<b>Effects of Solar Passive Architecture on Building Envelop</b> In different parts of the world, man has found various solutions for protection against climatically unkind conditions through locally available materials. For example, in the hot and humid regions of Asia, Indonesia, Polynesia and Amazon, the roof was more important than the walls for modifying the indoor conditions. In fact the walls could be omitted altogether. Hence, lightweight structures of timber skeleton, wooden frames, thatched roofs and woven, lath and venture walling were used in such regions. On the other hand, in the mountainous cold forest regions in the North West U.S.A., Scandinavia and Himalayas, one found well insulated timber houses. In the case of vernacular architecture, the roof played a determining role in the general form and appearance. Flat roofs appeared in hot regions, vaulted roofs in hot and dry regions and inclined roofs in temperate dry climates. Higher pitched roofs were used in wet temperate and cooler places. Both domes and vaults were popular in the hot arid regions of the Middle East and Northern Africa, where low humidity leads to intense radiation exchange, and the variations between day and night temperatures are high. The logic here probably deduced from centuries of experience is that a hemispherical vault has about three times the surface area as the base of a square roof, so the solar radiation is diluted to that extent. Also, the cooling by radiation exchanges to the night sky is faster. In the proto historic period, community based collective house forms evolved. Bio climatic aspects such as orientation, house form, open spaces, etc. were well integrated in vernacular residential architecture. Building envelop, orientation, thermal storage, solar passive 1660-1665 Issue-4 Volume-4 Ar. Apoorva Ajmera