We should recognize that vernacular architecture all over the world, especially in the warmer climates, had evolved ways of building to achieve acceptable levels of comfort. These ways of building meant that the building configuration and its fabric would largely attenuate adverse climatic conditions in favor of thermal comfort. If additional devices were required to enhance comfort there would be of a supplementary nature. This strategy when compared to the modern building practice would be inherently more energy conserving.
Also, unlike most traditional buildings, the functions that contemporary buildings serve are specialized and demand multiple levels of sophistication in terms of building services and control over the indoor environment. For facilities such as hospitals, laboratories and pharmaceutical production plants there are likely to be very precise requirements for control of air borne dust, temperature and humidity. Luxury hotels, department stores and cinemas would each have their peculiar needs for a controlled indoor environment.
These two factors led to the heating and air-conditioning industry adopting standards for defining comfort. These standards which were worked out by the American and European industry institutions for their home markets were adopted practically across the globe along with the spread of heating and air-conditioning technologies. These systems are generally based on the use of electricity and fossil fuels as sources of energy. It is estimated that today about 30 percent of all energy consumption is attributable to buildings and their operation. Heating and air- conditioning systems account for about 60- 70 percent of energy consumed in the operation of the buildings where they are installed.