Performance evaluation of air and liquid-based solar heating systems in various climates in East Asia

Abstract

This study evaluates the performance of liquid and air-based solar heating systems according to climatic conditions and the thermal insulation performance of buildings. The relationship between thermal energy demand and the effects of applying solar heating systems according to building characteristics is also clarified. The effectiveness of the solar heating system depends on the characteristics of the region and the building (heating energy demand and hot water energy demand depending on the outside temperature) and the amount of solar radiation in the target area. In particular, in the case of the air-based solar heating system, separate heat exchange is required to use as a hot water supply, and due to the heat loss generated therefrom. As a result, the effect of using indoor heating is greater than the effect of using hot water. Conversely, in the case of a liquid solar heating system, hot water can be used directly for hot water supply, but when used as radiant heating, efficiency is relatively reduced due to heat loss outside the target space. We examined the annual energy demand, the annual energy-saving amount via solar heat utilization and the energy-saving rate by a simulation of representative points of 88 climates in East Asia using solar heat utilization climate classification. The liquid-type solar heat collection system is suitable for solar heat utilization in areas where the hot water supply energy demand is approximately 34% or more of the annual energy demand in low-insulation houses. On the other hand, in high-insulation houses, the air-based solar heating system is more effective when hot water energy demand is less than 73% of the annual energy demand. The results of this study can be used as a basis for determining the solar heating system suitable for the target building, and it is considered that it leads to the result of increasing the solar utilization in the houses.