Tom Lane

At first sight, the launch of the Future Homes Standard consultation in October was a welcome surprise after five years of government inaction on reducing carbon emissions from new homes.

The industry has now had time to consider the finer implications of the proposals for consumers and for business.

>> Read: Future Homes Standard - get ready for a domestic revolution

The interim standard that takes effect next year proposes two options. The government’s preferred choice is a 31% carbon emissions reduction achieved through modest fabric improvements and photovoltaic (PV) panels. The second option is a 20% reduction achieved via tougher fabric performance standards. On the face of it, the 31% option looks more appealing as the impact assessment shows a typical household will save just £59 from the fabric-first approach and £257 with the addition of PV panels.

Boiler installers, who will presumably switch to fitting heat pumps, will need to retrain. This could take 10 years to get right

The impact assessment suggests gas boilers can be used to provide heat and hot water under both options. But analysis by the architect HTA shows that it isn’t possible to meet either target if a gas boiler is fitted. 

A home with fabric standards well in excess of that called for by the consultation still wouldn’t meet the 20% target when fitted with a gas boiler. And in any event, fossil-fuel boilers will be banned from 2025 once the full Future Homes Standard takes effect.

The government anticipates that heat pumps, particularly the air source variety, will play a “major role” in providing low-carbon heat. This is because heat pumps are said to produce about 3 units of heat per unit of electricity.

Wide adoption of heat pumps presents several challenges. Two Energy Saving Trust field trials revealed that air source heat pumps had an average system efficiency of just over 2. Poor performance was said to be down to issues with design and installation. 

This doesn’t bode well given that boiler installers, who will presumably switch to fitting heat pumps, will need to retrain from scratch. Heat pump installations are complex and if experience with district heating is any guide, this will take at least 10 years to get right.

According to engineer Max Fordham, a well-designed and efficient air source heat pump system providing heating and hot water will perform with an efficiency of about 2.5. This isn’t bad, but would lead to bigger heating and hot water bills than gas. 

At current rates, the huge disparity between gas and electricity prices means a home fitted with an air source heat pump with an efficiency of 2.5 will still cost 66% more to heat than one fitted with a gas boiler. The fabric performance for the preferred 31% option is barely any better than current standards, which means bigger bills if there isn’t space to fit enough PV panels to offset the hike.

The answer is higher fabric standards than those proposed to offset the risk of increasing electricity demand and pushing up bills. This would have the added benefit of limiting overall demand when heat pump and electric car adoption is going to make it hard for our electricity infrastructure to cope.

Thomas Lane, group technical editor, Building