Thermal bridging occurs in various locations within the building envelope. The focus here is on one of the most typical and impactful ones - the balcony penetrations in reinforced concrete structures. The use of Structural Thermal Breaks reduces the energy loss through the penetration by up to 90%.
The total amount of Heating Energy saved will depend on the building location. An acceptable approximate calculation is the use of Heating Degree Days (HDD):
(the following typical linear transmittance values may be used, if no project specific ones are available)
Linear transmittance of conventional (unbroken) balconies = W/mK
Linear transmittance of thermally broken balconies = W/mK
The energy savings per year will be:
What impact would this have on the compliance with Performance-Based Codes?
The impact would considerably depend on the floor area and the length of balconies along the perimeter.
For building dimensions x meters and % of the perimeter with balconies, the Thermal Energy savings per year would be:
This number may be put into context, by considering the Toronto Green Standard, as example, which sets the maximum annual Thermal Energy per square meter currently at 70.0 kWh/m2 and 50.0 in 2022, with the goal for 15.0 in 2030.