#TopicRdSAP Conventions 9.92 v8.1Issue date
1. General
1.01Use of RdSAPRdSAP is for assessment of existing dwellings only. Where an EPC is required for a new dwelling under building regulations it must be a SAP EPC. Any new dwelling, including dwellings created by change of use, must be assessed using SAP. For this purpose a new dwelling is, in England, Wales or Northern Ireland, one completed on or after the relevant date. In Scotland this applies to a new dwelling submitted for building warrant on or after the relevant date. The relevant date is 6 April 2008 in E&W, 30 September 2008 in NI, or 1 May 2007 in Scotland. For a new dwelling, where no on-construction EPC has been lodged, a SAP EPC is still required, irrespective of whether the dwelling has been occupied. However, if – the SAP data set (i.e. the full set of data used for building regulation compliance) is not available and the evidence for its lack of availability has been provided, or – the SAP data set is available but the dwelling has been altered in such a way that the data is no longer applicable and the details of the alteration are unknown (evidence that the dwelling has been altered and evidence for lack of building regulation approval providing details of the alterations to be provided) it can be assessed using RdSAP 9.92. Note. In Scotland, a new dwelling for which the building warrant application was submitted before 1 May 2007 or a dwelling created by change of use (a defined conversion) does not require a SAP EPC under building regulations but will, under EPB regulations, require an RdSAP EPC when offered for sale or rental.RdSAP conventions: Sept 2009, amended Jan 2012, amended Dec 2012, amended April 2015
1.02Flat or maisonetteA dwelling that does not extend to all storeys of the building is a flat or maisonette. RdSAP makes no distinction between flats and maisonettes as regards calculations; it is acceptable to select either type as definitions vary across the UK.RdSAP conventions: March 2010, amended Mar 2011
1.03Address close to England/Scotland borderAssessors must ensure that the correct country is identified so that the EPC will be lodged in the appropriate register.RdSAP Conventions 9.92 v8.1 April 2015
1.04Separate part of dwellingA property can have a physically separate building or ‘annex’ which if self-contained needs to have its own EPC.

If not self-contained but contains rooms that are used as part of the main dwelling, e.g. bedrooms, study etc in a large detached garage or outbuilding converted into part of the living accommodation of a main property:

– if heated by the main heating system (as defined for the main dwelling), include in the assessment
– otherwise omit.

April 2015
2. Measurements and geometry
2.01MeasurementsState on site plans whether the dimensions recorded are external or internal. Where a combination of external and internal is used this must be made clear for each dimension indicated.

When measuring internally, measure between the finished internal surfaces of the walls bounding the dwelling. Where that cannot be done directly (i.e. when measuring room by room) include an allowance for the thickness of internal partitions.

2.02Precision of lengthsMeasure to one decimal place (0.1 m) or better. Retain higher precision when that has been measured (especially room heights)Sept 2009
2.03Sheltered wall length (unheated corridors)Include in the heat loss perimeter.

When a dwelling (flat or maisonette) has a sheltered wall to an unheated corridor on more than one storey the sheltered length is the total for all storeys with a sheltered wall (example: 2 storeys with sheltered wall on each storey, length of sheltered wall is 5 m on each storey: enter 10 m for the sheltered length).

The sheltered wall can be in any building part but must be recorded as an alternative wall (see 2.13).

Where the sheltered wall extends over more than one building part, e.g. it extends across the main and an extension, assign the sheltered wall length to the building part with the longer sheltered wall and deduct the relevant amount from the heat loss perimeter of the other. Example: total unheated corridor length is 10m of which 2m is in the main building part and 8m in the extension. Record the extension as having the sheltered alternative wall of length 10m and deduct 2m from the heat loss perimeter of the main dwelling.

Sept 2009, amended Oct 2010, amended April 2015
2.04Habitable room countHabitable rooms include any living room, sitting room, dining room, kitchen/diner, bedroom, study and similar; and also a non-separated conservatory.

Excluded from the room count are: any room used solely as a kitchen, utility room, bathroom, cloakroom, en-suite accommodation or similar; any hallway, stairs or landing; and also any room not having a window.
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.
A non-separated conservatory adds to the habitable room count if it has an internal quality door between it and the dwelling.

Sept 2009, amended April 2015
2.05Roof rooms / Attics (whether to include in the assessment and rules for detailed measurements)Include when accessed via a permanent fixed staircase such that one is able to walk downwards facing forwards. Does not necessarily contain 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 1.8 m for at least 50% of the common wall (excluding gable ends or party walls). The common wall is a vertical continuation of the external wall of the storey below.

There is no explicit allowance for dormer windows except to include in the floor area of the roof rooms.
See appended diagrams.

Detailed measurements are required only if evidence exists that the slope/stud wall/gable wall have differing levels of insulation or their U-values are known.

If all elements of the roof room (slope/stud/gable) have the same insulation and the U-value is available, the U-value can be overwritten whilst leaving the RDSAP assumed areas as is.

Where detailed measurements are made and the floor area of the parts of the dormer windows protruding beyond the roof line 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. Otherwise total the vertical elements of all dormers in that building part and enter as stud wall and the flat ceiling elements as flat ceiling.

A roof room can be “connected” only if there is another building part of the same dwelling with a storey (roof room or normal storey) at the same level; no assumptions are to be made about an adjacent property.

March 2010, amended Jan 2012, amended Aug 2014
2.07Rooms within a Mansard roofA storey having non-vertical walls of at least 70° pitch constitutes a separate storey; it is not treated as roof rooms. Use alternative wall if appropriate.March 2010
2.08Whole dwelling (or building part) within roofWhen the property or a building part of it is a single storey entirely located within a roof, model as:

– lowest occupied level
– timber frame construction of appropriate age band
– room height must be entered as 2.2 m
– include area and perimeter measurements as a normal storey – enter roof as pitched roof.

If there are two storeys within the roof, enter the lower storey as above and the upper storey as rooms-in-roof.

March 2010, amended Dec 2012
2.09Porches (whether to include in the assessment)If heated always include (separated or not).

If external and not heated, disregard.

If internal, not heated and thermally separated, disregard.

Sept 2009
2.10Mezzanine floorEnter the part of the property above and below the mezzanine deck as a two storey extension. Treat the remaining part as a single level with the full floor to ceiling/roof height.

If the mezzanine is located such that it has no heat loss perimeter then assign a nominal 1 m perimeter to each floor of the mezzanine part and deduct 1 m from the heat loss perimeter of the other part.

March 2010,
amended Oct 2010
2.11Vertical extensionWhere an extension has been built over part of the existing dwelling, divide the part built over into two, one of which has “same dwelling above” and for the other describe the roof construction and insulation.

Enter the new upper floor as an extension with “same dwelling below” and the original part with “same dwelling above” for the roof description.

It is possible for an extension to be both above and alongside the rest of the dwelling. Such a building part is not defined in RdSAP and in this case divide the extension into two, one above and the other alongside.
A roof room cannot be a vertical extension in its own right.

March 2010, amended Mar 2011, amended Dec 2012
2.12More than 4 extensionsAdd together floor areas and exposed perimeters of extensions (or add extension to main dwelling) to reduce to four extensions.

Combine parts having the most similar age bands (refer to SAP Appendix S for U-values of relevant constructions). Use alternative wall where appropriate.

March 2010, amended March 2011
2.11Alternative wallIn determining whether an alternative wall is applicable the significant features are construction type, dry lining, age band, insulation and whether sheltered by unheated corridor.

A sheltered wall between the dwelling and an unheated corridor or stairwell is always an alternative wall.
Walls of the same construction but different thickness within a building part are not considered alternative walls unless they are stone walls.

For stone walls assess thickness at each external elevation and at each storey and use alternative wall if the thickness varies by more than 100 mm, see also 2.22.

Disregard when less than 10% of total exposed wall area of the building part (including windows and doors) unless documentary or visual evidence exists of different retrofitted insulation either of the alternative wall or of the remaining wall in the building part. When entering alternative wall area into software exclude the area of any windows and doors contained in the alternative wall.

Consolidate walls of same type.

If there are two areas of external wall of different construction types within a building part that should be regarded as alternative wall, review the way in which the property has been divided to try and eliminate this situation. Where that is not possible the alternative wall is the one with the larger area.

March 2010, amended Jan 2012, amended Dec 2012, amended April 2015
2.14Window areaIn RdSAP the definition of what is a window and what is a door is defined by the area of glazing in relation to the area of the whole opening, i.e. door and frame.

To be classed as a window a glazed door and frame must contain glazing amounting to 60% or more or its surface area. Generally 60% or more glazing is likely to occur only in a patio door.

However a window with less that 60% glazing is not a door; a door always provides a means of entry to the property.

If the property has patio doors, see 2.15.

March 2010, amended Dec 2012, amended April 2015
2.15Glazed areaConsider the whole dwelling (windows, glazed doors and roof lights), including any extensions (but not conservatories).

Typical applies if the surface area of the glazing in the dwelling is essentially as would be expected of a typical property of that age, type, size and character. Even if there is slightly more or less glazing than would be expected, up to 10% more or less.

More than typical applies if there is significantly more surface area of glazing than would be expected (15%-30% more), perhaps because there is a sun room or 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 take out windows, but a property may have an unusual design with few windows.

Much more than typical and Much less than typical should be used for those dwellings with very unusual amounts of glazing; such as a glass walled penthouse flat or a Huf Haus. Due to this option allowing measurements of each window to be accounted for, it should also be used if a dwelling has a mixture of glazing types e.g. single, double, secondary and triple, or a mixture of glazing gaps. See convention 3.15

March 2010, amended Mar 2011, amended April 2015
2.16Secondary glazingIf single glazing with secondary glazing, record as secondary glazing.

If double glazing with secondary glazing, record as newer double glazing (newer double glazing means 2002 or later in E&W, 2003 or later in Scotland, 2006 or later in N. Ireland).

If secondary glazing has been removed in summer, enter as above only if assessor can confirm that the panels exist and can be re-fitted. Evidence to be recorded on site notes.

March 2010, amended Mar 2011
2.17Sun roomFor a highly glazed part of the dwelling, such as a sun room, which does not meet the criteria for a conservatory (50% of walls and 75% of roof glazed), in most cases use the glazing option of “more than typical”. That adds 25% to the total glazed area of the dwelling. If you deem that this is not appropriate, assess window area by either:

a) measuring all windows and roof windows throughout the dwelling, or
b) measuring all windows and roof windows in the sun room, and use Table S4 to obtain the window area of remaining part of dwelling which is entered as a single window with orientation East.

Record method used in site notes.

Oct 2010, amended Dec 2012
2.18BasementsDo 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.Oct 2010
2.19Store rooms and utility rooms
(whether to include in the assessment)
If heated always include.

If accessible only via a separate external door and not heated, disregard.

If directly accessible, not heated and thermally separated, disregard.

Oct 2010
(whether to include in the assessment)
If heated from main heating system, always include. The presence of a boiler within the garage does not make it heated.Oct 2010
2.21Dwelling adjacent to commercial premisesIf a dwelling or part of a dwelling has commercial premises below record as partially heated space below.

If a dwelling or part of a dwelling has commercial premises above record as another dwelling above.

If a dwelling has commercial premises alongside it, treat the separating wall as a party wall.

March 2011
amended April 2015
2.22Wall thickness (per building part)Measure wall thickness in mm of each external wall (elevation) and any alternative wall within a building part. Photographic evidence is required for each different thickness.

It can be measured at door or window reveals or by internal/external measurement comparison (which can be direct measurement or estimated by counting bricks).

Where thickness varies for the same construction use the average of the measured values. See also 2.13.

January 2012, amended Dec 2012, amended Aug 2014
2.23Sloping sitesWhere an individual wall (elevation) is not heat loss for its full height (because of stepped arrangements either within the dwelling or between the dwelling and an adjacent one) obtain the “effective heat loss perimeter” for the individual wall as follows:

1. Where documentary evidence is available use it to calculate the wall’s heat loss area. Divide this area by the room height to obtain the “effective heat loss perimeter”.

2. Where documentary evidence is not available but the assessor is able to measure the heat loss area, this area is divided by the room height to obtain the “effective heat loss perimeter”.

3. If neither 1 nor 2 is possible, make a visual estimation and use these guidelines:

a. if height of heat loss area is not more than 25% of the room height, the “effective heat loss perimeter” is zero (disregard as heat loss wall);

b. if height of heat loss area is more than 75% of the room height, “effective heat loss perimeter“ is equal to the actual heat loss perimeter;

c. if height of heat loss area is more than 25% and less than or equal to 75% of the room height, the “effective heat loss perimeter” should be considered to be 50% of the wall’s actual heat loss perimeter.

4. If estimation cannot be made, use 3 c.

The “effective heat loss perimeter” of the individual wall is then included in the heat loss perimeter of the building part

August 2014
2.24Party wall lengthsTo be recorded in all cases (except detached properties).

A flat in a block having only an unheated corridor adjacent to it is treated as detached (no party wall).

April 2015
3. Construction and insulation
3.01Cavity wall typeWhere a cavity wall has been identified, enter as such irrespective of the width of the cavityMarch 2010
3.02System build type/td] [td]If there is a system built wall that has evidence of retro cavity fill, record as system build with internal insulation and include Addendum 1.
See also convention 3.14 relating to high rise.

Timber frame should be recorded as such and not as system build irrespective of the external cladding.

March 2010, amended Jan 2012, amended Aug 2014, amended April 2015
3.03aAs built (walls, floors, roofs)Assume as-built if there is no evidence of retro-fitted insulation, including:

1. a pitched roof with sloping ceiling insulation or a flat roof where there is no documentary evidence.

2. a roof with rafter insulation if no evidence of retro-fitted insulation

3. roof rooms where there is no access and no documentary evidence.

April 2015
3.03b“Unknown” insulation (walls, floors, roofs)This convention refers unknown insulation, not unknown insulation thickness.

Do not use the “unknown” option for insulation inappropriately as this automatically suppresses any insulation recommendation.

“Unknown” should be used only in exceptional circumstances, such as:

• when there is conflicting evidence (inspection and/or documentary) of added insulation whose presence cannot be ascertained conclusively

• for a fully boarded loft unless householder has documentary evidence (maximum thickness is depth of joists) or is prepared to lift the boards.

• where there is a pitched roof and no access to the loft space or access prevented (see 3.04) and no documentary evidence

In these cases clarification must be provided in site notes.

Note: if the floor construction cannot be determined, “unknown” construction is appropriate.

March 2010,
amended April 2015
3.04Loft insulation and rafter insulationWhere the loft is accessible, loft insulation should be measured and photographic evidence provided of its measured thickness.

“No access” means there is no loft hatch or other means of gaining access to the loft space.

If there is a loft hatch or other means of gaining access but it could not be used on the date of the site visit (e.g. painted over, obstruction preventing access for health and safety reasons) record as “access, loft insulation unknown”.

If loft is fully boarded enter “pitched, access, loft insulation unknown” unless householder has documentary evidence (maximum thickness is depth of joists) or is prepared to lift the boards.

If the property has multifoil or foam insulation at joists or rafters the depth of the insulation is entered as an equivalent thickness of double its actual thickness.

If joist and rafter insulation are both present base the assessment on the joist insulation only, unless the rafter insulation has greater equivalent thickness in which case base the assessment on the rafter insulation only.

If varying levels, apply an area-weighted average. However if there is an area with no insulation the dwelling should be split to give different roof scenarios.

Partly boarded lofts are treated as follows:

– <= 25% boarded: treat as not boarded and record thickness of visible insulation – >25 to 75%: divide into extensions
– > 75%: treat as fully boarded

In the case of a thatched roof for age band J onwards use ‘as built’ rather than rafter insulation if there is rafter insulation in addition to the thatch.

March 2010, amended Mar 2011, amended Jan 2012, amended Aug 2014, amended April 2015
3.05Age band for conversions
(see also convention 1.01)
For a conversion which was a change of use (e.g. barn converted to a dwelling) or where a dwelling has been sub-divided (e.g. house to flats) use the original construction date, unless there is documentary evidence that all thermal elements have been upgraded to the building regulation standards applicable at the conversion date.

Enter insulation levels only for those elements for which evidence is available.

March 2010, amended Dec 2012, amended Aug 2014
3.06Internal wall lining (creating an airspace behind)This includes any type of internal lining that creates an airspace behind it, e.g. plasterboard on dabs, lath and plaster. Use tap test for plaster board on dabs or on battens. If tap test is inconclusive regard as not dry-lined.

Note. Applies only to stone, solid brick and cavity walls in age bands A to E.

January 2012
amended April 2015
3.07Internal or external insulation for walls
Floor insulation, Rafter or flat roof insulation
If insulation is multifoil or foam insulation the thickness is entered as double the actual thickness. This is the same convention as for insulation at joists.
If there is both internal and external wall insulation add the insulation thicknesses together and enter as external
January 2012
3.08U-value entry (walls, roofs, floors)The U-value is that of the whole element, including any added insulation. Documentary evidence applicable to the property being assessed (see convention 9.02) must be provided and recorded if overwriting any default U-value. This evidence shall be either:

– relevant building control approval, which both correctly defines the construction in question and states the calculated U-value; or

– a U-value calculation produced or verified by a suitably qualified person.

Evidence of suitable qualification is through membership of a recognised U-value calculation competency scheme (BBA/TIMSA), OCDEA membership1 or any other scheme formally agreed between Accreditation Schemes/Approved Organisations and Government.

U-values for sheltered walls should not include a shelter factor, since it is added by RdSAP.

The assumed insulation thickness or U-values from tables in the current edition of SAP (e.g. Table 6e for windows) or RdSAP (e.g. Table S10 for roofs and Table S15A for doors) can also be treated as documentary evidence provided that the evidence on which it is based is demonstrably robust (e.g. in relation to the age band for Table S10 or S15A).

Where it is known that only part of an element has been insulated use the alternative wall if possible for the insulated part, or use extensions

January 2012, amended Aug 2014, amended April 2015
3.10Windows (U-values and g-values)U-values and g-values can be overwritten only if documentary evidence is provided, which can be either a Window Energy Rating certificate (as defined by BFRC) or manufacturer’s data. The U-value is for whole window, not centre pane.January 2012
3.11Draught proofing (of openable windows and doors)In this convention window refers only to openable panes.

All external doors and at least 2 windows per building part should be examined.

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

If the state of the draught proofing cannot be determined then take triple, double or secondary glazed as being draught proofed, and single glazed windows and doors as not draught stripped.

Include glazing in a non-separated conservatory.

The percentage draught proofed is [(number of draught proofed openable windows & doors) divided by (total number of openable windows & doors)] x 100

January 2012, amended Dec 2012
3.12Glazing ageFor double glazed windows, the year of manufacture can often be found either on the spacer bar at the edge of the glazed unit, or the year is stamped into the frame.

Choose unknown date if there is no evidence of the date (on spacer bar or frame or documentary evidence such as a FENSA certificate or manufacturer guarantee).

August 2014, amended April 2015
3.13Age band for roof roomSame as the building part unless evidence proves otherwise.August 2014
3.14High rise propertiesHigh rise properties (greater than 4 storeys) built with non-traditional construction methods (i.e. not timber frame, solid brick, cavity brick, stone) are deemed to be system built and should be recorded as such.

For high rise properties built during or after 1967, that have a cavity/stretcher bond exterior wall, enter the wall as ‘Cavity Wall’ and select ‘Access Issues’ in Hard to Treat Cavities and include Addendum 1, ‘Wall type does not correspond to options available in RdSAP’.

If the high rise property has multiple exterior wall types of cavity and other constructions, e.g. concrete panels, record the construction as system built and deal with the cavity wall following convention 2.13, Alternative wall.

If a cavity wall is entered as an alternative wall, select ‘Access Issues’ in Hard to Treat Cavities and Addendum 1 ‘Wall type does not correspond to options available in RdSAP’.

For high rise properties with cavity walls and evidence of retro cavity fill, record as ‘Filled Cavity’ and include Addendum 1.

August 2014, amended April 2015
3.15Glazing gapThis is the width of the spacer bar between the two panes of glass. It is required for windows with PVC frames pre 2002 or unknown. Select the nearest value to 6, 12 or 16 mm. If the gap cannot easily be identified, select either 6 or 16.

Where a mixture of glazing gaps or glazing types are present, all windows should be measured.
If there is a mixture of PVC and non-PVC frames record the frame type according to which is prevalent.

April 2015
3.16Party wall construction in loft spaceThe essential party wall characteristic to identify is masonry construction with a cavity which could be filled. Solid masonry and other constructional types are classified as “solid masonry or timber frame or system built”.

The primary method of identification is from a view of the party wall within the loft space. With brickwork, solely stretcher bonds indicate cavity construction while stretchers and headers indicate solid wall construction. A solid blockwork wall has blocks laid flat; the pattern looks like stretcher bond but the unit size is much larger. Note that it is only the construction in the loft space that is relevant; a cavity wall can separate the dwellings themselves but change to solid in the loft space.

Where identification is not possible the construction is indicated as “unable to determine”.

The party wall should be indicated as filled cavity only where it is known to have been filled.
Where a property is divided into two or more building parts the party wall is assessed for each building part bounded by a party wall.

If two party walls in a building part where one can be determined but not the other (e.g. one to a heated corridor and one to another dwelling), or the constructions differ, divide into two building parts.

(If “unable to determine” in a flat/maisonette RdSAP assumes no party wall loss.)

April 2015
4.01Heat emittersIf one heating system feeds both underfloor and radiators, enter radiators. This is because for radiators a higher flow temperature is assumed (unless flow temperature is known).

Where known the design flow temperature should be entered for condensing boilers and heat pumps. This applies to both radiators and underfloor systems.

The design flow temperature for condensing boilers and heat pumps should be recorded as unknown unless there is documentary evidence that the system has been designed and commissioned as a low temperature one.

Sept 2009, amended Jan 2012, amended April 2015
4.02Storage heatersIf storage heaters are present as main heating but there is only a single rate meter – enter as panel heaters and include addendum 6. If the storage heaters are fan-assisted or high heat retention suppress the recommendation for high heat retention storage heaters.

A storage heater can be classified as high heat retention only if the model is located in the database. If there are both high heat retention storage heaters and other types, treat as two main heating systems

Sept 2009, amended Mar 2010, amended April 2015
4.03Boiler missing or not workingIf boiler/heating system is present but not working (or condemned) it should still be entered as the main heating system.
If boiler not present but intended – enter no heating system.
Sept 2009
4.04Micro-CHPIf micro-CHP and the system cannot be found in the database enter as condensing boiler and include addendum 5.Sept 2009,
amended Mar 2011
4.05Definition of community heatingA system in which a heat generator provides heat and/or hot water to more than one premises.

Each dwelling to be assessed individually.

If the heat generator is in the dwelling, it is the heating system for that dwelling.

If the heat generator is not in the dwelling treat as community heating.

Sept 2009, amended April 2015
4.06Heat sources and fuel used by community heatingWhere the community scheme can be identified in the community network database, it is to be selected. If there is more than one data record only the current record can be used.

Otherwise try to find out what the fuel is. If it cannot be ascertained select mains gas.

Sept 2009, amended April 2015
4.09Two main systemsThere is an option for two main systems to cover the situation of different systems heating different parts of the dwelling.

If main system 1 heats all habitable rooms, there is no main system 2 unless it serves DHW only (see 6.04).

Main systems 1 and 2 cannot be room heaters except in the case of the dwelling’s heating consisting solely of room heaters.

A main system is generally one that would be described as central heating (a heat generator providing heat to several rooms via a heat distribution system), although the term does also include for example storage heaters and fixed direct-acting heaters in each room.

When there are two main systems, system 1 always heats the living area and:

– where two systems serve different spaces, the percentage recorded for each system is in proportion to the heated floor area served by each system;

– where two systems serve the same heating circuit the default assumption should be a 50/50 split. A different ratio can only be used if there is clear documentary evidence to back this up.
When there are two main systems and a recommendation is made for heating system upgrade, include addendum 9.

A second main system is not to be confused with a secondary heater. The latter are rooms heater(s) heating individual room(s) either as a supplement to the main heating in the room (e.g. a wood burning stove in the main room) or for rooms not heated by the main system(s). See section 5 for rules on secondary heaters.

If there is more than one main system within a room, select one of them according to the rules in SAP Appendix A and disregard the other.

If there is more than one type of storage heater (old large-volume, fan-assisted, integrated storage/direct acting, high heat retention): treat as two main systems.
If then either main system 1 or main system 2 has more than one type, choose the most prevalent.

March 2011, amended Jan 2012, amended April 2015
4.10Liquid biofuelsUsed only for appliances selected from the database.March 2011
4.11LPG subject to special condition 18Applies only if documentary evidence confirms that the property receives LPG at mains gas pricesMarch 2011
4.12Straw bales and other biomassFor straw bales and other types of biomass fuel that are not available in RdSAP, select wood logs and include addendum 12.December 2012
4.13TRVsInclude when on 50% or more of the radiators (all radiators, not just those in habitable rooms).August 2014, amended April 2015
4.14Electric underfloor heating matsTreat as electric panel heaters.April 2015
4.15Electric CPSUAn electric CPSU uses 10-hour or 18-hour tariff. If on 7-hour tariff treat as water storage boiler. If on single tariff record as direct-acting electric boiler.April 2015
4.16Weather compensatorsInclude only if located in database.April 2015
4.17Time and Temperature Zone Controla. separate plumbing circuits, either with their own programmer, or separate channels in the same programmer, or

b. programmable TRVs or communicating TRVs that are able to provide time and temperature zone control (conventional TRVs without a timing function provide only independent temperature control). In this case the device must be located in the database;

in both cases subject to conditions in SAP 9.4.14

In the case of direct-acting electric systems, including underfloor heating, it can be achieved by providing separate temperature and time controls for different rooms.

April 2015
4.18Central heating pump ageSeparate pump only, not within boiler. Record age as unknown if cannot be seen (including pumps within the boiler). Age is 2013 or later if it has a label stating the EEI (energy efficiency index); otherwise it is 2012 or earlier.April 2015
5.01Secondary heatingInclude if fixed emitter present regardless of whether main system(s) heat all rooms.

If more than one secondary: select the device that heats greatest number of habitable rooms.

If the same choose cheapest fuel – if same fuel select the device with the lowest efficiency.

Electric focal point fires are included even if not wired by fixed spur.

Sept 2009, amended Mar 2011
5.02Open fireplaces (for heating)An open fireplace is to be considered in the heating assessment if capable of supporting an open fire (that includes having a grate suitable for holding fuel), even if no fuel is present. The fuel to be specified is smokeless fuel in smoke control areas and dual fuel outside smoke control areas.

Open fires in bedrooms are disregarded when identifying the heating systems (main and secondary) and heated habitable room count. They are counted in the number of open chimneys (for ventilation), if appropriate.

March 2010, amended Oct 2010, amended April 2015
5.03Fuels for solid fuel fires and room heatersIf it can burn only one fuel, specify that fuel (includes exempted appliances burning wood in Smoke Control Areas). Otherwise:

Smoke control area: Open fire – smokeless fuel; closed heater – anthracite

Not smoke control area: Open fire – dual fuel; closed heater – wood logs if capable otherwise anthracite

Oct 2010
6.03Dual immersion with single tariffEnter as a single immersion and include addendum 6.Oct 2010, amended Mar 2011
6.04Separate boiler or heat pump for DHWSometimes there is a separate boiler or heat pump providing DHW only. A generic boiler can be selected from the water heating options. If the boilers or heat pumps are located in the database, specify two main heating systems with:

– main system 1 is the one providing space heating
– main system 2 is the one providing DHW
– percentage of main heat from system 2 is zero
– water heating is from main system 2.

March 2011, amended April 2015
6.05Enclosed hot water cylindersFor an unvented pressurised steel or plastic encased hot-water cylinder (e.g. Megaflo), treat insulation value as 50 mm factory-applied foam and assume cylinderstat is present. For Elson (wooden box) type record the actual thickness and check for the presence of a cylinderstat (unless “no access”).August 2014,
amended April 2015
6.06Hot water thermal storeTreat as cylinder.August 2014
6.07Hot water cylinderstatInclude only when mounted on the side of the cylinder and has an electric connection.April 2015
7.01LightsLEDs are considered as low energy lights.
Where there are 4 or more downlighters / ceiling lights divide the bulb count by 2.

Include fixed under-cupboard kitchen strip lights.

If no lamp is present: do not treat as a low energy outlet unless it can be fitted only with a low energy lamp.

Sept 2009, amended Aug 2014
8.01Suppression of recommendationsRecommendations should be removed only if there is documentary evidence showing that a specific recommendation is not appropriate. A listed building or a property in a conservation area is not sufficient grounds in its own right to suppress a recommendation.

If a recommendation is removed this must be recorded in site notes.

Further guidance on specific recommendations can be sought from an appropriate professional organisation, for example heating engineers, building control officers, product manufacturers, trade associations, etc.

Sept 2009, amended Dec 2012
8.02Mains gas availableOnly if a gas meter or a gas burning appliance (e.g. gas cooker) is within the property. A closed-off gas pipe does not count.

Where a boiler is present attached to a heating system (not in a box), and the mains gas meter has been removed for security reasons, enter a gas boiler as the main form of heating and indicate that mains gas is present.

Sept 2009, amended Mar 2010
9.01Open fireplace count (for ventilation)Include all open chimneys/fireplaces in the fireplace count (both downstairs and upstairs).

The definition is a vertical duct with a flue diameter of at least 200 mm or its equivalent. The following are not counted as open fireplaces:

• Any open flue that is less than 200 mm diameter
• A permanently blocked up fireplace, even if fitted with an airbrick
• Any heating appliance with controlled flow of air supply i.e. appliance has closing doors
• A flexible gas flue liner sealed into the chimney (because the diameter is less than 200 mm)
• A chimney fitted with a damper enabling the flue to be mechanically closed when not in use

Temporary means of blocking a flue, e.g. cardboard, newspaper bungs and similar, are not a permanent means of controlling ventilation and therefore the chimney is counted as an open fireplace.

Note that this relates only to the number of open fireplaces (it affects the ventilation rate assumed for the calculation). Other rules apply when considering the choice of main or secondary heating systems.

March 2010
9.02Documentary evidenceDocumentary evidence
Acceptable documentary evidence includes official letters from the applicable Registered Social Landlord (RSL) or certificates, warranties, guarantees, building control sign-off, from anybody else, including RSLs. The assessor must be confident, and able to demonstrate, that any documentation relates to the actual property being assessed and that there is no physical evidence to the contrary.

Evidence of intent to install does not qualify as acceptable documentary evidence.

March 2010, amended Aug 2014, amended April 2015
9.03Lodgement of incorrect EPCIf you lodge an EPC in error and lodge a corrected EPC, inform your accreditation scheme so that the erroneous one can be marked “not for issue”March 2010
9.04Cooling system presentFixed systems only, do not include reversible heat pumps.March 2011
9.05PhotovoltaicsIf photovoltaics are present, look for a schematic wiring diagram which may be adjacent to the electricity meter or the consumer unit or an MCS installation certificate, either of which should state the peak power (kWp) of the PV array.

Record the following:

– kWp;

– estimate of pitch of the PVs (as the nearest to horizontal, 30°, 45°, 60° or vertical; if midway between two of these use the higher value);

– if not horizontal, the orientation of the PVs (N, NE, E, SE, S, SW, W, NW);

– overshading of PVs (very little, modest, significant or heavy; if in doubt select modest).
If there are PV panels on different planes of the roof, enter as different systems. If a single kWp figure is provided, in this case estimate the relative area of each and apportion the kWp accordingly.

If the kWp cannot be ascertained, record the percentage of the total roof area occupied by PVs. Here total roof area includes main dwelling and all extensions where present.

Connection to dwelling’s electricity meter: check wiring diagram if possible or any documentary evidence. If connection to dwelling’s meter cannot be determined, assume not connected.

In the case of a building containing both domestic and non-domestic parts (e.g. common areas), do not include the PVs unless verified as being connected to dwelling’s meter.

March 2011, amended Jan 2012, amended April 2015
9.06Flue gas heat recoveryInclude only if found in database, identified in same way as for heating systems. When the model cannot be found no default option is available but the presence of the device should be recorded in site notesJanuary 2012
9.07Wind turbineDocumentary evidence is required to overwrite default values.January 2012
9.08Waste water heat recoveryavailable but the presence of the device should be recorded in site notes.

For instantaneous types:

– Number of rooms with bath and/or shower includes rooms with only an electric shower. If two showers found in a room, count as one;
– Only mixer showers count for instantaneous waste water heat recovery. Mixer shower means a shower where the hot water is provided by a boiler (combi or regular), heat pump or immersion heater;
– The shower must be permanent i.e. not temporarily attached to bath taps when in use’
– In the case of a shower that is integral with bath taps, i.e. designed as part of a unit switchable between shower and taps, it is counted as a mixer shower only if there is a shower bracket at least 1.5 m above the plughole and there is a curtain or screen present.
For storage types:
– Record the total number of baths and showers of any type;
– Record the total number of baths and showers connected to the waste water heat recovery system.

January 2012, amended Dec 2012, amended April 2015, yellow shaded text added Aug 2015
9.09Solar water heatingDocumentary evidence is required to over-write collector or solar store values. Orientation, tilt and overshading can be overwritten with visual evidence.

If the panel/collector details are available but the solar store information is not, the default values can be used for the solar store.

If the solar store is combined and details are being recorded the volume of the combined cylinder must also be recorded.

Shower type is required when solar water heating details are known. In this context “electric shower” means a shower where the water is heated by electricity as the shower runs. If the shower is supplied from a hot-water cylinder it is classified as non-electric even though the cylinder is electrically heated.

January 2012, amended April 2015
9.10Hard to treat cavity wallsAn access issue is any façade where it is not possible to pitch a 5 metre ladder considering health and safety requirements. This includes e.g. a narrow passageway, a busy thoroughfare a building of more than 2 storeys, a conservatory or large outhouse attached to the property, etc.

A narrow cavity is indicated by a stretcher bond brick pattern with wall thickness 220 to 250 mm.

Possible high exposure should be recorded for any dwelling in exposure zones 3 or 4 (see map at end of these conventions). If in doubt record as possible high exposure.

January 2012
9.11Transaction typeIf more than one transaction type is applicable, seek clarification from the client and in case of doubt select the one nearest the top of the listDecember 2012
9.12TenureWhen transaction type is rental, tenure must be rented (social) or rented (private).

When transaction type is marketed or non-marketed sale, the tenure will usually be owner-occupied (although there can be exceptions, such as the sale of a property with a sitting tenant).

If the property is vacant on the inspection date, try to find out the last tenure and select this e.g. owner occupied, rented (social) or rented (private).

December 2012
9.13Electricity metersUsually the dwelling uses either the standard domestic tariff (single meter) or an off-peak tariff (dual meter).

In these cases select single or dual meter and an addendum is not required.

In some cases of older installations the property may have two separate single rate meters present and it is unclear whether dual meter or single meter should be identified. If that applies:

– if the main space heating is electric, select dual meter if the main space heating is an off-peak electric device, and single meter otherwise (direct-acting heaters);

– if the main space heating is not off-peak electric but the water heating is electric, select dual meter if it has a dual immersion and single meter if it has a single immersion;

– if neither of the above applies, select single meter

– if dual meter selected include addendum 10;
– if single meter selected include addendum 11.

December 2012
9.14Park homesFor the purposes of RdSAP a park home is a pre-fabricated dwelling of modular lightweight construction without its own foundations (although it may sit upon a concrete base) and which is capable of being moved from one place to another.

Convention 3.08 applies to U-values. For U-values of existing park homes, documentation obtained from the manufacturer can be used.

Park homes have their own set of age bands.

August 2014, amended April 2015