Development of building energy simulation methodology for daylight utilization

Abstract

Daylight plays an indispensable role in improving the energy efficiency of buildings and satisfying the requirement of occupants' health and productivity. Office buildings are often with open-plan layout and constructed with glazing curtain walls. The operation hours of office building is mostly during daytime period. These features provide a prerequisite to apply daylight utilization as the building energy-efficient measure. Fully exploring the potential of daylight utilization in energy efficiency of office building is of profound significance to assist China in the construction of urbanization and economic transformation. Due to the complexity level of daylight-related research, the evaluation of daylight availability and the optimization of design parameters are mostly implemented by the integrated simulation of daylighting and energy consumption. Although the selection of a suitable meteorological data file is the premise of getting valid results from building energy simulation, at present there has been no Typical Meteorological Year files (TMYF) or generation method specifically developed for the energy simulation of daylight-utilized building. To fill this gap, the feasibility of existing TMYF and generation methods are analyzed. A new TMYF generation methodology specifically used for energy simulation of daylight-utilized building is developed. As the possible occurrence of external obstruction in the ambient environment during building's long lifespan may bring side effect to the energy-efficient performance of daylight-utilized measures, the effect of various different external obstruction patterns on daylight-related energy simulation is studied through a parametric analysis. The results show that the impact of external obstruction on the energy saving of daylight-related building is not necessarily negative. Under certain patterns, external obstruction can reduce the overall energy consumption of building lighting and air conditioning systems. It is indicated that the application of daylight utilization as an energy-efficient measure has some flexibility, which is conductive to the achievement of design target during operation stage. In cooling season, the introduction of daylight may accompany with excessive heat as well. This study proposed a metric named SGR to evaluate the overall influence of real-time shading control state on building energy consumption. A numerical simulation workflow of dynamic shading control strategy based on SGR performance (SGR-Optimal) is developed to take the cumulative contribution of the heat gains to the cooling load into account. For the operation stage of daylight-utilized building, the design energy-efficient target does have the risk of failure due to the occupants' adjustment behavior, such as the manual override actions of shading control. This study tries to solve the problem from two perspectives. First, a thermal preference predictive model from individual level is established using Random Forest algorithm to enhance the predictive accuracy of the thermal motive of the occupant adjustment behavior. Then a hybrid optimization control strategy of dynamic shading (Hybrid-SGR-manual) which actively incorporates occupant adjustment behavior is proposed to reduce the uncertainty of building energy-efficient performance and limit the negative results brought by occupant random adjustment.