How neighborhood form influences building energy use in winter design condition: Case study of Chicago using CFD coupled simulation

Abstract

The energy use in building is affected by various factors including building shape, climate conditions, building envelope, equipment efficiency, HVAC system, and occupant behavior. Besides those factors, the wind environment of the microclimate and the neighborhood form, are potential factors influencing energy use. In this research, a neighborhood-scale building energy simulation scheme coupled with computational fluid dynamics (CFD) simulation is developed. The convective heat transfer coefficient (CHTC) obtained from CFD simulation is dynamically coupled with EnergyPlus simulation. To understand how neighborhood form and wind environment will change the energy use in different types of buildings inside a neighborhood in winter, the energy uses of different types of prototype buildings conforming to ASHRAE 90.1 2004 and 2016 standards are evaluated and compared. It is found that the CHTC and mean external wall temperature for each building have wide distributions under various neighborhood forms. The energy use intensity (EUI) in high-rises including office and residential buildings (ASHRAE, 2004) range from −10.2% to 20.7% and −13.3%–19.2% respectively against the mean EUI scenario. Generally, in winter design case, the increase in building multiplier will increase neighborhood EUI. The impact of building orientation on electricity and gas use intensity is different and shows a sinusoidal pattern, while the larger the setback, the less the energy use intensity (EUI) is. The EUI in ASHRAE 2016 buildings is less affected by neighborhood forms and the wind environment in Chicago due to better thermal insulation and higher building equipment efficiency. It is found a more scattered and low-rising neighborhood facing south is energy efficient on the winter design day in Chicago.