What is balanced ventilation?
Balanced ventilation is a mechanical ventilation system in which both the supply of fresh outdoor air and the extraction of stale indoor air are controlled by fans. The system incorporates a heat recovery unit that transfers warmth from the outgoing air to the incoming fresh air, minimising energy loss.
How it works
In a balanced ventilation system, two separate airflows are mechanically controlled. One fan draws in fresh outdoor air and distributes it through ductwork to living spaces such as bedrooms and living rooms. A second fan extracts stale, humid air from wet rooms such as the bathroom, kitchen, and toilet.
Inside the heat exchanger, both airstreams cross paths without mixing. The warmth from the exhaust air is transferred to the cold incoming air. Modern units, often referred to as MVHR (Mechanical Ventilation with Heat Recovery), achieve an efficiency of 90 to 95%, meaning only a small fraction of heating energy is lost through ventilation.
Benefits
Balanced ventilation offers several advantages. First, it ensures a consistently healthy indoor climate with a steady supply of fresh air, without the need to open windows. Second, it delivers significant energy savings by reclaiming heat that would otherwise be lost. Third, the system filters fine particles, pollen, and other pollutants from the outdoor air, which is particularly beneficial for people with respiratory conditions or allergies.
Requirements
For balanced ventilation to function optimally, the building must have a well-insulated and airtight building envelope. Air leaks through gaps and cracks reduce the system’s efficiency considerably. Regular maintenance of the filters — typically every three to six months — is essential to maintain good air quality and system performance.
In many European countries, balanced ventilation with heat recovery is now a standard requirement for new-build homes that must meet near-zero-energy building (NZEB) standards.
Related terms
- Heat recovery ventilation (HRV)
- Mechanical ventilation with heat recovery (MVHR)
- Heat exchanger
- Airtightness
- Passive house
- Indoor air quality
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