Jamie Bursnell, head of technical and innovation at Bellway, explains how research is helping the housebuilding industry prepare for the Future Homes Standard.
Air source heat pumps (ASHPs) are set to become the default heating solution for new build homes once the Future Homes Standard comes into force next year.
This is a massive change for the housebuilding industry – but a change that we at Bellway have been working towards for the past six years.
We’ve been conducting a series of tests in an experimental house built within The University of Salford’s Energy House 2.0 climate chamber, with the latest results demonstrating the optimum specification for the installation and operation of ASHPs.
This is a vital step in ensuring the successful adoption of the Future Homes Standard.
Contrary to what you might have heard, gas boilers aren’t being banned as such, but it will become virtually impossible to comply with the new building regulations using fossil fuel heating. And given the vast majority of homes in the UK currently have gas boilers, the extent of the challenge can’t be underestimated.
As part of preparing for this change, we’ve taken a collaborative approach with academics and industry partners to take significant steps forward in our understanding of how to design, install and operate an ASHP system as efficiently as possible.
Part of the reason that this is so important is the cost of electricity, with the price cap for electricity currently at 27p per kwh, compared to gas at 8p. The fact we’ve been able to demonstrate that ASHPs can be four times more efficient than a gas boiler in a well-insulated new-build home during typical UK winter temperatures means that we’ve shown they are a viable and affordable alternative to fossil fuels for the mass market.
Our ASHP Optimisation Project is the third set of research conducted within Bellway’s test house at Energy House 2.0. We’ve previously established that the house has verified fabric values which match those in the Future Homes Standard consultation, and that a combination of ASHP with under-floor heating to the ground floor and radiators to the first floor is the most effective configuration of electric heating systems, both in terms of running costs and thermal comfort for customers.
The Optimisation Project then examined this configuration in further detail, making significant modifications to the ASHP’s design and performance. This included eliminating micro-zoning and other third-party controls and reinstating the manufacturer’s flow-temperature control, commissioned in line with the original system design.
Comparative testing demonstrated an increase in co-efficient of performance (COP) of 0.6-0.7 at external temperatures of 5C and -5C under constant internal temperature operation.
This shows that a ‘less is more’ approach delivers a lower-cost build for Bellway and increases the efficiency of the heat-pump system for customers.
At the forefront of our thinking is making sure we deliver high levels of thermal comfort and low running costs for customers. That’s because if customers are not happy with the level of warmth provided by an ASHP or with the cost involved in running it, we risk a loss of confidence in the product which could jeopardise both the successful transition to the Future Homes Standard and the UK’s entire net zero project.
Our research has demonstrated that customers will need to get used to using their heating systems differently. ASHPs don’t work like gas boilers which you turn on and off as desired – they work best when they are left running at a constant low heating (18C in the living room and 16C in all other rooms) and then increased to comfort levels (21C in the living room and 18C in other rooms) for periods in the morning and evening when heating is required.
Understanding how the optimum building fabric, ASHP and emitter configuration and heating profile complement each other to achieve optimum energy efficiency is what makes this research so useful.
We have already incorporated these learnings into the design standards for Bellway house types to bring these efficiencies into the real world, with more than 1,000 ASHP homes built at Bellway developments over the past two years.
And as we’re seeing increasingly frequent heatwaves, there’s growing interest in the ability of ASHPs to keep our homes cool as well. The team at Energy House 2.0 has also tested ASHPs operating in cooling mode at temperatures of 32C in the climate chamber, demonstrating that continuous cooling using heat pumps can significantly reduce overheating and maintain comfortable temperatures in living spaces.
There’s no doubt that the transition to heat pumps requires an enormous change in working practices across the entire housebuilding industry, and while we’ve made progress, there’s still a considerable way to go.
We need heat pump manufacturers to be able to supply heat pumps at pace and at scale and we need plumbing contractors to gain the required certification to install them. Technical teams need to redesign smaller homes which would previously have had combi gas boilers with space for hot water cylinders. Sales and customer care teams need educating about how heat pumps work efficiently so they can explain them to customers.
Our work to find the most efficient solutions for customers continues. We’re now exploring how we can use technology to further minimise energy bills. One example of this is using electricity at off-peak periods, knowing how long it takes for the system to achieve the desired temperature from its setback temperature, and taking advantage of the energy-efficient fabric of the home to retain the heat generated until the time it is needed. Tech can also help predict weather patterns and when there will be sunshine, generating free electricity to run the ASHP’s weekly pasteurisation cycle.
Customers need to have confidence in the new technology for this transition to work – which means that we as housebuilders have to get it right.
