Energy-efficient buildings

Transkript

1 v Českých Budějovicích Strana 1 (celkem 8) Odborný modul: Building construction Professional module: Pozemní stavitelství Název tématu: Energeticky úsporné domy Topic name: Energy-efficient buildings Tvůrce tématu: Ing. Blanka Pelánková Název kurzu v anglickém jazyce Energy-efficient buildings Tvůrce kurzu v anglickém jazyce: Mgr. Kamila Tröstlová Annotation: The energy-efficient buildings are divided into several categories in accordance with the quantity of the energetic need of the object. The quantity of the energy, which is needed for the house operation, is dependent on the amount of the thermal insulation, on the perfection of the constructional detail solution, on the way of natural energy usage (sun shine, heat pumps etc.) and on the way of the back use of the inner warmth of the object. Key words: Low-energy house, passive house, zero energy house, active house, solar panels, photovoltaic cells, heat loss, heat transfer coefficient. Energy-efficient buildings Energy-efficient buildings are buildings, which have less energy consumption for heating and other operation of the object than typical buildings. They can be divided into: - low-energy constructions - passive constructions - zero constructions

2 v Českých Budějovicích Strana 2 (celkem 8) - active constructions It is necessary to carry out the calculation of the energy consumption of the object for the classifying of the construction into one of these categories. The calculation evaluates the need of energy for heating, the need of energy to heat water, the need of energy for lights, the need of energy for ventilation and other air adjustment, the need of energy for cooling and the need of energy for the operation (all appliances). Out of these factors, we can most influence the need of energy for heating. A low-energy structure is a structure which has the consumption of energy between kwh/ m2 per year. A passive structure is a structure which has the consumption of energy for heating lower than 15 kwh/m 2 per year. The total amount of the primary energy connected with the operation of the structure (heating, heating of water, air adjustment and the electric energy for devices) must not exceed 120 kwh/m 2 per year at the same time. A zero structure structures which have the energy consumption for heating lower than 5 kwh/m 2 per year belong to this category. Active structures these structures usually use the heat pumps, solar energy for heating of water and photovoltaic cells make such amount of energy that the object t produces more energy than it uses during the year. The construction is connected to the public electricity network. In the period, when the sun does not shine, it takes the electricity. When the sun shines, it produces the energy which supplies the energy into the network. One of the first passive houses built in 1990 in German Darmstadt.

3 v Českých Budějovicích Strana 3 (celkem 8) The first attempts to build the low-energy houses were carried out in 1939 in the USA. Then, more or less successful attempts continued. The first passive houses were built in Germany after The European Union brings one of the biggest changes in the history of civil engineering, which should significantly lower the influence of people on the environment. According to the already approved directive on energy performance of buildings, it will be possible to build only the passive houses after S-HAUSE is the ecological passive house made of wood and straw built in 2005 in the Lower Austria. The first of the important factors for the design of the low-energy and passive houses is their location at the plot, the shape of the house and mainly the orientation to the cardinal points. The shape of the house should be as easy as possible, with the minimum of the cooled space. The indented object has too large external surface and therefore is its heat loss too big. If we want to save the energy, we must use everything which is provided by the nature. Firstly, it is the sun energy. Most windows should be put designed into the southern part, the minimum of windows into the northern part. This is also the reason for the interior composition solution, the rooms for living should be placed into the southern part of the house, the repository in the northern part. The sun energy is taken by the sun collectors and photovoltaic cells. Sun collectors ensure the heating of the hot water. The photovoltaic radiation also has a wide range of ecological and operational advantages in comparison with other sources. However, there are some disadvantages in our climatic conditions:

4 v Českých Budějovicích Strana 4 (celkem 8) Advantages: The use of a virtually inexhaustible source of energy. The creation of no emissions or other harmful substances during the operation. The operation is totally silent, there are no moving parts. The easy installation of the solar system. The operation virtually does not need any service, the easy electronic regulation. Disadvantages: Relatively low average annual solar radiation. Short average annual sunshine hours. Large variation in light intensity during the year. Low efficiency of the conversion and the resulting demands on the surface of the cells. High investment costs for the installation. Relatively small lifetime (20 years) in the relation to the price. When the weather is advantageous, the photovoltaic device makes the electric energy and transmits it to the public network. According to the amount of the taken energy, the object can be classified into the group of low-energetic houses (takes bigger amount of energy), passive houses (takes less amount of energy), zero houses (the amount of the used and made energy is almost the same) and active houses (supply more energy than it takes). Mountain cottage Schiestthaus in Hochschwabu from height 2156 asl.- the passive construction

5 v Českých Budějovicích Strana 5 (celkem 8) The other determining factor of the energetic saving is the demand on heat for heating. It is given firstly by the heat losses of the object and secondly by the designed way of the heating system. The heat losses can be influenced by the right design and implementation of the construction. All external constructions must be well insulated. The external clodding must be provided by the adequately thick insulation. The thick layer of the insulation ( mm) is also a part of a ground floor in the terrain and in a ceiling composition upon the floors and under a roof. The mostly used insulation materials are glass wool, mineral wool, polystyrene, foam glass, straw, cellulose, sheep wool, hemp, flax. A very important part of a construction is a gap filing. It is usually the place where most heat is lost at the typical constructions. The most important parameter for evaluating of the quality of windows and doors for energy-efficient buildings if the heat transfer coefficient U. It is the value for the entire window, i.e. the glazing and the frame. Standards requirements for this parameter are constantly tightened but the recommended value for the passive house window is now U W = 0,8 W/(m².K). The triple glazing is used for the glazing of the windows. Frames fitting of the winds are designed by the 6-chambered system with an insulated liner. Most windows of the passive houses are firmly glazed, because it improves their thermal features. These objects have a special ventilation air system with heat recovery. Opening windows are designed only in a limited number for the case of the air ventilation system failure. A plastic window with a triple gazing and the insulating triple-glass and 6-chambered frame, U=0,76 W/m 2 K

6 v Českých Budějovicích Strana 6 (celkem 8) A wooden window with the insulating tripleglass, U=0,9 W/m 2 K It is necessary to pay the attention also to the details of the construction. These are mainly the places of the typical thermal bridges, such as wreaths, beams, connections of the balconies, wall plates, foundation walls etc. It is not enough to solve the details only in the building documentation, they must be carried out perfectly at the construction. After this, the passive or low-energy object works in the right way. The most amount of the energy consumption used for the heating should be used from its own inner resources in a passive house and a low-energy house. Even though, it is necessary to design the active way of the heating, for the case when the inner resources are not efficient enough. If the amount of the needed warmth is 10 W/m² or lower, a house does not need the special heating system and it is efficient enough to use its inner air for the temperature regulation. Although the way of the heating is not determined for the passive houses, the typical system of the radiators is inappropriate for its difficult regulation and excessive dimension. The floor heating of the ladder radiators is usually used in bathrooms. It is appropriate to use for example the solar system for the heating of water, it can help also with the floor and wall heating, can heat also the storage tank. The other of the options is the use of the heat pump

7 v Českých Budějovicích Strana 7 (celkem 8) connected to the ground collector. Such system can cool the space in the summer as well. The other option if the heat pump connected to the ventilation system of the house which uses the heat of the transmitted air. Dictionary: Výraz,člen/mn.č. Překlad Questions: vzor Why should the construction site be fenced in? Exercises: Cvičení podle uvážení autora, podle výskytu morfologických či lexikálních jevů v textu Mind map: otázky k zamyšlení, moderní trendy, klady a zápory atd. Construction site Safety Machines and tools Ground works

8 v Českých Budějovicích Strana 8 (celkem 8) Solutions: vzor cvičení - 1 Solutions: Exercise 1: Negate following sentences: Example: I am tall. I am not tall. (I am short.) a) The room is separate. b) That is wrong for sure. c) He s comming tomorrow. Solution: a) The room is separate. The room isn t separate. (The room is passable.) b) That is wrong for sure. That s not wrong for sure. (It s certainly right.) c) He s comming tomorrow. He isn t comming tomorrow. (He s comming any other day but tomorrow.) Použité zdroje dle zásad citování, text a obrázky zvlášť