How the urban environment affects the microclimate and the building energy demand for the City of Rome

Abstract

Original scientific paper https://doi.org/10.2298/TSCI19S4035VUrban heat island has significant impacts on buildings' energy consumption. The phenomenon is associated with increased urban air temperatures compared to the air temperature of the surrounding rural or suburban areas. The ambient air temperature growth due to climate changes and the urban heat island phenomenon are dramatically increasing the cooling demand in buildings. This is worsened by irradiation conditions, construction technologies, and subjective comfort expectations. This paper examines the impact of the urban environment on the energy demand of buildings, considering the case of two districts of the city of Rome, Italy: one is representative of a central zone, the other of a rural zone. Weather data were then used to calculate the thermal demand of a typical Italian building, ideally located in the monitored areas of the city. Standalone building with modified weather file was modeled in TRNSYS. Results show that urban heat island intensity causes an increase in cooling demand up to +33% for the urban area (+20% for the rural area) compared to the demand calculated using weather data from airportual areas. On the other hand, urban heat island intensity has a positive effect on heating demand which turns out to decrease up to -32% for the urban area (-14% for the rural area).

Simulation analysis and optimization research on cooling and dehumidifying effects for evaporator

“…two-phase surface heat transfer coefficient of boiling in tube, (W m -2 K -1 ) α refr.l surface heat transfer coefficient of liquid phase in tube, (W m -2 constant pressure specific heat of water vapor, (kJ kg -1°C-1 ) c pm constant pressure specific heat of wet air, (kJ kg -1°C-1 ) t 1,2 average temperature of humid air as entering and exiting the evaporator, (°C) t w wall temperature, (°C) d 1,2 average moister content of humid air as entering and exiting the evaporator, (g kg -1 dry-air) d w moisture content of saturated air at wall temperature…”

“…One of the major concerns of our days is to reduce energy consumption and the environmental impact of cities and buildings. [1]. In developed countries the HVAC systems consume around a third of the total energy consumption of the whole society [2].…”