What is passive house?
A passive building is a building in which indoor thermal comfort (ISO 7730) is ensured exclusively by preheating or precooling the amount of fresh air required (DIN 1946) for the correct indoor atmosphere, without the use of additional air recirculation.The passive building it is one building model which offers at the same time high energy efficiency (energy house), comfort, economy and is environmentally friendly. The Passive Building it is not a brand, but a design philosophy which is open to all and this has been proven in practice. Therefore, the passive house and building is more than just an energy efficient building or a simple energy house. The KOFINAS company, an official member of the Passive Building Institute, is able to implement certified passive design constructions, offering you all the benefits combined with the high quality of the company's materials and construction!
Regardless of climate or region, Passive Buildings they maintain a comfortable and pleasant temperature all year round with minimal energy requirements. Buildings are passively heated, i.e. they make efficient use of the sun, internal heat sources and heat recovery, resulting in conventional heating systems not necessarily even on the coldest days of winter. During the summer, a Passive house - building uses passive cooling techniques, such as the correct design of shading and natural night ventilation, in order to keep cool. In any case, the materials of excellent quality and technology and the careful design guarantee that the temperatures they remain all year round, at stable and pleasant levels for the tenants / users.
A Passive Building uses up to 90% less energy for heating and cooling than conventional buildings in Central Europe, resulting in less than 1.5 liters of oil or 1.5 cubic meters of natural gas being required per year to heat one square meter of habitable space. Exceptionally great economy, however, is also achieved in the hottest areas, where buildings need cooling. Limiting energy use leads to limiting greenhouse gas emissions, and so the Passive Building is a really sustainable choice in relation to conventional structures.
As demonstrated by the way buildings operate (i.e. the only way to determine the true cost of a building), the operation of Passive Buildings has reduced expense requirements, while at the same time their manufacturing costs are surprisingly affordable. The investment in high-quality construction materials, based on the specifications of the Passive House Standard, is balanced by the absence of the need to purchase conventional cooling and heating systems. Additionally, this investment in energy savings is many times cheaper and more efficient in the long run from the unilateral investment in RES or its easy solution fuel change.
Passive Buildings succeed Thermal comfort space with very low energy requirements. The mechanical ventilation systems with energy recovery continuously provide the required clean air by offering excellent quality atmosphere, without being noticed due to a reduced operating noise level. The combination of stable temperatures and proper air exchange prevent moisture damage and mold growth.
How does it work
The strategy of a passive building is the reuse of "free" heat for heating the house.
This "free" heat is produced by all electrical appliances, such as ovens, refrigerators, computers, lamps, etc. building envelope of a passive house must be very good insulated and airtight, so that this "free" heat does not leave the interior of the house unused.
- 1 Insulation
- A properly insulated building shell, during the winter, keeps the heat inside the building, while in the summer it prevents it from entering it.
- 2 Windows
- Properly designed, insulated and installed frames contribute to the optimal utilization of solar gains.
- 3 Ventilation with Energy Recovery
- Passive Building ventilation systems provide clean air, free of pollen and dust, with maximum energy efficiency through heat recovery and humidity control.
- 4 Air tightness
- Passive buildings are designed in such a way as to avoid air leaks in the building shell, thus increasing energy efficiency and preventing the occurrence of drafts and moisture damage.
- 5 Thermal bridges
- The minimization of thermal bridges and weak points in the building shell contributes to the creation of a pleasant and stable temperature, while eliminating moisture damage, while increasing energy efficiency.
Shading, Night Natural Ventilation, Light Geothermal Air and Correct Planning of the thermal mass contribute to the best performance of passive buildings in Mediterranean climates.
So, descriptively what happens is the following:
- One mechanical ventilation system with one heat exchanger air - air, is installed so that it can simultaneously bring fresh air and subtract a corresponding amount stale air.
- In winter the cold exterior clean Air enters the exchanger, receives the heat of the rejected stale air and enters the house.
- In the summer the exported stale air cools the warmer incoming fresh air.
- In the winter the warm stale air that leaves the house, "carries" the "free" heat, which through the exchanger heats the fresh air who enters the house. Correspondingly, the cold in the summer stale air it will cool the heat exchanger fresh air.
- In case the above system is combined with geothermal energy (o clean Air to diffuse first from the earth and then go to the exchanger,) the profits in both winter and summer are multiplied.
- Installing a conventional heating and cooling system can be avoided.
Costs and profits
As an example, the cost of a passive house of 100 sq.m. is against 10% larger from a typical house of our company. This extra cost is negligible if you compare it to the energy saving which we achieve with a passive house. Not only will we pay for it immediately, but we will benefit significantly since the annual energy needs of the passive house are negligible.
What benefits does one get from implementing a passive house?
The benefits are manifold – there is great energy savings, which translates into a reduction in expenses. The needs of the residence for heating and heating are zero. On top of that, in a passive house the quality of life improves vertically, since the constant temperature conditions and the constant renewal of inhaled air have a positive impact on the health and well-being of residents. Finally, the house is more practical during living, since it does not require the resident to constantly intervene for the cooling, heating and ventilation of the house.
In the following diagram we see an energy balance of such a house in diagram form:
And what does that mean practically?
It is, therefore, obvious that a passive construction, is able to greatly reduce operating costs of a residence, since – practically – it does not require any energy for its cooling and heating.