Critical study of lighting quality derived from the natural lighting with response to tropical climate in selected hotel buildings in the southern coastal belt of Sri Lanka

Out of the five senses vision is the most precious to human being. Vision is primarily based on light and has become essential to human life. Since most human activities are solely dependent on light, occupancies of man must be provided with adequate light. Thus lighting has become an integral part of architect's designs. The objective of the control of light is to create appropriate lighting level for an intended task. The lighting level for a particular task differs and it's unique to that task. In order to arrive at the required quantity and quality of light the designer must made design decisions with regard to openings, external shade, distribution of light and surface characteristics of the space. This is defined as lighting strategy. Light is capable of changing the environmental quality of space. Day lighting and artificial lighting is incorporated in any building design process. But the day light get the highest value due to free availability. The great scholar Hopkinson stats that, " Day light is a gift of nature" in his book ,Day light.(1) In the case of tourist hotels, which are pleasure oriented, the required visual impact has to be immediate and significant. Therefore lighting strategy become important. As a tropical country Sri Lanka has a well-developed tourist industry. There is a great demand for cultural heritage, exotic beauty as well as the tropical atmosphere.( 2 ) When design in a hotel in a tropical environment, special attention must be given to thermal comfort. As lighting and ventilation go in hand, when one considers daylight, attention must be paid to ventilation as well. In hotel designs connectivity to this environment is very important. This is achieved by openings. Therefore a connection between aesthetic aspect and daylight can be seen. Architects take various design decisions to coordinate day lighting with other design requirements. Based on present day tourists we can identify a few key areas in a hotel. They are the lobby, restaurant, bar and guest room. The lobby is the prominent and impressive space in a hotel, which interacts with the guest first and foremost. As this also serves as an assembly point evenly distributed bright light is important. The lighting quality will enhance the quality of the space as well as keep the space alive. The restaurant aims to make dining an enjoyable relaxing and pleasurable task. To achieve this the brightness level within the space should be made lower as possible and the tables on which the food are kept should be directly expose to high brightness level. Similarly for a relaxing drinking experience brightness within the bar should be made lower as possible except at the bar counter, where high brightness level is recommended. The main function of the guest room is to relax the guest. To achieve this low brightness level is recommended. However relatively high brightness level are recommended for activities such as reading, writing and dressing perform within the guest room. During daytime to maintain natural lighting level as mentioned above, horizontal and vertical openings should be used correctly. But in a tropical environment to obtain sufficient ventilation large openings are required. Also as the view is important in leisure oriented hotel buildings, this too gives rise for the requirement of large openings. At certain points when attempting to obtain required writing level there can be conflict between ventilation and aesthetic aspect. When we look at the development of tourism in Sri Lanka, southern coastal belt stands out. Many leisure-oriented beach resorts can be see in this belt. As the sea has been considered main resource and, adequate sea view has been the main design requirement. Also in order to obtain the optimum sea view the building is oriented between the south and the west causing the design to face the challenge of the setting sunrays. To face this challenge architects of these hotels have had various design decisions. This study attempts to critically examine these decisions and the success and failures of such decisions