Plenty of glass, little heat: “Good insulation does not automatically mean good solar control”

We have once again experienced an exceptionally warm summer. Prolonged periods of heat are likely to occur more frequently in the coming years. Anyone building or renovating today must therefore think not only about keeping heat in during the winter, but also about keeping heat out during the summer. Especially with large glass surfaces. We asked Gert Gijbels, Sales Manager at Group Ceyssens, how solar control glazing can make a difference.

Large glass surfaces are popular. Does that not automatically lead to more heat in the house?

Gert: “That is a question we receive often. Large glass surfaces bring in a lot of light and create a sense of openness, but they also naturally let in solar heat – unless you choose our solar control glazing, of course. This is particularly significant on hot days for windows with a southern or western orientation.

That is why, when choosing glazing, you should not only look at insulation. You must also consider how much solar heat the glass allows through. Especially in minimalist architecture, where glass often occupies a large part of the facade.”

Many people today already choose double or triple glazing. Is that not sufficient?

Gert: “Double and triple highly insulating glass are primarily important for limiting heat loss. In winter, you want to prevent heat from escaping your home through the glass. For that, you look at the insulating performance of the glass.

In summer, the opposite problem arises. Then you want to prevent too much solar heat from entering. Insulating and solar control are therefore two different performances. A glass can insulate excellently without necessarily providing sufficient solar control. With large glass surfaces, you must carefully coordinate both properties.”

How exactly does solar control glass work?

Gert: “With solar control glazing, a specific coating is applied to the glass. This coating limits a portion of the solar heat that enters through the glass. As a result, a room heats up less quickly during sunny days.

The interesting thing is that you retain the great advantage of glass. With minimalist windows, you want as much natural light and an unobstructed view as possible. With the right solar control glazing, you can combine that transparency with much better summer comfort.”

Do you not lose light or transparency with solar control glass?

Gert: “That is certainly not necessary. The technology has evolved significantly in recent years. Today, there are various coatings and glass compositions that allow you to limit solar heat without compromising the minimalist character of the window.

That is why it is important not to simply choose ‘solar control glass’ in general. You must look for the right balance between light entry, transparency, insulation, and solar control. That balance differs from home to home.”

Does solar control glazing also influence energy consumption?

Gert: “Absolutely. Many modern new-build homes today use a heat pump that can also provide cooling. If a home heats up significantly due to the sun, that installation must work harder to keep the indoor temperature pleasant. And that costs energy.

With solar control glazing, you tackle the heat before it even enters. This reduces the cooling requirement. This translates not only into more comfort but also into more manageable energy consumption during hot periods.”

What kind of solar control glazing does a home need?

Gert: “There is no standard answer to that. The correct glass composition depends on several factors: the orientation of the windows, the size of the glass surfaces, the design of the home, and the thermal performance you wish to achieve.

A large south-facing sliding window, for example, requires a different approach than a smaller window on the north side. That is why we always look at the complete design. Glass should not be seen as a standard component that you only choose at the end. Especially with large minimalist windows, that choice has a direct impact on the ultimate living comfort.”

Planning for large minimalist windows? Group Ceyssens collaborates on the right glazing for your design and helps align views, energy performance, and living comfort.