Estimating the Thermal Performance of Curtain Wall Spandrels
Abstract
A frequent request of users of the Building Envelope Thermal Bridging (BETB) Guide and Thermal Envelope (www.thermalenvelope.ca) is for linear transmittances of curtain wall horizontal expansion (stacked) joints and intermediate mullions. This request comes from the need to extrapolate available data for simulated spandrel sizes to other project specific spandrel sizes.
However, there are questions related to the viability of using linear transmittances for curtain wall spandrels:
1. How much complexity is necessary to accurately apply linear transmittances to curtain wall spandrels?
2. What is the variability of linear transmittances for different spandrel sizes?
Ultimately, the answer to both questions must be “not significant” if applying linear transmittances is a practical approach for curtain wall spandrels. Moreover, the procedure must be repeatable and easier to use than prevailing approaches to justify the approach.
In this context, this Evoke Insight explores the feasibility of using linear transmittances for curtain wall spandrels and provides insights for setting performance expectations.
