Double versus triple glazing

There’s a debate around the need for triple glazing on the side of the house that’s facing south. Some argue that double glazing is more effective in areas that are most exposed to the sun while others say triple glazed should be installed all around. Here are the pros and cons.

If you have a restricted budget but wish to consider triple glazed windows as part of a new build project, then a sensible approach may indeed be to use triple glazing for the northern elevations where there is no opportunity of solar gain, with a combination of triple and double glazed windows on the remainder of the dwelling.

If increasing solar gain into your home is of interest and benefit to you in terms of your heating strategy, double glazing should be selected instead of triple glazing on the southern elevations. This is because double glazing allows more light and heat to filter through.

On the flip side, triple glazing will be better at limiting the potential for overheating within the room. It follows that where heat loss is your primary concern in relation to your home, then triple glazing should be selected instead of double glazing.

Whether you choose double or triple glazing, if you plan to have extensive glazing on the southern elevations, you will need a solar shading system externally to reduce overheating in the summer months.

In an existing home, before you choose triple glazing consider a whole house insulation strategy so that any heat loss benefits that are achieved by using triple glazing are not lost due to poor insulation standards elsewhere in the home.

To make your final decision you will need to rely on the DEAP (ROI) / SAP (NI) analysis of the overall design of your home. This will accurately compare the difference that including either double or triple glazing shall make to the final energy consumption of your specific house.

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Aleyn Chambers

Written by Aleyn Chambers

Aleyn is an Architect and certified Passive House designer based in Dalkey, Co Dublin.

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