Abstract

Abdeen Mustafa Omer

Geothermal energy is the natural heat that exists within the earth and that can be absorbed by fluids occurring within, or introduced into the crystal rocks. Although, geographically, this energy has local concentrations, its distribution globally is widespread. The amount of heat that is theoretically available between the earth’s surface and a depth of 5 km is around 140 × 1024 J. Of this, only a fraction (5 × 1021 joules) can be regarded as having economic prospects within the next five decades, and only about 500 × 1018 J is likely to be exploited by the year 2020. Three main techniques used to exploit the heat available are: geothermal aquifers, hot dry rocks and ground source heat pumps (GSHPs). The GSHPs play a key role in geothermal development in Central and Northern Europe. With borehole heat exchangers as heat source, they offer de-central geothermal heating at virtually any location, with great flexibility to meet given demands. In the vast majority of systems, no space cooling is included, leaving the GSHPs with some economic constraints. Nevertheless, a promising market development first occurred in Switzerland and Sweden, and now also is obvious in Austria and Germany. Approximately 20 years of R and D focusing on borehole heat exchangers resulted in a well-established concept of sustainability for this technology, as well as in sound design and installation criteria. The market success brought Switzerland to the third rank worldwide in geothermal direct use. The future prospects are good, with an increasing range of applications including large systems with thermal energy storage for heating and cooling, The GSHPs are in densely populated development areas and borehole heat exchangers for cooling of telecommunication equipment, etc. This article reviews some interactions between buildings and environment. The correct assessment of climate helps to create buildings, which are successful in their external environment, while knowledge of sick buildings helps to avoid unsuccessful internal environments. The sections on energy conservation and green buildings suggest how the correct design and use of buildings can help to improve total environment.