When a SAP assessment is produced for a house, new build or existing, the total energy consumption is calculated for the heating system, hot water, lighting and ventilation systems.
From this data it’s possible to work out the predicted kilowatt hours of energy used every year, the amount of CO2 produced every year, and the predicted cost of annual fuel bills. The Energy Performance Certificate (EPC) rating is worked out based on this fuel bill data.
Every few years the Government releases an updated list of fuel types with prices to be used in the SAP. For example, mains gas is currently listed as 3.1 pence per unit plus a £106 annual standing charge. Grid electricity is listed as just under 11.5 pence a unit for a standard tariff.
When these price figures are multiplied by the calculated consumption data from the SAP, you’ll get the annual predicted fuel bill. This figure needs to be taken with a pinch of salt, as there are a lot of factors which make it not completely accurate:
- The current prices are from 2010, and as we all know fuel prices have skyrocketed in the last three years
- The SAP does not include general occupancy use – this means white goods, power showers, TVs and the like are all excluded
- We use more heating in particularly cold winters which obviously has an effect on the annual energy use, but the SAP is based on average monthly temperature data for the UK
- Another element missing from the SAP is the people who live in the house. Some of us like a cool building, others like a sauna. Again, SAP is calculated on average data.
- If you have PV panels, the money you get back from the Feed-in-Tariff is not included. Instead, it’s assumed half the electricity you generate is used in the house, so the fuel bill is reduced in this way. If you have had a SAP assessment completed, the predicted fuel costs are listed in Section 10a of your Worksheet. The total fuel cost from this section is divided by the floor area of the house to calculate your EPC rating – so the cheaper your house is to run, the better rating your house will receive.
We can offer advice on how to achieve a better EPC rating as part of our SAP service. Contact us to find out more details.