- Project plans
- Project activities
- Legislation and standards
- Industry context
Last edited 15 Mar 2020
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.
- Solar transmittance (gtot).
- Thermal bridge.
- U value.
- Zero carbon homes.
- Zero carbon non-domestic buildings.
Featured articles and news
How to write them and what they should include.
Five outstanding aspects of the profession.
The seismic strengthening of historic churches.
Results show guarded optimism and payment concerns.
Noteworthy navigable aqueducts.
Technology is making remote work a reality.
Carefully placed structures add drama to pastoral vistas.
Report provides actions required by 2030 to achieve a zero carbon economy.
What type of cool roof is most suitable?
Active Travel programme prioritises cyclists and pedestrians.
CIAT issues caution for use of new standard.
Industry leaders discuss climate change, the economy and other influences.