Specifying Solar Control Glass for Warm Climates
Highly glazed building designs for both residential and non-residential projects have grown in popularity across the globe in recent years. By incorporating large glazing elevations into a building’s envelope, natural light is able to flow freely into the internal spaces, views are maximised and the overall design of the build is enhanced.
In some locations this can bring the risk of overheating in internal spaces due to solar gain from the sun’s rays travelling through the glass. This is why when specifying glazing for warm climates solar control glazing should always be considered.
Previously, high-glazed building designs would not have been suited to regions like this but with modern glazing technology such as solar control glass and electrochromic glass, this is no longer the case. Now south-facing, large glass facades are well within reach for any building design, no matter it’s location.
Areas such as Brazil, the Caribbean or parts of the USA like Arizona, have the advantages of warm weather and sunshine for most of the year, but this can also put interior spaces at rick of overheating when large glazing elevations are used.
What is Solar Control Glazing?
Solar control glass refers to an insulated glass unit, including structural glazing solutions, that have a solar control coating. Before understanding solar control coating we need to know what the terms ‘solar gain’ and ‘g factor’ mean.
What is Solar Gain?
Solar gain is the increase in heat energy in an internal space from the sun’s shortwave radiation. This happens when the shortwave radiation travel through a glass unit, and reflects off of surfaces within the space which then converts it into longwave radiation.
This longwave radiation is then unable to penetrate back through the glazing, becoming trapped inside and increasing the internal temperature. This is what is known as solar gain.
What is a G Factor?
The G Factor, sometimes referred to as the solar factor, is essentially how much solar energy is transmitted through a glazing system.
There are two ways this may be shown. Firstly, as a number between 0 and 1, with 1 meaning the glass transmits all of the sun’s solar energy through it, and 0 is that none is transmitted through. So when looking for solar control the lower the G Factor the better.
The other way it can be shown is as a percentage. If the G Factor of a glazing system was 0.35, this means that 35% of the energy is transmitted, and so could be shown as 0.35 or 35%.
In order to reduce solar gain and prevent overheating, we need to reduce the G Factor of the glass, and the best way to do so is by using a solar control coating.
What is a Solar Control Coating?
This coating is made of a thin, transparent layer of metal oxide that is applied to the internal face of the out glass pane, known as face two of an IGU.
Shortwave radiation from the sun is blocked by the coating from passing through the glass, and how much is able to travel through depends on the level of solar control coating that is used.
There is a range of solar control coatings available, affording you different levels of light transmission, external tints and solar control. Solar control glass is not necessarily coloured or mirrored glass, although such finishes can be applied for aesthetic purposes if desired.
Solar Control coatings must always be used on an insulated glass unit, either double or triple glazed.
How Effective is Solar Control Glass?
There are varying levels of solar control coating that can be specified with glazing, and the right one has to be evaluated on a project by project basis. This is why it’s important to get a professional glazier involved at an early stage of the project, so that this can be considered.
The most popular of these solar control coatings is a 70/35 solar control coating which maintains the unit’s light transmission at 70% for a natural appearance whilst reducing the G factor of the glass unit to 35%.
For regions such as Arizona or the Caribbean, a high level of solar control may be needed to avoid overheating within the building. Systems with solar control glazing should be used in combination with opening elements to ensure air flow as well in order to maintain an optimal temperature.
Guardian Glass, one of the largest suppliers of solar control glass in the world, created a building called La casa del Deserito in the middle of the desert in Granada, Spain. The stand alone building has glass walls all around that use two types of solar control glazing.
Various individuals were invited to stay at this unique getaway in order to test how comfortable the internal space was whilst directly in the sunlight with no shading and high exposure. The results were unanimous in that the solar control glass kept the interior space a cool comfortable temperate, even is such harsh conditions and in such as warm climate.
Solar Control Glazing Systems
Solar control glazing can be specified within any of our insulated glass units, whether its for an oversized sliding glass door, structural glass façade or a large glass roof. Used alongside glazing systems with a low e coating this creating glazing solutions that is highly thermally efficient, helping spaces to remain cool when necessary.
Solar Control Glazing in Oversized Sliding Glass Doors
When it comes to over sized glazing, large sliding glass doors are one of the most popular solutions across all types of builds. Being able to reach such impressive sizes with such minimal aluminium framing makes them ideal for creating entire walls of sliding glass.
When these large sliding doors are used in warmer climates or on south facing elevations in any project, we would recommend incorporating a solar control coating.
Solar Control Glazing in Structural Glass Facades
Structural glazing is a complex and unique glazing solution with an extremely flexible nature, this allows the glazing solutions to be designed to make almost anything out of glass including glass walls, roofs, floors and even bridges.
Many of our architectural clients use structural glazing for double height glass facades either for luxury new build homes, holiday resorts or contemporary office buildings. This grants impressive views whilst maximising natural light and giving any building a ‘wow factor’.
Similarly to oversized sliding doors, when large structural glass facades are specified for locations with hot climates or south facing, a solar control coating or some type of solar control solutions is needed to prevent overheating.
Solar Control Glazing in Glass Roofs and Large Rooflights
There is a wide variety of glass roof systems available on the market, from structural glass roofs to large, automated sliding rooflight systems. throughout the day glass roof tend to receive the most sunlight, and so when using this type of glazing solution in warmer or sunny regions, solar control glass is an obvious choice.
Solar Control Glazing vs Other Solar Control Options
Although this article has focused on solar control glass for warm climates, this is not the only option for solar control. There are other options available such as electrochromic glass, which is another technical glazing solution IQ can offer, or use of external shading systems.
The main advantage that solar control glass has over other glazing solutions is the light transmission. The use of internal blinds or external shading systems can be a great choice for blocking the sun’s heat but these will also block the flow of natural light and obstruct views.
Solar control glass vs electrochromic glass isn’t as straightforward, as both of these allow natural light through and although solar control glass tends to let more light through, electrochromic also helps to prevent solar glare.
This is a perfect example of where is it not one size fits all when it comes to glazing, there are many technical glazing solutions available that can be specified within a number of glazing systems, and the right one for your projects will depend on a variety of factors.
When Should Solar Control Glass Be Used?
Years of experience have taught us that incorporating solar control glass into a project almost always has advantages.
Glass specification for any project should be unique to the needs, design and location of that specific build, but as a general rule of thumb, we would recommend using solar control glazing for any large south-facing glazing elevations, large glass roofs, or for glazing used in warm climates or regions that get a lot of sunshine throughout the year.
Solar gain can actually be used as a heat source for a space, and so for colder countries, solar control glass would not be necessary. For example, one of our UK projects was a large unique extension that had structural glass walls and minimally framed sliding doors all across the south-facing side of the build.
As the project had a focus on sustainability the solar gain from the sun was actually utilised to heat the space, and so here solar control glass would have had a negative effect on the project.
What Next?
If you are looking at the glass specification for solar control glazing just contact the team at IQ. We have a dedicated team working on projects all over the globe, offering specification advice tailored to your specification and design requirements.