The importance of site on house heating energy modelling in Wellington - Integrating EnergyPlus with ENVI-met for site modelling
Site is an important factor in the building design process, where it is analysed to determine design strategies for responding the microclimate. It is also considered important in Building Energy Simulations (BES) where a weather file is used to represent the site location and its microclimate. However, many cases of BES in the design process use weather file from a nearby weather station rather than site specific microclimate. In fact, site microclimate can be affected by nearby parameters such as ground surface and vegetation, with unknown effects. In the Wellington, New Zealand context, micro-climates vary widely due to the local topography while suburban houses can be located on the side or bottom of a hill. These houses are likely to have different exposure to the sun and wind which can influence energy consumption for space heating. Many studies about site-parameters impacts mainly focus on the vegetation and nearby buildings effect on microclimate. Only a few estimated the impact of site-parameters on building energy use and mostly their cases are in urban areas (flat terrain). Unfortunately, site parameters, such as altitude and slope, associated with the Wellington topography (hilly terrain) have never been examined. This thesis investigates the importance of site parameters on house heating energy modelling for the Wellington context. BES software, EnergyPlus, was used and explored to identify limitations in modelling site parameters. An attempt was made to solve these limitations through the integration with microclimate software. Three microclimate software programmes were reviewed: ENVI-met, UWG (Urban Weather Generator) and CFD (Computational Fluid Dynamic) software. ENVI-met was selected to generate the local air temperature and relative humidity affected by site parameters, which was used for EnergyPlus weather-file modification. A parametric study of ENVI-met basic input with model evaluation was also conducted. The results of parametric test integrating ENVI-met with EnergyPlus showed that ENVI-met mostly produce insignificant impacts of site parameters on house heating energy, unlike the results found in the literature review. This is likely due to the cool weather conditions (winter in Wellington) used in simulation, which suggests that the idea of microclimate modelling using ENVI-met is not applicable for house heating energy modelling in the temperate, Wellington context.