What is a passive house?

As a joke, for simplification, one might say that a passive house is a house without heating. The reports (Capital & Co) like to portray them as houses or simply light a candle to earn a degree.

To achieve this goal, many methods are possible, but to attain the standard "Passive House" defined by the PassivHausInstitut , three outcomes are imperative:

• Do not exceed 15 kWh / m ² / year heating
• That the total primary energy consumption (heating, water + electrical) does not exceed 120 kWh / m ² / year
• Excellent airtightness with a parameter n50 <0,6 h-1, a renewal of up to 0.6 times the volume per hour of home pressure or depression 50 Pascals

These figures compare to current standards and future with a moderation to be because the standards are not directly comparable

• Technical Regulations 2000: 150-200 kWh / m ² / year
• RT 2005: 100 kWh / m ² / year
• Effinergie (target RT 2012): 50 kWh / m ² / year
• Passive House: 35 kWh / m ² / year excluding appliances or 42 KWh / m ² / year with Appraisals (Germany). The standard of 120 kWh / m ² / year is a safeguard for the construction service.

Why 15 kWh / m ² / year for heating?

Simply because the theory and existing achievements prove that under this threshold, a house does not need independent heating system.

It heats up "alone": the inputs and the sun and its people enough to maintain a comfortable temperature (19-21 degrees) and this throughout the year (ie all that the winter summer).

How to achieve this goal?

Rationale: Optimizing the bulk

Design concepts for optimizing the energy demand are sought for several years. Too often, however, they have needs the implementation of technology too sophisticated.

The interest of the passive house concept is precisely its simplicity. As its name suggests, the energy saving is achieved mainly through the use of passive strategies. By optimizing the main elements needed, a conventional heating system is unnecessary.

Minimise heat loss before heating to maximize gains

• First, we must aggressively reduce heat loss. The heat transmission losses can be reduced by an excellent insulation of the building envelope. The ventilation losses can be reduced by sealing the entire building to the air, in combination with a mechanical ventilation system forced double shifts and a heat recovery system with high efficiency.

• With a well chosen orientation of windows and windows and their proper sizing, solar radiation can be used as passive external heat input. In addition, the heat generated internally by the occupants and household applications constitute a useful contribution to the residual demand of heat.

1. Use all the ambient energy
2. Achieving a perfect thermal insulation
3. Ensure air barrier
4. Acquiring a double-flow ventilation with heat recovery
5. Choose complementary energies

A passive house costs more!

Yes and no. Gains on the equipment and consumption such as heating (ten times lower than those of a standard house) partially offset the additional costs in the insulation and ventilation more efficient.

The extra initial theory is the order of 10-15%, but can be much higher if the approach is complemented by a passive approach "ecological".

In considering the cost "global" in a building over a period "possession" mean, the design concept as the standard "passive house" is the most economical and is now much more profitable over time than others constructs the initial investment may be more "light".

Nobody builds

Alias: there is none so why bother

If the latest figures were talking about 10 to 12 000 passive buildings in 2007, things have changed since 2009 sees the 20,000 mark exceeded by the European project Passnet .

The geographical distribution is terrible for France, but he must still move up before too late.

Selected references:

In addition to references "institutional" on the page LINKS , here are some links point with relevant explanations.

The passive construction by our research department (FIABITAT). Feel free to turn their files

A definition a bit more technical LaMaisonPassiveFrance

After Ekopedia in Links, here version Wikipedia

An excellent presentation by the multimedia home platform passive Belgian

A conference detailed Adeline Guerriat on the concept of the passive house

And remember our list of questions and answers . ...