CarbonLight Homes, Kettering, UK

For the first Active House in the UK, the VELUX Group envisioned a design that would serve as a model for future housing by offering a comfortable, sustainable living environment that could enhance quality of life. The buildings would ideally reduce energy use, advocate a respect for the environment, and be sympathetic to local aesthetics.


Energy-efficient, sustainable – and affordable

Completed in 2011, the state-of-the-art CarbonLight Homes in Kettering, Northamptonshire, were the first homes designed and built to meet the UK government’s Zero Carbon Standard for Homes.

The two semi-detached homes offer proof that building energy-efficient, sustainable housing that is a joy to live in is not only possible, but also affordable. The homes use the latest technologies and offer comfortable living environments with indoor climates that have a positive impact on biological rhythms, well-being and performance.

In accordance with core Active House principles, the CarbonLight Homes actively integrate energy, indoor climate and environment in their design. As a result, the homes have succeeded in minimising energy use, increasing a sense of environmental responsibility, and generating a sense of community. And while the design aesthetics harmonise with the homes’ surroundings, they also have an appealing, modern identity of their own.

You see new houses and it’s all brick with tiny little windows and you think: ‘It must be so dark in there’. Living here has changed our perception. What [other] people consider light is not what we consider light."

Photos: Adam Mørk

Architect: HTA Architects

Illustration of light coming through roof windows

Key design elements and achievements

Ample daylight

The starting point in the CarbonLight Homes design process was to maximise daylight. Through extensive modelling, the architects at the London-based firm HTA achieved an excellent minimum average daylight factor of 5% throughout the house.

The homes’ window-to-floor ratio is 1:4 and includes an impressive view of the sky. The many façade and roof windows are equipped with blinds and shutters to keep daylight levels and temperatures comfortable no matter the weather or season.

An efficient hybrid ventilation system

The CarbonLight Homes rely on natural and mechanical ventilation to ensure a comfortable indoor climate full of fresh air year round.

In the summer, natural ventilation is used for cooling and to create air movement that pushes stale air out, brings fresh air in, and maintains good levels of thermal comfort. Together with external sun screening, natural ventilation also ensures a comfortable room temperature. Here, the many façade and roof windows play a key role – particularly in the three-storey atrium around the stairs, where the windows allow fresh air to circulate both across and in a stack effect. And in the summer, the windows can be opened and the homes cooled through purge ventilation.

During the winter, a mechanical ventilation system with heat recovery supplements the natural ventilation system, extracting heat from the kitchen and bathrooms and recycling it into the home to reduce the demand on the heating system.

Minimal energy consumption

The sun provides nearly all of the energy for the CarbonLight Homes’ hot water and heating, and the houses are designed to reduce fossil fuel energy (such as electricity) to a minimum.

With their solar collectors and air-to-water heat pumps, the CarbonLight Homes achieve a 70% reduction in CO2 emissions. The remaining 30% of emissions are offset through agreements with the local government to improve the energy efficiency of other homes in the area. This ensures that the CarbonLight Homes surpass their required 100% reduction in CO2 emissions.

Intelligent, automated controls

The CarbonLight Homes’ windows, solar screening and heating systems are controlled by the sophisticated, automated Building Management System, which reduces energy consumption and ensures a healthy indoor climate.

Daylight factor

An avarage DF below 2% generally makes a room look dull and electrical lighting is likely to be frequently used, whereas an interior will look substantially daylit when the avarage DF is above 5%

Simulations were made by the VELUX Daylight Visualizer 2, a software tool dedicated to daylighting design and analysis. For more details and download, visit

Floor plan with daylight factor visualized


The CarbonLight Homes have been developed in a strategic partnership between the VELUX Group, HTA Design, the Kettering Borough Council, Willmott Dixon, and the North Northants Development Company. Product partners WindowMaster, VELFAC, Drexel und Weiss, and SONNENKRAFT have also contributed to the house.


CarbonLight Homes emerged as the winner of the Innovation Award for Building Technology at the prestigious British Homes Awards (BHA) held in Central London in 2013.