Daylight utilisation in commercial buildings and potential energy savings

Abstract

Energy is one of the most vital contribut ions to sustainable development strategy of Sri Lanka. However, the r ising cost of energy generation, the deplet ion and the unpredictability of availability of energy resources and the adverse impacts of energy generation and its usage on the environment, have been causing much anxiety and great concern from recent t imes. Within this context, buildings have been considered as one of the largest consumers of energy and have therefore been ident ified as one of the target areas for energy conservat ion. Statistics have revealed that the proportion of energy consumed for light ing in buildings is much greater than what is consumed ind ividually for providing thermal comfort or other ancillary services. Therefore adding of daylight for space, architectural designing has become a vital overcomes above problems. Adding adequate sunlight, integration with artificial light ing and reducing the cooling load on HVAC systems are effect ively providing wide energy savings in buildings and houses. The principle object ive in this research is therefore to explore strategies of designing buildings with opt imal utilisation of natural light, efficient application of electrical energy for inter ior light ing and minimising energy usage of HVAC systems. A simulation modelling on daylight implementation was carried out under this research, with different kinds of light ing arrangement against a few different external characteristics within the control of the designer. The computer simulation software DIALUX 4.11 version was used to analyse illuminat ion level inside the building and a n extensive literature survey on maximising ut ilisation of daylight and its effect on HVAC system was also carried out under this research project. As per the research energy savings from daylight design in buildings cannot be realized unless the electric lights are dimmed or switched in response to the amount of available daylight. The analysis results shows , that there is potential for saving 51% of energy consumed for building light ing with daylight implementation for the building. But due to practical limitation, exist ing light ing arrangement is not suitable for daylight implementation and therefor e new light ing arrangement was considered under this research and new light ing arrangement shows that there is potent ial for 50% of energy saving with daylight integration. The analysis was further carried out for new type of luminar ies to find out further energy saving potent ial with implementation of energy saving lights with integration of daylight. This analysis results shows, that there is potent ial for 52% of energy saving with new type of luminaries and its arrangement. Effect on HVAC system due to daylight implementation was also analysed and it is shown that there is 10% increase of building cooling load due to daylight implementation. Also this research presents guide lines for designing of daylight efficient buildings light ing systems to contribute towards energy conservation, environmental protect ion and establishment of sustainable economic system as well. This research can be further extended to analysis for different kind of building with different wall colouring and internal objects arrangement for opt imal energy saving with daylight implementation for commercial buildings.