An assessment of cooling loads in Commercial buildings due to Urban Heat Islands - A study of Ahmedabad’s Central Business District
Around 69% of urban population in India is concentrated in its Tier 1 cities. The city of Ahmedabad, currently the seventh largest metropolis in India, currently has approximately 52 million m² of commercial space. By 2040, AUDA will have developed the proposed Central Business District .Envisioned as a high density Centre in the city with a distinct character and urban form, the CBD has a proposed FSI of 5.4 which is almost three times the currently permitted FSI of 1.8, meaning threefold increase in built space. The Urban Heat Island effect has been described as a critical environment issue for dense urban areas and is expected to increase the cooling loads on commercial buildings in the proposed CBD. This paper is aimed at quantifying the UHI intensity in the CBD area and its impact on the cooling loads of commercial buildings. Appropriate UHI effect calculation methods are used to quantify the current UHI intensity and cooling loads. UBEM for the CBD are developed for the baseline models 2021 and 2040 taking into account future weather conditions and climate change. EnergyPlus and other software simulations are carried out, UHI intensity and cooling loads are projected for the year 2040. The study shows that during peak conditions, for an increase in 1oC rise in ambient temperature the cooling loads increased by 10%-15% and double FSI can increase the cooling loads by up to 45%. Parametric study to test the possibility of mitigating UHI through use of high performance building envelopes show a potential of reduction of 25% in cooling loads of commercial buildings in the CBD in 2040.
