Rooflights & Skylights
The benefits of daylight to the building environment should not be under estimated. Research by the De Montfort University shows that natural light improves mood, concentration and creativity in people at whether at work, home or involved in recreational activities or education.
Vertical windows have their place, but light can only travel inside the building up to 6 metres or so where as a well designed rooflight system will capture light throughout the day regardless of the sun’s position and improve peoples’ well being and reduce energy costs.
The type of glass used in skylights can control the building environment. Solar control glass can reduce solar heat gain by up to 70% in the summer and low-emissivity coatings retain heat in winter, thus saving heating and cooling costs throughout the year.
Natural daylight is proven to enhance performance in pupils at school, reduce absenteeism in the work place and improve recovery of patience in hospitals. Many care homes are now building facilities for the elderly featuring a central atrium rooflight ensuring a healthy environment for less able elderly who may otherwise rarely venture out of doors.
So what options for rooflights are available to designers?
We describe a few common types of skylights below:
Rooflights for flat roofs are increasingly popular with the growth of the home improvement sector. More fashionable than a conservatory, most home owners are opting for flat roof extensions featuring bi-fold doors and additional daylight created by a flat glass rooflight to create an inside/outside day room. Flat rooflights are typically single pane or can be continuous and made up of several linking glass roof panels.
An example of a multi-pane flat rooflight can be seen below:
From time to time building owners require the rooflight to provide either ventilation or access to roof terrace or roof gardens. Hinged opening rooflights can be fitted with a variety of opening mechanisms including electric or manual gears for day to day ventilation or folding arms that open the skylight to 90 degrees allowing easy access to the flat roof. AOV Rooflights (Automatic Opening Rooflights) are also available for smoke ventilation and it is important to ensure any smoke ventilator that is designed to save lives has been tested to EN12101 and the necessary certification obtained for CE marking.
Extra strong glass can be specified suitable for walk-on skylights. These can be small single pane rooflights or larger multi-pane rooflights featuring re-enforced intermediate glazing bars to support the very heavy glass and pedestrian traffic. Most walk-on rooflights available as standard are only suitable for domestic use, so if the rooflight is in a public area where foot traffic is higher, then calculations should be carried out by a structural engineer to ensure the correct glass is specified to cope with the higher load.
Roof lanterns and skylights feature integral ridge and hip members and a cill section or ring beam for fixing to a curb or upstand on flat roofs. Various shapes and sizes are available including hipped, gable ended, octagonal, faceted or pyramid rooflights. Some feature glazing bars at regular intervals and some may be described as ‘frameless’ rooflights as larger glass panels are used and bonded with silicone rather than a conventional rafter section and capping. Some systems permit the addition of opening ventilators which may be manual or electrically operated and include control panels for remote or thermostatic control.
Large area glazing may still be referred to as a rooflight, but more often large glass roofs are better described as sloped glazing, roof glazing, inclined glazing or atriums. In the simplest form, patent glazing can be used to provide overhead glazing for stations, markets, canopies and walkways combined with single glazing for unheated spaces. Where the building is heated, then a thermally broken rooflight system is required featuring double or triple glazed units which can provide Uvalues as low as 0.6W/m2.K. Air-tightness is another important factor in rooflights as this enables better control of the building environment especially when low-emissivity and solar control glass is specified.