Impact of Urban Heat Island under the Hanoi Master Plan 2030 on Cooling Loads in Residential Buildings

Abstract

This study aims to evaluate the influence of urban heat island (UHI) under the Hanoi Master Plan 2030 on the energy consumption for space cooling in residential buildings. The weather conditions under the current and future status (master plan condition) simulated in the previous study (Trihamdani et al., 2014) were used and cooling loads in all the residential buildings in Hanoi over the hottest month were estimated under the simulated current and future conditions by using the building simulation program, TRNSYS (v17). Three most typical housing types in the city were selected for the simulation. The cooling loads of respective housing types were obtained in each of the districts in Hanoi. The results show that the total cooling loads over June 2010 is approximately 683 Terajoule (TJ) under the current status, but it is predicted to increase to 903 TJ under the master plan condition. The increment is largely due to the increase in number of households (203 TJ or 92%), but partially due to the increase in urban temperature, i.e. UHI effect (17 TJ or 8%). The increments in new built-up areas were found to be larger than those in existing built-up areas. The cooling load in apartment is approximately half of that in detached house, which is approximately half of that in row house. Moreover, it was seen that although sensible cooling loads increased with the increase in outdoor temperature, the latent cooling loads decreased due to the decrease in absolute humidity and the increase in air temperature.