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Roller blinds on a sloped façade at CityPoint in London

What is solar gain?

By: Oli Birch Category: Insights

Solar gain, also referred to as solar heat gain, is the increase in temperature in a space, object or structure that results from solar radiation.

The sun radiates energy in the form of short wave radiation, otherwise known as light. When this short wave radiation reaches an object like a building or window, it is absorbed and re-radiated as longwave radiation, otherwise known as heat.

A good example of this is on a sunny winter’s day. As it will be bright outside, short wave radiation is produced from the sun, but the temperature will still be cold. However, inside a car, where the windscreen is obstructing the light, the short wave radiation is turned into longwave radiation, or heat, and the temperature inside will rise very quickly. This is solar gain.

How this affects commercial offices

In the context of buildings, external glazing is widely used to maximise natural daylight and provide a view of the outside world. It is also the single biggest source of solar heat gain.

This diagram helps to explain:

A rendered image describing the effects of solar gain

Solar gain diagram

Though it can be incredibly useful in winter at providing a cost effective and sustainable way of heating a property, it can also lead to buildings overheating in the summer months.

How to address solar heat gain

Window blinds help to reduce the effects of solar heat gain by blocking the short wave radiation that has penetrated beyond the glass and the long wave radiation created by the glass.

Blind fabrics with a highly reflective metallised backing such as Silverscreen are very effective at reducing the effects of solar gain. The metallised backing allows Silverscreen to reflect up to 85% of solar energy entering a building through the glass. This has a huge impact on air conditioning usage and costs, and also staff health and well-being.

By knowing the science behind solar shading, architects, designers and end-users can make intelligent decisions about the type of window blinds they require, which then helps to reduce their running costs and their carbon footprint. They will also boost their productivity and profitability by providing a stimulating working environment.

If you’d like to learn more about solar gain and high performance roller blind fabrics, keep an eye our for our next RIBA-accredited CPD presentation,  Improving Sustainability through Performance Solar Shading, where we delve into great detail about this topic, or contact us here to book a lunch and learn with our Specification Team.

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