Solar Blind System- Solar Energy Utilization and Climate Mitigation in Glassed Buildings

Abstract

In the past few decades, energy scientists have focused on “renewable energy”, and solar energy in particular. Several technologies are commercialized for utilizing solar energy in the buildings by absorbing solar radiation and converting it to heat and electricity. These technologies can be categorized into the passive and active systems. A special case is a commercial greenhouse, which can be considered a passive solar building. A greenhouse is a structure which is covered by a transparent device such as glass in order to use solar energy while controlling the temperature, humidity and other parameters according to the requirements for cultivation and protection of the particular plants. The cooling demand in the commercial greenhouses is commonly supplied by e.g. ventilation and thermal screen. In the ventilation method a portion of the absorbed solar energy will be lost through ventilation windows and by applying the solar shielding, solar radiation will be blocked. In this study, by considering the solar blind concept as an active system, PVT panels are integrated to absorb the surplus solar heat (instead of blocking) which is then stored in a thermal energy storage for supplying a portion of the greenhouse heating demand at a later time. The overall objective of this study is to assess the potential of cutting external energy demand as well as maximizing solar energy utilization in a commercial greenhouse for Northern climate condition. Thus, a feasibility assessment has been carried out, examining various system configurations with the TRNSYS tool. The results show that the heating demand for a commercial closed greenhouse with solar blind is reduced by 80%, down to 62 kwh/m2 as compared to a conventional configuration. Also the annual total useful heat gain and electricity generation by solar blind in this concept is around 20 kwh/m2 and 80kwh/m2, respectively. The generated electricity can be used for supplying the greenhouse power demand for e.g. artificial lighting and other devices. Moreover, the cooling demand in a closed greenhouse is reduced by 60% by considering the solar blind system.