Mtr Jayasinghe

Roof orientation, roofing materials and roof surface colour: their influence on indoor thermal comfort in warm humid climates

The excessive heat transferred through the roof is one of the main causes of thermal discomfort in warm humid climatic conditions, which prevail in the tropical zone. Therefore, the selection of the most appropriate roof orientation and materials will be important for desirable thermal performance of passive houses. This study investigates the effect of the roof orientation, roofing materials, insulation and the surface colour of the roof on the maximum indoor temperature of a house located in a warm humid climatic region. It is shown with the aid of computer simulations that the roof orientation has no significant effect on a properly planned passive house. However, the use of appropriate materials and insulation could afford significant improvement, which could be further enhanced with the use of light colours for the roof surface.

Strategies for improved micro-climates in high-density residential developments in tropical climates

High-density residential developments on outskirts of cities with a large number of detached multistorey houses on small blocks of land are actively promoted as a solution to urban migration in many countries. Such a concentration of houses can have adverse effects on the micro-climate due to the presence of a large number of roofs which have a tendency to warm the surrounding air, leading to heat island effects. The use of insulated roof slabs provides an alternative that may enable the creation of green cover at roof level. In this research, the performance of different insulation thicknesses has been evaluated, indicating that a minimum thickness of 25 mm would be desirable in tropical climatic conditions. The effect of creating green cover was determined with actual models. It is proved with comparative studies that shading screens can be used to simulate the presence of green cover with computer simulations. This is important in predicting the performance of insulated roof slabs for buildings of different layouts.

Thermal comfort in proposed three-storey passive houses for warm humid climates

Electricity, which is the backbone of the industrial sector, plays a vital role in the development of a country. In Sri Lanka an adequate increase in the supply of electricity to meet the rising demand is unlikely to materialize, and therefore the price of electricity can be expected to rise in the future, resulting in a corresponding rise in the operating cost of houses. This paper explores the possibility of adopting environmentally friendly passive techniques to inhibit the thermal discomfort experienced in houses, and proposes the three-storey house as the best type because of its superior thermal performance over two- or single-storey houses. By means of modelling of a proposed three-storey passive house using the DEROB-LTH simulation tool, it shows that proper incorporation of passive features can lower the indoor temperature in certain cases by as much as 6°C. It highlights the economic benefits of the adoption of passive concepts, both at user level and to lesser degree at national level, and the sustainable development that results in minimizing the degradation of the environment.

Thermally comfortable passive houses for tropical uplands

In many countries located close to the equator, such as India, Sri Lanka, Myanmar, Thailand, Malaysia, Indonesia, and countries in parts of Africa and South America, certain regions can be considered tropical uplands. In such regions, the cold discomfort that occurs during the night and warm discomfort that occurs during the daytime could become a problem unless houses are planned with careful consideration. It is shown using computer simulation with case-studies carried out for the climatic data pertaining to tropical uplands of Sri Lanka that the adverse climatic effects could be minimised by carefully planning houses so that their occupants can adjust to the prevailing conditions. The result of this study is also presented as a set of rules with an example of a conceptual house so that designers can easily include such rules at the conceptual design stage of house-planning.

SEMI-TIERED HOUSING FOR LATERITE EARTH SLOPING LANDS—A SUSTAINABLE SOLUTION WITH ALTERNATIVE MATERIALS AND METHODS

ABSTRACT Increased demand for affordable housing and the limited availability of flat terrain for its construction are two major problems facing the provision of houses of acceptable quality in man...

Improvements to Portal Frame Design Using Stressed Skin Action of Sandwich Panels

Abstract When used as roof and wall claddings, sandwich panels can offer many advantages such as better appearance, thermal insulation and strength. They can also develop a significant stressed skin action that can be used to resist wind loads on portal frame buildings. However, this beneficial effect is generally ignored by Australian designers since roof claddings are crest-fixed. To utilise this effect, a suitable design methodology and associated strength parameters must be developed. This paper investigates the possibility of combining three dimensional computer modelling with the results of a detailed experimental program to produce economical and safe portal frame buildings with crest-fixed sandwich panels. A design method is presented along with guidelines for three dimensional computer modelling.