Shading coefficient for buildings
Shading coefficients can be used to describe the amount of solar heat that passes through a transparent or translucent material compared to the amount of solar heat that passes through a sheet of clear float glass with a total solar heat gain coefficient of 0.87 (i.e. a sheet of clear float glass 3 mm thick which has a shading coefficient of 1).
Solar transmittance is important for determining the solar heat gain into an enclosed space during sunny conditions. Solar heat gain can be beneficial in the winter, as it reduces the need for heating, but in the summer it can cause overheating.
The total solar heat transmittance is equal to the solar heat that is transmitted through the material directly, plus the solar heat that is absorbed by the material and then re-emitted into the enclosed space.
Shading coefficients can be measured using an illuminated hot box under simulated summer and winter conditions, and from these values, solar heat gain under a range of different conditions may be predicted using known data about solar heat gain through standard clear float glass.
This enables the behaviour of translucent or transparent materials to be predicted under different environmental conditions without having to measure the angular optical properties of every individual material.
Manufacturers are now moving towards the use of solar heat gain coefficients (SHGC) or window solar factors (g-values) rather than shading coefficients. These represent the fraction of incident solar radiation transmitted by a window, expressed as a number between 1 and 0, where 1 indicates the maximum possible solar heat gain, and zero, no solar heat gain.
 Related articles on Designing Buildings Wiki
- Code for Sustainable Homes.
- Computational fluid dynamics (CFD).
- Emission rates.
- Energy certificates.
- Environmental legislation.
- Green deal.
- Leadership in Energy and Environmental Design.
- Light shelf.
- Low-e glass.
- Solar heat gain coefficient.
- Solar reflectance index.
- Thermal bridge.
- U value.
- Zero carbon homes.
- Zero carbon non-domestic buildings.
Featured articles and news
Read about RSHP's British Museum extension which has been shortlisted for the 2017 Stirling Prize.
Read our introductory article to building a house extension.
More updates from DCMS about the large-scale testing of cladding systems and the number of buildings affected.
UandI secure resolution to grant planning consent for major new regeneration project.
IHBC article considers how heritage is dealt with when infrastructure schemes are authorised.
It was the tallest structure in the world for 3,800 years, but to this day the exact construction techniques are a mystery.
Shortlist for the industry's most coveted award announced.
Government responds to Mark Farmer's review of industry, rejecting the call for a levy on clients.
Peter Hansford to examine what wider lessons can be learned from the fire.
Every project is subject to uncertainty. How can construction better understand uncertainty for performance improvement?
MAD Architects reveal their designs for a futuristic campus for electric car manufacturer.
Homebuyers could borrow more with better forecasting of energy bills, according to industry consortium's new report.
Read our introductory article on carbon capture and storage.