Solar architecture is not a new phenomenon but has been used as far as 2500 years ago by all early civilisations. Past civilisations evolved architectural styles that took advantage of the natural space conditioning effect of the Sun, wind and water to keep their rooms comfortable. This involved consideration of orientation, shape, colour, and materials of the building, the windows as well as the shape, style and location of the external shading.
The ancient Greeks used passive solar techniques, which helped them to reduce the need for firewood in the winter and to cool their homes during the hot summers. Their buildings had open south-facing porticoes, which permitted winter sunshine into the main living rooms, but provided shade during the hottest parts of summer when the sun was directly overhead. Dark stone floors and thick masonry absorbed heat within the building and this was gradually released during the evening as outside temperatures fell. Heavy walls at the rear sheltered the building from cold northern winds while low walls at the front and sides cut down draughts. As their experience grew the Greeks even applied these principles to high-density housing and built several solar cities such as Olynthus and Priene.
One of the most ancient and sophisticated examples of solar passive design can be found at the Pueblo Indian city of Acoma in North America. This settlement had three extended terraces that ran east to west and were built in tiers to make the most of the winter sun. The roof of each tier was layered with straw and other materials to insulate the rooms form the full blaze of the summer sun. In ancient Colorado, the Mesa Verde people built their homes under an overhanging cliff so that during winter, when the sun is low in the sky, sunlight could enter the structure and heat it directly, whereas during the summer when the sun is high in the sky the cliff shields the settlement from the harshness of the sun, keeping it relatively cool.
In India too, the Indus valley cities showed remarkable understanding of the environmental conditions and their architecture evolved as a response to the local climatic conditions. The rooms were arranged around courtyards, which served the purpose of natural ventilation and also provided lighting in the absence of too many windows. At the same time windows were small to prevent the entry of radiation. Walls were thick and served as heat stores in addition to providing insulation. Fatehpur-Sikhri and the Red Fort are also excellent examples of in-built solar passive architectural concepts. Even residential buildings like the ‘pols’ in Gujarat and other community spaces were designed to suit the season. For instance, the ‘Vavs’ or stepped wells of Gujarat were used as meeting and resting-places during summer since their cool interiors offered unbelievable respite from the scorching sun outside. In the summer people warmed themselves on the spacious sunny corridors while wide verandahs offered shelter during the rains. Similarly a private verandah type dwelling achieved this remarkably well. Much of the day-to-day living went on in the verandah away from the prevailing angle of the sun, in outdoor levels of air movements, eliminating the need for cooling devices such as fans, etc. The wells were lowered and a substantial amount of air could move through the enclosed spaces. The light-weight materials of construction themselves cooled rapidly to keep the interiors cool while the more massive construction outside retained sufficient heat during the day to keep the air warm at night.
The willingness and ability of people to organise their daily activities in the desired space frame was the most important tool used in traditional building design. A flexible building envelope also helped in meeting the comfort needs of the inhabitants. These tools have been lost in the present world with human beings looking for a specific degree of comfort, not willing to adapt himself to the environment but trying to fight it through artificial means. Today we take pride in the fact that we have transcended the fluctuations of the weather conditions and gained supremacy over environmental factors. The cost of this victory, however, is now becoming clear as the impact of this progress on the Earth is fully realised.
The traditional design elements for maintaining comfort in hot and humid climate such as screens, water sprinklers, ventilators, skylights, chowks, verandahs and windows that could aid night radiation, cooling and control thermal mass have been discarded with the availability of cheap fossil fuels that could provide artificial control of the built environment. A return to a more natural lifestyle is the need of the hour.