Green Home Grants

Which Solution is right for your project ?

Here at DiscreteHeat, we manufacture ThermaSkirt in both ‘wet’ and electric versions. We don’t manufacture, sell or install heat pumps, boilers or PV solar panels (some of our Commercial Partners and Installers do, however) so we believe we can provide fair and objective information about which heat source is right for you. The Government Green Home Grants & RHI Incentives has made Heat Pumps more affordable, but gas boilers and electric still have a place.

Heat Pumps

Heat pump
NIBE Heat Pump

Heat Pumps

A heat pump has been described as like a fridge in reverse, in that it draws heat energy from the environment (either air or the ground) and using the physics of condensing a gas into a liquid and evaporating it back into a gas, releases heat energy; usually into water storage cylinder. This heated water can then be used to provide showers and baths or heating.

The heat energy they provide is most efficiently generated at lower temperatures than those found in a gas boiler; usually 50°C or less. This means that  a) the heat emitter needs to be larger compared to a standard radiator to deliver the same amount of heat, and b) the property needs to be well insulated to perform effectively; usually with an EPC rating of C or better.

Until recently these emitters have usually been limited to underfloor heating, oversized or even fan assisted radiators

For this reason, heat pumps are best suited to new build projects or ones undergoing substantial improvements.


The average cost of an air source heat pump installed is around £5~£10,000 & £15~£20,00 for Ground Source plus any costs to change the emitters. Grants up to £5,000 and RHI incentives are available under the Governments Green Homes Grant and the Renewable Heat Incentive.

As they use electricity, and electricity is typically 3 ~ 4 times the cost per KwH of mains gas (15~18p vs 4~5p)¹ then the Coefficient of Performance (or CoP) is vital. The heat pump needs to perform with a CoP of at least 3 or 4 to provide parity with a gas boiler. If the property is poorly insulated and the CoP drops below 3, the running costs are likely to be more than a new gas boiler


Best suited to replacing properties on oil or LPG gas. Ideal for new build or substantially improved properties. Can reduce the CO2 footprint of a property especially if solar PV is installed


More expensive to install and run than a gas boiler. Fewer installers & maintenance engineers UK wide. Requires outdoor space or garden. Sometimes struggle in very low temperatures and/or exposed locations

We Recommend:

Using the ThermaSkirt H2O BM3 profile as the larger surface area permits lower flow temperature. Less disruption than a UFH system means easier retrofit. BM2 profile may be employed upstairs if UFH is preferred at ground floor.


As more than 90% of the UK is covered by a mains gas supply, gas condensing boilers are the most popular form of heating.

All new gas boilers must have an efficiency rating of more than 90% which means that for each Kw of gas energy they use, they create at least 0.9kw of heat energy (usually in the form of heated water).

With an average efficiency of 86% across the network from storage facility to hot water tank, the CO2 footprint of gas has been calculated to be 215g per KwH 2

The Government has commitments to reduce the CO2 footprint of the UK as a whole and so there have been suggestions that gas boilers would be ‘outlawed’ from 2030 or even 2025.

However, with more than 20m properties connected to the gas network, complete transition to low carbon technologies such as heat pumps is unlikely. More likely is the introduction of low carbon alternatives such as Hydrogen/mix to reduce the CO2 footprint of the grid as a whole.


Typical cost of a gas boiler is in the region of £800 ~£1500 plus installation. Replacing an existing boiler for a new one should cost less than £2,000, and under £3,000 even if there is any new pipework or relocation required.

Gas has the advantage that it can provide high grade heat up to 80°C so that it can provide enough energy to heat older, poorly insulated properties. However, the cheapest form of heating is insulation, so before you replace an older boiler, check out the costs of improved insulation such as double glazing, loft and cavity wall and draughtproofing costs; grants are available.


Large network or suppliers and installers. Well proven and reliable technology. Provides a higher level of instantaneous heat without the need for water storage (combi boilers).


Requires a flue and safety inspections periodically. Now more carbon intensive than electricity (215 g vs 207g per KwH)2 . Hydrogen capable boilers still 3 ~ 5 years away

We Recommend

Replacing any boiler more than 10 years old with a smart new one, with weather compensation and variable flow temperature. Use ThermaSkirt H2O as can heat the room at lower temperatures than a standard radiator saving between 8~13% in running costs³

Direct Electric

Until recently electric heating was considered an anathema, due to the carbon intensity of the generation process. However in 2019, due to the reduction in coal and gas power generation and the increase in solar and wind, electric undercut gas CO2 emissions per KwH (207g per vs 215g). This has led to a resurgence in interest in direct electric heating.

Electric storage heaters use overnight cheap rate electricity to thermally store heat in heavyweight materials such as clay and concrete. Opening a vent releases the heat energy as required. Any energy cost savings have proven to be largely illusory as the heat may trickle away if unused the next day, and the additional economy 7 or 10 meters usually incur a higher daily standing charge and a higher daily rate for ‘normal’ electricity.

As a result, direct electric heating, especially in high rise apartments is increasing rapidly as it is now ‘clean’ simple to install and there is no risk of leaks. Recent legislation to heating controls has further improved the affordability of electric heating


The cost of an electric heater vary enormously; from a simple £50 panel heater up to a £1,500 storage or smart radiator.

They all will require their own heating circuit (it is not advisable to connect fixed appliance heaters into the socket outlet circuit). Replacing storage heaters with new direct electric heaters is straightforward and will require minimal alterations.

Smart ‘LOT 20’ controls are now required which reduce electrical consumption using learning algorithms, presence detection and/or window open detection


Simple to install, especially on existing ring main circuits. Large network of installation engineers. No risk of leaks. Instant and direct control. Can be supported by Solar PV


More expensive per KwH than gas to run, so good insulation and controls a must.  Standard panel heaters may overheat if covered over so additional precautions may be required.

We Recommend

ThermaSkirt e has a unique control to limit energy usage to 50% when close to room target temperature to avoid overheating and wasting energy. Unique fire safe heating element provides additional safety even if covered over.

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