Energy Performance Certificates (EPCs)

An Energy Performance Certificate is required for properties when constructed, sold or let. The Energy Performance Certificate provides details on the energy performance of the property and what you can do to improve it. This estimates primary energy consumption and associated emissions for only certain elements of a property, so does not represent all emissions. Notably it does not include emissions from domestic sources such as cooking, white goods and entertainment. Primary energy sources can be: electricity from the grid, mains gas or LPG; heating oil; coal; and biomass.  On-site renewable generation estimates are used to offset these.

When an EPC is issued it lasts for 10 years. EPCs are issued by Domestic Energy Assessors.

An EPC includes:

  • A rating A to G for current and potential energy efficiency
  • Estimates of:
    • Current and potential CO2 emissions
    • Energy consumption
    • Environment impact
  • Cost estimates for:
    • Space heating
    • Hot water heating
    • Lighting

What do EPCs say about housing in Teignbridge?

EPCs have included values for CO2 emissions since October 2008. EPCs for an area can be downloaded from 1 This shows that in Teignbridge EPCs have been issued for over 37,000 of approximately 58,000 dwellings. Currently average annual emissions per dwelling are 4.23 tonnes of CO2 equivalent.

The distribution of energy ratings current and potential is shown in the following chart:

Currently 23,137 dwellings (62.1%) are rated D or worse. These dwellings emit 127 kt of CO2, whereas the better rated dwellings emit just 31 kt of CO2.

Just 58 dwellings in Teignbridge currently have an energy rating of A, and only 27 of these dwellings have zero or negative carbon emissions. Most of the 27 are one off custom builds, but 13 are new estate houses built by Redrow in Kingsteignton. Most new build houses have a B or C rating, but this shows that zero carbon is possible for new build estate houses, so why aren’t they all zero carbon?

How might we improve

For many dwellings EPCs contain recommendations for improvements and estimates of potential CO2 emissions and energy consumption. If all the suggested improvements were carried out then:

  • Emissions per dwelling would drop from 4.23 tonnes to 2.37 tonnes, a reduction of nearly 44%.
  • Only 5,949 dwellings (15.97%) would be rated D or worse, against 23,137 (62.1%) currently. Despite the great reduction in numbers, those households rated D or worse would still account for 36.5% of CO2 emissions.
  • Dwellings that are rated A,B or C would emit 1.79 tonnes each or 56 kt in total, whereas those rated D and below would emit 5.42 tonnes each or 32 kt in total.

Many of the measures recommended in EPCs are quite expensive, so it is reasonable to assume that many have not been implemented.

If more radical measures were applied to the difficult cases to ensure these were at least as good as those rated C and above, then total domestic emissions could reduce to 67 kt, an overall improvement of about 68%.

In addition to improving the existing stock, we need new buildings to be zero carbon or negative as soon as possible. Ideally negative, to mitigate emissions from existing dwellings that are difficult to treat.

What are the EPC recommendations

The top EPC assessor recommendations are:

  • Install Solar PV 2.5 kWp (29,642)
  • Install Solar hot water heating (26,591)
  • Install Low energy light bulbs (24,075)
  • Replace boiler with new condensing boiler (11,994)

The number of certificates with each recommendation is shown in brackets.

These are followed by various insulation recommendations.

As we need hot water all year round, solar water heating will reduce energy imports in the summer.

Low energy lighting is probably the simplest measure to apply, LED lights are now available in a wide variety of fittings and in many cases all that is needed is to directly replace an existing bulb with an LED one.

It is optimistic to assume that fitting half of all dwellings with Solar PV would reduce emissions significantly as solar panels are only really effective in the summer during daytime, when energy is not required for heating or lighting. Solar panels are only likely to reduce emissions in the summer if the electricity generated is not exported. A storage battery can ensure that you have electricity at night, but there is no prospect of storing energy in the summer for use in winter. Now that time of use based tariffs are appearing following smart meter roll out, a battery could also be used to take advantage of low off peak rates, when hopefully more of the energy mix comes from renewables.

Electric heating has the potential of being zero carbon, whilst gas does not, so it is disappointing that heat pumps do not feature as a possible solution in the recommendations, but that gas boilers do. This probably reflects that:

  • Heat pumps are more expensive than gas boilers
  • Heat pumps work best with lower flow temperatures, so need larger emitting surfaces, ideally underfloor heating.

How well do EPC emissions estimates match reality

According to EPCs the total emissions for Teignbridge are 157.7 kilo-tonnes (kt).

An estimate is made for each year by BEIS for local authority emissions by fuel and sector, this can be found here Domestic emissions for Teignbridge for 2017 from this source are 183.1 kt. This estimate is based on actual consumption figures, so is more accurate.

EPCs only represent 37,247 dwellings, whereas there are about 58,2063 dwellings in Teignbridge. EPCs are not a representative sample of the dwelling population, because all new and rented dwellings are required to have an EPC, whereas existing buildings only need an EPC when they are marketed or apply for various schemes such as FIT or RHI. If non-compulsory buildings are excluded from the data, then 22772 remain that are representative of the remaining population of 43731 dwellings. A factor is applied to EPCs that are representative of non-compulsory buildings only in order to estimate district emissions. This gives a gross figure of 271.8ktCO2e for the district. So EPC derived emissions overestimate BEIS derived by 48%.2

This is probably down to a number of factors:

  • Space heating calculations used in EPCs assume a standardised temperature of 21C during heating periods in the living area. It is likely that most houses are heated to lower temperatures.
  • When assessing existing buildings assessors have to make assumptions about construction, as the assessment must be non-destructive.
  • Calculations derive CO2 emissions from calculated energy consumption using standard conversion factors for each fuel type. Over time these factors have changed, most noticeably the electricity factor to reflect increased use of renewables. This means that EPCs will overestimate emissions from some fuel types.
  • Preliminary analysis of EPCs by heat source suggests that the biggest over-estimates are in areas where there is no mains gas. This could be because other fuel sources are in some cases difficult to measure and so are not accurately represented in the BEIS statistics.

A more accurate estimate of domestic emissions for small areas could be calculated from actual consumption. Domestic gas consumption is available by postcode, and electricity is available at census LSOA (Lower Super Output Area) level. The data associated with this article has been updated to reflect this analysis, a second article is planned concentrating on these findings.

EPC data is a useful starting point for Parish and Town councils who have declared a Climate Emergency.  It will help to set carbon targets and implement initiatives that help reduce emissions.  An alternative approach would be to calculate emissions from BEIS data on a pro-rata basis, or use the results of our consumption based analysis once it is available.  Ultimately the most accurate and up-to-date method is for individual property owners/occupiers to do this assessment themselves, either by commissioning a new EPC, or by simply reading their energy bills or meters.  Please contact ACT’s Built Environment group for information on how to do this.

Where are domestic emissions in the district

The EPC data includes a postcode for each property, so EPCs can be analysed against a number of geographies including:

  • Parish boundaries
  • Census 2011 output areas
  • Teignbridge wards
  • Teignbridge district

Mapping EPCs

To finish this article here are maps. If you click the mouse over an area on the map, you will be shown some statistics about the area. Both the maps below are synchronised so that they always show the same place at the same scale.

The map above shows current and potential emissions per EPC for each census output area. This shows the relative performance of buildings in each area, but several people have pointed out that this presentation gives the impression that Dartmoor has the most domestic emissions, which is not the case.

The pair of maps below shows domestic emissions per hectare for each output area calculated from EPCs, this shows a more realistic picture of where the most domestic emissions occur, but is less useful as a general indication of building performance, because towns and villages that are densely populated emit most, even though individual buildings may perform well.

Here are some links to map only pages:


  1. If you follow the link to the opendatacommunities site you may get a security warning, this can safely be ignored.
  2. The original version of this article scaled all EPCs to derive district figures. This approach gave a lower estimate of 228.7 being an overestimate of 25%.
  3. ONS Population forecast 2016 Table 406 – Households by local authority.


Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.