56 RCI 0714

RCI JULY 2014

ROOFLIGHTS & ROOF VENTS Brightening the day with rooflights The sun is out, and the (mostly) glorious summer days are in full swing. But with the sunlight comes the age old question, how can we make the most of this natural light? And what exactly are the benefits? This light has travelled on average 150 million kilometres from the sun, so why not fully welcome it into the workplace? A wide belief exists that natural daylighting is highly beneficial – not just to productivity but to the health and wellbeing of workers, children in schools and more. Natural light is constantly shifting in intensity, direction and colour which all provide passive stimulation for the eyes which can lead to higher serotonin and hormonal levels improving the feeling of wellbeing. In addition, cost savings as a result of natural daylight compared to artificial light are well documented, which is enough for anyone to feel better! That being said, natural daylight is not without its faults. Namely the sunlight glare and solar heat gain coefficient (SHGC). The SHGC is the amount of heat that enters a building as a result of solar radiation, while useful during the colder months, a high SHGC value during the summer can potentially lead to overheating and worker discomfort. While windows or vertical glazing are still a viable method – and in some cases still the best method – of allowing daylight in, natural light can only reach six metres from a window into a room, however where glass windows fall short, in my opinion polycarbonate skylights can excel. Naturally transparent, UV resistant, lightweight, and cost effective; in addition to providing a diffused natural light throughout a room, polycarbonate is a highly versatile material. The diffused light can be achieved through the use of ‘opal’ glazing – a milky white material which reduces the harshness of direct sunlight and 056 JULY 2014 RCIMAG.COM By Robert Fletcher, technical marketing, Surespan evenly diffuses it throughout the room. This makes them ideal for classrooms and small offices whereas clear glazing provides the most amount of light, ideal for higher ceilings. It is this diffused natural light which can have the most positive effects to health and wellbeing. A study carried out by the Heschong Mahone Group in 1999 displayed results consistent with a 20% increase in student performance in Elementary schools that used a well-designed rooflight (one which diffused the light throughout the classroom and allowed control over the amount of light e.g. fig 1). These results have been echoed throughout various sectors in industry; for example similar studies have concluded that the presence of skylights in consumer shops was the third most important criteria contributing to increased sales volume. (Heschong Mahone Group Inc, 1999) What is a well designed rooflight? So what can be described as a ‘well-designed’ rooflight? The first thing that must be understood are the various sky conditions. Generally speaking there are three main types; overcast skies, partly cloudy and clear skies. Each type brings with it a different form of lighting. The diffused light mentioned throughout this article is naturally occurring during overcast skies, however due to the reflectance of clouds, direct overcast light from above is three times brighter than horizontal lighting, whereas clear skies are three times brighter on the horizon. However, as skylights capture light from directly above, during winter solstice they operate at a reduced effectiveness due to the lower position of the sun. With this information, the negative impact of rooflights such as direct glare and the reduced effectiveness can be largely avoided. Take for example a skylight installed near a north facing wall (fig 2) – on a clear day, the powerful horizontal sunlight coming from the South will be reflected off the North wall into the room, producing an evenly diffused light while avoiding glare if the rooflight was installed closer to the south wall (fig 3). Negative effects can also be mitigated in the rooflight itself through using opal glazing, multiple layers, and other modern designs such as Surespan’s evenly distributed layers, the rooflight can be tailored to specific job roles. These designs not only lend themselves to better noise isolation but better thermal efficiency as well, ideal for winter months. Further to reducing costs, older rooflight designs can be easily replaced with newer Surespan lids using the existing upstand and requiring no change to the roof structure. CE Marked Further advantages of Polycarbonate rooflights come in the form of their multiple functions including Smoke Ventilation. The importance of CE Marked NSHEVs and AOVs cannot be overlooked when specifying. The legislation which came into effect a year ago, ensures that products sold have gone through rigorous testing in a wide range of conditions to ensure a high standard of quality which will never fail. As a member of NARM, at Surespan we have invested heavily to raise the bar for thermal efficiency and safety, particularly in skylights, in order to meet and exceed current regulations. Rooflights truly offer multi-purpose utility providing natural daylight, daily ventilation and smoke exhaust, all available in a wide variety of sizes and shapes. Working with Surespan, during the early specification stages will pay dividends in maximising energy savings, lighting and workplace productivity while still achieving regulatory compliance. www.surespanrooflights.com Above: (fig 1) Opal diffused rooflight with electric blinds for controlling light Above top (fig 2) well designed lighting. Below (fig 3) poorly designed lighting


RCI JULY 2014
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