HTA Architects


Clancy Consulting, HTA Architects, Esbensen Consulting Engineers A/S


Willmott Dixon Housing LTD

Carbonlight Homes


The primary objective was to perform at a high level regarding the Code for Sustainable Homes without the use of photovoltaics or continuous mechanical ventilation with heat recovery. It was decided to use low-temperature radiators fed from a ‘buffer’ tank which is heated using a combination of solar thermal collectors and an air source heat pump.

  • Highly insulated building fabric with a ‘U’ value of 0.11 W/m2 °C for the walls, floor, and roof.
  • Very airtight envelope to achieve an air permeability through the structure of less than 3m3/h.m2 at an air pressure of 50 Pascals (50N/m2).
  • Triple glazed windows on the colder side (East elevation) to provide improved thermal protection and double glazed windows on the warmer side (West elevation) to take advantage of solar gain.
  • High levels of glazing to take advantage of solar gain and improved natural daylight.
  • Hot water and space heating using solar thermal collectors, air source heat pump, and mechanical ventilation with heat recovery.
  • Natural ventilation strategy all year round with mechanical support (with heat recovery) during the heating period.
  • Low energy light fittings throughout.
  • Automated window operation and blind control to reduce solar gain, prevent glare, and reduce internal CO2 levels.
  • All of the above to achieve a 70% reduction in CO2 emissions on-site, with the remaining 30% of emissions being offset using an agreed ‘allowable’ solution with the local government office.

The added challenge was to build to an East/West orientation to prove that you do not need a south-facing plot to achieve an optimum solution.


The houses are designed to Active House principles to provide a vision of buildings that foster healthier and more comfortable lives for their occupants without a negative impact on the climate – moving us towards a cleaner, healthier, and safer world.

The CarbonLight Homes are intended to be real homes for real people by putting the occupants at the heart of the design process.

  • The CarbonLight Homes have challenged the rules on space requirements and are around 30% bigger than the average size for a conventional 3 or 4-bed house in the UK.
  • Above-average daylight factor of 5% throughout, to improve health and well-being and to reduce/remove dependency on artificial lighting for everyday tasks. This helps to define the character of the building and creates a home bathed in light and in touch with the seasons.
  • Use of natural ventilation – utilizing natural fresh air is by far the healthiest way to ventilate a house, and it’s free!
  • The WindowMaster building management system will monitor the heat, light,  and CO2 levels within the dwellings and will automatically adjust the window and blind positions to suit the optimum indoor comfort levels required.

Hard floor surfaces throughout prevent pollutants from becoming trapped in floor finishes and reduces the incidence of allergies.


Active House design focuses on energy, indoor climate, and the environment to ensure that buildings contribute positively to human health and well-being without compromising the livability aspect.

The automation of the houses is designed to make intelligent use of nature, with high levels of daylight and plenty of fresh air. The view of the sky from inside the houses helps to promote a sense of well-being. Also, the form of the houses has created a ‘wide screen’ garden where the view of the sky from outside is increased by the slope of the main roof coming down to garden level.

Through the careful positioning of windows and consideration of the open-plan layout, the houses have been designed to re-connect modern life with the rhythms and patterns of nature. The garden area will be sympathetically laid out to act as an extension of the homes and not just ‘outside space’, thereby helping in our desire to bring the outside, inside.

Each house has a 3,500 liter rainwater harvesting tank under the back garden which is fed from the house roofs and will provide water for flushing toilets, running washing machines, and charging the fire sprinkler system should it be activated. The front driveways use a permeable paving solution which allows the rainwater to filter back through the ground and run off into the adjacent ditch course which connects to a local stream.

Modern homes should be places for modern lives that can respect and nurture our environment – encouraging families to spend more time at home, working, caring for the allotment, entertaining, or just relaxing.

The local government office already regards this project as a benchmark solution for all new-build housing in the local area, where 5,500 houses are due to be built over the next 10 years.

The key is to make the design as flexible as possible to accommodate the varied lifestyle choices that people make today.