Energy Performance

For the purposes of design and building Bobbin House plus getting a grant towards the heat pump, three Energy Performance Certificates (EPCs) have been commissioned for Bobbin House. Strangely, a number of the energy saving features used in Bobbin House do not influence the score (see below):

  • Design SAP (June 2010): C (80)
  • RdSAP, existing dwelling (May 2014): B(85) – for green deal assessment
  • As-Built SAP (March 2015): B(87)

An EPC rating of B is between 81-91 and 92-100 is an A.

The CO2 rating in all EPCs was B.

What Doesn’t Count?

The odd thing about EPCs is that having a heat pump doesn’t contribute to the energy performance or the environmental impact (Co2) rating. The EPCs above (and as of 2023 the current EPC process) do not base their calculations just on energy efficiency (or low-carbon generation) but also the cost to run. With the recent changes in energy prices the cost of running a gas boiler or a heat pump has become broadly equivalent but heat pumps are penalised in the current EPC process compared to gas and oil heating. See for an interesting article on this problem.

As of 2023 the Government is looking to reform the energy performance certification process but is unlikely to make any huge changes as it would invalid existing EPCs.

In fact the bias in the EPC to energy costs and not just energy efficient means using a Mechanical Ventilation with Heat Recovery (MVHR) system, a borehole, photo voltaic solar panels, water solar panels and a heat pump fails to be reflected accurately in the EPC score for Bobbin House.

Finally, lighting is an interesting element of how an EPC is calculated. Incandescent lights generate heat as a by-product of providing light which the EPC calculation takes into account in space heating calculations! LED lights are around eights times more efficient than incandescent lights but this will only have a marginal benefit in an EPC.