Maximise natural light without the risk of overheating – the perfect solution for every room in which we live or work. Careful window specification is key to achieving this goal, and will help deliver the ideal indoor climate.

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Building envelope design determines up to 90% of a building’s energy consumption. At the same time, we spend approximately 90% of our lives indoors. It’s therefore vital that a building is designed to both reduce energy use and deliver a good indoor climate.

Architectural tools to help optimise visual indoor climate

Let daylight into every room

  • Window area should equal 25-40% of floor area

  • Large windows and windows installed at height provide the opportunity for better light distribution

  • For maximum light reflection, specify light coloured frames


Exploit window orientation and uninterrupted views

  • Allow daylight into a building from every direction, especially through windows installed at height
  • Avoid placing transoms or glazing bars within the field of view


Bringing daylight and energy into a building are among the most important functions of a window, and the greater the glass to frame ratio in the window unit, the greater the benefit of both. VELFAC windows feature a slim frame resulting in a high glass to frame ratio and a significant increase of light and energy. At the same time, the shape, size and position of every window within a façade will have a significant impact of the distribution of daylight across every room.

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