Single vs Double Glazed Skylights: The Difference Thermal Performance Makes.
While replacing single glazing with double glazing where I live, it became the inspiration for this article.
Over the years, we’ve come across many homes with large, single glazed overhead and architectural skylights.
I remember one elderly customer in Grey Lynn with skylights approximately 1.8 x 3 metres, and another home in Remuera with a large skylight above a sweeping stairwell overlooking a park.
These older skylights were often cleverly designed for their time. An air gap at the base allowed the skylight to ventilate, helping reduce condensation.
The problem is that what helps with condensation can be terrible for thermal performance.
Great for tomatoes not so much for you
In winter, warm air naturally rises through the house towards these large areas of cold glass. With single glazing and permanent ventilation, a significant amount of that heat can be lost.
In summer, the opposite problem occurs. Solar energy coming through a large expanse of overhead glass can create a glasshouse effect.
Great if you’re growing tomatoes. Not so great if you’re living underneath it.
Both homes I mentioned struggled to stay warm during winter. Residents would close off their main living areas and dress for what sometimes felt more like the outside temperature before heading upstairs to their bedrooms. Air Conditioners running with there associated cost.
The difference better glazing can make
In both cases, upgrading these large skylights to insulated double- or triple-glazed systems dramatically changed how the homes felt.
We observed temperature improvements of approximately 7°C in one home and 9°C in the other following the glazing upgrades.
Every building is different, and glazing is only one part of a home’s overall thermal performance, so those figures shouldn’t be taken as a guaranteed result. But they demonstrate just how influential a very large area of overhead single glazing can be.
Modern glazing also gives us considerably more options. Depending on the skylight, we can look at insulated glass units, low-E coatings, double or triple glazing and glazing specifications designed to manage both winter heat loss and summer solar gain.
Have a large or unusual skylight?
Changing the glazing in a large architectural skylight isn’t simply a matter of replacing one piece of glass with another.
The additional glass weight, existing frame, drainage and condensation management, ventilation, glass safety requirements, thermal movement and the original watertightness design all need to be considered for the type of roof Ashfelt, Tile, Metal (various types) , Shingle
If you have a large, older, custom or architectural skylight and are considering upgrading from single glazing, reach out to Auckland Skylights.
Through our Architectural Skylight Service, we can inspect the existing system and provide independent advice on whether refurbishment, double or triple glazing, modification or replacement is the most appropriate solution.
Auckland Skylights installers and independent advice for skylights, natural light and ventilation
solutions.
09 4409820
