Passive house construction aims to create energy-efficient and comfortable homes that consume a minimum amount of energy. To achieve this, passive houses must be built to strict standards that ensure proper control of four critical elements: water, air, vapour, and thermal. These four control layers are crucial in creating a well-insulated, airtight building envelope that prevents unwanted heat loss or gain, moisture buildup, and air infiltration.
The water control layer is the first line of defense against water damage. It includes a combination of roofing, flashing, and waterproof membranes to prevent water from entering the building structure. The water control layer must be properly installed and maintained to ensure its effectiveness over time.
The air control layer plays a crucial role in reducing unwanted air infiltration, which can lead to heat loss and air infiltration. A well-sealed building envelope is essential to prevent unwanted air movement, and the use of airtight building products, such as caulks and seals, is recommended. The air control layer also involves proper ventilation to maintain indoor air quality and prevent the buildup of moisture and pollutants.
The vapour control layer helps prevent moisture buildup within the building structure, which can lead to mould growth and other indoor air quality problems. A vapour barrier, such as a polyethylene sheet, is typically installed to prevent moisture from entering the building structure. The vapour barrier must be properly installed and sealed to be effective.
The thermal control layer is the final layer of defense against heat loss or gain. Insulation is the primary component of the thermal control layer, and its effectiveness is measured by its R-value, which indicates its resistance to heat flow. Proper insulation helps maintain a consistent indoor temperature and reduces energy consumption.
Proper ventilation is critical to maintaining indoor air quality and preventing the buildup of moisture and pollutants. Passive houses typically use mechanical ventilation systems, such as heat recovery ventilators (HRVs), to ensure consistent and efficient ventilation. The HRV provides fresh air while recovering the energy from the outgoing air, reducing energy consumption and maintaining indoor comfort.
The four control layers (water, air, vapour, and thermal) play a critical role in creating a well-insulated, airtight building envelope in passive house construction. The combination of a well-sealed building envelope, proper insulation, and efficient ventilation is crucial in reducing energy consumption, maintaining indoor air quality, and ensuring the comfort and durability of a passive house. Investing in proper construction and ventilation strategies can lead to long-term cost savings and a healthier living environment.
Learn more in our Passive House FAQ
