Investigating effects of urban configuration and density on urban climate and building systems energy consumption

Abstract Urban configuration plays a pivotal role in the current energy crisis by providing more thermally appropriate local microclimates leading to the efficient functioning of building systems. In this regard, the present research aims at an important research gap: the simultaneous effect of urban morphology and density on the near-building microclimate and the outdoor-installed cooling systems performance. To this end, a proposed coupling algorithm between CFD and Building Energy Simulation is employed by using two open-source tools of OpenFOAM and EnergyPlus. The main purpose of the coupling process is the accurate simulation of near-buildings microclimate. Experimental data captured by a monitoring campaign validate numerical simulations. Research outcomes of several typical urban patterns demonstrate the urban-layout-independent behavior of split units. Up to 50 K temperature difference between hot sunlit surfaces and low-temperature glass windows creates a trade-off to aggravate and alleviate local Urban Heat Island (UHI) intensity, which stabilizes air temperature near the ambient. On the other hand, the upward movement of warm air and the dominant impact of extremely radiated roofs engender a thermally critical area for rooftop units. It is most striking (UHI intensity of 3.8 K) in the street canyon layout, where long rows of buildings minimize heat removal by entirely deviating the wind flow. However, a cluster of single buildings provides a cooler built environment resulting in the better performance of building systems. Finally, this research concludes that decreasing urban compactness mitigates UHI intensity by allowing thermal wakes evacuation, which eventually provides up to 16.4 percent energy saving.