Using rooflighting for lighting
Rooflights are a good way to introduce natural light for lighting purposes. When deciding on how many rooflights to install and what material to use, it is important to take into consideration various factors such as the size of the building, what it is used for, the type of lighting required (direct or diffuse), the brightness of light required and how that relates to heating, as well as the automation of artificial light sources.
The question of whether a building should have rooflights, and if so to what percentage of the floor space they should cover, is largely determined by the size of the building. For smaller buildings vertical glazing (windows) is generally sufficient to provide areas within six metres of the window with enough light.For larger buildings, where there are fewer external windows relative to the building’s operational floor area, rooflighting or a combination of both rooflighting and wall glazing is needed. If well planned, rooflighting can provide exactly the amount, type and distribution of natural light required to meet any given building’s requirements.
The use of a given building will determine the required level of light, and whether this will be measured horizontally or vertically.For manufacturing environments and office spaces, the tasks being illuminated are usually on a horizontal plane, so it is usually more appropriate to measure light levels horizontally.For some applications (eg storage facilities and racking), the illumination of vertical surfaces is more relevant and light levels should then be analysed vertically.
In any given building the vertical illuminance levels are generally lower than the horizontal, although lower light levels are often more acceptable for tasks viewed vertically (such as storage facilities) than those viewed horizontally.