What is solar control glass and when is it needed?
Solar control glass is one of the easiest ways to prevent overheating within a property, but how does it work?
What is solar control glass and how does it work?
Solar control glass is a double or tripled glazed unit with a metal oxide coating on the internal face of the external pane of glass. Using this coating is one of the easiest ways to integrate solar control into any glass structure, especially a structural glass unit.
This coating is designed to allow light and vision through the glass whilst reflecting solar radiation. It cannot be applied to single glass panes, only double or tripled glazed units. The metal oxide coating reduces the amount of short-wave radiation that travels through the glass unit, thus reducing the increased heat levels inside.
Radiation from the sun travels in short wavelengths which can penetrate through the glass into interior living spaces. As these waves hit objects inside, they are absorbed and then emitted at longer infrared wavelengths, which can’t travel back through the glass. This increases the internal temperature of a property and is known as solar gain.
Solar control coatings prevent a significant amount of the suns radiation from entering the property. Solar control glass also reduces heat loss by reflecting the heat waves back into the internal environment.
Whilst there are many solar control coatings available which range in levels of light transmission, external reflections and solar control, the most popular is a 70/35 Solar control coating which reduces the G factor of the glass unit to 35% while maintaining the units light transmission at 70%.
Solar control glass in school and workplaces
A buildings internal environment can massively impact its occupants, especially in workplaces and educational settings where productive environments are imperative. There are many factors that need to be considered when creating the ideal, productive atmosphere for schools and workplaces. This includes thermal comfort, ventilation and amount of natural light coming in.
If offices or schools opt for large glass windows and walls, the temperature of the internal environment can increase at a rapid rate when the sun is out. Increasing the amount of glass, and in turn, the amount of natural light doesn’t mean you need to compromise the thermal comfort of these spaces.
On average humans spend 90% of their day inside and during winter months when the sun sets earlier, people find themselves arriving and leaving school or work when it’s dark. This means that a lack of windows or glass walls can result in people missing out on the little sunlight there is.
Research shows a building with more natural daylight helps improve the occupants productivity, however in summer having this large amount of glass can cause issues with overheating, which can cause a decrease in productivity.
An excellent example of solar control glass being used in a workplace is Wigmore Street in London. This project included the largest structural glass panes available in the UK for the structural glass façade, maximising natural light within the offices. Solar control coatings were applied to the panes to ensure comfortable temperatures all year round.
When glass with a solar control coating is used in conjunction with other thermal controlling measures, such as opening windows or central heating, it results in these types of buildings being able to maintain optimal working conditions, benefitting those inside.
Glass box extensions
Glass box extensions are a beautiful addition to any property. They can be designed as completely frameless, offering uninterrupted views of the surrounding area.
One concern with these glass box projects tends to be the risk of overheating during warmer months, particularly if glass boxes are installed on the top floor of high rise commercial buildings. Integrating solar control glass and opening elements into the design helps to reduce this issue by blocking the suns infrared rays and providing ventilation.
IQ provided the full glazing package for the renovation of a commercial premises in Mayfair, London. One of the main features in this project was the creation of a glass box rooftop extension which included a pocket door, rooflight and windows. Part of the project utilised laminated solar control glass, and the project won the RIBA London Award 2018.
In curved glass applications, solar control glass maintains it’s aesthetic, optical and performance properties. Bending constraints are based on coating type, choice of process, radius and concave vs. convex applications.
When is solar control glass necessary?
We recommend that solar control glass is used for all roof glazing, structural glass facades, glass links and south-facing glazing units. It is important to bear in mind that as the G Factor of the glazing is reduced, the visible reflection from the exterior of the glazing may increase and the glass can become tinted.
This coating helps to achieve optimum thermal insulation and comes in a wide range of colours and performance levels so that the desired appearance and performance can be achieved. Solar control glass is similar to clear uncoated glass in its neutral appearance, however, there is a range of tinted colours that can be applied. Colours include but are not limited to warm grey, green, black and white.
Tontine street features a structural glass façade which was specified to mimic the wave movement of the sea, this combination uses both curved and straight panes of structural glazing. The fixed structural glass units along the four-storey face were made up of flat and curved structural glass panels to create a ‘wave’ effect across the front of the building.
IQ projects designed and installed a glass box extension to a listed building in central London, located parallel to the Tower of London. The specification for this project was to create a completely transparent look, expanding the space of this coffee house using 5m long structural glass beams in low iron glass and solar control to create a comfortable environment for the users.
Montrose Hotel utilized two glass box extensions, one on the side of the hotel and one to create a glass link between two parts of the building. The one at the side creates a middle ground between the hotel’s outdoor seating area and the internal spaces. Due to the configuration and amount of glazing, it was important for IQ to consider the heat gain within this space, due to this solar control was used to regulate the heat within this space.
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