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VELUX calls for average daylight factor increase

VELUX is calling for the average daylight factor (DF) required in all new homes to be increased to improve the indoor environment for occupants and help cut carbon emissions.

Velux_logo_FMJ032013The call comes in light of early results from its CarbonLight Homes, designed by architects HTA, which have achieved an average of 7.5% DF in post construction testing.

The CarbonLight Homes were designed to be cost-effective for volume house builders and achieve an average 5% DF in every room. The target has been comfortably met in each of the two semidetached homes, with VELUX and architects HTA exceeding it by as much as a third in the homes’ living spaces.

Requiring house builders to build to more than the current 1.5% stipulated by the Code for Sustainable Homes (CSH) in living spaces and 2% in kitchens and establishing targets for bedrooms and bathrooms, where none currently exists, could significantly improve occupant health and reduce the need for electrical lighting.

Although windows play an important part in the CarbonLight Homes, the DF results have been achieved despite glazing only accounting for 25% of their total floor area. Instead, strategic positioning of windows, maximising glazing to the east elevation where maximum daylight can be achieved with minimal glare, open plan layouts, transparent materials and light diffusing colours to aid internal reflection have been used.

Paul Hicks, design manager at VELUX, said: “The current average daylight factor of 1.5% in living spaces is not conducive to creating an attractive and healthy indoor environment and certainly does not help occupants to reduce their reliance on electrical lighting. Our own research has found that rooms achieving 3% DF, double that required in living spaces as part of the Code for Sustainable Homes, may still need artificial light during daylight hours. We would urge a change in regulation and industry best practice if we are to succeed in building new homes that will be more beneficial in which to live.”

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