Passive House

What is a Passive House ?

Passive House  

A Passive House (or Passivhaus) is a house that consumes very little energy so it is possible to live in it without a traditional heating solution.

The need for primary energy for the cooling on one hand and for the heating on the other hand does not exceed 15kWh/m².year. This is more than 10 times less than existing buildings in France or other countries.

In total the energy needs (including heating, cooling, ventilation, auxiliaries, production of domestic hot water, lighting and appliances) must not exceed 120kWh/m².year.

Une Maison Passive (ou Passivhaus) est une maison qui consomme très peu d’énergie de sorte qu’il est possible de faire l’économie d’une solution de chauffage traditionnelle.

A passive house is not necessarily a house without heating :

Although it is possible!
Indeed, the combination of the solar contributions and the heat loosened by the inhabitants and the electrical equipments of the house should be able to compensate the energy loss of the building and thus keep temperatures pleasant. Therefore the name “passive”.

However, for security reasons (fear of being cold) or because the free inputs are not sufficient enough, a backup heating can be planned. It is directly made on the air carried by the mechanical ventilation.

Wohn-Büro-Passivhaus Fussenegger, Lustenau
EFH Witzmann, Schlins
© Fussenegger, Lustenau
© EFH Witzmann, Schlins

Passive House and Low-energy House (BBC Effinergie) 

Main differences
Specific constraint on the need for heating
The low heating requirement due to the ‘Passive’ can do without a traditional and more expensive heating solution.
Different objectives depending on the climate
Low energy consumption (BBC) sets the limit to 40kWh/m2 in colder areas; depending on the altitude.
Specific treatment of summer comfort
The passive sets with 15kWh/m2.year the need of refreshment. It imposes specific calculations to take into account the influence of the soil on the construction elements and the absorption of solar radiation by the opaque surfaces. Specific simulations must also cover the ventilation solutions in summer.
Taking into account the total energy needs
The Low energy consumption (BBC) excludes induced consumption by appliances, but sets a much higher level of general consummation than required by the passive.
Total level of requirement (in "hot" areas)
Also the calculation methods differ much more than they look as the calculation tools of the Passivhaus Institute are more complete and show results closer to reality than those to be used for the low-energy consumption (BBC). In addition the PHI tools are more readable and easier to use.

Note: The same as for the BBC label, the Passivhaus certification implies a constraint on the airtightness of the building. The test of the airtightness should not exceed 0.6Vol/h under 50 Pa which corresponds to 0.03vol/h under normal conditions.

Is it appropriate to build a passive house in Provence or on the Cote d'Azur ?

passive house in Provence and on the Cote d'Azur
  • As it is not so cold, it is much easier to achieve a Passive performance;
  • The fact of not having to invest in a solution of traditional heating is twice considerable;
  • Good insulation and airtightness protects one not only from the cold, but also from the heat;
  • The approach of passive design requires a very far-reaching consideration concerning the issue of the summer comfort in order to create a comfortable living standard far superior to conventional buildings throughout the year.
  • The passive approach adapts to all styles of architecture and lifestyles.
  • In extreme weather conditions (cold, heat, humidity, air pollution), the passive house can remain securely closed while maintaining a hygro-thermal comfort and ideal indoor air quality .
passive house

How to obtain this level of performance ?

level of performance  

The quality of the design that is done beforehand is essential. The choice of companies and the control of the execution quality are also important.

How do you achieve the thermal performances of a passive house ?

passive house

Sources: Department of Urban Housing and Construction, France

1. A suitable and seamless insulation :

  • The discontinuities of the insulation or thermal bridges are to be avoided
  • The performance of windows is also very important.
  • The isolation level of opaque walls (walls, ground floor, roof) must be calculated to be optimized based on the actual need to achieve the objective.
seamless insulation  

The actual need is influenced by :

  • The local climate see the microclimate of the site;
  • Free solar contributions: they depend on the orientation of the building, on the position and on the size of the windows and on the outer solar masks.
  • Architectural specifications: complexity of the form and surface as well as orientation of the windows (even with a very high performance level they are far from achieving the thermal performance of a solid wall)

2. Good airtightness :

Being in the framework of a building with a very high energy performance, induced losses by air leaks at wall connections, coffered shutters, window frames, punctures made for networks and sheaths (electricity, ventilation) ... become significant. It is therefore very important to pay a particular attention to these singular points.

3. Controlled ventilation performance :

4. A specific and pushed treatment for the summer comfort :

If one saves energy in winter the point is not to spend it for summer cooling. It is to design an inexpensive and flexible summer ventilation strategy to manage the inertia of the building.

5. Using renewable energies :

eneUsing renewable energies   

The use of conventional energy sources such as electricity or fossil fuels is penalized by the cost equivalent to primary energy, while it is the contrary for renewable energy.
It is thus a question of conceiving solutions for heating, cooling and domestic hot water that correspond best to renewable energies (including geothermal and solar energy).

6. Limiting the consumption of electricity for lighting :

By facilitating the natural lighting and considering energy-saving lamps.


Relying on the right person to pilot the construction of a Passive House :

Passive House  
  • Concept BIO is not a construction company.
    Concept BIO includes architects and engineers who accompany their clients independently. From the feasibility study to the delivery of the work, through the selection and the follow-up of the companies that will realize your house.
  • Concept BIO is a committed member of "Passive House France" (la Maison Passive France) which is the only French organization capable of delivering the Passive House label in France.

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Frequently asked questions