IMPACTS OF CLIMATE CHANGE ON ENERGY DEMAND OF A MID RISE OFFICE BUILDING – A CASE OF NEW DELHI

Abstract

Climate change is a most concerning issue in the last few decades. As per the IPCC (Emission Scenarios) [1] this phenomenon is expected to result in a global temperature increase of 1.5 °C. Apart from its impact on annual mean temperature, it has brought significant changes to the temporal weather events. Such a change is seen as a critical factor for building designers given its impact on building's thermal behaviour, occupant's thermal comfort and resultant energy use. Buildings which are designed to current day's cooling and heating design day scenarios may exhibit inferior performance in the above context. In this context, this study intends to decipher the climate change phenomena using a bottom-up approach and delineate strategies for climate change resilience. The study has the following objectives (a) to map the impact of climate change based on the magnitude and temporal variations of dry bulb temperature, relative humidity and global horizontal irradiance; (b) to establish the effect of climate change on the energy use of a mid-size office building; and (c) to delineate design strategies for climate change resilient building envelope. The scope of the study is limited to a mid-sized office building located in the composite climate of Delhi. For this purpose, a review of plan-form configurations is carried out. Based on this, five representative spatial layouts are prepared. The weather data made available by Indian Society of Heating Refrigeration and Air conditioning Engineers (ISHRAE) for the year 1990 is morphed for the years 2020 and 2050 using the climate change world weather file generator. This tool uses IPCC TAR model summary data of the HadCM3 A2 experiment ensemble. A statistical analysis of dry-bulb temperature (Ta), relative humidity (RH) and global horizontal irradiance (GHI) is carried out to map the magnitude and temporal variation between the years 1990 (base), 2020 and 2050. It is found that the climate variables exhibit a significant change in magnitude due to the impact of climate change. The analysis further reveals the presence of significant temporal variations. In order to assess the implication on the energy demand, a representative office building in the city of Delhi (Development Alternatives World Headquarters) is modelled using Design Builder software tool. The energy demand of the building is simulated for the years 1990, 2020 and 2050. A comparative assessment of energy demand and the impact of changes in climate variables is presented. Desirable changes to the building envelop are identified in order to cap the energy demand of the building to the base year's limits. Further the representative office building layouts are 2 modelled as per ECBC and Super-ECBC criteria and the impact of climate change on their energy demand is presented. The climate-change resilient building envelop interventions are discussed for these layouts.