Case Study of Trombe Wall Inducing Natural Ventilation through Cooled Basement Air to Meet Space Cooling Needs

Abstract

Underground spaces normally are at cooler air temperature than ambient air temperature because of earth-sheltered walls. This cooler air can be circulated to occupied spaces using a solar chimney effect to exhaust air from the basement to where it is needed. This work aims to study the viability of using natural ventilation induced by a Trombe wall to draw fresh air from underground basement floors for space cooling in the dry desert climate. Outdoor air is delivered to the basement through an earth tube. A numerical model integrating thermal models of the basement space and the occupied zone, and the Trombe wall is used to predict the air temperature variation with time in the occupied space air temperature and to predict thermal comfort. The feasibility of implementing the proposed system is assessed in a case study of a residence in the inland dry desert climate of Lebanon during the summer. It was found that the proposed system achieved thermally comfortable conditions at 80% acceptability for a considerable number of hours without the need for mechanical ventilation (83.3% in June and 58.3% in August). The electric energy consumption of the system over summer (June through September) was estimated at 7.71 kW·h/m2 of floor area.