Getting Technical



Light transmission – five factors you should consider

Rooflights can provide much more light than windows, and deliver more usable light into a building, particularly in large structures and enclosed areas that cannot be lit through a window.

When installing rooflights, there are five important factors to consider for an effective daylighting plan.

  1. Direct vs diffused light
    Direct light passes through transparent materials such as glass and polycarbonate. Diffused light is scattered through purpose designed diffusers or translucent naturally diffusing materials such as GRP.
  2. Light transmission
    Different rooflight and insulant materials provide very different levels of light transmission. It is important that the total rooflight assembly performance is properly taken into consideration.
  3. Intended building use
    Windows and wall lights become ineffective at distances over 6m into the building where daylighting through rooflights located for optimum effect then become the most effective method.
  4. Energy saving
    In newer buildings where excellent thermal performance is now being achieved, the most significant savings in operational energy can be gained by using the free resource of natural daylight.
  5. Solar gain
    There should be limits on the level of daylight. For any building there is a light level that will give optimum building energy performance without causing excessive heat gains.