ilmanpitävyyskerroksista

Ilmanpitävyys, also known as airtightness, is a crucial concept in building science and construction. It refers to the degree to which a building's envelope prevents uncontrolled air leakage into or out of the building. This leakage can occur through cracks, gaps, and openings in the building's structure, such as around windows, doors, electrical outlets, and where different building materials meet.

Achieving good airtightness is important for several reasons. Firstly, it significantly impacts a building's energy efficiency. Uncontrolled air infiltration can lead to heat loss in winter and heat gain in summer, increasing the demand on heating and cooling systems and thus raising energy consumption and costs. Secondly, airtightness helps to control indoor air quality. By preventing the uncontrolled entry of outdoor pollutants, allergens, and moisture, a well-sealed building can contribute to a healthier indoor environment. Thirdly, proper airtightness is essential for the effective functioning of mechanical ventilation systems, such as heat recovery ventilation (HRV) or energy recovery ventilation (ERV) systems. These systems are designed to provide controlled ventilation and air quality, and their efficiency is compromised if there is significant uncontrolled air leakage.

Assessing and measuring airtightness is typically done using a blower door test. This test depressurizes or overpressurizes the building to measure the volume of air that leaks through the building envelope under a specific pressure difference. The results are often expressed as air changes per hour (ACH) at a standard pressure, such as 50 Pascals. Building codes in many regions specify maximum allowable air leakage rates for new construction to ensure a certain level of energy performance and comfort.