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What is a passive house ?

  It was in 1990 that the first passive house was built in Germany.  Even today, this concept attracts more and more architects. But what is a passive house? What are  the main advantages of a passive building? How does a passive house differ from a traditional house?

A passive house is a very energy-efficient building, which guarantees comfort in summer and winter alike. During most of the year, the house can remain at a comfortable temperature, without using a conventional heating system.

For a house to be passive, 4 requirements are needed:

Imperative n° 1 : maximum insulation

Good insulation is undoubtedly the best investment, both for new construction and for renovation. Without good insulation, the heat in the house will be lost. The better you insulate, the less heat will escape through the floor, walls or roof.

You will therefore save on your energy use and, as a result, on your energy bill.

Most often, 15 to 25 cm are needed to insulate the floor, 15 to 35 cm for the walls and 20 to 40 cm for the roof, depending on the case. The windows are triple glazed, with thermal break frames; with the effect of not feeling a draft near the windows.

Imperative no. 2 : perfect airtightness

If we compare the insulation to a woolen sweater, we could call the airtightness a windbreaker, which protects the house against cold wind and drafts.

In many homes, heat literally escapes through cracks and gaps.

Uncontrolled air leaks lead to poorly ventilated indoor air, the dissemination of odors, contamination, mold

In a passive building, special attention is therefore given to airtightness, in combination with good ventilation.

This obviously implies careful attention to the planning, implementation and control of the construction, as well as to the choice of appropriate materials and techniques.

Imperative no. 3 : take advantage of external contributions

To minimize the need for heating in a passive house, we must not only limit heat losses, but also increase heat gains as much as possible, i.e. optimize the heat that enters "free" into the House.

Most of this heat is provided by the sun.
In a passive house, the triple glazing, super insulated, allows the sun's rays to pass through, bringing in more heat than it loses.

Electrical appliances and the inhabitants themselves are also a source of heat. On the other hand, a good solar protection system is necessary to avoid overheating in summer.

Imperative no. 4 : optimal ventilation

Ventilation, the real lung of a passive house, is ensured mechanically and continuously by means of a VMC (Controlled Mechanical Ventilation) which always guarantees optimal air quality.

In a super insulated envelope, the balanced ventilation prevents the dangers of condensation and mold and guarantees air quality.

In winter, fresh outdoor air is heated in the heat exchanger, and stale air is expelled. In summer, the hot air intake is cut off by a bypass system, to prevent the fresh air from being heated.

Passive house :

the practical, economic and fiscal advantages

The passive house stands out from a classic house for the comfort and independence it offers, thanks to its excellent level of insulation which makes its rooms pleasant to live in.  In a passive house,  there is no air stratification, which makes the temperature of each room uniform: its insulation protects the interior from the cold in an optimal way. Its insulation standard regulates temperatures in all seasons and thus avoids intense heat, humidity, mold or even cold.

The windows of a passive house benefit from a great thickness which contributes to good acoustic insulation. If you want to live in a healthier and less polluting house, the choice of living in a passive house is ideal. In addition to its practical advantages, a passive house is ecological and economical: benefiting from an external source of energy (wind turbine, solar panels, etc.), it provides more energy and allows significant energy savings.  Moreover, because it requires less heating, it preserves the environment.

Even if its construction is more expensive than that of a traditional house, it is more economical in the long term, because its energy needs are much lower than for that of a classic house. At the fiscal level, the State favors passive house investment projects and this is the reason why, on January 1, 2005, the tax credit  dedicated to equipment expenditure for the main house is now intended for equipment requiring renewable energies.

Passive house construction:

new perspectives for the years to come

A new standard, RT 2020,  plans from the year 2020 an improvement of the passive house: the construction of a house  positive that produces even more energy in relation to its consumption. This type of habitat, also called Bepos which means passive energy building,  will simply be a more efficient and more advantageous house in terms of natural energy favoring the sun's rays and heat. To produce more energy than it consumes, it will be built in such a way as to exploit more renewable energy sources.

Its energy needs will also be reduced to a minimum. Although it is quite an expensive investment project, the benefits and long-term payback are certain. The builders of the RT2020 house will in particular use technical solutions to accumulate heat through walls, roofs or windows in order to produce electricity. The maximum reduction of energy consumption will be one of the major objectives of the construction of a passive house. For this type of housing, the planned energy expenditure must be less than 0 kWh/m² per year. In this project, it is possible to exploit the surplus of energy not consumed by the positive residence for uses in the public electricity network.

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