Origin of passive houses
The first passive construction standard was established in 1988 by Prof. Bo Adamson and Dr. Wolfgang Feist.
As a result of this work, in 1991, the world’s first passive building was constructed in Darmstadt-Kranichstein (Germany).
This building had:
- 90% reduction in heating costs compared to traditional constructions;
- More than 27 years later, it continues to demonstrate the same energy efficiency it had at the time of its construction.
What characterizes a passive house?
Passive buildings combine thermal comfort, indoor air quality, and low energy consumption.
At first glance, it is not possible to distinguish a passive house from a traditional building, as it is a performance standard, not a specific construction method.
Passive buildings must meet strict energy consumption criteria, but the materials and construction techniques (such as concrete or wood) can be chosen freely.
A passive house allows for a 90% reduction in energy consumption for heating compared to a conventional building, and about 75% in the case of new constructions.
It is a concept applicable anywhere in the world — there are already more than 4,000 certified houses — and suitable for different types of buildings, from homes to cinemas, schools, or offices.
The heating and cooling techniques are adjusted according to the local climate.
A short explanatory video to understand passive houses in 90 seconds.
And what about the renovation of existing buildings?
Achieving the Passivhaus standard in renovation projects is a challenge, especially due to the difficulties in eliminating all thermal bridges and in adequately insulating the exterior.
For this reason, a specific version of the standard for rehabilitation was created, called EnerPHit (Energy Retrofit with Passive House Components), which has:
- More flexible performance criteria, adapted to the limitations of existing constructions;
- Quality assurance for the owner during the modernization and energy improvement process of their home.
Fundamental principles of a passive house
The essential principles of a passive house include:
- High-quality thermal insulation throughout the exterior envelope of the building;
- Efficient frames and high-performance glazing, preferably certified by the Passivhaus Institute;
- Maximum reduction of thermal bridges;
- Air-tight envelope, ensuring that the building is air-tight;
- Controlled mechanical ventilation system with heat recovery to ensure comfort and indoor air quality.
Criteria and technical requirements of a passive house
For a building to obtain Passivhaus certification, it must comply with all the following criteria — otherwise, the project will not be eligible:
- Energy requirements for heating/cooling ≤ 15 kWh/m².year or heating/cooling load ≤ 10 W/m².
➜ In a conventional house, consumption is between 60 and 150 kWh/m².year, that is, 4 to 10 times higher than that of a passive house.
➜ The maximum heating load in a traditional residence is 30 to 50 W/m² (about 3 to 5 times higher). - Air tightness (n50) ≤ 0.6/h.
➜ In a common construction, small cracks and openings can be equivalent to a hole of 40×40 cm in the wall.
➜ In a passive house, the total area of air leaks is equivalent to the size of a €1 coin. - Primary energy needs ≤ 120 kWh/m².year
or renewable primary energy needs ≤ 60 kWh/m².year. - Frequency of excessive temperature (above 25 °C) ≤ 10 %.