Heating a home uses a lot of energy and makes up a significant part of your energy bill. What are the different ways that a home can be heated? Maybe there's a more efficient or cheaper (not always the same) way to heat yours? We're Energy Performance Certificate Assessors and we've created this guide as a overview for home owners and landlords.

Heating a Home & The EPC

When calculating EPC scores, there are two different types of heating in a home, primary and secondary. The article will cover the primary heating source of a home which includes boilers, electric heaters and heat pumps. Secondary heating usually relates to a fire or other standalone heat source which we will cover in another article. The primary heating source of a building can make a difference of full bands on the EPC so if you are looking to upgrade your heating system, getting it right can make a big difference to the energy efficiency of your home.

Electric Heaters: Least Efficient

A popular misconception of the EPC is that it relates to the CO₂ a building produces. This is not the case. The main measurement factor is the cost of running that property. The cheaper the property is for the occupant to live in, the higher the EPC score. Currently, in the UK, one unit of electric is around four times more expensive than a unit of energy from gas. This means that any heating system that uses electricity will usually come off worse on the EPC than a gas system, even air source heat pumps.

Electric heaters, come in two types, instantaneous and storage. They both work by running a charge through a wire to heat it up to produce heat. The wire in a storage heater is surrounded with ceramic blocks that heat up, hold the heat and release it over the course of a few hours or days. These devices are classified as being 100% efficient, transferring all of their electrical energy into heat

Although both storage and instantaneous electric heaters are 100% efficient, they do not do well on the EPC. They are at least 3 times more expensive to run than a gas boiler.

These devices are standalone units, wired or plugged in to the ring main individually. To improve your score on the EPC you can add an element of centralised control to them. By including a thermostat or programmer that can switch the devices off at a certain time or temperature, this will prevent wasted heat and make a small, positive change to the EPC and your heating bills.

Storage heaters work well with the Economy 7 type tariffs. Home owners can heat them up through the night with cheaper electric which will release the heat throughout the day.

Boilers: Most Common

As EPC Assessors working in Warrington, 90% of homes we survey have a boiler and 95% of those boilers are gas fired. In addition to gas, we've surveyed a few homes with electric and oil fired boilers. Just one wood burning stove with a back boiler. Remembering that the EPC is related to cost, gas usually comes out better on the EPC, then oil and finally electric. We also do not take in to account the price that you pay for your fuel. Our software has standard prices set for each fuel type. So if you get your wood for free or have got a steal on your tank of oil, this will not affect the EPC result.

All these types of boilers work in the same way. They use your fuel of choice to heat up water and a pump sends it around your home to your radiators.

Modern gas boilers are very efficient, almost 100% in some cases. Older boilers vary between manufacturer and model. We recently completed an EPC on a home with a 20 year old Baxi combi boiler that had an efficiency of 80%. Comparing the cost of this older boiler to electric heaters that are 100% efficient, per unit of energy used, this would cost 9.6p (Gas - 8p per kWh) compared to 32p (Electric kWh). Remember, your gas boiler could be a 24kWh model or more and an electric fire may be 2kWh, we're just comparing units of energy.

As with other heating systems, to improve the efficiency, you can introduce controls. The more control you have, the better. TRVs, a thermostat and a programmer is great, but if you can add some sort of zonal control too, you'll save money on your energy bills and improve your EPC score.

To go one step further, you can add Flue Gas Heat Recovery (FGHR) to your system. This will take heat out of the boiler's flue and recirculate it back in to the system. We're yet to see one of these installed. The amount of energy that this recovers in minimal and the installed costs of the units are upwards of £1,000. I ran a quick test on how it impacted the EPC and on this test, no points were gained with a FGHR system.

Heat Pumps: Most Efficient (Probably Not The Cheapest)

On your energy bills, both gas and electric are charged in kilowatt hours (kWh). On my bill, I'm currently paying around 8p for a kWh of gas and 32p for a kWh of electric. If we compared a gas heating system and an electric heating system both with efficiencies of around 100%, per kWh, an electric system would be around four times more expensive to run. There are electric systems that have efficiencies greater than 100%. One example is air conditioning units which have an efficiency of around 200%. A more modern example is heat pumps which are now reaching efficiencies of up to 400%.

Heat pumps, whether ground source or air source, work by boiling a refrigerant using ambient temperatures. When this boiling refrigerant is compressed it releases enough heat to heat up water for your heating system.

With some of these heat pumps now reaching efficiencies of 400%, it makes the operation cost roughly equivalent to that of a 100% efficient gas system. However, the installed price of the unit is around double of a gas system. Heat pumps really come into their own when paired with solar panels where the average price of electricity is significantly reduced, maybe even zero.

So whilst these heat pumps are up to four times more efficient, you need to make sure that yours is correctly spec'ed and do the maths to make sure that it will be the most cost efficient method of heating your home.