St. Modwen Homes completes construction of first affordable carbon negative homes delivered by a major housebuilder

St. Modwen Homes has launched two brand-new carbon negative properties at its Heathy Wood development in Copthorne, making it the first major housebuilder to have developed and completed affordable homes of this kind.

The homes are part of a trial that will demonstrate the potential to deliver some of the most energy efficient and commercially scalable properties in the world.

The three-bedroom homes are designed to produce more energy than they consume and could reduce a family’s total energy bills by 52%* when compared with a standard new build house and around 79% compared with the average UK home.

St. Modwen Homes completes construction of first affordable carbon negative homes delivered by a major housebuilder image

Simple improvements to building fabric, insulation, and ventilation have transformed the efficiency of the homes compared to traditional builds, with the properties 10 times as airtight as industry standards**. The homes are also fitted with photovoltaic solar panels, a battery, an electric vehicle charger, an air-source heat pump, a smart hot water tank, heat recovery ventilation and a wastewater heat recovery unit to minimise energy use and reduce emissions.

Due to the shift in reliance on fossil fuels to usage of electric-powered technology, the homes are also capable of delivering a 125% reduction in CO2 emissions compared to current standards.

The homes are built with a timber frame and the foundations have been formed using low-carbon concrete, meaning the embodied carbon has also been reduced from the outset.

Dave Smith, Managing Director, St. Modwen Homes, said: “With energy prices continuing to rise, creating energy-efficient homes that are affordable to build is more vital now than it ever has been.

“As an industry leader in using low-carbon modern methods of construction already, we have a responsibility to use this experience to prove that carbon negative houses can significantly cut energy bills and reduce emissions. Over the course of this year, we will be analysing the results of this latest trial to aid us in our objective to build these new homes at scale for the benefit of homeowners and the environment.”

St. Modwen Homes completes construction of first affordable carbon negative homes delivered by a major housebuilder image

The first of the homes were completed in April 2022.

Working in partnership with British Gas, the homes will be fitted out with Hive Smart Home technology. This will include elements like a Hive smart thermostat and smart radiator valves to enable the household to control their usage. British Gas has also installed an electric vehicle charger for further energy efficiency outside the home.

Jana Siber, Managing Director at British Gas said: “Partnerships like this are an essential part of the UK’s journey towards a decarbonised future. While on a small scale at this stage, we are exploring how we can help customers lower their carbon emissions using smart technology. The need to provide carbon neutral homes has never been greater. That’s why we are working with companies like St. Modwen and why we’ve committed to training 3,500 apprentices over the next decade, many of whom will gain specialist green skills to support with the demand that’s coming.”

St. Modwen will be analysing the results of the trial over the course of 2022.


* Based on a St Modwen three-bedroom Standard Specification home

** One of the key requirements of the Passivhaus standard is a maximum air leakage of 0.6m3/m3/h. A standard new build house would typically have an air leakage of 5 to 6 m3/m2/h, but it is permitted within current Building Regulations to have an air leakage of up to 10m3/m2/h. Please note that the Passivhaus requirement is not measured in exactly the same way as the standard Building Regulations requirement.

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