Thermally comfortable passive houses for tropical uplands of Sri Lanka

Abstract

The main aim of this project is to determine the ways and means possible to create a thermally comfortable environment in the house located in tropical uplands with the use of passive elements. Initially, a broad literature survey was conducted to determine passive techniques desirable for tropical highlands. The technique used here was to establish comfort zones for tropical uplands and investigate the effect of various passive features on thermal comfort such as orientation of the buildings, the roof, the windows and the number of air changes. The thermal effect of the various design options was established by using computer simulations carried out with the aid of DEROB-LTH. The outdoor climatic conditions were obtained from Meteorological Department of Sri Lanka. The required climate data were maximum and minimum temperatures, sun shine hours and relative humidity. The software was validated for tropical upland areas by using actual measurements. As an outcome of this detailed study, a set of rules were developed along with a conceptual house. It is shown that this conceptual house could give a very good improvement for the internal minimum temperatures when the passive features given in the guidelines were adopted. Halls s having an upper floor In a part of it should be constructed except under the geological and structural circumstances, financial problems or any other circumstances. Since the effect of ridge direction is insignificant, ridge of the roof should be directed to either north-south or east-west. New GI sheets are highly recommended as a roofing material. If asbestos sheets are used they should be painted in dark colour as recommended below. Burnt clay tiles should be strictly avoided. The orientation of the house should be faced either south or north. By this, heat transfer in to the house through glazing can be reduced. Hence overheating can be avoided. All the roofs and walls should be painted in dark colour which has higher absoptance values. The colours like Green, Blue and Grey are recommended. All the openings, doors and windows in the house should be closed at night time. The curtains should be provided from the top of the window including the lattice. The maximum effort to avoid infiltration in the nighttime should be taken. Ceilings should be provided to avoid cold air entering in to the house .. Windows should be provided on north, east and south. West should be avoided in order to control the hot discomfort. If and only if, one of the walls are gable walls of the house, providing windows facing west is allowed. Fins, sunshades and all the types of shading devices can be removed if and only if, they are not used to divert the wind which flow in to the house.