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Energy-conscious thinking: The conception of the Passive House
The constantly rising energy costs and the harmful effects on the environment give good grounds for establishing more energy conscious conceptions on planning in building and construction, the extensive application of renewable energy and finding various alternatives in order to be able to ensure the running of our buildings using minimum energy.
A conception of this kind is materialized by the so-called “zero energy house” or Passive House. Such buildings are virtually self-sustaining, individually designed houses. Their aim is to reduce the energy used for heating or cooling the house to the minimum by means of alternative energy sources and heat insulation. By not being connected to public utilities a house can be made passive, and it will become independent due to its self-sustaining abilities.
Specially designed geometrical proportions are typical features of the construction of these houses, so that energy taken in can be used the most efficiently possible. Designers try to keep the greatest possible cubic capacity and minimize heat loss by means of building perimeter walls of the smallest possible surface. The undivided multistorey buildings, with excellent qualities in terms of heating and thermal insulation, are designed with large windows oriented towards the South, with local conditions taken into consideration. The foundations of “passivity” can be laid with keeping these principles in mind during construction.
As in Hungary there is no such institution that would classify these buildings, the requirements concerning energy consumption, on which our Western neighbours base their “Passive” qualifications, can only be illustrated with figures from Austria and Germany.
If the house’s heating requirements, based on the calculated figures, are less than 10W/ m2, the house can be qualified as “Passive”. What does this mean? Using an example, to heat a 10 m2 room well, even the thermal energy of a 100 W lightbulb is enough. The data are appalling, especially knowing what figures can be calculated referring to an average house in Hungary today. According to the estimations, the energy consumption of an average Hungarian family house is 80 kW/m2/year, as opposed to 15 kW/m2/year, which has been determined as the upper limit of the energy consumption of a Passive House.
Energy consumption is brought down through efficient use of energy. In order to achieve this, zero energy buildings typically:
- are provided with efficient thermal insulation and are made with a technology that eliminates thermal bridges
- have increasedly insulated and oriented windows
- have a ventilation system provided with a heat exchanger
Basically these are the differences that make a building passive. Beside the basic characteistics, the most frequently arising question is where the energy that covers the energy consumption of the Passive Houses comes from, supposing they are not connected to the public utilities, as mentioned above.
Primarily from the Sun. From the thermal energy that is formed from the solar rays in a similar way to the greenhouse effect. The sunbeams enter the house mainly through great south-facing glass surfaces. Directly, without any building services equipments, from the purest and most natural source. The adaption of the energy available to all of us is planned, and it is the most optimally consumed heat gain. Due to the excellent thermal insulation, the energy that has gone inside cannot escape the building.
Secondarily, a Passive House gains energy from the everyday activities of its occupants, such as cooking, operating electrical devices, or the heat of the bodies of those staying in the building. It is surprising; one would think that these sources of heat are not notable, but let us think it over: how much heat is evolved when making a coffee, watching television, not to mention cooking dinner. Altogether these secondary thermal energy sources have a share in covering the heat consumption of a Passive House.
Thirdly, re-gaining the used up warm air is a very important factor, since when letting fresh air in by simply opening the window we let thermal energy brought in at great costs get out of the house, harming the efficiency of the house’s energy consumption.
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