Managing heat gain and loss though your roof windows

December 8, 2023

Skylights and roof windows, amazing for bringing extra light into dark spaces and opening up views to the inside of your home, but they also transfer heat and cold into your thermal envelope. This varies greatly depending on the time of year with amount of daylight hours, sun angle, outside air temperature etc.

We are governed for the most part by the New Zealand Building Code and Healthy Homes legislature but this can't hope to cover all scenarios and particularly if we are working with older, existing homes. Bearing all this in mind, what are our best options when we really want to open up our home from above while still staying weather proof and comfortable in our homes?

Size, orientation and location are the first obvious factors to consider and also having a good sense of the path of the sun throughout the year will help avoid any unwanted direct sunlight or assist with sunlight incursion when you DO want it. Once these have been decided upon, you should really only then be having to deal with glass specification and possible the addition of blinds. If direct sunlight can't be avoided into areas that need to be shaded then there are certain glass types that will help with both light and thermal transmittance to a minimum. There are several coatings and tints that are available along with the ability to use triple glazing, all helping to keep the inside of your home at a comfortable uniform temperature.

Having the skylight opening is also an easy way to help heat escape, along with built up steam in shower areas etc. There are various methods of opening and closing skylights and also ways to power them (solar etc). On electrically operated skylights, a rain sensor is always recommended.

Frame materials all have an influence on thermal transfer and are often the weakest component in the system. Modern manufacturing process and access to a wide range of materials has certainly broadened the market offerings and everything from traditional materials such as wood to PVC and composite, thermally broken products are all readily available.

If you are having second thoughts about getting a skylight installed due to uncertainties around how hot or cold your house may become, give us a buzz to help talk you through the options.

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