Reducing thermal energy demand in residential buildings under Spanish climatic conditions: Qualitative control strategies for massive shutter positioning
The effects of dynamic controls on external massive shutter positioning are studied as refurbishment measure to reduce energy demand in residential buildings. This kind of shading device can not only regulate solar radiation, but it also provides additional thermal insulation that reduces heat conduction when closed. Based on their capability for controlling both processes, a comparison of different qualitative shutter positioning control strategies are proposed to minimize thermal energy demand. To this aim, a simulation model based on the constructive characteristics of an experimental building has been developed with TRNSYS. The results show that when more input variables are considered greater thermal demand reduction is achieved. However, the most relevant input variables for reducing thermal demand are solar radiation and real demand of the building. A large reduction in thermal energy demand is also displayed in the comparison between massive shutters, and non-massive blinds, increasing from 23% to 35%. Surprisingly, this improvement can be achieved using simple radiation-based control strategies, whereas the inclusion of heat conduction as control variable only improves the results by 0.2%. Therefore, there is no need to increase the complexity of the shading control of the massive shutters to take advantage of their insulation properties. The thermal energy reduction is comparable to the effect of refurbishment of an ordinary double-glazed window (U=2.46 W/(K·m2)) with high-efficiency triple-xenon glazing (U=0.59 W/(K·m2)).