Solar Gain, Glare and Control

Incorporating large windows, doors and glass facades into your home has many advantages. The main one is the huge influx of natural light which can help spaces appear bigger, complement and highlight interior design elements and provide mental and physical benefits for the occupants.

Using large glazing elevations also provides living spaces with a strong connection to the outdoors. This bond with nature can help reduce stress and boost creativity levels.

If the glazing in a home is south facing or a glass box extension is used, the energy from the sun’s rays may cause uncomfortably warm living spaces and solar glare can cause discomfort.

Overheating and solar glare can be controlled by utilizing modern advances in glazing technology, such as solar control coatings.

large fixed casement window in the bedroom of a new build home with solar control glass to control solar gain

What is Solar Gain?

Solar gain refers to the increase in the thermal energy of a space or object. The heat energy from the sun’s rays is absorbed by materials which results in an increase in temperature.

For highly glazed spaces such as glass extensions which receive a significant amount of direct sunlight, the sun’s rays are able to penetrate through the glass and as the rays reflect off objects in the internal area, they have a shift in length and are unable to travel back out through the glass.

The heat energy becomes trapped in the space causing an increase in temperature which can result in an uncomfortable living space. As Sieger’s slim framed glazing systems can reach impressive sizes, with bifold doors up to 5 m tall and sliding doors up to 4m wide per pane, this is something that should be considered early on in any project.

The G Factor (sometimes referred to as the G-value) is the coefficient used by glazing manufacturers to measure how much solar energy is transmitted through a glazing system.

In some cases, a higher G-factor may be sought after as the solar gain from glazing can be used to heat internal spaces to save money on heating bills and help reduce a home’s carbon footprint.

The right G Factor for your glazing will depend on a variety of factors such as the placement of the glazing and type of system. Our team at Sieger are on hand to help advise on the most appropriate glazing for your project specification.

glass box extension with solar control structural glazing to prevent overheating and reduce solar gain and solar glare
explanation of how solar control coatings for glass work

What is Solar Glare?

Solar glare refers to excessive exposure to bright sunlight. In a home where you may be using computers for work, education or general tasks, having bright sunlight hitting your eyes or reflecting off the screen for an extended amount of time can put a strain on your eyes and cause headaches.

This problem may be common if you have a large glass façade in your home or south-facing glazing. Although this issue is more common in commercial spaces, it is still something that should be considered in residential home design.

Sieger’s slim glass doors and minimally framed window systems can be used in conjunction with structural glass or roof glazing to create impressive glazing solutions that maximise natural light within the home.

Controlling Solar Gain and Glare

When it comes to preventing overheating and reducing solar glare, there are a few options. Shutters or blinds can be used both inside and outside the home or for a more minimal design there are glass coatings that can be applied.


Solar Control Coating

Solar control coatings are one of the most popular options when designing glazing systems that are south facing or for glass extensions. This coating is a thin metal oxide layer that is applied to the internal face of the external pane of glass in an insulated glass unit.

This coating is designed to allow light and vision through the glass whilst reflecting solar radiation. There are different variations of solar control coatings with a range of light transmission and g factor values.

The metal oxide coating reduces the amount of short-wave radiation that travels through the glass unit, thus reducing the increased heat levels inside. It also helps to filter light and therefore can be used to reduce solar glare.


External Shading Solutions

There are a range of shading solutions that can be used alongside our slim framed aluminium glazing systems. This includes shutter systems, blinds and curtains.

Which one is right for your project is down to personal preference, some homeowners prefer curtains for a softer approach and some are more inclined towards blinds. Many blind systems can now be automated and designed to be hidden within ceiling finishes when open.


double height extension on a London terraced home with large fixed windows and sliding glass patio doors
Corner opening sliding glass patio doors with solar control glass to prevent solar gain and overheating in this modern home extension
Ultimately, the slight risk of overheating due to solar gain and solar glare should not deter anyone from specifying large glazing solutions as this is not an issue for everyone. The benefits of using an abundance of glazing far outweighs any disadvantages.

For any projects where these factors may cause discomfort there are a range of options to prevent this. Our skilled technical team will be able to assess the risk and advise necessary precautions on a project by project basis, ensuring your internal living spaces remain comfortable at all times.


For more information about our high-quality aluminium glazing systems, solar control or if you have any questions, get in touch with the Sieger team.

Call 01494 722 882 or email [email protected]

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