Simplified Convective Heat Transfer in Vertical Airflow Regimes with Shading Device

Abstract

The design of ventilated glass-glass facades in large buildings seems a promising technology to enhance energy efficient building design. In order to describe the optical and thermal heat transfer mechanism in glass-glass configurations with vertical airflow regimes radiation and conduction models have been developed and validated. The convective heat transfer can be calculated depending on air temperatures and air velocity. But obstructions in the vertical airflow regime (i.e. shading device) with reflective and absorptive properties demand the set-up of a new heat transfer balance. Radiative, conductive, and convective heat transfer coefficients for the heat transfer through glass-glass configuration with internal obstructions were developed. The simulation results were validated with measured data of air temperature regimes and different solar radiation in an existing ventilated double-skin façade. The comparison show very good agreement and give confidence in using the model for further energy analysis of this type of façade.