As part of declaring a national climate emergency, the UK government has set a legally binding target that the country will be ‘net zero’ by 2050. The Europa Way Triangle development in Leamington Spa shows that net zero dwellings can be constructed well before that date, thanks to SAP assessment and design support services offered by Darren Evans.
Warwick District Council (WDC) has declared it will be a zero carbon authority by 2025, and will help the district become carbon neutral by 2030. WDC targeted ambitious carbon reductions in all possible areas, looking at embodied carbon and aiming for a 100% reduction in regulated carbon for the 54 new homes at Europa Way.
Working with WDC and Corstophine + Wright Architects to deliver the scheme, Vistry Partnerships West Midlands engaged Darren Evans to develop a specification that would meet the demanding target for regulated carbon.
There are different ways of measuring carbon emissions caused by construction projects. ‘Regulated’ emissions are those controlled by the Building Regulations. They include factors - such as building fabric heat losses and heating system efficiencies - that are entered into SAP calculations as part of assessing compliance.
‘Unregulated’ emissions are those resulting from the activities of the building user, and which are not accounted for in compliance calculations.
‘Embodied carbon’, meanwhile, is the measure of carbon emissions associated with all stages of a building’s life cycle. It ranges from emissions due to the production and transport of building materials, the processes on site during construction, the operation of the building, and the way in which components are reused, recycled or demolished at the end of a building’s life.
Part L 2013 was the applicable building regulation for energy efficiency. The government had not yet responded to the consultation on Part L 2021 (as part of progressing towards the ‘Future Homes Standard’), so it was up to Warwick District Council to decide on a target that surpassed the regulations and met their zero carbon commitment.
“The Council Housing Development Officers, together with their appointed energy consultant, Enhabit (led by Dr Sarah Price), set the target on the scheme and decided to aim for net zero regulated carbon,” explained Brandon Wippurfurth, Senior Sustainability and Energy Consultant at Darren Evans. “Calculated in SAP, the dwelling emission rate (DER) would be zero compared to the target emission rate (TER) set by Part L 2013. It made sense for the scheme, because a 100% reduction is easy to understand.”
A planning application for the scheme was submitted and work began on developing a precise performance specification. “Reducing embodied carbon drove a change from brick and block masonry construction to timber frame,” said Ben Sandford, Development Manager at Vistry partnerships West Midlands.
Richard Hill, Associate Director at Corstorphine + Wright Architects, had the responsibility of producing the working drawings for the scheme.
“We converted Vistry Partnerships’ house-type drawings from masonry to timber frame,” Richard said. “Darren Evans defined the performance specification for net zero regulated carbon. Brandon explained the target U-values that the building fabric needed to achieve. The most significant change was updating the timber frame company’s standard wall details to accommodate the extra insulation.”
Brandon and Richard worked together to refine the insulation specification. With Darren Evans already on board, the design changes could be modelled and incorporated straight away, saving time and unnecessary extra cost, and giving the confidence that the scheme would still achieve its end of goal of net zero regulated carbon.
As Richard explained: “Changing the wall thickness to accommodate extra insulation requires a judgement call. Is there space to move the walls of the house outward, or do the plot sizes mean you move them inward and decrease the floor area slightly?”
The final specification featured an insulated plasterboard product applied to the inside face of the timber frame.
As part of achieving a high level of building fabric performance, it was necessary to ensure that the thermal bridging details for the different house types minimised unwanted heat loss. The change to a standard timber frame wall build-up meant checking the existing details and altering them to achieve the low psi values needed.
“Brandon at Darren Evans worked with Corstorphine + Wright Architects and the timber frame company to develop bespoke thermal bridging details,” Ben Sandford said.
In addition to good building fabric performance, WDC wanted the dwellings at Europa Way triangle to feature air source heat pumps (ASHP), photovoltaics (PV) and waste water heat recovery (WWHR). Once the building fabric specification had been finalised, the SAP calculations could be revisited to refine the building services.
The services complemented the fabric-first approach, and made the final step in achieving net zero regulated carbon which would have been impractical through the building fabric alone. “Darren Evans was able to look at reducing the amount of PV on the scheme, ensuring we weren’t over-specifying and adding unnecessary cost.” continues Ben Sandford.
“They were really flexible, easy and good to work with, and always on hand to offer advice. They really know the detail of what they’re telling you.”
The Europa Way Triangle project has been a learning experience for all involved. As Brandon Wipperfurth from Darren Evans described it: “This was such a high target for a scheme of so many units.”
“Our first experience of this won’t be the last,” added Ben Sandford. “The exercise of working through all the different items to achieve the net zero target will help our planning for future projects.”
For Richard Hill, the scheme has attracted attention from his colleagues: “Everyone at Darren Evans was very good, very knowledgeable. They’ve shown that it’s possible to achieve net zero carbon by tweaking existing approaches.
“There’s a perception that zero carbon is hard to do and means starting from scratch. While it certainly requires some thought, it’s not as off-putting as it seems.”
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About Darren Evans
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We use our in-depth knowledge of building regulations and current technology to offer a range of options. Services and solutions are tailored to your needs through analysing and quantifying carbon and energy reductions.
To find out more about exceeding energy performance and sustainability requirements without excessive costs, contact us.
