Towards a simplified model for partially open windows - connecting acoustic and thermal comfort

Traditionally, the internal environmental quality (IEQ) aspects of acoustic and thermal comfort have been considered and designed separately. However, where occupants rely on opening or closing windows to achieve these dimensions, they are not independent in use. To consider both simultaneously, it is crucial to have a simple model of a partially open window that can predict both acoustic and thermal conditions internally. CIBSE TM59 defines the assessment method for adaptive thermal comfort. In the thermal model the ventilation performance of open windows can be described with an "Equivalent Area" (EA). We propose to use the EA to calculate the facade sound insulation based on a simple assessment according to Annex D of ISO 12354-3, i.e. as a facade element with an area of EA and zero sound insulation. This study presents field measurements of sound insulation according to ISO 16283-3 with road traffic sound sources, to evaluate the acoustic uncertainty of using the EA to calculate internal sound levels. Results show encouraging correlation between measurements of element-normalized level difference, Dn,e,w + Ctr and calculations based on the EA. This model is considered adequate for acoustic design purposes, and represents a significant simplification compared with previous proposals.