Enhancement of heat transfer in office buildings during night cooling − reduced scale experimentation

Abstract

Most office buildings are designed to be ventilated and cooled using mechanical systems. However, in a temperate climate, passive ventilation and cooling techniques can reduce energy consumption when the outdoor temperatures are favourable, e.g., at night. Nevertheless, decorative components like the suspended ceiling (SC) contribute to insulation, preventing the desired thermal exchange with the slab. This work investigates an innovative solution to the optimization of the night cooling phenomenon by using a SC with a peripheral gap and taking advantage of the plenum formed by the space between the slab and the SC for cooling purposes. The experiments were carried out on a reduced scale model. It was found that a SC with a gap allows part of the heat dissipated in the room during the occupation period to be used to heat the slab, thus reducing the air temperature during the day, in comparison with a conventional SC with no gap. Moreover, a SC with a gap, and with supply and extraction slots placed above it, improves the air cooling during the night, and reduces the temperatures in the occupation zone during the following day, in comparison with a conventional SC with no gap, and with the ventilation slots located below it.