Passive construction is another milestone toward the energy efficiency. By passive house we mean a building which both, in winter and summer, allows for high “quality of living”, while maximally reducing energy consumption for heating and air conditioning. A passive house utilizes the available solar radiation, which passes through the windows. On the other hand, it does not allow the excessive transfer of the heat released by solid objects inside the home.

Passive construction offers many benefits, such as:


  • reduction of operating costs, in particular the cost of heating
  • only 15m3 of gas is enough for a year to heat 1m2 of the building living area (it is about 10 times less than in the average new building built nowadays in Poland)
  • comfortable micro climate in rooms: fresh air, thermal comfort, optimal humidity
  • perfect solution for people suffering from allergies: the air inside a house is cleaned of pollen, mites and moulds
  • protection of the environment

The areas through which most of the heat escapes outside are windows, which is why they are an important element of a passive house. To fulfil their function, they must feature numerous properties:


  • profile with thermal pads and warm steel reinforcement
  • aluminium overlays, which are mounted on the outside of the casing, sash and the post (if any)
  • dual chamber glass panes with a warm frame featuring high thermal insulation coefficient (Ug ≤ 0.7 W/m2K = 0,1234 Btu (th)/hour/foot²/°F)
  • 3 seals ensure the perfect tightness


In order for windows to completely fulfil their functions in the passive house, they must be properly installed. The embedding depth must be calculated to ensure the optimal isotherm course. Windows in passive houses are often installed outside the wall, on a steel section or on a specially formed console. The console can be made of wood or prenite. Then, insulation is applied to the wall with the window already mounted. To ensure proper tightness between the window casing and the wall during installation, special sealing tapes are used both on the inside and outside of the window casing.

Heat losses in passive houses are very insignificant. In order to balance the losses, there suffice the so-called passive energy sources, such as solar energy passing through windows, heat generated by residents or heat emitted by household appliances. In passive houses, no special heating installation is needed, because the buildings are so warm. that they require heating only during the periods of extreme freezing temperatures. The additional heat is then usually supplied via the ventilation system.

The construction of a passive house is not much more expensive than this of a standard building with an average energy demand. European experience shows that the additional expenditure incurred can be recovered within about 5 years. This period may be even shorter, if we take into account the rising energy prices (including heating oil and gas), and the increasing availability of building materials designed for passive houses. Passive construction requires high quality building materials with very good thermal insulation. Window joinery in passive houses is on the inside so warm, that there is no cold air current coming from the window.

The BERTAND company offers special window and door joinery for the passive houses. The window profile with overlays presented above achieve the heat transfer coefficient of UW≤0.8W/m2K. The system has a certificate confirming compliance with the requirements for passive construction. It is also possible to manufacture windows without the aluminium overlays. BERTRAND has both, qualified personnel and technical capabilities to professionally install window joinery in the passive houses.


The BERTRAND company participated in the construction of a passive house, which was built under supervision of the Polish Institute of Passive Construction in Gdańsk.