The consequences of poor air tightness
Inadequate air tightness can cause various building diseases:
- heat loss and increased energy consumption;
- formation of interstitial and superficial condensation;
- mold growth and deterioration of materials;
- reduction of acoustic comfort;
- worsening of indoor air quality.
According to studies conducted by ENEA (National Agency for New Technologies, Energy and Sustainable Economic Development), air infiltrations can be responsible for up to 50% heat loss in a poorly insulated building.
The Importance of the Blower Door Test
To evaluate the air tightness of a building, the most effective method is the Blower Door TestThe Blower Door Test allows you to measure the air exchange rate at 50 Pascals (n50) and identify the infiltration routes.
The How the Blower Door Test Works is based on the creation of a pressure difference between inside and outside the buildingusing a calibrated fan mounted on a frame inserted in a door or window. By measuring the airflow required to maintain this pressure difference, the airtightness of the envelope can be calculated.
The Blower Door Test Cost may vary depending on the building dimensions and to the complexity of the structurebut it represents a fundamental investment to guarantee energy efficiency and the healthiness of the internal environment.
Regulations and reference standards
In Italy, the Blower Door Test It is not yet mandatory for all new constructions, but it is strongly recommended and required for buildings certified according to standards such as Passivhaus. The UNI EN ISO 9972 standard defines the methodology for carrying out the test.
International standards, such as those promoted by the Passive House Institute, require n50 values less than 0.6 h⁻¹ to ensure excellent airtightness.
Solutions to improve air tightness
To solve the problems related to poor air tightness, it is essential to adopt an integrated approach, as suggested by Building Science Corporation:
- accurate design of the building envelope;
- use of appropriate materials and construction systems;
- correct installation of windows and system crossings;
- application of vapor barriers and breathable membranes;
- accurate sealing of joints and connections.
Particular attention should be paid to theElimination of draftswhich can significantly compromise the airtightness of the building.
The role of controlled ventilation
A building with excellent air tightness benefits significantly from the installation of a controlled mechanical ventilation system (CMV). VMC not only ensures adequate air exchange, but significantly improves the quality of indoor air. This is particularly important considering that we all emit CO when breathing.2 and that in winter a constant exchange is necessary to maintain a healthy environment.
VMC systems with heat recovery represent an optimal solution, as they allow to maintain high energy efficiency while ensuring a continuous supply of fresh air. Contrary to the manual opening of windows or uncontrolled drafts, the VMC offers a healthier and more controlled approach to air exchange.
Although the VMC it is not an obligationit significantly enhances the living comfort and health of the occupants. As indicated in the ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) guidelines, a well-designed ventilation system can significantly contribute to the well-being and energy efficiency of the building.
Conclusions
There correct management of air tightness is essential to prevent building diseases and ensure healthy, comfortable and energy efficient buildings. The adoption of appropriate construction techniques, the execution of verification tests such as the Blower Door Test and the implementation of controlled ventilation systems are essential steps towards the creation of high-performance and sustainable buildings.