For low-energy houses is considered CSN 730540: 2 buildings with specific annual demand for heating exceeding 50 kWh / (m2a) if they use a very efficient heating system. This criterion applies irrespective of the shape of the building. With a suitable compact form will obviously be more easily met than in the form of very rugged. From a practical standpoint, however, is not as effective as low-energy house without a forced ventilation system with heat recovery.
Why choose low-energy house?
low heating costs
a constant supply of fresh air
do not form the draft
no temperature difference in the room
pleasant temperatures in winter and in summer
Eco-friendly living to nature
What is necessary for low-energy house?
greater thermal insulation layer
high-quality windows and frames
effective ventilation with heat recovery
Thermal insulation of low-energy houses
Prerequisite for energy-efficient houses is less heat consumption. To do it would deliver less energy than a standard house, and yet it remained thermal comfort, it is necessary to heat in the house to protect it. A thick layer of insulation without thermal bridges significantly reduces heat loss.
The average home is about 95% implemented ventilation gaps and ventilation units (fume hoods, fans). This is accompanied by loss of heat and no return. Often then we meet with various myths and superstitions regarding the use of thermal insulation. The most common argument opponents thermal insulation (especially polystyrene) is that the structure after insulation "breathing".
The low-energy house is used for breathing and ventilation other, more effective ways, such as recuperation. For low-energy houses is suitable thermal insulation of the system at least 200 mm. Fittings are ready for a simple finish, thin plaster exterior, interior also, or you can use the core with stucco or plaster.
Another part of the thermal insulation of the envelope is the roof structure. Requirements for thermal insulation of flat or sloped roofs are almost identical. If we want to get into the low-energy standard, we choose the least Ustřechy = 0.15 W / (m2K). The choice of material for the flat roof is affected by the stiffness and heat insulating material, because it is often used as a walkway, or is formed on the surface layer of vegetation.
If a house without a basement, it is always a better solution, and there are more effective alternatives insulation. One such possibility arises then, when the construction of a reinforced concrete floor slab, then it is possible to design a thermal insulator under the board (eg. ISOQUICK system or crushed foam glass as a sub-base) and contact with the peripheral structure then shows no thermal bridges. For basement of the house must be separated by spaces either thermal insulation under the ceiling, or it is possible to have thermal insulation as part of the floor, but here we have to choose stronger material.
Windows and frames with low-energy houses
Windows with low-energy houses have an important role, namely fulfill a dual function. Not only do they allow X-ray rooms, but also contribute significantly to savings in heating energy. The energy that gets through the windows into the interior, reducing the need for heating. This is especially useful in winter. Conversely, in summer when the sun is more, we have to reckon with some of shielding systems.
These systems may operate aesthetically, e.g. overlap balcony. Or we can replenish window blinds or shutters. Achilles' heel of the window form a frame that is necessary to insulate well (best break lining exterior parts). Even so, it is important to choose a frame with excellent thermal insulating properties and it does not matter whether plastic, wood, or a combination. In the selection window it is important to focus on the overall heat transfer coefficient, i.e., including the frame, which should not exceed 1 W / (m2K).
For low-energy houses use multiple glazing system. The minimum is to use double glazing, most often triple, which are filled with argon or krypton. Today, as part of the glazing using heat mirror or if MirrorTM Heat, which is a polyester film coated with special layers of metal oxides, whose location is in the middle layer between the panes. This application significantly improves the heat transfer coefficient of glass, but the purchase price of such a system glazing is somewhat higher.
Some windows can be designed as neotvíravá. This will improve the overall thermal characteristics of the window, but on the operational aspect of the proposal (possibility washing windows, possibility of escape).
Ventilation and heat recovery with low-energy houses
In low-energy houses without ventilation without heat advantage, definitely we do not want. For this purpose the controlled ventilation system with heat recovery. The device automatically sucks in fresh air from outside and brings it inside. While the air passes through a filter which deprives pollutants, and before entering the room still heats to room temperature. The air that leaves the room through a heat exchanger passes a large part of the heat and air supply.
The effectiveness of these so-called recuperators can be up to 95%. Means that reheated, either electrically or warm water, we need only the remaining 5%. And that's a big saving heat. The house is always fresh air, which is due to quality filters free of dust, pollen and other impurities, which is an important factor especially for allergy sufferers. The entire system is held in the floor or ceiling.
However, the system is constructed so that the house you are nothing but pipe. The air inlet in the residential area (rooms, bedrooms, living room) located using diffusers on the floor or in the wall just above the floor. Exhaust air is in the central area (hall, corridor) and logically where we need to exhaust pollutants and moisture, ie toilet, bathroom, kitchen and cloakroom appropriate. In these rooms can be lowered ceiling and so it is ideal to place the suction head into the ceiling design or just below the ceiling.
The ventilation unit is most often placed eg. In the utility room, where there is such a high demand for sound insulation, but the overall operation of ventilation is practically inaudible. The perfect effect it is appropriate to combine the unit with air geothermal heat exchanger, which is essentially a pipeline buried approximately 2 m below ground level. During winter, it works as a natural protection against frost and vice versa during the summer allows pre-air and improved thermal comfort in the building. It is due to the fact that at a depth of 2 m is a constant temperature of about + 10 ° C.