The NORTHSUN 90 conference provided a forum for scientists from high latitude countries to discuss their experience of solar energy. The book is divided into two parts, Part One deals with energy conservation and management in buildings and solar and low energy architecture. Part Two covers all aspects of renewable energy; materials science and photovoltaic conversion, weather data, heating and cooling of buildings, hot water systems, wave energy, geothermal energy, energy storage, country programmes and other related topics. In northern latitudes energy savings in buildings of up to 50% can be achieved. NORTHSUN 90 encouraged the attainment of this goal, promoting the use of solar energy in heating and collective work on solar projects of direct benefit to the region.