This paper presents the findings of two recent studies on the thermal preferences of householders in upland and coastal tropical environments. The aim of the studies was to investigate those behavioural factors that influence a householder's appreciation of an indoor environment. The studies involved 159 households in Kampala, Uganda, and 104 households in Surabaya, Indonesia. The studies indicated that householders made choices regarding their indoor environments based not on comfort sensation alone, but on "real-world factors".

In buildings with passive downdraught evaporative cooling (PDEC), occupants are subjected to environmental conditions which might be characterised by elevated relative humidities, increased air speeds, and time-varying internal conditions. A new physiological model which describes the human thermophysical system, and the active control exercised on it, has been produced. The model predicts skin and core temperatures, sweat rates, etc. on different parts of a seated, standing or exercising human.

In the mid 1990's the 'need' to mechanically air condition school buildings became a political issue in North Queensland. Research suggests that school children are susceptible to heat stress, acclimatisation or cultural factors aside. Cooling strategies are also desirable to protect capital investment in building fabric, resources and electronic equipment. Community expectations suggest that air conditioning in the tropics is a 'necessity' to maintain an acceptable 'standard of living'.

Human thermal comfort in warm conditions can often be improved inexpensively by increased air movement. Two automatic ceiling fan systems are described that regulate air speed to maintain comfort in changing conditions. One system is based on the ASHRAE comfort standard and the other uses the PMV comfort model. In comfort tests at 29°C and 50% RH both automatic systems provided the same level of comfort at steady state conditions as manual control. However the automatic systems were faster in bringing the subjects to comfort.

The vote of acceptance of the thermal conditions of a built space varies with the individual. The design of the space should consider the occupant's thermal comfort therefore the future users' opinion on thermal conditions. People's opinion regarding the acceptance of thermal circumstances of a room can be expressed by several indices the PMV the scale being the most used for this purpose.

The building may be seen as a "container" of a conditioned environment where man comfortably carries out a number of activities. The achievement of acceptable indoor environmental conditions depends on the way such a container is realized. In other words, the whole building, which is designed to create a space in which man can suitably carry out certain activities, contributes with all its parts to controlling the desired environmental conditions.

The thermal behaviour of an office building is presented and discussed, as well as the results of a sensitivity study, which analyses the impact of architectural decisions and the effect of occupancy in terms of energy consumption (cooling and heating loads). This study was carried out using one floor of an office building, with large glazed facades, recently built in S. Paulo in Brazil, which was monitored for a short period (11 days)]. This building has been used as reference, for the sensitivity studies carried out for two climates, S. Paulo in Brazil and Lisbon in Portugal.

The buildings of this Environment Educational Center, designed with innovative energy saving features, minimize the impact on the preexisting environment. Renewable energy concepts have been applied to the building design, and intelligent control of lighting and air-conditioning has been included. Most of the buildings are green roof underground buildings, where domes that allow spans up to 42 m have been designed. Average energy saving is over 70% on heating and cooling demands and 60% in lighting.

Although Saudi Arabia empowers the world with energy, the country is faced with unprecedented demand on electric energy. The issue, however, is neither affordability nor shortage but the exponential growth of demand on electricity, which reached an annual rate of 17% [Ministry of Industry and Electricity (MIE), 1995). This figure indicates that we need to double the number of our power generation plants within few years in order to meet the kingdom's present and near future demand.