Space Cooling Application with Unglazed Solar Absorber

Increasing outdoor air temperatures, rising number of electric devices and higher comfort requirements lead to significantly rising cooling demands. Free-cooling measures reach high efficiencies, which are limiting the electricity demand for cooling. In the SCCER EIP WP4 the reuse of treated wastewater for evaporative cooling is investigated. On the building level a system configuration with integrated evaporative cooling by outer building surfaces is developed, which can for instance be realized by unglazed solar absorbers or PV/T collectors and also cover the space heating and domestic hot water demand, enabling a cost-effective integration of the cooling operation. Simulations with boundary conditions according to the Swiss guidelines SIA 2024 and SIA 2028 for a single-and multi-family house as well as an office building according to the Swiss building directive MuKEn 2014 or better in Zurich yield high free-cooling fractions of 100% in residential application and from 80% to 100% in office use depending on the boundary conditions. By wetting the absorber the cooling capacity can be notably increased. Overall system performance is in the range of 4.5-6, which corresponds to ground-coupled heat pump system performance. The paper focuses on results of the multi-family house simulation.