Ventilation consists of replacing stale air with fresh air, a process referred to as air renewal, and this is achieved by two means: air infiltration (uncontrolled ventilation) and purpose-built ventilation.
Air infiltration consists of draughts. A draughty house will need to be heated to a much higher degree than a home that is considered airtight, which is why building an energy efficient house often means putting in lots of insulation, then making it all airtight and ventilating it in a controlled manner.
Purpose-built ventilation systems control how fresh air enters the home, either passively through openings in the house envelope (natural ventilation) or mechanically with fans.
Astrid Madsen is the editor of the SelfBuild magazine. She previously held the same role in an Irish trade publication, before that she worked at the National Standards Authority of Ireland. She graduated with a BA in Urban Studies from Columbia University in New York and holds an MBA from the Instituto de Estudios Bursatiles in Madrid. France of origin, she now lives in Portarlington, County Laois, where she's taken on the task of renovating a listed building! Email firstname.lastname@example.org