Solar Lighting: Concepts and Methods

Households usually use fluorescent lamps, and even incandescent bulbs for some, as a source of lighting. These devices consume so much electrical energy which is sadly a great strain to the bills of household owners. However, lighting can be achieved naturally instead of using electrical lamps. We can utilize a free and abundant source – the sunlight. (image source)

Solar lighting is a method of harnessing the light from the sun to provide illumination to a space. Sunlight is collected and distributed throughout an area using specialized equipment or through the structural design itself. It implies wise selection of window types, sizes and orientation. The energy-saving idea is very useful in places receiving ample sunlight since no electricity is utilized to light up a space during the day. Individual features include clerestory windows, skylights and light tubes.

Clerestory windows are high, vertically-placed windows. They are used to increase direct solar radiation or to admit diffuse daylight that evenly lights up an area such as an office, classroom, or supermarket. Most usually, the inside space of where clerestory windows are installed is painted white or another light color. This reduces the direct effect of sunlight to make it softer and more diffuse.

Skylight is any horizontal window installed at the roof of the building. It is also termed as roof lantern or oculus. The optimal area of skylights is usually 4-8% of floor area, but it can vary according to climate, latitude and the characteristics of the skylight. Skylights admit more light per unit area than common windows, and distribute it more evenly over a space. During warm seasons, skylights can cause increase in heat to the space so it is best to place white translucent acrylic over or under the transparent skylight glazing. Moreover, poorly constructed or installed skylights may cause leaking problems and condensation problems. (image source)

Light tube or solar tube resembles recessed ceiling light fixtures and is place into a roof and admits lights to a focused area of the interior. They do not allow as much heat transfer as skylights because they have less surface area. The tube itself is a passive component consisting of either a simple reflective interior coating or a light conducting fiber optic bundle. It is frequently capped with a transparent, roof-mounted dome “light collector” and terminated with a diffuser assembly that admits the daylight into interior spaces and distributes the available light energy evenly. (image source)

Other features that introduce solar lighting include installation of light reflectors, light shelves, sawtooth roofs, smart glass, and solarium.