Enhancing building energy efficiency estimation by incorporating microclimate conditions

The UK government aims to achieve net-zero emissions target by 2050. The building sector plays an important role as it accounts for over a third of greenhouse gas emissions nationwide and 36% of energy consumption globally. In buildings, heating, ventilation, and air-conditioning (HVAC) contribute to over 60% of energy consumption. The building fabric is an important element which distinguishes indoor and outdoor environments at the same time enhances building energy efficiency (because of its surface radiation and thermo-physical properties). In order to comprehend the effect of these properties, several computational BIM tools have been developed such as EnergyPlus, eQuest, and DesignBuilder. These computational tools essentially require weather data as one of the boundary conditions along with other inputs. However, various studies indicates that the building energy calculations are more dependent on microclimatic conditions rather than weather data (obtained from the weather stations) hence leading to inaccurate building energy estimations. Therefore, this research aims to investigate the effect of reflective façade on micro-climatic condition and energy efficiency under UK weather conditions. A comparative analysis was carried out for a real-scale (2-storey) typical UK residential settlement using computational simulation to evaluate the impact of microclimate conditions. The findings show that the current tools, on their own, lack the ability to incorporate the microclimate conditions which impacts the accuracy of the energy estimations. Therefore, an improvised approach by integrating multiple tools (i.e., ENVI-MET with building performance tool)is proposed in this study. The output from ENVI-MET (micro-climate simulation tool) can be used as the input for subsequent building performance tool for an enhanced energy estimation. This proposed approach overcomes the issues and presents a realistic boundary condition for the building energy estimation. It is observed that there is a distinctive difference for both summer as well as winter period for UK climate conditions.