Energy conscious buildings for Sri Lanka : a study with special reference to efficient use of energy in lighting

Abstract

Energy is one of the most vital contributions to the sustainable development strategy of Sri Lanka However, the rising cost of energy generation, the depletion and the unpredictability of the availability of energy resources and the adverse impact of energy generation and its usage on the environment, have been causing much anxiety and great concern from recent times. The entire world has therefore looked up to energy conservation through frugal and efficient use and through the use of alternate renewable energy sources, as a solution to this grave problem. Within this context, buildings have been considered as one of the largest consumers of energy and has therefore been identified as one of the target areas for energy conservation. Statistics have revealed that the proportion of energy consumed for lighting in buildings is much greater than what is consumed individually for providing thermal comfort or other ancillary services. The principle objective in this study is therefore to explore strategies of designing buildings with optimum utilisation of natural light and efficient application of electrical energy for interior lighting. A number of verification experiments on daylighting were carried out for this task, with different types of scale models of office buildings and windows against a few different external characteristics within the control of the designer. Also, an extensive literary survey on the subject of energy efficient artificial lighting was carried out as related to office lighting The survey on daylighting clearly revealed that multiple windows which were inclined, high ground reflectivity together with top lighting where necessary contributed to obtain good quality lighting in buildings. Such an exercise would totally eliminate the need for artificial lighting during the day or reduce it to an absolute minimum in the worst situations The literary survey on artificial lighting, proved beyond any doubt that task lighting combined with minimum ambient lighting was the most efficient approach to artificial lighting of office spaces Also, the daylighting data and the artificial lighting information collectively provided clues to the ways in which the two types of interior lighting could be effectively combined as when necessary. It is quite evident from the total study that artificial lighting is indispensable It is at least needed as a supplementary light to make any shortfalls in natural lighting or to balance the brightness in an interior when there is an excess of natural light in one part of the space. Therefore, daylight efficient building designs and efficient artificial lighting systems would immensely contribute towards energy conservation, environmental protection and the establishment of a sustainable economic system. Accordingly this study has opened new vistas in to the realms of energy efficient architecture relevant to the Sri Lankan situation.