FHS Launch - The gas boiler 'ban'

We’re told the Future Homes Standard will require most new homes to use heat pumps. That’s most, not all.

So does that mean there’s scope to sneak through the occasional gas boiler under the new Part L?

No. For two reasons...

Heat pumps will be required in the vast majority of new homes in order to comply with the Future Homes Standard.

1️⃣ In the new SAP10.3, the emission factor associated with electricity has been reduced to just 86g of CO2 per kWh.

In the current SAP (10.2), it’s 136, and the previous version was 519.

This continuing reduction shows the UK's electricity supply is getting greener year on year. 💚 

In 2025, 30% of the UK’s electricity came from wind. Just 12 years ago, 30% came from coal. (and, despite what you may read online, the final coal power station in the UK closed in 2024).

Under the Future Homes Standard, using electricity to heat our homes is easily the greener option. The 86g of CO2 per kWh compares to 214 for gas and 298 for oil.

Elsewhere in SAP, the notional target calculation is changing from a gas boiler (under SAP10.2) to a low efficiency Air Source Heat Pump (CoP 2.5). This is 3x as efficient as a new gas boiler, and uses a fuel source (electricity) that emits 2.5x less emissions than mains gas.

Combined, the maths makes it impractical to offset the use of a fossil fuel boiler in a new home. ⚖️ Compliance in SAP10.3 with a fossil fuel heating system is nigh-on impossible.

But, just in case an assessor finds a way, there’s another moat to this fortress... 🏰 

2️⃣ The new Approved Document Part L (Section 4.4) says heating systems in new dwellings must use a fuel with an emission factor <=86g of CO2 per kWh.

Clearly this isn’t a coincidence, and is a very English way of banning fossil fuel heating systems without saying so.

This doesn't rule out all fuels. These options can be considered as alternatives for heating your home:

✅ Wood chips and pellets;

✅ logs;

✅ bioethanol;

✅ biogas;

✅ recycled vegetable or cooking oil.

But even if you install a biogas boiler, SAP will still compare you against the efficiency of a heat pump, so you’ll still have a load of offsetting to deal with. 

🔹 And in case you’re wondering whatever happened to green hydrogen as a heating option to replace mains gas, it’s fair to say we’re not ready to consider this a mainstream option just yet.

There are 300 homes in Fife being connected to the world’s first green hydrogen network. That leaves approx 22,999,700 houses to go.