Skylights are now also rated by the Skylight energy rating system, and 5-star energy efficient skylights are available. The rating calculates the performance of the unit in winter and summer.
The WERS (Window Energy Rating System) for Skylights provides you with an energy rating analysis and comparison. The scheme takes account of key differences between the energy performance of windows and skylights and how your home will respond to the different units.
However all skylights are not created equal, and if you are after a truly energy efficient skylight, dont just settle for double glazed. After talking with past and present leaders of the Skylight Institute Association, it seems that there are really only three brand names that offer independent verification of a high quality energy efficiency rating. These are Atlite, Velux and Skydome.
WHICH SKYLIGHT TYPE IS BEST FOR YOUR HOME?
When choosing skylights you can select between a sky window, which opens up for ventilation, or a skylight/dome light. Depending upon the manufacturer of the skylight, these may have slightly different names.
Sky windows are particularly suited to rooms that have a cathedral or raked ceiling but no roof space. Having an openable sky window is great for warm summer months to release heat that gathers at the ceiling
Double-glazing and the use of selective low-e coatings reduce solar transmission. The use of a sealed IGU (industry talk for insulated glazing unit) allows the option of argon gas in the gap instead of air, which reduces further still the heat transfer through the unit.
Sky window frames can be timber with external weatherproof aluminium cladding, but may also be made from aluminium or steel construction. In cool and alpine climates, uninsulated metal frames are not recommended because of the condensation they create.
Sky windows can also be combined with shafts in homes that have flat ceilings. This can help create a sense of space and grandeur in a home. However, remember that shafts for skylights cost more because they need to be framed out, plastered and painted.
Dome skylights typically have long shafts and a diffuser panel fitted at ceiling level. Ensure that the shaft walls are closed/lined and insulated so not to act as a giant hole in your ceiling insulation.
Tubular skylights reduce absolute heat loss and heat gain because of their small cross-sectional area. This lighting effect relies on the units ability to capture direct-beam sunlight and diffuse it at ceiling level around the room.
They will work best in your home only if your climate has a high incidence of clear, sunny days. On cloudy days the amount of daylight admitted is considerably less than for a large-area, conventional skylight.
A reflecting tube is used to direct sunlight downward. Generally, the best results are achieved by a straight tube with a silvered lining. The flexible tubes can be effective provided their internal reflectance is high. Diffusers are used at the ceiling level of tubular skylights to reduce glare and spread the light over a broad area.
But how do I get the most energy efficient skylight?
Energy-efficient technologies used in modern windows are generally able to be applied to skylights. Simply because the skylight is more vertical, a skylight can let in over three times as much light as a vertical window of the same size.
High Performance double glazing features can include low-E coatings for increased energy efficiency plus a laminated pane for added safety and protection from fade-causing UV rays. Efficient skylights will also provide a reduction in the noise that they transmit.
Incorporating high performance double glazing and internal blinds can reduce the UV light and infra-red heat transmitted through the skylight by up to 95%
You can select your skylight type to prevent undue heat loss or heat gain. And this selection is determined greatly by your climate. Not only whether you are in Townsville or Beauty Point, Tasmania, but also the cloud-cover for your region.
Yes, but it doesnt have to be a 5-star skylight does it?
In most cases skylights are usually only a few percent of the floor area, compared with around 20% for typical windows. So depending upon the location in your home of the skylight, and a number of other specific factors, it is true that the effect of installing a skylight in your home may only result in a minor loss of the total energy required for heating and cooling.
However there is a big BUT.
If it is a poor quality skylight, that doesnt suit your climate and it is installed badly it will be a burden. And you will know it every single time you look at it.
What type of skylight is best suited to my local conditions?
Four key components to determining the right skylight for your location are:
Do I live in a hot or cold climate?
The angle of the sun in the sky (different in Tasmania to Rockhampton)
The amount of overcast versus sunny weather at your place
Are there high levels of air pollution and haze?
The Your Home technical manual suggests that Locations with a high incidence of cloudy skies are better served by roof windows or conventional skylights with large areas and diffuse glazing systems. In sunny locations tubular skylights deliver very high illumination levels when the sky is clear.
Where to now?
To get the best result when selecting and installing a skylight:
1. Find a reliable and knowledgeable supplier of skylights in your region.
2. Select a product that suits your climate and home.
3. Select a skylight that is well rated by the WERS rating system
4. Have it installed by a professional that guarantees their work