CIBSE OVERHEATING ASSESSMENTS

What is it?

This type of assessment reviews in detail, usually on a room by room basis, if the development has a risk of overheating in summer months. The methodology is more adequate than other methods used to review if the proposed design has any risk to future occupiers.

To have accurate results, it is fundamental to use dynamic simulation, including specific weather conditions for a location, assessing it on an hourly basis (24 hours by 365 days per year). Other calculations, such as Criterion 3 of Approved Document Part L of Building Regulations in the UK, use a steady state analysis with average monthly temperatures and other assumptions that provide inadequate results. CIBSE standards also take into account project specific characteristics of the development, including windows types with free areas, enabling more accurate results and prediction of overheating risk.

What is it for?

Read more...

This type of assessments provides detailed results to enable informed design decisions regarding building form, materials and ventilation strategies. This evaluation reduces the risk of overheating in buildings. Assessments such as CIBSE TM49 and its weather files enables designers to analyse the summer performance of their buildings and investigate the impact of urban macroclimatic factors and climate change when carrying out overheating risk assessments for buildings in London.

“The Part L overheating assessment is relatively simplistic, thus potentially leading to inappropriate design decisions regarding building form, materials and ventilation strategies.” CIBSE Technical Symposium, Dublin, Ireland, April 2014.

Requirements and Standards

Greater London Authority (GLA) London Plan, Guidance on Preparing Energy Statements now include specific requirements on dynamic thermal modelling at the detailed planning stage to quantify the risk of overheating as per current and future climatic conditions. CIBSE Standards include:

• CIBSE GUIDE A ENVIRONMENTAL DESIGN,
• CIBSE TM37 Design for Improved Solar Shading Control,
• CIBSE TM49 : Design Summer Years for London,
• CIBSE TM52 Limits of Thermal Comfort: Avoiding Overheating.

Finished Projects