CWCT has received several inquiries regarding the thermal performance of louvres that are glazed into fenestration (transoms above doors, windows and similar) or into curtain walls. Speaking with our Technical Committee and various parties from industry it seems this is a source of confusion. We have come to understand that the associated heat loss through the louvre-frame interface is commonly over-estimated or completely ignored; in some cases, the heat transfer of louvre in its entirety is ignored.
Ignoring or over-estimating the performance of these systems will result in buildings that do not achieve the anticipated performance, create potential drafts or discomfort, and risk internal condensation and mould. We recommend the performance of louvre systems glazed into fenestration and curtain walls be correctly modelled and considered when specifying products, demonstrating compliance with building regulations and assessing performance.
To help us further understand the approaches being taken or the nuances of the issue, please contact us with any information, experiences, or suggestions.