The daylight factor is a quantitative measure of the amount of natural light that reaches a specific point in a room, expressed as a percentage. It is calculated by comparing the amount of daylight available indoors to the amount of daylight available outdoors under overcast sky conditions.
In the context of UK housing, the daylight factor is crucial for habitable spaces, as it directly influences occupant comfort, health, and wellbeing. Adequate natural light reduces reliance on artificial lighting, enhances mood, and can contribute to energy savings. Building regulations often specify minimum daylight factors for different types of rooms to ensure adequate lighting levels.
For instance, in a newly built residential flat, an architect may design living areas to achieve a daylight factor of at least 2% to ensure that the space is well-lit. This is typically assessed during the planning stage using software simulations that model light penetration based on window sizes, orientations, and surrounding obstructions. If the calculations show a daylight factor of only 1.5%, the architect might need to increase window sizes or adjust the layout to meet the regulatory requirements.