Hard to heat homes
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Source:
Energy Efficiency Partnership for Homes
Date of data:
March 2006
Data supplied:
August 2007
Identifying and Quantifying the Prevalence of Hard to Treat Homes
Below is an extract from the final report to the Energy Efficiency Partnership for Homes (Insulation Strategy Group and Hard-to-Treat Subgroup) by the Centre for Sustainable Energy.
17 March 2006
Mapping access to Gas
Lack of ‘access to gas’ is an important predictor of ‘hard to treat’ housing. It is a problem particularly associated with rural areas, although it also occurs in certain urban areas (e.g. areas that traditionally used solid fuel as their main heating source) and property types (e.g. high rise).
CSE obtained gas connectivity data from Transco’s Demand & Generation Forecasting Department in 2003. The database lists 6 digit postcode areas with a gas supply in 2003 (there are 1.2m postcode areas in England). The database is more detailed than that made publicly available on Transco’s website. CSE acknowledges the support of Professor John Chesshire in acquiring this database.
CSE has assumed that all properties within listed postcodes receive gas, although this may not always be the case. This will lead to a slight overestimate of gas connectivity. There may also be some properties that are connected to gas but do not use it. The database does not include postcodes supplied by independent gas operators. This will lead to a slight under-estimate of gas connectivity.
Solid wall housing
‘Properties built with solid walls’ construction is another predictor of ‘hard to treat’ in that they, on average, have lower SAP values than those built with cavities. Furthermore, it is of course not possible to install cavity wall insulation in solid wall properties, which is a very cost effective method of improving SAP standards.
However, higher cost solid wall insulation options are available, e.g. dry lining, external cladding, and insulating plaster products such as Wall reform. CSE work to quantify rural fuel poverty for EAGA Charitable Trust has shown that the proportion of solid walled properties increased substantially with each increase in level of settlement dispersal (from ‘urban’ to ‘town’ to ‘village’ to ‘hamlet’). The proportion of solid wall properties in ‘hamlets’ ranged from 50% to 60% across the Warm Front phase 1 area. By contrast, solid wall properties in ‘urban’ areas ranged from 21% to 27%.
CSE originally intended to use the simple English multiplier recommended by the Association for the Conservation of Energy (ACE) for constructing its small area database of solid wall properties (ACE 2002). ACE suggests that the number of solid wall properties in any given area in England can be estimated by multiplying the number of pre-1919 properties by 1.44. The English House Condition Survey provides property age data according to 5 broad categories: pre-1919, 1919-1944, 1945-1964, 1965-1980 and post 1980 (ODPM, 2004). The multiplier is designed to give a broad reflection of the fact that properties built before 1919 do not contain cavities but a proportion of properties built between 1919 and 1945 do.
Following some work carried out by CSE in Cornwall (where virtually all properties built before 1945 do not contain cavities), CSE decided to use a regional multiplier to arrive at a proxy for solid wall properties, since there are considerable regional variations in the distribution of solid wall properties. This will still lead to inaccuracies when applied at the small area level. However, it is intended to provide a slightly more accurate guide than use of a crude all-England multiplier.
English Multipliers used to estimate total solid walled from pre-1919
East Midlands Urban 1.663, Rural 1.175
It is also important to appreciate that the indicator is only intended as a predictor of ‘hard to treat’ housing. There are, of course, a range of other factors that can also contribute to ‘hard to treat’ but for which there is little small area data. These may have particular significance at a small area level, e.g. use of non-traditional construction types.
CSE has purchased a license for the use of RESIDATA to provide post code area data on age of property. RESIDATA is a commercial database produced for the building insurance industry which is updated annually. It is considered to provide accurate data on a range of property characteristics, including property age. CSE has applied the regional solid wall multipliers to ‘number of pre-1919 properties’ to produce a small area database of solid wall properties. CSE was therefore able to provide an estimate of the number of solid wall properties for every OA in England.
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