A passive house is very economical low-energy house. In winter and summer, providing high quality internal environment while allowing significantly reduce energy consumption for heating and running at all. A passive building does not require conventional heating or air conditioning and saves the economy of its natural resources.
It is a building (house) with 10 times less annual heating requiremenet than conventional construction, ie up to 15 kWh per m² of usable area (per year). It also meets several other criteria (Leak n50 <0,6 h-1 and the need for primary energy consumption <120 kWh / m² a) and recommendation (eg heat loss up to 10 W / m²).
Passive (heating through windows), and possibly active (collectors) uses solar energy, the ventilation system with heat recovery and very good isolation (in opaque structures around 0.1 and in windows to 0.8 W / m². K). The concise increasing investment costs much reduced cost to operate the house, saving non-renewable resources and reduce CO2 emissions, while increasing the comfort of living, provides summer thermal comfort without air conditioning and heating needs conventional heating system – using solar and internal heat gains, heat can rest bring ventilation.
Each energy passive house document:
- Calculation of heat necessary for heating, using a specialized program or computer simulation (maximum value is 15 kWh/m2.a)
- Test of the building tightness (blower-door test), which is the vacuum pressure and 50 Pascals verify that the leak escape for an hour more than 60% of the total volume of air in that area,
- Calculation of the total primary energy consumption, including household appliances (includes losses in production and distribution of electricity), the maximum value is 120 kWh/m2.
Features defining the quality of passive buildings
There are not clearly defined values and conditions, as well as related to the size of the building and its architectural design, but often they also include: coefficient of heat transfer in opaque circuit designs should be below 0.15 W/m2K (the family house in our climatic conditions must be less than 0.1 W m2 K), U-ups should be below 0.8 W/m2K and if we rely on the use of passive solar gains, they should fire windows at least half solar. Construction should be addressed without significant thermal bridges and controlled ventilation with heat recovery of air ventilated (minimum efficiency Regenerative unit 80%). The decrease of primary energy needs can contribute significantly to the use of solar collectors or heat pump. We should embrace these criteria and respect – just to avoid degradation of the term “passive house” on an empty slogan, received with suspicion ironic!
The uniqueness of the passive house is energy efficient use of local heat sources, in particular:
- the use of passive solar energy,
- the use of internal heat sources (people, appliances);
- re-use the heat from indoor air.
Such energy gains can be achieved primarily through
- thermal insulation packing heat structure (approximately U <0.15 W / (m2.K));
- well-insulated windows with frames (approx. Uw 0.5);
- elimination of thermal bridges in the structures,
- airtight packaging, heat the building structures. Penetration of air leakage must be less than 0.6-times the volume of the building for 1 hour at differential pressures of the external and internal air 50Pa, ie n50 <0.6 1 / h)
- controlled ventilation with heat recovery (with a minimum effective 80% efficiency).
Energetically passive houses are at first glance does not differ from ordinary homes – from construction-technological point of view is “only” about so-called improvement. low energy house. The passive buildings will not place higher demands in terms of project preparation, care in drafting structural detail to the exclusion of leaks and thermal bridges. Particularly important is the implementation of training without any deviation from project documentation.
Principles of energy passive house
Using solar energy is an important function in glazed surfaces. Solar radiation penetrates through the windows and warms the inside of the house, passive house in the rule to cover a third of the heat necessary for heating. However, the south-oriented glass allows least half the energy of sunlight into the interior – solar glazing factor g should be greater than 0.5. Using such quality glazing during cold sunny days we get even more heat than they lose through the night. Furthermore, the sun heats the window for us, even if frost is out. Solar energy is cheap and available – but how it can be used, depending on the proposal of the house.
In winter, they are sufficiently heated just south oriented. In contrast, the summer heat trying to profit from the sun to reduce – the external shading of windows is usually a necessity if improvements can also contribute to the quality of glazing varies according to the cardinal orientation (eg in the west we propose “dethermal” glasses).
Elimination of thermal bridges
Elimination of thermal bridges is one of the most important measures in the design of structures of passive houses. In well insulated house can these losses constitute a significant proportion of heat loss and heat around the bridge can be cool so that there will only condensation of water vapor. It depends on the expertise of the designer and the performance of the company as they can together by these weak structures solved (and it is necessary that the architect has followed his work from the first sketches to final approval). Typical examples of thermal bridges are contacts with the bases of walls, balcony bracket, installation of windows and window frames, transfers leadership structures and corners of rooms.
Air-tightness of the house
Prerequisite for the proper functioning and efficiency of controlled ventilation and hot air heating is high tightness of the building envelope. Airtight to prevent undesired heat loss but also prevents the ingress of moisture into the design and subsequent building failures.
The massive structure is easily achieved by air-internal and external plaster. Particular attention is needed regarding contact with the window openings kits and places where the cladding interrupted other structures, such as various installations. It is recommended to place contacts sealed with sealing tape or foil filled elastic putty. The lightweight construction is secured air-vapor barrier, which must never be interrupted or damaged (for example, careless to guide pipes installations).
The test building is airtight, so. Blower-Door Test (hereafter BDT) is essential to measure the air permeability of building envelope at a pressure of 50 Pa for the accurate calculation of heat loss and therefore the draft heating system. Leaks in the energy shell of the building impair the quality of construction. BDT will enable them to locate and is a prerequisite for successful removal before the end of the building. Using measuring devices in the home creates pressure 50 Pa (the pressure difference is generated by the current wind gusts in the range 4-10 m / s). This pressure difference allows devices to locate the flow of air through leaks in the shell of the building and repair them. The intensity of air exchange rate at a constant pressure differential of 50 Pa (N50) would not be passive house energy exceed 0.6-times the total volume of air per hour measured object.
Advantages of passive houses
People felt the room temperature does not depend on air temperature, but also from the surrounding wall surface temperatures. Thanks to very good thermal insulation, the difference between air temperature and wall surfaces and windows is very small, which contributes to a pleasant sensation of warmth in the room.
Air movement and humidity
Even the relatively slow movement of air in the interior evaluate how unpleasant. The passive house is excluded leaks causing drafts. Ventilation unit brings enough fresh air to ventilate the windows so it is not necessary. This system is advantageous, especially in winter when ventilation eliminates the need for open windows, dependent people. To vent the unit can also add a pollen filter, which allergy sufferers especially welcome.Humidity in the house should be moved in the range 30 to 60%. The constant supply of fresh air ventilation unit ensures that the humidity is standard in this range.
Direct sunlight in the interior, and protection from summer overheating
The presence of the sun in the house is an important factor for a pleasant feeling of home environment, but too much sun overheated interior is uncomfortable. Passive house concept takes these facts into account. Thanks to optimum size, quality and orientations of windows with summer shade, the proportion of mass accumulation and the ventilation system is passive house in a pleasant climate throughout the year.
Minimum energy consumption = low bills. Energy passive house thanks to its design saves during his lifetime and 90% of the cost of heating bills for consumed energy is tenth the cost compared to conventional homes. We are currently witnessing a continuous growth in oil and natural gas, which is driven by increasing demand and limited resources of raw materials. If people have a passive house, energy crisis has a big impact on us. It is a certainty, which is teaching in retirement.
Investment costs for the construction of passive buildings are usually higher than the normal building – about 10 to 20%. Careful project preparation to prepare design details, better windows, greater thickness of thermal insulation, high quality demands of the project when completed, all construction price increases. But few people realize how massive it is the operation of the house during its use. Experience with passive energy houses ranking more than 10 years ago say that the cost of their operation remain permanently low. The additional costs are thus “repay” small operation.
High quality construction
Consistent design and maximum compliance in the implementation of the investor brings superior user comfort and durability of the building.
Construction of a friendly nature
Contribution to climate change mitigation
Energy passive house that has low power consumption, has less negative impact on the environment. Reduction or elimination of burning fossil fuels such as coal, oil and natural gas by energy passive house is not only important in terms of reducing the increased greenhouse effect and climate change, but also in terms of taking responsibility for the depletion of non-renewable sources of energy to future generations.
Use of natural materials, further develops the concept of the passive house
Energetically passive houses are generally architecture and overall friendly environment. Often they also used natural building materials such as insulation from recycled cellulose, wood components, clay plaster. When we think of the relationship of architecture and environment, taking into account not only the actual operation of the house, but also where to obtain materials to build a house, how they affect the environment and what happens to them when the house doslúži.
Disadvantages of passive energy house
Increased investment costs
Energy passive house is more demanding in terms of design preparation, required thickness of thermal insulation, use of better construction materials, filling of holes, but more detailed work in the feasibility stage. These factors imply an increase in investment. International experience say about 10 to 15 per cent increase. Increased initial investment will be progressively released due to minimal operational costs and increased market value of such house.