Understanding Building Airtightness for Passive Housing Constructs

Building airtightness relates to the degree to which a building envelope is able to prevent air leakage.

This is important for passive housing constructs in order to maintain energy efficiency and comfort throughout the year.

As passive house constructs are becoming increasingly popular, understanding how building airtightness works and how it can be improved is key to ensuring a successful project.

Synonyms: Air permeability, building sealing, building tightness

Example: “To increase energy efficiency in this passive house construction, all walls and windows must meet strict standards of building airtightness.”

Pronunciation: BILD-ing AIR-tight-ness

What is Building Airtightness?

Building airtightness refers to the degree in which an envelope or façade surrounding a home prevents air leakage.

The elements of a sealed façade may include walls, ceilings, roofs, floors and windows.

Ideally, the envelope should be completely sealed so as not to compromise on energy efficiency or comfort within the dwelling.

With proper seals or systems installed into each element of the envelope, airflow will be minimal and heat transfer will be minimized as well.

Why is Building Airtightness Important?

Building airtightness is important for passive housing constructs because it helps maintain total system energy efficiency by limiting the amount of outside air that infiltrates into the dwelling.

Keeping a tight seal on all elements of an envelope keeps heating and cooling costs down by reducing unnecessary movement of hot or cold outdoor air into the home’s indoor thermal space.

Additionally, maintaining high-quality seals on windows also improves occupant comfort since poorly sealed windows can cause drafts leading to uncomfortable temperatures within a room or space.

Fun Analogy

Think about building airtightness like having caulking around window frames in your home.

To avoid any warm air leaking out during winter months and cool air escaping during summer months it’s crucial that each window frame has proper caulking applied correctly no matter what material it’s constructed with - wood, vinyl or aluminium - so you can keep yourself cozy at all times!


Building airtightness is essential for maintaining both energy efficiency and occupant comfort in passive housing constructions.

Ensuring that all components of an envelope (elements such as walls, ceilings, roofs floors and windows) are properly sealed against airflow infiltration indoors helps significantly reduce heating/cooling costs while simultaneously improving occupant comfort levels no matter what environmental conditions are present outdoors throughout different seasons of the year!