Is a glass extension cold in winter?

One of the questions we are often asked when talking to people about our glass extensions is: Do they get cold in winter?

Mention a home extension – especially one that’s fully glazed – and many people immediately think of those old, draughty conservatories that have become the stereotype of all that’s bad about adding a new room to your property. You know the ones – too cold in winter and too hot in summer. Basically, something that extends your living space but ends up being pretty much unusable for a large part of the year.

Thankfully, times and technology have moved on and there are some excellent alternatives to the conservatory of old. There are even some extensions made almost entirely of glass that can offer outstanding climate control and enable you to use your lovely new room all year round. Here, we take a look at how – and it’s thanks in large part to something called a thermal break.

Is a glass extension cold?

A thermally broken glass extension doesn’t get cold in winter and will function like any other room in your home, meaning it can be used throughout the seasons. A glass extension that is thermally broken and is made from high performance glazing has excellent thermal properties which help maintain the indoor temperature.  As with any room in your home, you may wish to add heating, ventilation or shading options to your glass extension, but its thermal break will ensure that it won’t get cold in winter and it will also stay cool in summer.

What does thermally broken mean?

‘Thermally broken’ is a term that applies to the metal frame of a glazing system. Aluminium doors and windows have become a popular choice among homeowners, particularly when installing bi-folding doors and sliding doors. This is because aluminium is extremely strong and so is able to support large moveable walls of glass with just a slim frame and narrow sightlines. The development of aluminium doors and windows has opened up the possibilities for homeowners to create amazing, modern light-filled spaces that offer expansive and unobstructed views of their outside space.

However, aluminium is a highly conductive metal and therefore does not have the best insulation properties, which means warm air can be lost through it and cold air allowed in. This is why it’s important to ensure that your doors and windows are thermally broken to keep your room at an optimum temperature and improve the energy efficiency of your home. A thermal break can also help minimise condensation in warmer rooms.

How is a thermal break created?

A thermal break is a barrier that stops the movement of heat through the aluminium frame of a door or window. A material with low-conductivity (such as polyamide or polyurethane plastic or fabric) is placed within the aluminium frame during the manufacturing process. This stops the movement of heat and cold through the metal, isolating the outside temperature from the inside space. It can also help to make the aluminium frame stronger.

Consider your glazing

If you are looking for greater thermal efficiency, consider the quality of your glazing too. Regardless of the kind of frame they have, doors and windows are one of the biggest sources of energy loss from homes.

Double and triple glazing will further increase the energy efficiency of your glass extension, and in some cases can help it to meet Passive House standards. The U values of the doors and windows in your glass extension will give you an idea of the thermal performance of the glazing – for Passive House the U values need to be as low as 0.8 W/m2k. However, for glass extensions, you should look at the Uw value, which more specifically indicates the thermal performance of the whole structure, glass and frame included.