Two-Stage System for Utilization of Renewable Solar Energy in Modern Building Facade Technology

Abstract

We research a technical solution for utilization of solar energy in modern buildings with double-skin facades. The solution involves thermal conditioning of cold outdoor air in the physical cavity of the double-skin facade and utilizing the warmed up air as primary air for an air heat pump. The system for utilization of solar energy consists of two stages. The 1st stage involves transformation of the short-wave solar radiation to the long-wave heat radiation in the double-skin facade. This contributes to the reduction of heat losses from conditioned rooms because of the lower temperature difference between the rooms and the cavity. In the 2nd stage the thermally conditioned air is fed in the inlet of the air heat pump during heating season. Computer simulations performed for a cavity of a 4-storey double-skin transparent facade have shown that both the intensity of solar radiation and the air flow through the cavity significantly influence the air temperature at the outlet from the cavity. The air temperature rise in the cavity was ranging from 3.7 K for the solar radiation of 150 W/m2 and the airflow of 200 m3/min, up to almost 23.0 K for the solar radiation of 600 W/m2 and the airflow of 50 m3/min. Even at the least favourable climate conditions such increase in temperature of the primary air leads to a considerable improvement of the performance of the heat pump.