Calculating Dwelling Energy Performance
Energy performance should be calculated at the design stage of the build to make sure the new dwelling will comply with the regulations.
The main points for new builds are:
EPC < 0.4
The EPC (Energy Performance Coefficient) is a calculation compares the energy performance of the new dwelling with a reference dwelling of the same size and shape with standard details for insulation and heating systems and controls.
The criteria means that a new build must be 60% more efficient than the standard build. IN practice this will generally mean a rating of at least an A3.
CPC < 0.46
Similarly, the CPC (Carbon Performance Coefficient) is a comparison of the carbon dioxide emissions of the new dwelling with a reference dwelling of the same size and shape with standard details for insulation and heating systems and controls.
The new dwelling must have less than 50% of the carbon dioxide emissions of the standard build.
A minimum level of energy provision from renewable energy technologies is required :
- 10 kWh/m2/annum contributing to energy use for domestic hot water heating, space heating or cooling; or
- 4 kWh/m2/annum of electrical energy; or
- a combination of these which would have equivalent effect.
In a lot of cases this can be achieved with solar water heating (with a wood burning stove as a secondary heating system also required sometimes).
These regulations are set out in Technical Guidance Document (TGD) Part L 2011