Stored Energy in the Urban Canopy, Heat Island and Energy Consumption of Buildings in Tropical Climate.

Abstract

The objective of this study is to evaluate the relationships between the energy stored in the canopy, the heat island (ICU) and the energy consumption of buildings located in urban and rural sites, in a tropical climate. Meteorological stations were used to collect data on energy balance, flow of heat stored in the soil, temperature and absolute humidity of the air, in the dry and rainy seasons. The heat flux in the soil was measured using a flow meter and the energy stored in the urban canopy was estimated. The Cooling Degree-Hour parameter was used to derive the energy consumption for cooling the bedrooms of a hypothetical building, located in urban and rural sites. The results indicated differences between the balance of available energy and stored energy in urban and rural sites, as well as between air temperature and humidity. The difference of 0.3MJ m-2day-1 of energy stored more in the urban environment in relation to the rural one, in the dry month, corroborated to raise the ICU intensity of 2.2°C, on average, in the urban canopy. In the rainy season, the difference was 0.8MJ m-2day-1 and an increase of 1.4°C was observed in the ICU. The bedrooms in the building located in the urban environment demanded 4.6kW/(m2month) more in September, to maintain the same thermal conditions as in February, which required 1.4kW/(m2month). The results demonstrate that buildings under the effect of the urban heat island phenomenon require greater energy demand to maintain similar conditions of habitability than in rural areas.