Energy use in Building Envelope of a Residential Apartment Building in the Warm and Humid Climate of Guwahati, Assam

In recent years, Guwahati city is witnessing a rapid urban growth due to ever-increasing human population sacrificing existing green pockets. This constant increase of built form is resulting in environmental imbalances and microclimate changes, contributing in a rise of indoor air temperature and that ultimately results a gradual increase in the energy consumption to maintain indoor thermal comfort in the inner-city areas. Although the urban growth pattern of Guwahati is controlled by prevailing GMDA building bye-laws, these building parameters are unable to control the organic growth of the city since there is no climate-sensitive approach available in the GMDA bye-laws. This paper aims to discuss the energy use in the building envelope by analysing the energy efficiency of a residential apartment building of Guwahati and reviews most common energy efficient codes that influences the heat gain or loss, natural ventilation, and day lighting, which, in turn, determines indoor temperatures, thermal comfort, and sensible cooling or heating demand inside urban residential buildings. Four relationships of building parameters are studied and analysed their impact on energy use. The amount of heat gain or loss, natural ventilation and day lighting that are allowed by building envelop will be calculated for each relationships and compared. All the relationships specify building envelope design that helps to improve the energy efficiency in residential building, but none suggested a basis for its proportion. This paper analyses the use of daylight and natural ventilation within a building envelope helps to minimise the energy consumption. A climate conscious urban design approach associating common energy codes such as window to floor area (WFR) ratio, Visual light transmittance (VLT) and residential envelope transmittance value (RETV) against average daylight and natural ventilation can be utilised as preliminary urban design techniques in development control regulations especially in the residential zones in the inner-city areas of Guwahati metropolitan development authority (GMDA).