Cooling in residential buildings becomes more important due to the rising insulation requirements and the increasing human comfort. Therefore, systems that provide heating as well as cooling with a low primary energy consumption will be in future more preferred than conventional single-unit systems. Solar thermal installations can here provide in addition to the domestic hot water and heating demand a significant contribution to the cooling requirement in residential buildings. In this study, low-energy residential buildings with different solar heating and cooling systems are analyzed concerning their primary energy consumption. To cover a large range of different weather conditions, two locations (Madrid and Wu¨rzburg) with different solar energy supply are considered. Further, a conventional solar heating supply system including one or more typical room air-conditioners is as reference system selected. The different systems are modeled by the system simulation platform TRNSYS. In a first step, the question is addressed of whether a solar thermal system with standard dimensioning, taking the domestic hot water and heating demand into account, is sufficient to meet the cooling requirements. To cover the cooling demands, a small-scale thermally driven absorption chiller has been selected. In a next step, the studied systems are compared in terms of primary energy saving as a function of the solar cooling fraction. The simulation results have shown that regions with a high solar energy supply do not take advantage of solar thermal cooling, due to the higher cooling demand. On average, 70% of the cooling demands can be covered by a standard dimensioned solar thermal system. At the same time, a primary energy saving up to 90%, compared to currently installed room air-conditioning units can be achieved.
Performance Analysis of Solar Thermal System with Heat Pump for Domestic Hot Water and Space Heating
