What Is Heat Recovery Ventilation — Complete Guide

Heat recovery ventilation is a mechanical ventilation system that continuously exchanges indoor air with fresh outdoor air while recovering the thermal energy from the exhaust stream. In winter, the system captures up to 95% of the heat from outgoing stale air and transfers it to the incoming fresh air — so you ventilate without losing warmth.

The core component is the heat exchanger — a device where warm outgoing air and cold incoming air pass in close proximity through thin plates or membranes. Heat transfers from the warm stream to the cold stream without the two airflows ever mixing.

There are two fundamental approaches to heat recovery ventilation. The right choice depends on your building type, budget, and whether you are building new or renovating.

Modern building standards demand airtight construction, which saves energy but creates a ventilation problem. Heat recovery solves this by providing continuous fresh air while keeping energy bills low.

Heat recovery is not a magic solution for every situation. Here are the honest trade-offs to consider:

• Upfront cost — Central systems require significant investment (€3 000–8 000). However, the energy savings typically pay back within 5–8 years.
• Installation complexity — Ducted systems need to be planned during construction. Retrofitting ductwork is possible but expensive and disruptive.
• Regular maintenance — Filters must be replaced or cleaned regularly. Neglected filters reduce efficiency and can worsen air quality.
• Electricity consumption — The fans need power (typically 30–100 W). This is far less than the heating energy saved, but it’s not zero.
• Not a replacement for heating — Heat recovery reduces heating demand but does not eliminate it entirely. You still need a heating system in cold climates.

Want a detailed cost breakdown? See our complete price guide with real-world examples.

Heat recovery ventilation is most effective in these scenarios:

• New builds — Modern energy codes require mechanical ventilation in airtight buildings. HRV is the most efficient way to meet these requirements.
• Deep renovations — When improving insulation and replacing windows, adding HRV completes the energy efficiency picture.
• Homes with condensation or mould issues — If you see foggy windows or mould in bathrooms, inadequate ventilation is likely the cause.
• Allergy sufferers — HEPA-filtered supply air significantly reduces pollen, dust and allergen exposure.
• Urban properties — Where opening windows means noise and air pollution, mechanical ventilation is the clean alternative.

Not sure which system fits your home? Our guide to heat recovery for homes walks you through the decision step by step.