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Solar Energy Passive







Solar energy – passive

How does passive solar design use the sun’s power?

Passive solar houses are designed to let heat into the building during the winter months and block out the sun during hot summer days. This can be achieved using deciduous trees or bushes to the south of the buildings. During the summer, the leaves on these trees block out a lot of the sunshine and unneeded heat. These trees lose their leaves in the winter, allowing an increase in the solar gain during the colder days. Also the building can be designed to have louvre’s or shutters systems to block out sun when it is high in the sky while allowing it in during the winter when it is lower in the sky.

Simple features can be incorporated at the design stage such as large south-facing windows and building materials (thermal mass) that absorb and slowly release the sun’s heat. Passive solar designs can also include natural ventilation for cooling with windows playing a large part in passive solar design. http://www.esru.strath.ac.uk/EandE/Web_sites/01-02/RE_info/passive_solar.htm

Passive solar houses in antiquity - rural Greece ...using the sun as a heat source is nothing new. In XENOPHON'S MEMORABILIA, written 2400 years ago, Socrates observed:

"Now in houses with a south aspect, the sun's rays penetrate into the porticos in winter, but in the summer, the path of the sun is right over our heads and above the roof, so that there is shade. If then this is the best arrangement, we should build the south side loftier to get the winter sun and the north side lower to keep out the winter winds. To put it shortly, the house in which the owner can find a pleasant retreat at all seasons and can store his belongings safely is presumably at once the pleasantest and the most beautiful." http://www.dennisrhollowayarchitect.com/html/SolarDesignb.html#anchor728202

Austria and Germany ABSTRACT

In the Western world the built environment takes about 40% of all energy consumptions. Therefore, reduction of energy use in buildings is an important issue in the policy of European countries. Within the European Union, in particular Germany and Austria have implemented very low energy building concepts. In Germany, the Passiv Haus Institut of Darmstadt took the traditional concept of passive solar building as a starting point and developed concepts for very low energy buildings. The principles of passive solar building are combined with a very well insulated and air tight building envelope. Thanks to the high thermal quality of the building, and superb air-tightness the house does not need an additional heating system. Heating for very cold days is provided by raising the temperature of the ventilation air (which is much less complicated than conventional air heating). By definition, passive houses do not exceed 15 kWh per square meter floor area for heating per year. This is a saving of 90% compared to the amount of heating energy that is needed for the existing housing stock. The total primary energy consumption (so included DHW and consumers electricity) does not exceed 120 kWh/m2. Apart from the excellent energy performance, the comfort level of these houses is very high and in Germany and Austria the price of the houses is as an average only 8% higher compared to traditionally built buildings. The goal to reduce the extra investments to less than 4% can be achieved within 10 years. In recent years more than 4000 passive houses have been built in Germany already and more than 1000 in Austria, and more and more non-residential buildings are built following the passive house technologies. For the coming years, again many of thousands of passive houses will be built in Germany and Austria.