“Light is not only an amount of energy,” says Marilyne Andersen of MIT’s Department of Architecture. “It also provides us with the means to reveal spaces and volumes and interact with our environment.”
Andersen and others in the Building Technology Program have been working on how to better incorporate natural light into building design, recognising that natural light has many positive effects – including considerable financial savings in energy bills as well as benefits for occupants’ health and wellbeing. According to their findings, natural light improves mood and health by regulating human circadian rhythms, for instance. “Natural light is one of our biological needs. Intuitively, we prefer daylight to electric light,” she says.
In South Africa the new energy efficiency standards for buildings establish a further motivation for greater use of natural light, if only to reduce energy usage.
Christo Pienaar, a director of the Ampaglas Plastics Group, says that architects worldwide are making use of translucent materials – not only glass but plastics as well – to light up homes, offices and warehouses. New Zealand firm Mitchell and Stout specified translucent plastic to build a roof and walls resembling a sail in an eco-friendly beach house in Auckland. Narrow Neck House won a 2009 New Zealand Institute of Architects award. The concrete and plastic-winged house, with flaxes growing on the roof and a studio folly, evolved from the owners’ objective to deal with the principles of sustainability “in a poetic way”. Plastic roofs that extend from the house like wings create privacy and protection. “By bringing in natural light from all sides, along with timber accents and tiled floors, the interior spaces take in and respond to the views beyond,” the award judges stated.
Pienaar also cites New York firm Stamberg & Aferiat’s colourful and award-winning Shelter Island Pavilion which incorporates polycarbonate walls and roof sheeting. The polycarbonate allowed for greater transmission of light and provided great flexibility in design.
In South Africa, translucent materials can also reduce electricity costs quite significantly by letting natural light through to interior spaces. Pienaar suggests that unless there are specific reasons for artificial lighting, designers should always assume that natural lighting will be the primary source of light during daylight hours, in order to reduce energy wastage. He points out other benefits too: the “perfect white light” that natural lighting provides creates an atmosphere of warmth, openness and tranquillity.
It is said that horizontal rooflights provide two and a half times more light than vertical windows as they are not obstructed by trees, buildings or other structures. They also provide occupants with views of the sky and the movement of the sun through the day.
Pienaar recommends that rooflights should be installed where vertical windows with views are not possible. “Rooflighting can also be used to balance other sources of natural light. For example, a rooflight can be installed above the furthest wall from a window to even out natural light, or central rooflights can be installed to give consistent light distribution,” he says.
Rooflights can be made from any translucent material, but polycarbonate is one of the most popular. It has high impact resistance, high levels of light transmission, high levels of UV resistance, good fire resisting properties and is available in a wide range of clear, tinted and opaque finishes. Polycarbonate can also be supplied with a co-extruded UV protective layer that eliminates up to 95% of ultraviolet radiation.energy efficiency green buildings indoor environmental quality natural lighting in buildings roofing and cladding rooflights sustainable buildings translucent plastics