Performance Optimization Design For Office Buildings In Cold Regions

The climate in cold regions is characterized by polarization of cold and hot weather in the Winter and Summer,respectively,as well as abundant sunshine.The workers in office buildings usually sit at their desks for long periods of time.With high personnel and equipment densities in office buildings,a large amount of energy is consumed to maintain the comfort of the indoor lighting and heating environment.Office building design emphasizes functional layout and exterior design,relying on active systems to provide comfort,whereas the influence of architectural design elements and natural environment on building performance is often neglected.To solve the problems of inadequate response of architectural design to climate environment,separation between design factors and building performance,and difficulty in balancing of multiperformance objectives,a performance optimization design method that integrates mode FRONTIER and Grasshopper/L+H is proposed in this study,which automatically searches for the best combination of configuration,interface,space elements,and parameters of an active system,thereby realizing simultaneous optimization of energy consumption and light-thermal performance of office buildings in cold regions.The main objectives of this study were the following.1)Analyze climate characteristics,energy consumption,and light-thermal performance of office buildings in cold regions;identify the design elements that affect building performance;and determine appropriate passive design strategies.The existing performance optimization design methods were analyzed,and then an improved performance optimization design method based on an optimization platform was proposed.2)Establish a performance model related to energy consumption and light-thermal performance of office buildings in cold areas based on climate characteristics and the concept of achieving energy conservation and light-thermal performance through building elements optimization.3)Optimize building energy consumption and light-thermal performance by taking building form,interface,space elements,and active system setting parameters as variables.For the multi-variable and multi-objective optimization problem,a factorial experiment was conducted to set up test plan and analyzed the test data.4)Summarize multi-objective optimization methods suitable for office building performance optimization in cold areas,including optimization algorithm,optimization process,and analysis of optimization results.5)Build a multi-performance optimization design platform for office building by integrating mode FRONTIER with Grasshopper/L+H,and to apply it to an office building to test the practicability and optimization efficiency of the platform.The innovative results of this study are the following.1)Natural lighting and ventilation have the potential to save energy without reducing the photothermal performance,and a performance model is established that is able to correlate energy consumption and photothermal performance.The artificial lighting operation schedule calculated based on natural lighting and the natural ventilation schedule calculated based on indoor and outdoor temperatures are used for energy consumption simulation to improve the conventional unified lighting schedule and the natural ventilation schedule according to seasons.Correlation analysis shows that there is a strong correlation between building energy consumption and predicted percent of dissatisfied,whereas there is a weak correlation between building energy consumption and useful daylight illuminance.2)Based on sensitivity main effect analysis,it is concluded that the key design factors affecting building performance are the window-wall ratio,length-width ratio,orientation,thermal performance of windows,office depth,slat inclination of blinds,and recommended values.Based on sensitivity interaction effect analysis,there are interactions of active system setting parameters to window-wall ratio,thermal performance of windows,heat-transfer coefficient of external walls,slat inclination of blinds,office depth,orientation.Thus,the design strategy combining active and passive elements is proposed.there are interactions of orientation to window-wall ratio,thermal performance of windows;and interactions of window-wall ratio to length-width ratio,heat-transfer coefficient of window,office depth,height,heat-transfer coefficient of external walls;and interactions of slat inclination of blinds to office depth,width.Thus,the design strategy combining passive elements is proposed.Furthermore,some suggestions are put forward for the relevant indexes of China’s energy conservation standards.3)NSGA-II is suitable for performance optimization of office buildings in cold areas.The appropriate algorithm parameters are population size being 5 times the number of variables,default values for the crossover rate and mutation probability,and the number of generations for the optimization being determined based on building size and optimization objectives.One-step optimization has the best optimization efficiency,followed by stepwise optimization,cluster optimization,and cluster-based reoptimization.Cluster analysis is performed on the Pareto optimal solutions,and the range distribution characteristics of design elements of the optimal solution are summarized.The multi-criteria decision is used to automatically rank the optimal solutions.4)The performance optimization design method and platform for office buildings proposed by integrating mode FRONTIER with Grasshopper/L+H.The platform not only has functions such as parametric design,performance simulation and evaluation,and multi-objective optimization,but also includes functions such as factorial test and data post-processing.Thus,problems of existing performance optimization methods,such as complex interactive operation,a lack of analysis of optimization results,limited number of optimization algorithms,and inability to automatically select the optimal solution,are solved.