Publication - Research and analysis

Energy Efficiency Standard for Social Housing: peer review

Published: 22 Oct 2013
Energy and Climate Change Directorate
Part of:
Environment and climate change

Peer review scrutinising the example dwellings in the Energy Efficiency Standard for Social Housing consultation document.

Energy Efficiency Standard for Social Housing: peer review
Appendix B - Annex C of the SHQS

Appendix B - Annex C of the SHQS

Element reference number Description of elements Element type (internal to dwelling, common element or external to dwelling) Interpretation for social landlords Technical notes on measuring failure
Effective insulation (3 elements) One or more element failures under items 31-33 means outright failure of the energy efficiency criteria (C) and thus outright SHQS failure. Thus, elements 31, 32, 33 must be passed in addition to passing criteria 35 in order for SHQS to be met in full.
31 Cavity wall insulation External to dwelling or common element This will include a need to test for the presence of cavity wall insulation that has been installed to the external wall since the property was built depending on the accuracy of records of which properties have had cavities filled. This is only required where the installation is technically feasible and appropriate. 1. In some types of dwellings (such as stone built properties and some forms of non-traditional build housing) it is not possible to install cavity wall insulation as no cavity is present.

2. In other cases, installation may be prohibited by building regulations because cavity wall insulation would lead to other problems such as water penetration and dampness. This is particularly true in the wettest areas and where properties are have the greatest exposure to the elements.

3. A property that is not capable of receiving cavity wall insulation for either reason does not fail SHQS on this criteria.

4. Further advice is available in a separate SG guidance note on SHQS technical feasibility, exemptions and abeyances which is published alongside this technical guidance.
32 At least 100mm minimum of existing loft insulation e.g. glass wool or equivalent (or 270mm for first time insulation or first time additional insulation or as a further measure to reduce carbon emissions) Internal to dwelling or common element 100mm is the minimum existing level of loft insulation which will meet the SHQS. If the roof space is partially boarded without any loft insulation under the boards, or where the loft insulation is of uneven thickness, landlords need to ensure that the average thickness across the loft floor area is over 100mm.

1. In properties without a loft space it is not possible to install loft insulation so that property should not be regarded as failing on this element (see Annex I on exemptions and abeyances).

2. Though the SHQS minimum is 100mm of loft insulation, in order to minimise carbon emissions, Scottish Government would encourage up to 270mm of loft insulation as recommended under current Building Standards. We are aware that many landlords have gone beyond the 100mm depth in any case though would stress this is the official minimum necessary for passing SHQS. Up to 270mm is desirable however and can be fitted at a relatively small marginal cost.
33 Hot water tank and pipe insulation & cold water tank insulation as an ancillary measure Internal dwelling Hot water tanks (wherever they are located in the house) should have either spray-on insulation to a minimum thickness of 25mm or have an added tank jacket to a minimum thickness of 80mm. Where pipe work or cold water tanks are located in the loft space and are part of the distribution of heat within a wet heating system or delivery of hot or cold water to kitchens or bathrooms, these must be suitably insulated to protect against potential freezing conditions.

1. Alternatively, this requirement can be met if tanks and pipes are covered with a general insulation blanket or where they are completely located in a space with a rigid insulation system fixed to the underside of the roof (otherwise known as a 'warm roof'). Insulation is not required where exposed pipes will contribute to the heating requirement of the room space in which it is situated.
Full, efficient central heating (1 element, 2 sub-elements) One or more element failures under items 34A-34B means outright failure of the energy efficiency criteria (C) and thus outright SHQS failure. Thus, elements 34A-34B must be passed in addition to passing criteria 35 in order for SHQS to be met in full.
34A Full central heating Internal dwelling The definition of full house central heating is that all habitable rooms (i.e. excluding kitchen and bathroom which are not habitable rooms) covering at least 50% of the dwelling's floor area must have a heating system controlled from a single point in the dwelling. 1. Independently controlled heaters (i.e. not controlled from a single point), even if present in all rooms, do not constitute a central heating system and therefore would not meet the criteria. Thus, a number of independently controlled room heaters of various types do not constitute central heating and therefore do not pass criteria 34A even if a heating source is present in every habitable room.

2. Full electric central heating can consist of off-peak electric storage heaters and on-peak panel heaters which, together, cover all of the dwelling. The storage heaters should be controlled from a single point in the dwelling which is usually a timeclock or teleswitch controlled by the energy supplier. These will provide heating to the rooms they are located in plus 'drift' heat to those rooms not containing storage heaters. In addition, on-peak, independently controlled panel heaters can be used to supplement the heating to other rooms (with or without storage heating) where necessary.

3. The SHQS definition of habitable rooms is consistent with the definition of habitable rooms used in the Standard Assessment Procedure (SAP, element 35).
34B Efficient central heating Internal dwelling 1. An inefficient full central heating system is defined as being: a solid fuel boiler with an annual seasonal efficiency of 55% or less; a natural gas boiler with an annual seasonal efficiency of 55% or less; an oil-fired boiler with an annual seasonal efficiency of 65% or less; any gravity or semi-gravity heating system.

2. An inefficient electric storage heating system is defined here as being : free-standing large volume storage heaters; free standing compact storage heaters; electric fan-assisted storage warm air heating; electric wired under floor heating set in solid floors; electric ceiling heating. As a further guide to deciding on the efficiency or otherwise of such systems these storage heating systems, to be classed as inefficient, must also have been installed before 1984.
1. See footnote 2 at the bottom of this table.

2. The efficiency of individual central heating systems of differing fuel types can be validated in the Standard Assessment Procedure (SAP) handbook. The efficiency of individual boilers can be validated at

3. A 100% stock database is the most effective tool for identifying the detailed central heating characteristics of individual properties. There is no actual requirement for landlords to establish a 100% stock database though there was a recommendation that, over time, landlords should work towards a 100% stock database (as opposed to a 100% stock survey) by 2015 that would be capable of recording all relevant SHQS information (including central heating) for individual properties.

4. These efficiency ratings, specified in 2004, broadly equate to a 'G-rated' boiler or better suggesting that the requirements for an efficient central heating system under SHQS are not onerous. However, this definition of an efficient heating system was specified in 2004. To reduce fuel poverty and carbon emissions from the social housing stock, Scottish Government would strongly encourage landlords to aim for the most efficient boilers available on the market (i.e. A-rated) which will in practice mean going beyond the minimum specified in 2004.
A minimum energy efficiency rating (1 element) All other elements of the energy criteria must be passed in addition to passing criteria 35 in order for SHQS to be met in full.
35 An energy efficiency rating of either National Home Energy Rating (NHER) 5 or Standard Assessment Procedure (SAP) 2001 of 50 (gas systems) or 60 (electric systems).(4) See conversion table below to adjust SAP 2001 ratings to SAP 2005 or SAP 2009. Internal dwelling 1. This criteria was referred to as 'additional energy efficiency measures' in the original (2004) guidance. However, we have changed the emphasis of this criteria (though not the criteria itself) to make it clearer and to reflect the fact that the property must meet a certain energy efficiency rating rather than exhibit actual the 'additional energy efficiency measures' themselves.

2. The measures that would enhance energy efficiency will be well-known to landlords but might include (a) going above the minimum to criteria for elements 31-33 e.g. more loft insulation or a highly efficient heating system or (b) introducing other separate heating/insulation measures additional to those outlined in criteria 31-33 such as low energy lighting, double or even triple glazing.
1. If a property has met all of criteria 31,32, 33, 34A and 34B and still fails to achieve a minimum NHER rating of 5 or a SAP 2001 rating of 50 (gas) and 60 (other fuel types) then the aforementioned 'additional energy efficiency' measures should be introduced subject to technical feasibility and proportionate costs.

2. There is no need to re-survey stock given the ongoing changes in the SAP system from SAP 2001 to SAP 2005 and again to SAP 2009 for example. Changes in the SAP scale do not change SHQS which is specified in SAP 2001.

3. A SAP 'conversion table' for SAP 2001, 2005 and 2009 is provided below. This table essentially shows the threshold for a 'pass' on criteria 35. This table may change periodically with ongoing changes to SAP.

1. The failure rates recorded here are substantially higher than expected. This may be because of the technical difficulties in checking for the presence of cavity wall insulation e.g. bore holes have been covered by external rendering, surveyors no longer checking for the presence of CWI by looking down into the cavity from the loft space. These technical difficulties are expected to be reduced or overcome by the time of the 2010 SHCS thus it is quite possible that the 2010 failure rate will be significantly lower than 2009 failure rate.

2. The initial Scottish Executive Guidance (February 2004 and July 2004) on electric storage systems failing if they are 'over 20 years' old should be disregarded. This was an oversight on the part of that Guidance. The correct failure criteria is that systems will fail element 34B if they were installed pre-1984 i.e. 20 years before the first draft of the SHQS was published.

3. The SAP requirements of SHQS (aimed at the social sector) are slightly different from those of the Scottish Government's Energy Assistance Package (which is aimed at all households). Details can be found here:

Conversion table showing minimum NHER/SAP 2001/2005/2009 ratings necessary to pass SHQS criteria 35
Fuel source for central heating systems National Home Energy Rating) NHER Standard Assessment Procedure (SAP) 2001 Standard Assessment Procedure (SAP) 2005/RdSAP Standard Assessment Procedure (SAP) 2009
Gas 5 50 50 48
Oil 5 60 54 54
Liquid Petroleum Gas (LPG) 5 60 54 63
Electric 5 60 58 63
Solid Fuel 5 60 59 63
Biomass (new since 2004) 5 60 59 64


Email: Agnes Meany