The Hitchhikers Guide to Skylights
Daniel Jillings, Glazing Vision (Pty) Ltd, Cape Town, 2nd November 2004
Glass Rooflights or Skylights are not just functional day-lighting products but an architectural design feature with a host of benefits. Skylights not only provide the most effective route to natural daylight whilst offering an extension to the visual volume, they can also be a source of ventilation, roof terrace access, or an indulgence into the open-air living experience. For comfort and energy efficiency the ingress of daylight must be controlled in accordance with the seasonal ambient conditions, achieving the optimum balance of light and heat transfer.
The best way to ensure maximum daylight, whilst controlling condensation, solar heat gain and internal heat loss is to employ double-glazing with a low emissivity coating. The double-glazed unit comprising of 2 glass panes hermetically sealed with an air gap between. The use of high performance glasses will reduce glare and heat gain but also the level of light transmission, hence the demand for a variable system of either internal or external mechanical shading from blinds or louvers.
The addition of light, sky views and fresh air to living spaces can transform the quality of both home and work environments, but only if the correct product is selected.
Determine the function
Daylight, ventilation, access or ambience?
Source and select the Product
Skylight glazing is a specialist business; the industry is awash with improvised solutions, ageing defects are prevalent resulting from poor quality design and materials. Choose a professional company with a proven product and track record in the industry, websites are a good source for this information, recommendation is the best of all. The decisions:
Cost: Budget may be the deciding factor. The least expensive solutions are standard products in standard sizes, the cheapest range of materials are the plastics. For a comparison of these materials, visit Our Glass vs Polycarbonate Comparison Page The most expensive will be those bespoke designs with high performance glazing and integrated solar and lighting control. The more shape and function the higher the cost will be.
Design: Functionality versus aesthetics.
Why Double Glazing?
• Thermal insulation
• Noise insulation
• Increased security
• No condensation
SkyLight Selection
There are many options available for skylights, in terms of function and aesthetics. Your specification would depend on many factors, which would narrow down the choice to the ideal product suited to your criteria.
Roof Type
Roof type: Flat roof, pitched roof. For a flat roof there are normal flat skylights, pyramid shaped, vaults, extended hipped pyramids. For Pitched roofs one could specify a fixed skylight or the new ridge type skylight which brings light in from the roof ridge apex and creates an impressive internal feature. (GV: Flushglaze range, Skyline and Ridge Flushglaze)
Ventilation or Access
Should the skylight be open-able to provide ventilation for the interior space? Would the skylight be an access point to roof for maintenance? There is a range of opening systems both manual and electric, which address these needs. (GV: In-Vent & Skyglide).
Options Include
1. Trickle ventilation - fixed unit with louvers to allow natural airflow
2. Hinged ventilation - Skylight unit hinges open on one end using a manual or electric opener.
3. Sliding open - Skylight sits flush on a runner system and slides horizontally to open. Usually with electronic motor automation.
4. Access - The opening skylight can be used as a multi-functional access point to roof terraces or simply as maintenance access to a roof.
Architectural style
Where the architectural style of the building is distinctive and sightlines, forms and materials denote a constant theme, the skylight should either contribute to this aesthetic or have unobtrusive framework to allow for a seamless merging. A system that has no internally visible framework, is the most versatile.
Amount of light/shading
We have already covered the benefits and reasons for using double-glazing insulated units. The issue of how much light is required can be resolved by the following:
1. Size of skylight opening. Glazing Vision has a unique Flushglaze? system which allows for large continuous spans. Glass fins can provide an attractive means of support for very large spans.
2. If light transmittance needs to be controlled, there are options of tinted or reflective glass or integrated internal pleated blind systems . (Glazing Visions Inte75-Kerb )
Shape
Normal flat, pyramid, hipped pyramid, eaves, octagon, these can all be done with glass. Shapes like domes and vaults usually require polycarbonate to allow for curved shapes.
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