Assessing the effects of CO2 reduction strategies on heat islands in urban areas

• Published in: Sustainable cities and society Vol. 26; pp. 383 - 392
• Main Authors: Hirano, Yujiro, Yoshida, Yukiko
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.10.2016
• Subjects: Air-conditioning load; Built environment; CO2 reduction; Energy saving; Numerical simulation; Urban heat island; Urban thermal environment; Urban thermal environment; Numerical simulation; Built environment; Energy saving; CO2 reduction; Air-conditioning load; Urban heat island
• ISSN: 2210-6707; 2210-6715
• DOI: 10.1016/j.scs.2016.04.018

•This study assessed the effects of CO2 reduction measures on urban heat islands.•A coupled urban-canopy and building-energy model was used for evaluation.•Temperature changes due to the introduction of CO2 reduction measures were estimated.•Atmospheric sensible heat balances within the urban canopy were also investigated.•We concluded that such measures are not major factors in increasing temperatures. There has been a wide range of low-carbon solutions proposed to mitigate climate change. However, such measures must be compatible with the local environment and living standards of residents to be brought to fruition. Measures that adversely affect residential environments will be difficult to implement, so the impacts of measures on the local environment must be taken into consideration during implementation. This study assessed the effects on urban heat islands of efforts to reduce CO2 emissions, as one environmental impact associated with climate change. A simulated assessment was conducted, using an urban canopy model coupled with a building energy model (CM-BEM), to evaluate the effects of five specific measures: solar shading of windows using curtains and blinds, improvement of the thermal insulation of building walls and roof surfaces, implementation of energy-saving measures related to indoor appliances, installation of solar photovoltaic (PV) panels, and adjustment of preset cooling temperatures. The study focused on these effects as they occur within typical urban districts of office buildings, fire-resistant housing, and wooden housing. Results indicated that many of the energy-saving measures have slight temperature lowering effects, but solar panel installation and improved heat insulation, both associated with changes in surface heat balances, tend to raise daytime temperatures to some extent. However, effects on daytime temperatures were in the range of 0.1–0.2°C and, as such, none of the CO2 reduction measures considered was deemed a significant factor in raising urban temperatures.