The energy efficiency of England’s housing stock continues to improve as the Government strives to meet its international obligations to reduce energy consumption. In 2019, the average SAP rating of English dwellings was 65 points, up from 45 points in 1996 and 63 in 2018.
The Standard Assessment Procedure (SAP rating) is used to monitor the energy efficiency of homes. It is an index based on calculating annual space and water heating costs for a standard heating regime and is expressed on a scale of 1 (highly inefficient) to 100 (highly efficient, with 100 representing zero energy costs).
In 2019, the social housing sector had an average SAP rating of 69, higher than the private rented sector with an average rating of 64. The social sector was more energy efficient than the private sector, in part due to its wider use of solid wall insulation, but also because of dwelling type.
The social sector contains a higher proportion of flats compared to the private sector, and these have less exposed surface area (external walls and roofs) through which heat can be lost, than detached or semi-detached houses.
The proportion of dwellings in the highest SAP energy efficiency rating (EER) bands A to C increased considerably between 2009 and 2019, from 12 per cent to 40 per cent. Over the same period, the proportion of dwellings in the lowest F and G bands fell from 12 to 3 per cent. In 2019, the majority of dwellings (85 per cent) were in EER bands C or D, compared with 56 per cent in 2009.
In the social rented sector, the majority of dwellings (61 per cent) were in EER bands A to C, compared with 38 per cent of private rented sector dwellings and 36 per cent of owner occupied dwellings.
Improving energy efficiency
There are two key methods of increasing the energy efficiency of existing dwellings – upgrading the dwelling’s heating system or increasing the insulation.
Between 1996 and 2019, the proportion of homes with central heating increased (from 80 to 93 per cent) while the proportion of homes with room heaters as their main heating source – the least cost-effective and most inefficient method of heating – decreased from 12 to 3 per cent. The proportion of homes with storage heaters also decreased over this period from 8 to 5 per cent.
In 2019, owner occupiers and councils had the highest proportion of homes with central heating (both 95 per cent); private rented (86 per cent) and HAs had the lowest (89 per cent). The proportion of dwellings in the private rented sector with fixed room heaters was higher than in other tenures (6 per cent compared to 2 per cent in both the owner occupied and social rented sectors.
Condensing boilers are generally the most efficient boiler type and since the mid–2000s they have been mandatory for new and replacement boilers. The proportion of dwellings with condensing or condensing combination boilers has increased considerably since 2001, rising from just 2 per cent of homes in 2001 to 74 per cent in 2019.
Older, less energy efficient boiler types are more prevalent in the private rented sector. In 2019, 13 per cent of owner occupied dwellings and 9 per cent of private rented dwellings had a standard boiler, compared with just 3 per cent of social sector dwellings.
The second main method of increasing a dwelling’s energy performance is by increasing insulation. Standard insulation measures include cavity or solid wall insulation, loft insulation and double glazing.
In 2019, 86 per cent of homes in England had full double glazing, up from 73 per cent in 2009. Half (50 per cent) had cavity or solid wall insulation (up from 39 per cent in 2009) and 39 per cent had 200mm or more of loft insulation (up from 24 per cent in 2009).
The increase in wall insulation across the nation’s housing stock was mostly driven by an increase in the prevalence of insulated cavity walls. Taking dwellings with predominantly cavity or solid walls separately, 68 per cent of dwellings with predominantly cavity walls had insulation installed, compared with only 11 per cent of dwellings with predominantly solid walls.
Among dwellings with solid walls, the social rented sector had a higher proportion with solid wall insulation (28 per cent) than the private sector (8 per cent).
Among dwellings with cavity walls, the private rented sector had a lower proportion of dwellings with cavity insulation (56 per cent) than the other tenures (for example, 70 per cent of owner occupied dwellings and 72 per cent of social rented sector dwellings).
The rollout of smart meters is an essential national infrastructure upgrade that will make the country’s energy system more efficient and flexible, helping to deliver on the Government’s target of net zero emissions by 2050.
In 2019, 30 per cent of dwellings with mains electricity had an electricity smart meter and 28 per cent of dwellings with mains gas supply had a gas one, up from 22 per cent and 21 per cent respectively in 2018.
The proportion of homes with smart meters increased across all tenures. As in previous years, a lower proportion of homes in the private rented sector had smart meters than owner occupied or social homes.
For example, 21 per cent of homes in the private rented sector had an electricity smart meter in 2019, compared with 32 per cent of owner occupied and social rented homes. A similar pattern was observed for gas smart meters.
By Patrick Mooney, Editor