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High-performance new home: the importance of airtightness

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A high-performance new house must be airtight. With l'reinforced insulation and bioclimatic design, airtightness guarantees a house that consumes very little energy to ensure optimum comfort in all seasons. Why should a house be airtight? In what way? How to check the performance? This article takes stock of this great principle which makes it possible to have a ecological house consuming little energy.

 

Why is a high-performance new house airtight?

Today, a new home builder as Sic houses must respect the 2020 environmental regulations, known as RE2020. The latter promotes ecological houses, consuming little energy and low carbon. To achieve this, the manufacturer has developed effective and proven techniques. A high-performance new house, ecological and comfortable is based on the application of the principles of bioclimatism, a reinforced insulation, but also the airtightness and the ventilation.

To go further, read our article “ 10 reasons to build a low-carbon wooden house »

 

What is the airtightness of the new house?

THEairtightness of a wall is its ability to prevent gas exchange between the inside and the outside. It therefore completes thehouse insulation minimizing heat loss through the walls. In an uninsulated house, the opaque walls (floor, walls, roofs, etc.) are responsible for more than half of the heat loss. Air leaks, and thermal bridges are also responsible for a large amount of heat loss in winter and hot air inflow in summer.

 

What is a thermal bridge?

By being well insulated and airtight, the high-performance new house also eliminates thermal bridges. The latter, frequent in old houses, even renovated ones, are the areas where there is a lack of insulation but also often of airtightness. They are generally located at the junction between the elements (floor-walls, walls-roof, walls-windows, etc.) and are responsible for approximately 10% of the losses of a building. More seriously, these thermal bridges create a contact zone between the interior and exterior of the house. In winter, the water vapor produced inside the house then settles on this cold area, creating condensation. The latter is often responsible for the appearance of mold and damage to the building and the materials that compose it.

To find out more read our article “ 5 questions to understand the insulation of the new house »

mold develops in an old, non-performing house
This type of mold problem is not encountered in a new high-performance home.

 

What are the consequences of poor airtightness?

– Poor airtightness can disrupt the air circulation system. ventilation overall house. Indeed, parasitic air leaks disturb the planned air flows and can even cause the absence of ventilation in certain rooms.
– If air can pass, then heat can escape. Because it complements the insulation, poor airtightness significantly reduces the thermal efficiency of the insulation.
– If air passes, then water vapor passes. These significant transfers of water vapor and hot air in the walls lead to condensation and disorder in the building (mold, rotting, degradation of materials, etc.).

Airtightness of the new house, what does the RE 2020 say?

Efficient new house: airtightness control

Today, theairtightness of a building is well understood by building professionals. The technique is proven and your builder houses Sic knows how to create houses without air leaks or thermal bridges. A performance that is attested by the infiltrometry test imposed by the RE 2020.
Carried out at the end of construction, it ensures that thehouse sealing is carried out with precision. Called the test of BlowerDoor », or test of the blower door, this test ofblower makes it possible to measure the flow of air passing through leaks in the walls. This test thus guarantees the quality of the services provided.

How is the blower door test carried out in a new house?

A waterproof infiltrometer is installed in place of a door or a window. Equipped with a fan, the latter measures the pressure difference between the inside and the outside of the building. If the house does not respect the thresholds defined by the RE 2020 (the rate of air leaks from the outside to the inside must remain below 0,6 cubic meters per square meter of wall and per hour), a search for leaks by thermography or by the use of artificial smoke will be carried out. This makes it possible to visualize the leaks and thus to correct the errors. Thus, on delivery the new owner is guaranteed to have a high-performance new house built according to the rules of the art, which respects the announced performances.

To fully understand the news RE2020 regulations which governs construction in France, read our article “ New house RE 2020 in the South-West: what consequences for my project? »

 

How to ensure the airtightness of new houses?

To limit air leaks, the high-performance house builder in the South West uses specifically created products throughout the house. Access hatches to the attic, doors, chimneys, boxes and electrical outlets, everything is carefully studied. In the same way, all the junctions between the different parts of the house (outlines of windows, doors, floor-wall connections or ceiling walls, etc.) benefit from the careful implementation of seals. In brick house masonry as in wooden house ou mixed wood/brick house, membranes cover the insulation and provide airtightness. These films are implemented continuously and with care for a perfect airtight continuity. Finally, the interior and exterior coatings also fulfill this role.

interior insulation of a builder's brick house
The Sic house is insulated from the inside, the sealing being ensured by the plasterboard, the vapor barrier film on the insulation, the brick and the exterior coatings.

Go further with our article “ How to Ensure Indoor Air Quality in a Home RT 2012 »

 

Why airtightness and ventilation are inseparable?

To have a healthy air of quality in the house, the air must be renewed and sweep all the rooms. In a perfectly airtight house, the role of the ventilation is therefore essential. To limit heat loss related to air renewal, a controlled mechanical ventilation, or CMV, who can be double flow ou single flow. Without parasitic air inlets and outlets, it is the VMC which allows all the rooms to be ventilated and which provides healthy indoor air in the dwelling.

To go further read our article “ 8 advantages of double flow ventilation in the South West"

 

Build a high-performance new house don't improvise. To ensure performance, comfort and a healthy air in the house over the long term, you need a home builder conscientious, aware of the issues and who knows that each element of a house is important.

 

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