Komal thakur, K.P. Rewatkar
Daylight, Office Buildings, Energy Optimisation, Daylighting Design
|PUBLISHED DATE||January 2016|
|PUBLISHER||The Author(s) 2015. This article is published with open access at www.chitkara.edu.in/publications|
Office building designs have undergone manifold changes because of various technological innovations as well as social and economic transformations. At present, intense international competition is forcing many businesses to examine and rethink their organisational structure. Modern technology is making it possible to use time and energy in offices in new creative ways. Intensive use of modern technology has created issues such as global warming, greenhouse effect and, hence, requires us to think seriously about the importance of saving energy and the necessity of designing energy efficient buildings. Lighting is the major energy consumer in commercial as well as in office buildings.
Lighting generates heat and increases cooling load of buildings. Various tasks require different intensities and different types of lighting. Sufficient daylight is available during office hours and can be used without any load on electricity for lighting. Daylight is much more comfortable to work with as compared to artificial light. At the same time, sunlight can be very intense and, if not admitted properly in the building, can cause excessive glare, creating problem for users.
Though availability of daylight is useful for reducing energy consumption, simultaneously the designer needs to be very careful the about visual comfort of occupants. Good quality light helps to increase productivity and also saves energy. Studies show that out of the total energy consumption, 20-40% of electricity is used for artificial lighting which can be reduced by appropriate use of daylighting .
This paper is based on the premise that energy optimisation is possible in office buildings through design of daylighting. The motivation for the study was born of the fact that in India, among all building typologies, commercial buildings consume the maximum energy. This energy consumption is mainly for cooling of the building and lighting the interior spaces. Cooling and lighting up spaces generates heat in and around the building, which again increases the cooling load. Out of the total electrical energy required in the building, around 20-40% is used for lighting purposes. Despite availability of daylight during the working hours, artificial lighting is used in offices that have huge internal spaces with large spans. This paper aims at understanding the factors related to daylight penetration into office building in different situations and developing guidelines for achieving maximum daylight penetration in large spaces.
|ISSN||Print : 2321-3892, Online : 2321-7154|
In this study, daylight penetration in office buildings for various types of windows was studied. The impact of factors such as window size, its placement, window to wall ratio, height of floor, type of window protection on daylight penetration was calculated. Increase in window to wall ratio increases daylight penetration but also tends to increase heat gain inside the office building. Office buildings can benefit from ample amount of daylight due to duration of working hours in daylight. Thus, penetration of light is possible by appropriate design solutions and using light shelves with louvers during summer and winter and can help in energy optimisation in artificial lighting. The initial cost and installation cost of light shelves is 60%-75% more than traditional window cost. But this cost can be compensated within 5 - 6 years from installation.