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Heat Loss Calculations

Heat loss in buildings is predominantly through envelopes via conduction and non-linear junctions via infiltration. These must be addressed to create high performance buildings with low energy demands. SRE conducts Heat Loss Calculations addressing these issues through Thermal Bridging Analysis (Psi value calculations) and U value calculations.

Psi value calculations are the key in understanding heat loss through all the standard and non-standard junctions of a building and plays a critical role in determining or pin-pointing the cause of heat loss through the assessed junctions and how the junction can be improved. Different alternatives are proposed, and comparative analysis is done for the poorly performing junctions to improve and enhance their performance. Detailed Thermal Bridging Analysis is undertaken by SRE building physics specialists using the Therm and Psi-therm software to determine accurate Psi values of the assessed junctions to aid in heat loss calculations, energy modelling using SAP and SBEM software and in assisting Zero Carbon and Passivhaus schemes.

The U-Value (W/m2K) of a structure is the thermal transmittance that takes place through it. Lower the U- values lower the amount of heat loss through the structure and more efficient the structure is. A thermal envelope with lower U values enhance the thermal performance of the building by reducing the heat loss through the envelope and thereby reducing the building’s energy requirements. SRE uses software like Build Desk and Therm to calculate U-values to help in heat loss calculations along with its use in Part L compliance, psi value calculations and condensation risk assessments. SRE’s competent consultants are constantly tracking the new updates in products that could help in reducing the U values of the build envelope.