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).
It is typically used to describe the solar heat transmittance properties of glass, but has also been used for other translucent and transparent materials.
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.
Total shading coefficients (TSC) can be broken down into short-wave shading coefficients (SWSC) and long-wave shading coefficients (LWSC).
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.
In very approximate terms, the solar heat gain coefficient is equal to the shading coefficient x 0.87.
[edit] Related articles on Designing Buildings Wiki
- Architectural technology research at Sheffield Hallam University.
- BREEAM.
- Code for Sustainable Homes.
- Computational fluid dynamics (CFD).
- Emission rates.
- Energy certificates.
- Environmental legislation.
- g-value.
- Green deal.
- Leadership in Energy and Environmental Design.
- Light shelf.
- Low-e glass.
- Solar heat gain coefficient.
- Solar reflectance index.
- Solar transmittance (gtot).
- Sustainability.
- Thermal bridge.
- U value.
- Zero carbon homes.
- Zero carbon non-domestic buildings.
Featured articles and news
Heat pump announcements, what homeowners need to know
An 'ultimate guide to heat pumps' from a heating company.
Construction contract awards reach £7.1bn in February
Their highest level in seven months.
The journey to sustainability in heritage
Research is the key to better understanding.
Heritage approaches to adaptation, mitigation and loss.
Bridging the gap between policy, finance and installation.
Development on brownfield land
Definition, background, policy and the latest consultation.
With the Design Framework for Building Services.
Retrofit of Buildings, a CIOB Technical Publication
Pertinent technical issues, measures and the roles involved.
ECA joins HSE campaign to support mental health
Working Minds’ five simple steps based on risk assessment.
Mental health in the construction industry
Mental health issues in brief with related articles.
Transitional arrangements, Building Control and the BSR.
For pre-October buildings with substantial progress by April.
How to write an inspection and test plan
ITPs for quality control and assurance particular elements.
Why quality counts in domestic ventilation systems
From products, to systems to the installation.
Empowering the Future with CIOB Academy
Lifelong learning, upscaling, and reskilling for the built environment.
Winners of the 2024 ASBP Awards
Project, Product and Initiative according to the 6 pillars.