Comparison of building load performance between first principle based and implementable shading control algorithms

This paper presents the findings on the impact of two window shading control strategies on office building thermal and lighting loads over a year’s period through energy simulation in four different climatic contexts in the United States. While it is well known that window shades affect heat gain and loss through windows and thus building energy loads, there is limited information on the actual magnitude and specific behavior of their effects on the building thermal and lighting loads. The objective of the described study is to generalize the magnitude of the impact from window shading control strategies on building thermal and lighting loads over a year by modeling a representative office building construction in indicative geographical locations as well as internal window shades representative of those that are commonly used. Two control algorithms are developed and evaluated which are the ideal algorithm and implementable. The basic principle of both algorithms is to maximize heat gain and minimize heat loss when the building is in heating condition, and performs the opposite when the building is in cooling condition, subject to glare control. Some of the information that is used in the ideal algorithm is not available for a "real world" controller. Therefore, an implementable shading control algorithm is also described, which will take sensor measurable conditions as input. EnergyPlus is used to conduct the thermal and lighting loads computation. The control algorithm is implemented through the BCVTB (Building Control Virtual Test Bed). BCVTB is a software environment that allows expert users to couple different simulation programs for distributed simulation.