default heat loss values (U-values) for the wall, roof and floor and to calculate the window area. Clearly properties of different ages will perform very differently and the general rule is that the newer the property is the better the U values of its component parts. Houses of different ages also have different window to wall and window to floor ratios. The age bands for newer properties correspond to changes in Building Regulations and the older age bands, pre-1966, with changes in methods of building. The RDSAP age brackets are as follows and the job of the DEA is use their best efforts to date the property accurately and place it in the correct age band.

Roofs

Section P3 also deals with roofs on the main property and any extensions. Each is entered separately, starting with the construction type. Roofs types, their insulation and the options available in the software are described in Module Five.

Walls and Floors

This section deals with walls and floors and their insulation levels. For both, this is where you will enter the construction type, insulation type, insulation thickness and any U values that are known. For walls the overall thickness of the wall is required and whether there is a dry lining. Note that walls and floors are covered in detail in Module Five.

Alternative wall

This section of the software relates to alternative walls only and you will simply leave the section untouched if there is not such a wall at the property. You would enter an alternative wall type where the property has a significant area of wall that is of different construction or insulation level than the building part it belongs to, but this wall type cannot be identified as an extension since it does not surround any floor area. Where an area of alternative wall exists but it constitutes less than 10% of the total external wall area of the building part it belongs to, it can be ignored unless documentary or visual evidence exists of different retro-fitted insulation either of the alternative wall or the remaining wall in any building part. For example a cavity wall that has been cavity filled, but the areas beneath the bay windows have not been retro-insulated. The 10% of the wall area is identified including the windows and doors; it is only when measuring to the area of wall calculate the area to be included into the data summary that the area of any windows and doors is subtracted. This means that if you believe there to be an alternative wall then you will have to measure any window and door openings. Alternative wall types can occur as part of the main house, or part of any extension and you should record which of these applies. It is possible to enter up to five alternative walls. Note that alternative walls are dealt with in detail in Module Five.

 Dimensions

The software requires the following data for the main property and each extension:  The floor area in metres squared.  The room height in metres to the nearest centimetre.  The heat loss perimeter (HLP) in metres. See Module Four of this manual for detailed RDSAP measuring conventions.

Rooms in the Roof

Note that roof rooms are dealt with in detail in Module Four. This section of the software deals with rooms built within the roof space of a property and the section will simply be ignored if there is not one at the property. A room in the roof is a room built into what would normally be a loft space, above the main part of the dwelling, or above any extensions. Note that for such a loft space to qualify as a room in the roof for energy assessment purposes, it must incorporate fixed staircase access, i.e. not just a loft ladder. It will usually have sloping ceilings for part of the area and may also include dormer or Velux windows. If a roof room is present, the software requires you to enter the age range, floor area and the details of the insulation present. If you are able to obtain documentary evidence of the U-values of the component parts, you can enter this information in the extended data section on roof rooms (see Module Four).

Openings

Note that windows and glazing are dealt with in detail in Module Four. This section of the software deals with the openings in the property created by windows and also by any open fireplaces and ventilation systems. Details of any draught proofing are also entered here. The software asks that you enter whether the window area is typical of that type of property or whether it is more or less than typical. It also asks that you enter the proportion of the property’s window area that is multiple glazed–if any–and what type of multiple glazing is present.

Open Fireplaces

On the same page of the software in the ventilation section you are asked to enter the number of open fireplaces. These contribute greatly to the ventilation of the property and will remove some of the warmth generated by the heating. Note that open fireplaces are dealt with in detail Module Four of this manual.

Ventilation

The software asks you to enter the ventilation method and the options are:  Natural ventilation–this means the property is ventilated in the traditional way by windows and possibly vents in the walls and windows.  Mechanical, supply and extract–this is a whole house mechanical system which both introduces fresh air into the property and extracts heat from the stale air. Bathroom and kitchen extractors DO NOT qualify as mechanical ventilation.  Mechanical, extract only–this is a whole house ventilation system which mechanically extracts stale air from the property passive vents or gaps in the fabric of the building. This is sometimes known as MEV. Bathrooms and Kitchens extractors do not get classed as MEV.

Air Conditioning

The presence of air conditioning in the property simply requires a box to be ticked in the software.

Extended Openings

This section is for use when there is much more or much less than typical areas of glazing at a property and enables the location, dimensions, glazing type, orientation, U value and g value of each window to be entered individually. See also Module four.

Space Heating

This important section of the software deals with the MAIN heating systems within the property. It is possible to enter either one or two main heating systems and apportion the amount of work each does in maintaining the acceptable heating regime that was described earlier in this manual. The “Product Database” which contains specific technical information on a wide range of heating systems is located in this section of the software. Searching it for a system just requires clicking on the appropriate tab.

A number of entries are required about the main heating systems and given the complexity and range of possible entries, these have been covered in the heating section of this manual (Module Six).

Electric Meter

See Module Four of this manual for more about electric meters. The first entry to be made in this section is to describe the electric meters present. The choices are:

Dual rate

Single rate

Unknown 

24-hour

Heating Systems

Details of any secondary heating system are required including the fuel and system type. For a detailed definition of what a secondary heating system is please see Module Six of this manual.

Water and Secondary Heating

The secondary heating system should be entered next and this important area is covered further in Module Six. Details of the water heating system should be entered in this section of the software, including the heating type, system, fuel and immersion heater type, if applicable. If there is a hot water cylinder, its size, insulation type and thickness and whether there is a cylinder thermostat should be entered. This is covered in more detail in Module Seven of this manual. Bath and shower details are also recorded in this section, as follows:  Number of rooms with bath and/or ANY shower  Rooms with MIXER shower AND bath  Rooms with MIXER shower and NO bath This enables the software to make the appropriate recommendations in respect of waste water heat recovery systems (WWHRS).

Heat Recovery Systems

This section of the software asks for the number of waste water heat recovery systems (WWHRS - see section 7) and also allows for two flue gas heat recovery systems (FGHRS – see module 6) to be entered. Both systems have their own Product Database which allows for searching for and selecting specific models. 

Conservatories and Lighting

If a conservatory is present at the property, its type must be recorded and if non separated the floor area, whether double glazed, the glazed perimeter and the number of storeys in height it covers should be entered. See Module Four of this manual for a detailed look at conservatories.

Low Energy Lighting includes CFL, LED and fluorescent tubular lighting. You need to record:  The total number of fixed light outlets.  The total number of fixed low energy lights. Module Four of this manual explains low energy lighting in more detail including the conventions on counting combinations of lights.

Renewables

This section covers renewable energy systems; notably wind turbines, solar photovoltaics and solar hot water. Renewables can require some complicated software entries and these are covered in detail in module 8.

Addenda

This section in the software enables the DEA to better describe the property’s features within the format of the report by allowing certain anomalies to be explained to the reader. These include statements that explain that there are wall types that do not correspond to the options available in RDSAP and the presence of swimming pools. This section is the last of the data input screens and clicking ‘next’ at this point will take you to the Results: Recommendations section. The list of addenda is some optional statements that can be added to the EPC if required. They describe situations which as yet cannot be modelled in the software. The aim is to reduce complaints from householders about features that are not adequately described on the EPC. The list of addenda is currently as follows and is occasionally updated. In case you are wondering why the list is numbered 1, 4, 5, 6, 8, 9, it is because the missing numbers from this sequence represented addenda that have now been removed from the list because the software has developed to the point where it can deal with those issues. The screen shot below shows section P15 of the RDSAP software which allows the assessor to select addendum. The screen shot shows how the addenda appear in the EPC. They are listed on the last page of the EPC and although the DEA has control over which of these appear, he or she has no control over the wording of the individual addendum. 

Using the example of Addendum 1, you might want to include this addendum at the end of your EPC if you encountered a ‘clay batt’ wall. This wall type is not truly represented in RDSAP and a statement to that effect is helpful.

 Recommendations Screen

If you have fully completed each section so far, then at this point you will see a SAP Result expressed as a figure between 1 and 100.

If you have missed any sections you will see these listed in blue text and by clicking on each you can navigate back to the relevant section and complete it. Clicking on the ‘equals sign’ at the top of the page will always return you to the Results page. On this page will be listed the recommendations that the RDSAP software is proposing for the property. The DEA has the opportunity to remove any of these that he or she feels are inappropriate, by clicking on Edit Recommendations. See module 9 for information on removing recommendations. Clicking next at this point will take you to the Report Management screen that you saw earlier, except that this time each section has been completed. Under Review Reports you can now review the EPC before finalising it, to be certain that you are happy with its contents. There is also the option to review that data input before finalising. The data input report summarises every item of data you entered including many that do not appear on the EPC. When you are happy with the report click on Finalise Report. Clicking on Finalise Report now will mean that no further amendments can be made and discovering an error now will mean having to start the report again.

If the property has walls of cavity construction, there are additional questions about whether or not the cavity walls are ‘hard to treat’. That is, whether there are access issues such as adjoining conservatories, garages or other outbuildings that might make the physical installation of cavity fill insulation difficult. This could also include any situation where access by means of a 5 m high ladder is not possible such as at higher buildings or flats. Cavity fill may still be possible but will be more expensive. Cavity walls which are within areas of high exposure may be subject to higher levels of driving penetrating rain. The DEA should refer to the map below to decide whether or not the property is in an area of high exposure and if so the appropriate box should be ticked and an addendum generated.

Cavities which are less than 50 mm in width may require specialist cavity insulation or may not be suitable at all. Ticking the box to say that walls have narrow cavities will produce the appropriate addenda to inform the client of this. Narrow cavities may be identified by a total wall reveal thickness of less than 250 mm, yet a stretcher bond pattern to the brickwork.

Property Features

Some questions contained within this module only apply to flats and maisonettes. Where this is the case, it will be clearly stated in the text.

Some of the question titles (for instance, the number of rooms) appear to request the obvious, but do make sure you read everything through at least once, as there are a few points to remember. 

A basement is defined as a part of the heated and occupied area of the dwelling that is fully or partly below external ground level and where 50% or more of the external wall area loses heat to the adjacent soil rather than to the external air. In order to be included within the energy assessment, a basement must be accessed by a permanent fixed staircase such that a person can walk down it facing forwards, and it is either:  Heated by fixed heat emitters, or  Open to the rest of the dwelling. If recorded the basement will become the ground (or lowest occupied) floor. Note that there do not need to be any habitable rooms present in the basement. When incorporating a basement in the assessment do not mix internal and external measurements. If a basement is included in the assessment, it is likely that internal dimensions will be used throughout the dwelling.

Bay Windows

You are required to measure and enter details of all bay windows if they increase the floor area of the property. If any of the building elements of the bay are different to the rest of the house, i.e. the walls, floor or roof, then you will need to enter the bay window as an extension. Remember that an extension does not have to have been built later. The ability to enter up to four extensions gives you the flexibility to more accurately record such perturbations as bay windows. The bay in the photo is rectangular but bay windows can also be either a trapezium shape or a semi circular shape. The following diagrams should assist you in calculating the area of a bay window.

With bay windows the roof is often ‘thermally different’ to the main house, as in the photo above. It is rare to be able to assess the insulation in the roof of a bay window. This is usually enough to justify an extension BUT do apply some common sense to the situation. If the bay window area is small and therefore fairly insignificant to the calculation, you can ‘square off’ a trapezium shape to make a rectangle and still be able to make an accurate calculation. 

Conservatories

For RDSAP a conservatory is a structure with at least three quarters of its roof and at least half its external walls glazed. If the structure in question does not meet these requirements then it should be considered as an extension. The treatment of a conservatory depends on whether it is separated or non-separated from the dwelling.

A separated conservatory is effectively ignored for the purpose of calculating the dimensions and heat loss perimeters for the dwelling, although you do need to note whether or not it has fixed heaters. Most modern conservatories fall into this category; they will often have external quality uPVC doors separating them from the house. As a rule of thumb, if you imagine the conservatory was removed, you would need to ask: Would the doors offer sufficient protection from the elements? External quality doors are usually thicker and have features such as double-glazing, locks, bolts and weatherproof surrounds. A non-separated conservatory will either have internal quality doors–the thin, lightweight type that sometimes separate rooms, or will be open to the adjoining room. The doors may have been removed or the conservatory could have been designed to extend the room and have no doors. Consider whether the non-separated conservatory alters the number of habitable rooms. Several items of data are required about the non-separated conservatory:

Floor area, measured internally;

Glazed perimeter (ignore areas of brick wall;

Whether double glazed;

Conservatory height in storeys Images 1 and 2 show an example of a separated conservatory, with sliding ‘patio’ doors. These are of exterior quality, are double glazed, provide a good seal, and are lockable.

Images 3 and 4 are of a non-separated conservatory. The interior quality doors are not deemed to thermally separate the conservatory from the main dwelling. Although it is not visible from the images, these do not close properly owing to the lack of wooden trim to the frame, the latches are missing and they do not lock.

To recap: In RDSAP there are four options for conservatories:

A non-separated conservatory is like an extension in that the heat loss perimeter of the house does not include the length of house wall next to the conservatory. This is illustrated in the diagrams below. The exposed perimeter for the conservatory should be measured in the same way as for the main house and extension but it is the length of exposed glazed wall that is required. If there are areas of brick wall, these can be ignored. This is illustrated in the diagrams below. 

Remember to indicate if the conservatory is double-glazed and to estimate the average height of the conservatory relative to the main dwelling storey height.

What if the conservatory is not a conservatory? 

It is not uncommon to find a ‘conservatory’ that does not meet the RDSAP definition of such; i.e. a structure that does not have half its walls and three quarters of its roof glazed. Garden rooms may have a traditional flat or pitched roof. In these circumstances the structure should be treated as an ordinary extension except that you may need to make use of the ‘more than typical’ glazing feature of the software which is discussed in the section on windows further on in this module.

Separated conservatories provide shelter to the external wall, and also capture solar heat, which will partially warm the house. For most conservatories this effect is very small and both the solar heat gain and the sheltering effect are ignored in the RDSAP energy rating calculation. Some homes have exceptionally large unheated conservatories covering more than one storey and designed as a ‘solar space’ to deliberately capture solar gain and pre-warm the home. These properties can be recognised by the fact that the ‘conservatory’ will often extend to the full height of the dwelling and will make up a large proportion of the dwelling floor area. This can be dealt with by using one of the ‘more than typical’ glazing options–see the section on windows. An example is shown in the image below.

Detachment

Whether the property is detached, semi-detached, terraced or built in another form is important to the software so that it can select the appropriate set of default assumptions, including the pattern of window openings/glazing that should apply. Your choice of detachment will appear on the front of the EPC report. The options are described below.

Houses that are described as ‘detached’ have no party walls and so have exposed wall area on all four sides. Here are some examples. 

Link detached houses (houses that are essentially detached and are only linked to neighbours by a garage) should also be classed as detached.

Semi-detached houses share one side (the party wall) with a neighbour. This leaves exposed wall area on three sides. 

Although end-terrace and semi-detached properties are similar in terms of exposed walls there is a slight difference in the typical window areas for the two built forms. An end-terrace property will usually have a blank gable end wall, where as a semi-detached house will most likely have additional glazing in the side elevation, being glazed on three sides, rather than just front and back.

End of Terrace

As the name suggests this is the first or last house in a terraced row. End-of-terrace properties have three exposed sides like a semi-detached, but tend to have blank end walls. This means that the typical pattern of glazing will be the same as for a mid-terrace.

Mid-terrace houses have two party walls (one on either side) and two heat loss sides (front and back).

If the terrace has a passage through to the back of the house, classify it as a mid-or end-terrace house, include the length of the passage wall in the lowest floor heat loss perimeter and consider identifying the heat loss floor above the passageway through the ‘extension’ option. 

Enclosed mid-terrace

These houses are often called ‘back-to-backs’. Back-to-back properties are essentially terraced houses that also back onto another terraced row. From the street they will look just like a terraced house, but the rear of the property joins the back of a house from the next street, which gives us the phrase ‘back-to-back’. They have only one heat loss wall, as the side walls are common with their neighbours and the rear wall is common with the property on the terrace of houses at the rear.

Be careful if a house is described to you as ‘back-to-back’–sometimes this term is used to describe terraces that are built very close together with only a narrow yard separating them. These back-to-backs are not enclosed, they are normal terrace houses. 

Enclosed end terrace

n enclosed end-terrace will be the first or last house in a terraced row of back-to-back houses. They have two adjacent heat loss walls, and two adjacent party walls.

Modern ‘cluster’ homes are also enclosed end-terraces; the block is essentially four enclosed end-terraces without any mid-terraces in between.

A residential property adjacent to commercial premise:

It is possible to record a dwelling next to a shop or office in the following way:

If a dwelling has a commercial property below, record as ‘partially heated space’ below.

If a dwelling has commercial premises above, record as ‘other dwelling above’.

If a dwelling has commercial premises alongside it, treat as a non-heat loss wall.

EPC Training - Property Dimensions

Property dimensions are an important part of the energy rating calculation– remember that the energy rating is calculated by dividing the predicted fuel costs by the floor area so it is important that the floor area is calculated accurately. Your floor area calculation is displayed on the front page of the EPC. The heat loss perimeter (HLP) is needed to assess the heat losses through the building fabric and the room height is important, since the ventilation loss depends on the building volume, which is calculated using the room height. For a simple property such as a bungalow or a flat, the actual data entry could be as few as three items–floor area, room height and heat loss perimeter. For many houses, the floor area and HLP will be the same on all floors (but not the room height!), so the amount of data to input is often less than you might think. However, there are properties where the measuring can be more complicated. Imagine an irregularly shaped house with numerous extensions, bay windows, conservatory, etc; in such a case there is considerable measuring to do which will require a systematic approach.

A floor plan showing dimensions (and other property features) is essential in every case, even the simple properties. The plan should, among other data items, show the horizontal dimensions of the property, the room heights and the HLP. It is highly recommended that you highlight the HLP with a different colour, firstly to aid you in ensuring accuracy and secondly to allow someone checking your work to be able verify your accuracy. 

For houses, internal or external dimensions can be used depending on which are easier to measure on site. If you measure externally, the program uses those external dimensions by adjusting them to allow for the wall thickness, but the entire survey needs to be carried out using either internal or external dimensions. Flats are usually measured internally, as is room height and room in roof floor area. 

You must not change between internal and external when measuring different parts of the house. 

At a straightforward rectangular property, the floor area is calculated simply by multiplying the length of the property by the width. By using external measurements you will be calculating the Gross External Floor Area (GEA) and by using internal measurements the Gross Internal Area (GIA). The software adjusts whichever you decide to use to GIA for the EPC report. Complicated properties will require more dimensions to be taken on site and a more careful and detailed approach to making an accurate calculation. 

Do not include external unheated porches in the floor area. Do not include unheated areas (such as outhouses, outside toilets, garages or coal stores) that are not accessed via an internal door, even if they are within the footprint of the dwelling. Do include unheated rooms, e.g. internal utility rooms and lobbies, so long as they are within the external envelope of the property and are accessed via an internal door. 

The external or internal dimensions are used to work out the exposed wall perimeter. The exposed wall (heat loss perimeter or HLP) is extremely important for evaluating heat loss wall areas as well as the heat loss through the ground floor. Therefore it is essential that it is measured accurately. The energy assessor is required to record the heat loss perimeter (HLP) for the main house and, separately, for any extensions. The heat loss perimeter must also be calculated for each floor of the house and any extension(s) present.

For mid-terrace dwellings with a side passageway, the length of passageway wall is part of the exposed wall and its perimeter should therefore be added to the measurement for the exposed perimeter for the dwelling. 

Where there is an integral garage, or an attached garage, or any other external construction such as an outhouse adjoining the external wall of the dwelling, the perimeter of the house next to it is counted as part of the heat loss perimeter. This is because there will always be heat loss through the wall into the unheated space. Although the heat loss will be slightly reduced by the sheltering effect of the garage, this reduction in the heat loss through the wall is considered to be insignificant for RDSAP. So, the heat loss through the sheltered wall is calculated as if the garage or other external construction were not there. Enter separately the heat loss perimeter of any extensions–this is illustrated in Example 2. An example of an extension on the upper floor only is given in Example 3. For roof rooms, the heat loss perimeter is not required, since it is assumed that there is no heat loss wall on this storey. The software assumes that all the heat loss is through the roof/stud walls and calculates the areas of heat loss roof appropriate to a roof room construction, without need for a heat loss perimeter measurement.

Measuring perimeters when access is restricted:

There may be occasions where a part of the HLP for a dwelling is unable to be accessed. The below photo is an example where some of the HLP runs into the neighbour’s garden and from the inside it is impossible to tell where the party wall ends and the external wall starts. 

In order to obtain a measurement of this stretch of wall the only option available is to count the bricks. By measuring a single brick (including mortar) and counting the total number of bricks on this piece of external wall on the dwellings perimeter. The internal measurement would be required, so the thickness of the reveal from the patio doors would be subtracted to give a total.

Room height is an important dimension because it enables the RDSAP software to calculate the volume of the property accurately. You should measure to the nearest centimetre. 

The Domestic Energy Assessor simply has to record a single dimension for room height on each level of the property. This is often as simple as measuring from carpet level to the underside of the ceiling and the room height will often be the same in all the rooms on that level (a few check measurements may confirm this). If there are extensions then a room height dimension will be required for each extension and these may well be different to the main house. Do not add on any allowance for the depth of the floor structure or the ceiling structure above since the software already automatically adds an amount to allow for this.

Where a storey has a number of rooms with different ceiling heights, as is sometimes the case with older properties, you can calculate the area weighted room height for the whole storey.

Total storey area = 50 m2 Room 1: 15 m2 with room height 2.2

Room 2: 10 m2 with room height 2.3

Room 3: 10 m2 with room height 2.4

Room 4: 15 m2 with room height 2.5

[(15 x 2.2)+(10 x 2.3)+(10 x 2.4) + (15 x 2.5)] / 50 = 2.35

Another scenario is where a storey has sloping ceilings and you need to calculate an average room height; for example where a vaulted ceiling exists in a roof space (but does not qualify as a roof room). 

In this example you need to split the room into three sections as illustrated. The two sections at either end can then have their average height calculated: (2.0 m + 3.0 m) / 2 = 2.5 m The room height of the main centre section is 3.0 m. The overall average room height can then be calculated by averaging the separate section heights based on the overall room width

(1m + 4m + 1m):[(2.5 x 1.0)+(3.0 x 4.0)+(2.5 x 1.0)]/6 = 2.83 m

Galleried rooms/balconied bedrooms:

Dwellings that have balconied bedrooms and double-room height rooms are dealt with in a particular way by RDSAP. The following schematic drawing depicts one type of this situation.

The property is a mid-terrace with one bedroom on the upper floor. The upper floor is balconied and open to the rest of the property and only covers 50% of the ground floor area. The room height of 50% of the ground floor is 4.9m. In order to input this property, the area weighted room height for the ground floor needs to be worked out. Even though the dwelling is totally open-plan, treating the house as a single (very high) storey will not calculate the SAP correctly as it omits the upper floor area. In the SAP the floor area is integral to many of the calculations, such as hot water requirements and the zone 1 area. Therefore it is crucial that this additional floor area is included.

EPC Training - All You Need To Know About Extensions in RDSAP.

The Domestic Energy Assessor is required to identify any extensions at the property and up to four extensions can be recorded. The first thing to remember about the term ‘extension’ is that this does not always mean a part of the house that has been added on to the main house at a later date. In RDSAP terms, an extension is any part of the heated and occupied area of the house that is ‘thermally different’. By this we mean that it has been insulated to a different standard or has a different built construction from the main part of the house. The word ‘extension’ is in a sense slightly misleading. An extension will usually be a part of the property that has been built at a later time. However, it could also be because an occupant has insulated part of a house (rather than the whole property); or a part of the original construction might be thermally different (e.g. a mono pitched roof single storey off-shot washroom at the rear of a Victorian terrace). 

Ask yourself if there is a significant feature that makes part of the property different to the rest and therefore justifies classing it as an extension. Are the roof, walls or floors different? Is there a significant difference in room height in one part? Is one part insulated and one part not?

Splitting the property:

Entering a section of a dwelling as an ‘extension’ can be a useful way to artificially split a property to reflect the different thermal properties of different parts of the same property. For example, where two halves of a property have significantly different room heights the property can be artificially split in two–the differing room heights entered for each half. There is no reference made to ‘main’ and ‘extension’ on the EPC, so this will not lead to confusion for the customer. However, make sure to record in your site notes why you have artificially split the property. Entering the property into the software as having an extension allows the effect of different levels of insulation to the walls or loft/roof to be described separately. This gives the software a more accurate description of the property, and so increases the accuracy of the energy rating. For instance if a house has a pitched main roof, and part flat roof, this should be entered as a ‘main house plus an extension’ even if the roofs were built at the same time. The ability to use up to four extensions presents a means of quite accurately accounting for the various parts of complex larger properties. 

The entries for extension dimensions, age, wall and roof details are all separate from the main house details and there are appropriate sections of the software in which to record them. However, the EPC, once finalised, will not necessarily show the reader details of all of the extensions. If elements of an extension are considered too small to warrant inclusion (a 10% rule applies), they will feature in the background calculation but will not be mentioned in the EPC report.

Note that on rare occasions you will come across a property that you think cannot be accurately described using the extension fields (maybe because it has too many different types of construction). In such a case where you believe you could need more than four extensions it will be necessary to combine extensions so that the number is reduced to four. When doing this, you should combine those extensions that are closest to each other in terms of their construction and insulation.

For example, it is often possible to combine extensions from adjacent age bands. There is no difference in heat loss between an un-insulated loft from a house built in 1930-1949 and the same loft built in 1950-1965, but there is a big difference between un-insulated and insulated lofts of the same age band. Areas of a different thermal standard that are less than 10% of the total heat loss element in question can be ignored in terms of defining it as a extension. For example an area above a narrow passage. However, this area must still be included as part of the assessment of the dwelling.

Vertical extension:

It is possible to enter a new (or thermally different) upper floor to the software as a vertical extension. An example of this might be where a new floor has been built above what was previously been a bungalow.

Flats and Maisonettes:

For RDSAP a flat is a single storey dwelling located within a block containing at least two storeys. A maisonette is simply a flat that extends over more than one storey. It can still be part of a small block or a high-rise block. Flats require some additional items of data to be collected on site that don’t need to be recorded for houses.

The floor position is simply a number that identifies on which storey of the block a flat or maisonette is located. The floor position number is easy to remember as it starts at zero for the ‘ground’ floor. It follows that the first floor has a storey number of one, and the second floor a storey number of two etc. The floor position is used to work out the height of the flat and therefore the level of exposure to the wind (greater at higher storeys than at ground level). So even if the ground floor of a block of flats contains no dwellings (e.g. it may contain car parking or communal areas) this floor is still counted as zero. RDSAP treats a maisonette in exactly the same way as a flat so we refer to them as flats in this manual, but note that it is the lower floor of the maisonette which identifies its floor position.

In some instances, a block of flats may incorporate ‘basement’ levels, which may or may not include dwellings. In these circumstances the ‘bottom-most’ of the basement levels should be identified as the ‘Ground’/Level 0 ‘storey’, with consecutive numbering from this point upwards as before. Therefore, the Ground/Level 0 storey will always be the bottom-most level in any block and will have a floor that is in contact with the ground, i.e., no further space below.

The RDSAP software also requires the flat type (basement, ground, mid-or top floor) and the floor position within the block. For example, a flat on the second floor is entered as: flat type mid floor flat; floor position 2).

Additional Data For Flats and Maisonettes in RDSAP Software.

A few extra items of data are required for flats, since flats sometimes have heat losses from exposed floors, unheated corridors and stairwells which are not usually associated with houses. For maisonettes, use the same conventions as for flats.

Flats often have walls separating the occupied floor area from common areas, such as corridors, lobbies or stairwells. For simplicity the survey form refers to all of these as ‘corridors’. The heat losses from the flat into the common areas obviously depend on whether the corridor is heated or unheated. The survey form therefore requires you to tick one of the following:

No corridor

Unheated corridor

Heated corridor

And in addition for unheated corridors:

Length of sheltered wall (if unheated corridor)

The relevant section of the survey form is shown below. 

The amount of shelter from an unheated corridor within a building split into flats is more significant than the shelter provided by garages or conservatories. Additionally, in a flat, the area of wall that is sheltered is usually a larger proportion of the total heat loss wall area. This is why it is necessary to separately enter semi exposed wall lengths for flats, but not for houses and bungalows. If there is a heated or unheated corridor, it normally covers the main entry door into the flat. This helps to stop heat losses when the door is open–this is generally called a ‘draught lobby’. A flat whose front door opens directly to the outside of the building allows heat to escape whenever it is opened, and the draught lobby reduces this effect. 

Remember that the length of the unheated corridor must be included in the heat loss perimeter of the flat. 

The wall that separates a flat from the adjacent corridor may be of a different construction than the other perimeter walls of the flat. If this is the case, the wall can be classed as an alternative wall. This only applies when the corridor is unheated.

For flats or maisonettes where there is a small entrance on the ground floor that is not separated by an external quality door the following procedure applies. Divide the flat into main and extension, where the flat on the upper for is the main and the small entrance area is the extension, the extension is likely to be two storeys.

Flats: Heat Loss Floor.

As with houses the heat loss floor type needs to be collected.

Exposed floor: is above an open airspace, e.g. an archway to courtyard etc.

Semi-exposed (unheated): above an unheated internal area (internal car park, unheated store etc.)

Semi-exposed (part heated): above a space heated to a lower temperature, or heated at different times to the dwelling concerned. For example, a flat located above a shop or an office.

Other dwelling below: there is another flat below and the assumption is that there is not heat loss between the two.

Ground floor: is in contact with the ground.

Essential EPC Course Information - Habitable Room.

The Domestic Energy Assessor is simply required to enter the total number of habitable rooms in the entire property. Arriving at this figure, however, requires some understanding of what a habitable room actually is. The habitable room count field is used to estimate the proportion of floor area that is heated to a higher temperature than the rest of the dwelling. The energy rating model assumes that zone 1 (typically the lounge and any areas open to it) is heated to 21о and the rest of the house (zone 2) to 18о .

The habitable room count does not directly identify this area but is used to infer the zone 1 ‘fraction’ assumed by the software. The greater the number of habitable rooms, the lower the zone 1 fraction assumed.

The number of habitable rooms counted is important to the energy rating because more output is needed from the heating system to heat to a higher temperature, and heat losses are greater from the better heated rooms, i.e., the higher the zone 1 fraction, the greater the dwelling temperature.

To count the required number and type of habitable rooms in a property, include any living room, sitting room, dining room, kitchen-diner, bedroom, study and similar. Exclude other rooms such as any kitchen, utility room, bathroom, cloakroom, en-suite accommodation and similar; any hallway, stairs or landing; and also any room not having a window, or source of natural light.

For open plan dwellings count all spaces thermally connected to the main living area (e.g. a living/dining room or non-separated conservatory connected to the living room) as one room.

For example, a typical small two-bed mid terrace property might have six ‘rooms’ in total, made up of the following:

Lounge/diner

Kitchen

Master bedroom

Second bedroom

Bathroom

Hall, stairs and landing

In determining the habitable room count for RDSAP Software, the hall, stairs and landing, bathroom and kitchen are not included and the room count is therefore 3. The lounge/diner counts as one room, even if it has been created by removing a separating wall e.g. opening up a through lounge.

Conservatories as Habitable Rooms.

Non-separated conservatories should be included in the habitable room count depending on the presence of internal doors separating the conservatory from the main dwelling (conservatories will be explored in more detail later in this module).

If the conservatory is divided from the main property by internal doors, then it should be included in the habitable rooms count (assuming it is of habitable type, although it is unusual to find a conservatory that is solely a bathroom or kitchen etc.).

If the conservatory is unheated, it should be classed as an unheated habitable room. If there are no doors between the conservatory and the main house, the conservatory effectively becomes part of the habitable room that it is adjacent to, therefore the habitable rooms count remains the same.

For a kitchen (non-habitable room) to be identified as a kitchen/diner (habitable room), the requirement is that it must contain a discrete, separate area large enough for a dining table and 4 chairs. A kitchen with a breakfast bar would therefore not qualify as a ‘habitable’ room.

Room count: include only the types of ‘habitable’ rooms as described above.

How To Recognise Porches When Completing An EPC Course.

RDSAP distinguishes between two types of porches:

Internal porches

External porches

For RDSAP, a porch is defined as a small entrance area, which has doors at either end. Porches which are under the main roof of the dwelling, within its ‘foot print’, are deemed part of the main building structure and are referred to as internal porches.

The start position for assessing internal porches is that all internal porches are included in the assessed floor area, whether heated or unheated. However, if it is possible to identify the type of separation between the porch and the main dwelling the following conventions should be used:

Include all heated internal porches, i.e. those with fixed heat emitters.

Include all unheated internal porches (unheated includes those heated with portable heating units) that are not thermally separated from the main dwelling, i.e. have internal door separation only.

Exclude all unheated internal porches that are thermally separated from the main dwelling, i.e. those that have external door quality separation from the main dwelling.

For RDSAP an external or ‘off-shot’ porch is an entrance area (with doors at either end) built outside of the footprint line of the main dwelling. It may appear to be ‘added on’ to the front of the property.

External porches should be included if heated. It is highly likely that they will need to be considered as extensions because it is rare that you will be able to access the porch roof to be able to assess its insulation. The wall or floor construction may also be different to the main house.

External porches (with a door at each end) can be ignored if unheated regardless of the quality of the door separating it from the main house.

Record your reasoning for including or excluding a porch in your site notes.

Property Age in RDSAP Software

The property age is extremely important to the software. It is required for the software to select the default heat loss values (U-values) for the wall, roof and floor and to calculate the window area.

Clearly properties of different ages will perform very differently and the general rule is that the newer the property is the better the U values of its component parts. Houses of different ages also have different window-to-wall and window-tofloor ratios. The age bands for newer properties correspond to changes in Building Regulations and the older age bands (pre 1966) with changes in methods of building.

The RDSAP age brackets are given in the table and the job of the energy assessor is to use his best efforts to date the property accurately and place it in the correct age band. It is important to note that RDSAP makes certain generalisations that may not always be strictly accurate in all cases. For example, you may find houses built post1983 that DID NOT have cavity wall insulation fitted when they were built, even though RDSAP assumes it to be so.

It is very important to record clearly how you dated the property. There will be times when you have exhausted all the easy means of doing so and are forced to resort to an estimation based on stylistic clues. Recording your methodology will serve to defend your decision if you are later found to be incorrect.

EPC Course: How To Date A Property in RDSAP Software.

There are various ways of establishing the age of a house or flat. It is best not to rely on a single piece of evidence but rather to use other means to corroborate where possible. Property age is one of the most important factors in the EPC calculation.

It is worth noting that the date you input does not appear on the EPC for the client to see, but is part of the calculation in the background. 

 You can ask the occupants. There is a good chance they may know but don’t be surprised if they don’t or if they are shown to be mistaken. Don’t assume that people are always telling the truth. In some cases people can provide you with documentary evidence of completion of conversion or renovation work, even a NHBC certificate in the case of fairly new homes. If you ask people in advance, perhaps when calling to make the appointment, to prepare any documents they have, you are more likely to get to see them. You cannot rely solely on homeowners information, you must support this with your own enquiries or deductions and record this in your site notes

 Ask the estate agent, if there is one, or the housing association. If there is a solicitor involved in the transaction, they may help you, particularly if you already have a working relationship with them. Again, verify any information where possible. 

 If you see an elderly neighbour or resident walking past, ask them (tactfully) when the properties were built. Older people are often very knowledgeable. You must verify this information. 

 Contact the local authority, particularly the planning archive team who are often helpful. Once you identify a helpful person, make a note of their name for next time. 

 Use the internet. Google the postcode. There are websites such as Mouseprice.com that will often give you dates for houses or even whole streets and rely on surveyors and valuers to update them with new information.

 The Land Registry is a good source of copies of original deeds and plans of properties and will usually provide a date of build. However, there is a small charge which may be prohibitive. Your company may have access in some cases.

Older properties are easier to date and arguably less critical. You simply have to place them in the pre-1900 age band so you are not overly concerned whether they are built in 1700 or 1899. There is not much thermal difference in properties in the next age band, 1900-29, and if unsure which of these two bands to use you should test the difference with each using the RDSAP software. If there is no difference in the ratings you are safe to use either, probably using the worst case.

 For modern houses the date becomes much more important. Changes in thermal performance are significant between the RDSAP age bands. There are clues connected with Building Regulations. For instance the 1990 regulations introduced extract fans, and trickle vents into windows. If the house does not have these it may be before the 1990–95 age band. Be cautious using this rule, as the windows might have been replaced recently.

Dating by stylistic features can be very tricky to do and you can easily get it wrong. Roof pitches were sometimes shallower in the 1970s, a period which also saw chimneys go out of fashion, to return in the early 1990s. Making an informed estimate based on style–looking at the whole street, not just the house being inspected, can be useful, although beware of the recently built ‘infill’ property. Look at the windows on the neighbours’ houses. Stylistic clues can be misleading, so try to take a few into consideration.

The photographs on the following pages give some indication of stylistic clues to help you date properties based on their appearance.



EPC Training - Identity A Pre 1900's House.

 This age band contains the Georgian (1714-1830) and Victorian (1837- 1901) housing stock which in some areas forms a large percentage of the total housing. Often these houses of different styles and ages are found near the town centre, built from local stone with stone roof tiles. Many have, of course, been substantially modernised.

A summary of the characteristics of these houses:

The use of local materials, e.g. local stone, brick or timber frame.

Brick bonds typical of solid walls, e.g. Flemish and English bonds.

The original windows would often have been wooden sliding sash windows, with smaller panes of glass usually indicating an older house and larger panes meaning a house late in this RDSAP age bracket.

Car parking was not a consideration with these early houses. This means that the roads are now very congested by on-street parking.

The solid brick walls of these houses are often rendered.

EPC Training - Identity 1900's to 1920's House.

This age band includes the Edwardian (1901-1910) housing stock which took many of its stylistic features from the Victorians. Thermally, there was no significant improvement in the buildings. Insulation was not really a consideration yet. Window glass was now being manufactured in larger sheets, but essentially the windows still appeared Victorian in many cases. The brick walls still tended to be solid, i.e. not cavity construction. The example above shows the decorative use of engineering bricks, sometimes used to improve the foundations and reduce rising damp. Hallmarks of Edwardian (or late Victorian) houses: 

 Solid front door with fan light above.

Decorative supports for window sills.

Tiled floor to the porch.

Closer inspection reveals 9 inch (230 mm) thick walls.

The classical features of some of the Victorian houses made way for the Gothic revival of the Edwardian period.

Typical features include:

Decorated gables (e.g. on the semi-detached house below c1910).

Sash windows with large panes, often one pane above and one below the meeting rail.

Glazed doors are common.

EPC Training - Identity A 1920's House.

Not much house building had gone on during World War I, and the period afterwards was very significant in the development of housing in Britain. It saw the first ‘council housing’ and there was a great emphasis on ‘social housing’. The 1920s saw housing influenced by the Art Deco movement. A ‘70 ft rule’ governed the minimum distance between houses, reducing density dramatically: from 20-30 houses per acre (common in Victorian and Edwardian terraces) to as few as 6-8 houses per acre. House building immediately after the first world war was much influenced by the garden city movement and the Tudor Walters report.

Typical features of this period:

Spacious, detached, semi-detached and terraced houses.

Equally spacious hedge lined plots in an estate layout.

South facing gardens.



Note: The windows in the houses above have almost certainly been replaced with 1950s metal casements

Domestic Energy Assessor Training - Identifying a 1930's House.

Metal casement windows came into fashion in the 1930s and have much to do with the recognisable look of many houses from the 1930s. Typical features of the 1930s: 

Bay windows with horizontal banding;

The cavity brick wall, which was enshrined in the 1936 Model Bye Laws, came into more common use around this time;

Introduction of the hipped roof–expansive roofs with short ridges and tall chimneys;

Ribbon developments–suburbia as we know it began to grow along the approach roads of our towns and cities;

The car is accommodated on the plot, usually in a separate garage.

Building styles were influenced by developments on the continent, particularly by the Bauhaus (the influential German school of architecture). The ‘between wars semi’ is another classic house type of this period. Features that typify the ‘between wars semi’: 

Formal entrance with the half round opening to the porch area, front door is set back slightly.

Decorative glazing in door panels.

Roof extends forward over the bay window, with decorative timber or brick above the glazing.

The densities have increased from the luxuries of the garden city houses of the 1920s; this is particularly so in the private sector house of this period. More examples of 1930s dwellings are shown in the following photos.



EPC Course - How To Identify A 1940's House.

During the Second World War, house building came to a virtual halt except for the prefabricated dwellings. Many of these developments are still lived in today, many years after their design life expectancy of around 20 years.

Immediately after the World War II there was a rush to fill the housing shortage with system built housing estates. There are dozens of different types of system built houses, too many to cover here, but it is fairly easy to research those where you live with the help of local information from the library or the council. 

To identify a 1940s house, look for:

System built walls–concrete panels, although many of the houses will have been re-clad in brick with new windows fitted under housing defects legislation. These should be entered as ‘system built’ in wall construction.

Corrugated roofing systems.

Steel frames, often visible in the roof space.

The houses depicted above are ‘Woolaway’ houses. 

Domestic Energy Assessor - Identifying A 1950's House.

The 1950s saw the beginning of a major boom in housing developments, with mass production of building materials producing a standardisation across the country.

Typical 1950s houses features: 

Festival of Britain (1951) influences in the flat roofed porches supported on metal posts.

Plain brick walls (from the mass production of London bricks).

Metal casement windows.

Concrete roof tiles.

Bungalows became popular during the 1950s.

Open-plan estates where properties were less clearly separated from neighbours by clear boundaries e.g. no walled front gardens. 

Identifying a 1960's House.

Houses in the 1960s:

The chalet or dormer bungalow (notice the rooms in the roof).

Integral parking provision (a feature of the late 1950s and 1960s).

The kitchen/diner and open plan living room is often a feature of this period.

Flats in the 1960s:

In the public sector the 1960s saw major developments of flats in blocks of three or more storeys.

The tall tower block is often from this time period. 

Identifying 1970's Houses For RDSAP Software.

During the 1970s there was a positive reaction against the sameness of the 1960s. Signs of the 1970s:

Developments of two and three storey houses–a conscious attempt to create not only a variety in the built form but also a mix of house types catering for a varied population.

Increase in housing density created by the rise in land prices.

Reaction against the ‘open-plan’ estate, with the enclosure of private space by high walls and fences.

Greater attention given to external detailing.

Off plot parking and carports are a feature of this period.

Dominance of gas central heating results in a lack of chimneys, and increasing number of ridge vents.

Large windows reflect the use of double-glazing and the use of Velux roof lights can be seen.

The Essex Design Guide (a planning guide produced by Essex County Council) was influential in promoting cluster housing, breaking up the fronting and reducing road widths.

Identifying 1980's For An EPC Course.

1980s estates are also characterised by high densities. But there was a move back to a more conventional estate layout.

Cul-de-sacs with tightly packed houses are a common feature.

There is a conscious move to use different house types to give variety.

The large windows reflect the common use of double-glazing but there is often a nostalgic attempt to soften the effect with curved window heads and imitation leaded lights.

The chimney creeps back again particularly on the larger house type: but more as a result of the gas flame effect fire than any desire to revert to solid fuel heating.

Identifying 1991–1995 and 1996–2002 Houses For RDSAP

There is little difference in style between 1991–1995 and 1996–2002 but for relatively new homes like the one shown above it is more likely that the actual date of construction will be known.

Houses are closely packed, often in large volume estates. House builders may use a number of subtly different house types to create variety. There is also a conscious effort to break up box-like outlines with a mixture of popular features from the past, often jumbled together: bay windows, pillars, porches, decorative brickwork, cladding or tiles to parts of elevations are commonly seen.

The detached (sometimes only just) house is the most common built form on many estates. Post-1990 houses will also have:

Extractor fans (or sometimes passive vents in recent properties) in kitchen and bathroom(s).

Trickle vents to windows.

Allocated parking, driveways or garage (often two garage spaces for larger houses).

Roof timbers may exhibit a date of manufacture in large painted letters.

Electricity installations may be dated as may be hot water cylinders or gas meters.

Take care not to rely on windows for dating; they are often changed.

Identifying Post-2002 Houses For EPC Training

For almost brand new homes it is likely that the actual date of construction can be found. However, there are visible differences between post-2002 housing and estates built in the 1990s, due to the influence of central government planning guidance (the John Prescott rules). These asked for higher densities in an effort to reduce the impact of new build housing, and encouraged the redevelopment of brown field land instead of green field development.

Thus many post-2002 estates are redevelopments of inner city former light industrial areas. Houses are closely packed, often including three storey terraces and low rise apartment blocks.

Conversion Date

 When dating a property, in some instances the conversion date rather than the original build date of the property should be used. However, it should only be used if you have documentary evidence of the date of the conversion.

he conversion date will be more appropriate as conversions have to comply with Building Regulations and therefore their thermal performances will be improved. This does not apply to refurbishments, only conversions such as:

Barns/mills converted to dwellings;

Warehouses converted to dwellings;

Houses converted to flats. In addition, if a property has been completely refurbished, choose the age band in which the building control approval was granted.

Completely refurbished means walls, floors, windows and roofs. If a property has only been partly refurbished, the original build date should be used.

If you are able to establish in advance of the inspection that the property is a conversion, you can request documentation from the owner. Design your pre-inspection questionnaire or telephone question list carefully.

Roof Rooms 

For RDSAP rooms in the roof can take several forms:

A house designed for occupation of the roof space such as a chalet bungalow, usually built with dormer or roof light windows.

A conversion of what would normally be a loft space, above the main part of the dwelling, or above any extensions. 

Above left: Modern room in roof construction with ‘Velux’ or rooflight window.

Above right: dormer windows suggest rooms in the roof in this chalet style house.

A: basic roof room

B: roof room with vaulted ceiling

C: roof room with dormer windows

D: roof room with large dormer windows (chalet-style)

For a roof room be included in the RDSAP assessment it must be accessed via a fixed staircase. For fixed access to be described as a staircase it must be accessible and traversable in both directions by an able-bodied person moving in a forwards direction.

Loft conversions accessed by a fixed ladder rather than a staircase and require that you exit the room backwards in order to negotiate the ladder do not qualify as roof rooms and should be treated as loft spaces. A roof room does not need to contain any habitable rooms.

For a roof room to be classed as such and not a separate storey, the height of the common wall must be less than 1.8m for at least 50% of the common wall (excluding gable ends and party walls) If the common wall is 1.8m or greater the room in the roof should be recorded as a separate storey

A ‘common’ wall is a vertical extension of the external wall of the storey below. Don’t confuse this term with ‘party’ wall. 

Diagram A: Loft conversions are often constructed with stud partition walls that provide a vertical wall in the eaves, a space that would not be useful to the room. These stud walls lose heat into the void behind them, a space which is referred to as the residual roof space. Diagram A has a residual roof space to either side of the stud partitions which can often be accessed by hatches or small doors. In Diagram A the residual roof space is assessed as the main roof for the property and does not belong to the roof room. The height of the common walls in

Diagram A is zero and the diagram clearly represents a roof room.

Diagram B: The height of the common wall is denoted by the arrows. As it is less than 1.8 m this means that this diagram represents a roof room for RDSAP. There is no residual roof space

Diagram C: The height of the common wall in Diagram C is greater than 1.8 m and this means that this would be an ordinary storey rather than a roof room. An area weighted ceiling height would need to be calculated.

Roof Room or Ordinary Storey – Refer to Flowchart When EPC Training.

Where you identify the presence of roof rooms, details of this storey are entered in the ‘room in roof’ section and not as a normal storey. Remember that you should enter the floor area as either an additional storey or as a room in the roof, but not both. Therefore the chalet-style house on the previous page is recorded as a single storey dwelling PLUS a roof room. 

If you are certain that you are looking at a roof room (and extended measurements are not required – see later in this chapter) then you only need to measure the floor area internally. There is no need to measure a heat loss perimeter as the walls of the roof room are considered part of the roof. . The floor to ceiling height is also not required although it is good practice to make a simple elevation drawing as part of your site notes, to create a record of the situation you found.

Is Roof Room Adjoining?

If the roof room is connected to another roof room (in the same dwelling) or connected to another part of the dwelling then the ‘is roof room adjoining’ should be ticked. This will reduce the assumed area of heat loss through the walls of the roof room.

Note: a roof room within a terrace of houses, where the neighbouring house appears to have a roof room, is not considered adjoining. It must be adjoining part of the same dwelling.

Roof room insulation can be tricky to assess. The diagram below shows the possible locations of insulation. It may be possible to access the void above the flat ceiling (marked in blue) and the residual void either side of stud partitions (marked in yellow and entered as the residual main roof, rather than as part of the roof room). In these locations you would typically expect to find a layer of mineral wool fibre insulation. But it may be more difficult to assess insulation that lines the sloping part of the roof (marked in orange), the stud walls (marked in green) and the gable end (marked in grey). Access to these areas may be severely limited and it may be that you will have to rely on documentary evidence if a visual inspection is impossible.

The insulation depth levels set in RDSAP are for mineral wool type insulation that usually comes in rolls. Where you encounter expanded polystyrene insulation board or multi foil insulation the convention is that you should double the thickness of the board so that its better performance is more accurately reflected.

You may encounter other insulation types as insulation is a rapidly developing area. You can check with NES technical support if uncertain of how to record it.

The screenshot above shows the section of the software that deals with rooms in the roof. Information is needed on the main roof room (and up to four other roof rooms, if there are extensions present). The floor area is required and is measured internally. The age range of the roof room is required; this might be the original date of build of the house or the conversion date if you are able to reliably establish it.

Important Note: the residual roof spaces either side of the roof room are not considered below–they are part of the MAIN ROOF and NOT part of the roof room. The insulation assessment for the residual roof is recorded on the ‘P3: Age and roofs’ page.

The residual roof space is effectively the remainder of what was the main roof after the roof room was constructed. The possible insulation entries are as follows:

Unknown–this entry will mean that the software will use the default level of insulation for the year you have entered for the roof room. Pre-1966 this is likely to mean no insulation.

No insulation–this is self-explanatory and means the software will consider the roof room entirely un-insulated.

There may still be insulation at joists level in the residual roof space.

Flat ceiling only– this is when there is insulation present above the flat ceiling and nowhere else. There may not be a flat ceiling at all in cases where the ceiling is ‘vaulted’.

All elements comprises of the gable ends, stud walls and sloping ceiling (orange, grey and green in the parts of a roof room diagram).

There are 4 options for ‘All elements’:

All elements 50 mm;

All elements 100 mm;

All elements 150 mm;

All elements unknown–this is different to simply ‘unknown’.

It means that you can see insulation is present, believed to extend to all elements, but you are unable to sure of thickness.

When entering insulation as all elements you will need to also enter the thickness at flat ceiling separately. If the roof room has a vaulted ceiling, select ‘not applicable’ for the thickness at flat ceiling.

RDSAP calculates the area of the flat ceiling, slope, stud and gable walls based upon the floor area that has been entered. In most cases this approximation provides a good model of the heat loss of characteristics of the roof room. In situations where there is documentary evidence of the U-values of the slope/stud/gable AND those U-values differ, detailed measurements should be taken.

There are four measurements required as well as the floor area:

1. Area of the flat ceiling

2. Area of all stud walls: include all vertical (non-gable) parts of the roof room

3. Area of all sloping part

4. Area of the gable end(s) 

If you know the U-values of the slope/stud and gable AND they are the same, you can enter the U-value in the extended data and use the RDSAP default areas (see below). 

Where detailed measurements are being made and the floor area of the parts of the dormer protruding beyond the line of the roof is less than 20% of the floor area of the roof room, measure the elements of the roof room as if the dormers were not there. If the floor area of the protruding parts of the roof room is 20% or more, total all the vertical elements of the dormers in that building part and enter as stud wall. Any flat ceiling parts of a measured dormer should be entered as flat ceiling.

In most cases you will find that the dormer windows cover significantly less than 20% of the roof room area. This convention was introduced to make sure that large dormer windows in chalet bungalows (see photo) are included when measuring.

The extended roof room data for each building part allows data entry for two of each roof room element. This has been provided to help when a very complicated roof room is measured and it may be easier not to combine all the slopes or stud walls etc.:

Flat ceiling 1 and Flat ceiling 2 are any parts of the roof room that are horizontal. This could include the flat ceiling element of a dormer (if they are included). If there are no flat ceiling parts to the roof room (for example a vaulted ceiling) enter “0”m2 .

Stud wall 1 and Stud wall 2 are any parts of the roof room that are vertical walls added to the roof room, abutting the roof void. These could include the vertical parts of the any included dormer. In the unlikely event of there being no stud walls, enter “0” m2 .

Slope 1 and slope 2 are any parts of the roof room that are sloping. They can be tricky to measure, but you must enter the area of the slope, not the floor area that the slope covers. If there are no sloping parts to the roof room enter “0” m2 . 

Gable wall 1 and Gable wall 2 are the parts of gable end that form the roof room. You may find that there are no gable ends, a mid terrace house or stud walls erected to provide storage in the residual loft. If there is no gable wall enter “0” m2 . If the roof room includes a common wall and a measured dormer window includes the common wall, enter the common wall part of the dormer into one of the Gable wall fields.

There are three columns containing information about the default values of the roof room. These are described below:

Column A: these are the default areas for the four elements of the roof room, calculated from the floor area entered in the roof room details section. These figures cannot be overwritten and will remain visible for your reference when overwritten values in the other columns

Column B: As with column A these are the default areas for the four elements of the roof room. However, in column B you are able to overwrite these areas with your own measurements.

Column C: This column contains the default RDSAP U-values based on the information about age and insulation entered in the roof room details section. With documentary evidence these can be overwritten.

Remember: you will only need to take detailed measurements of a roof room when: Evidence exists that the U-values of the slope/stud/gable differ and you know all three U-values.

The gable end can be a little more complicated to measure, you will need to divide the area into triangles or trapeziums and rectangles 

All of the following photos are examples of rooms in the roof for RDSAP.

If a roof room is not a part of the original dwelling or extension, i.e. if it is a conversion made since the original dwelling was built, then how do you know how to age it? If the householder is present on an inspection and they know when the conversion was carried out, supplemented with documentary evidence, then you should use that age. Otherwise, as a worst-case scenario, you will have to assume the age of the dwelling or extension in which it resides.

There are three situations you may come across where you have a flat or maisonette and a roof room. These are illustrated in the diagram below. The shaded areas represent the parts of the building that are being assessed.

(A): Flat totally in the roof space. This shows a flat that is located entirely within the loft space. This flat cannot be entered as a roof room, as in RDSAP a roof room cannot be entered without a dwelling below it. In case (A) the flat must be entered as a separate storey, a top floor flat at floor position 3. The room height for this flat should be entered as 2.2m.

The floor area should be measured internal and is the area up to any stud walls. The heat loss perimeter should be measured and the wall construction assessed. The main wall construction should be entered as timber frame, if the gable ends are of a different construction these should be entered as an alternative wall. If the ceiling above the roof can be accessed then the insulation should be measured.

(B): Flat with roof room. For RDSAP this should be entered as a flat with roof room. The important thing to note with this example is that it is a top floor flat and the ‘floor position’ and the fact that it is only one storey. The floor position in this example is 2.

(C): Maisonette with roof room. As with Diagram B the roof room is not an extra storey and therefore the dwelling has two storeys and not three. This is a top floor maisonette with floor position 1.

Where there are both ‘standard’ rooms and ‘rooms in the roof’ on one storey, the dwelling should ideally be split between ‘main’ and ‘extension’ to separately identify the sections incorporating the different room types. Remember if a roof room in one building part is connected to a storey in another building part, the roof room should be described as ‘adjoining’ .Where it is not possible to split the property in such a way, the decision to enter the data as either ‘rooms in the roof’ or an extra storey is based on the following criteria.

To enter a complete storey as rooms in the roof, at least half the storey must be made up of such rooms. Where there are less than 50% roof rooms, the complete storey should simply entered as a separate storey in the conventional manner. Note that room heights may need to be ‘averaged’ and that the inclusion of alternative wall types may be appropriate to describe different walls within the mixed roof room/conventional room. 

In the example above the house should be artificially divided into main and extension along the red dotted line. The main house will be entered as a 2 storey and the extension as 1 storey with a roof room. The roof room will be specified as ‘adjoining’ to account for the non-heat loss wall along between the main first storey and the roof room.

A Mansard (or Gambol) roof is the top storey of a dwelling that is built into a lightweight timber framed and tiled structure very similar to a roof structure but built with near vertical external walls. RDSAP defines a Mansard as a structure with walls of external slope that are 70 to 90 degrees from the horizontal, rather than the typical 30 to 45 degrees of a ‘normal’ roof line. A Mansard construction may also have a low pitch ‘loft space’ directly above it that may be accessible for loft insulation assessment.

Where a Mansard roof is identified it should be entered as a separate storey and NOT as a roof room. It may also necessitate the use of an alternative wall type in order to differentiate the near-vertical ‘wall’, which is constructed of a timber frame and tiled, from the structure of the main dwelling.

How A Domestic Energy Assessor Assesses Windows in RDSAP Software For An EPC Course.

Windows can be framed in wood, metal or uPVC but for the RDSAP survey the frame material is not required. However the type of glazing (single, double or triple glazed) does need to be recorded. There are three key data items that are needed for windows, i.e. the total glazed area; the proportion of multiple-glazed area; and the multiple-glazing type. 

It is also possible, where presented with reliable documentary evidence, to enter the U-value and g value of multi-glazing. A g value is a measure of the total solar transmission, i.e. heat, through a window and is expressed as a number between 0 and 1. The lower a glazing’s g value, the less solar heat it transmits. A window’s g value is determined by the type of glass, or combination of types, that make up the glazing unit.

In most domestic situations the specification of glazing concentrates on admitting solar energy whilst preventing energy from being re-radiated from inside.

If entering U-values and g values, and having reliable documentary evidence, additionally identify whether the g value is a BFRC (British Fenestration Registration Council) value or otherwise. A BFRC g value is for the whole window, i.e. the glazing and the frame; other g values are just for the glazing. If unknown, then assume the g value is not a BFRC value. 

When assessing window areas, we include all areas of glazing of the whole dwelling except for conservatories which are dealt with separately. 

'Normal or typical’ applies if the surface area of the glazing in the dwelling is as would be expected of a typical property of that age, type, size and character. This applies even if there is slightly more or less glazing than would be expected (up to 10%).

‘More than typical’ applies if there is significantly more area of glazing area than would be expected (15%-30% more), perhaps because several sets of patio doors have been added.

‘Less than typical’ applies if there is significantly less glazing than would be expected. This is rare as homeowners tend not to remove windows. However, a property may have an unusual design with few windows.

'Much more than typical’ and ‘much less than typical’ should be used for dwellings with very unusual amounts of glazing; such as a glass walled penthouse flat or a garden room or sun room (that cannot be classed as a conservatory and therefore dealt with separately). This option allows the measurements of each window to be input into the software individually. This option can also be used if a dwelling has a mixture of glazing types, e.g. single, double and triple glazing and does enable a detailed and accurate entry of the windows to be made.

Some traditional stone and cob cottages may have less than typical window openings and older houses may also be found with bricked-up window openings leftover from the glass and window taxes of several hundred years ago.

Each window will need to be measured, the glazing type noted and the orientation of each window recorded using the eight points of the compass. The screenshot of the software below illustrates this and also shows where U- and g values are to be entered. 

It is not normally necessary to measure window area. The software contains defaults based on the age of the property, and whether it is a house or flat. These defaults have been obtained by measuring window areas on several thousand houses of different ages and represent the best possible approximation. However, if recording an alternative wall containing window openings, you may have to measure the windows within the area of the alternative wall.

A glazed door is classed as a window if the glazing totals 60% or more of its surface area.

Do not include conservatories in your property glazing assessments as these are dealt with independently elsewhere in the procedure.

Proportion Multiple Glazed: The software presents the following categories:

Pre-2002;

Post or during 2002;

Unknown install date;

Secondary glazed;

Triple-glazed.

The basic assumption for double-glazing pre-2002 in the software is for typical units that have a 6–12 mm air-gap between the panes. For identification purposes these will usually be starting to show their age.

The 2002 building regulations required replacement double- glazed units to reach a minimum standard for heat loss. In order to meet this standard, most new double-glazed units now come with a Low-E coating. This is why the survey asks for the window installation date, as modern glazing is better than typical older double-glazed units. 

If the windows have been retro fitted since 2002, the householder will most probably be aware, and should also possess a FENSA certificate (required by Building Control).

Sometimes it is possible to find a date of window build located on the metal strip around the edge of the sealed glazing unit; although this is not to be confused with any BS Kitemark dates that might appear on the panes themselves.

The RDSAP software allows the different types of double-glazing to be accurately entered, but this makes surprisingly little difference to the overall result, and does not alter any recommendation that the software may make to replace the single glazing. The gap between panes may be up to 20 mm. Record in your site notes how you dated the windows.

If you are uncertain whether a double glazing installation was made before or after 2002, the website of the Fenestration Self-assessment Scheme (FENSA) allows you to search by postcode for installation dates. Visit their website at: www.fensa.org.uk

Properly fitted secondary glazing should be counted as a type of multiple glazing. Where secondary glazing panels have been removed, e.g. during the summer in order to fully open windows, but the frames remain, if the assessor can be provided with suitable visual evidence that the glazing panels still exist and can be re-fitted, then the property can still be assessed as having secondary double glazing.

Triple-glazed windows consist of three panes of glass with two air gaps. They are quite rare and likely to be slightly thicker than double-glazing. If you come across double-glazing with the addition of secondary glazing (often found in houses next to busy roads), this should be entered as post 2002 (post 2003 in Scotland and post 2006 in Northern Ireland) double-glazing. 

Single-glazed units lose heat more rapidly than double- or triple-glazing and tend to be draughtier. However, because multiple-glazed units can be expensive, it is common for ‘multiple-glazed’ properties to still have some single-glazing, particularly in rooms where less time is spent, e.g. downstairs toilets, porches or store rooms. Since 2002, Building Regulations have prevented the installation of replacement single-glazing in most cases.

The RDSAP definition of a conservatory is that it is a structure with at least 75% its roof and at least 50% of its walls glazed; and of course to include the conservatory in RDSAP it must be non-separated (i.e., not separated by external quality doors). 

Sometimes you will come across a structure that has 75% + of the roof glazed (or polycarbonate) but not 50% of the walls glazed, or vice versa (often referred to in estate agent details as ‘sunrooms’).

In these cases you should make use of the extended glazing facility in NES one. The example below shows you how to enter the ‘sunroom’ details as an extension with extended glazing.

The sunroom in question is little more than a lean-to. It has three solid brick walls with small windows but a totally clear polycarbonate roof. In the illustration below, the blue highlighted area shows the clear roof and two small windows.

The way to treat this ‘sunroom’ is to enter it as an extension and use the extended glazing facility. This will enable you to put in the roof as a ‘rooflight’. If the glazing in the rest of the property is ‘typical’ there is no need to measure all the windows; use the windows area table to calculate an assumed area for the main property and enter this as 1 window. 

To show you what should be entered in the software lets assume that the roof in this case is 8.2 m2 and the two single glazed windows in the sunroom are 0.50 m2 each. The total floor area of the 1967 house with pre 2002 double glazing is 78 m2 .

Assumed window area: (0.1239 x 78) + 7.332 = 17.0 m2

Doors and High Performance Doors in RDSAP Software.

The DEA must record the total number of external doors which includes doors to unheated corridors and any doors within the heat loss perimeter:

Ignore doors to heated corridors

Include doors to separated conservatories, unheated garages, stores, etc.

Identify the number of insulated doors: this can only be done with documentary evidence;

Record the U-value of the insulated doors: again documentary evidence is required with this option;

With more than one type of insulated door, record the average U-value of the doors.

RDSAP requires the DEA to assess, identify and collect the number of windows and doors that are draught proofed:

The proportion of draught proofed windows and doors is entered as a percentage (%) and then allows a more accurate recommendation for draught proofing to be made. The following conventions apply:

All external doors and at least two windows per building part must be assessed.

If a window is locked or inaccessible endeavour to try another one.

If the condition of the draughtproofing cannot be determine, record in site notes and then assume multi-glazed units to be draught-proofed and single glazed units not to be.

How To Record Lighting in RDSAP Software on an EPC Course.

The Domestic Energy Assessor must record:

The total number of light fittings in the property (counted in accordance with the conventions outlined below).

The number of low energy lighting fixed outlets in the property (counted in accordance with the conventions outlined below).

Lamps that are plugged in and therefore portable are ignored.

Look at quick reference to the common types of lighting below.

A low energy light outlet is an individually wired lighting outlet that is either low energy by its inherent design, e.g. fluorescent strip lights, or a ‘standard’ outlet that has low energy lamps installed.

Low energy lights are efficient in the sense that more of the wattage goes towards producing light than with traditional tungsten lighting.

With a traditional non-low energy light, up to 80% of the energy powering it goes toward generating heat and only 20% to light. Try placing your hand close to a non-low energy light and feel the heat it produces.

Further clues to identify low energy lighting:  Low energy lights will often flicker when switched on.

They may not instantly reach full illumination.

They may be seen to flicker when illuminated, if viewed through your digital camera.

They will not radiate heat to the extent of a non- low energy light, if you place your hand close to the light.

All fixed lighting outlets are counted as ONE each, irrespective of the number of lamps they contain. However, there is one exception: where there are ‘grids’ of recessed ceiling lights (e.g. in kitchens and bathrooms) the quantity of fittings should be divided by 2 in order to reduce the ‘weighting’ of these fittings. This applies where there are four or more of such lights.

In very efficient homes, where the only recommendation is for more CFLs, you may notice that the heating cost on the EPC goes up after the improvement measures have been installed. This is because by installing more low energy light bulbs, which give off less heat, a small amount of heat gain has been removed from the house and thus, the heating system has to work a little harder. Therefore, a little bit is added to the heating cost, although the overall running costs are reduced due to the much lower running costs of LELs. 

How A Domestic Energy Assessor Identifies Electricity Meters in RDSAP.

According to the BBC’s Watchdog programme, over 6 million households in the UK have dual rate meters, which are used for off-peak electricity tariffs such as Economy 7, Economy 10 and Economy White Meter (Scotland only). The electricity is switched to the cheaper off-peak rate for use with electric storage heating systems and water heating with electric immersion. Cheaper electricity is available during the night when nationally less is being used. Remember that for the RDSAP assessment we are trying to establish the electricity rate ‘regime’ that applies to the property being inspected. That is, is the system currently working on a single or a dual rate? It is possible to find dual rate meters that are capable of operating dual rate but that are currently set only at single rate. In this case we would say that the meter is a single rate meter