Key takeaways
- MVHR is most useful in airtight, well insulated homes.
- It recovers heat from outgoing stale air while bringing in fresh filtered air.
- Ventilation, overheating risk and heating design should be considered together.
MVHR is not a heat pump, but it can support the design
MVHR and heat pumps often appear in the same project because both suit efficient, comfort-led homes. A heat pump provides heating and hot water. Mechanical ventilation with heat recovery provides controlled fresh air while recovering heat from outgoing stale air.
This guide is for self-builders and renovators deciding whether MVHR belongs in the same design conversation as heat pumps, UFH and low-temperature heating. The answer depends on the building fabric, airtightness and ventilation strategy.
How MVHR works in plain English
An MVHR unit extracts air from wet rooms such as kitchens, bathrooms and utility spaces. It brings fresh air into living rooms and bedrooms. Inside the unit, a heat exchanger transfers much of the warmth from the outgoing air into the incoming air, while the two air streams remain separate.
The result is controlled ventilation with less heat loss than simply relying on uncontrolled gaps, trickle vents or windows in a well sealed home.
- Extract stale air from wet rooms.
- Supply fresh filtered air to living spaces.
- Recover heat from outgoing air.
- Reduce ventilation heat loss in suitable homes.
When MVHR makes the most sense
MVHR works best in homes with good airtightness. If a home is leaky, the unit cannot control air movement properly because too much air bypasses the system. In a new build or deep retrofit, MVHR can be designed alongside insulation, airtightness, heating and cooling comfort.
It is not a magic fix for every property. In some renovations, simpler ventilation improvements may be more suitable. The design should follow the building, not a product trend.
| Project type | MVHR suitability | Design note |
|---|---|---|
| New build | Often strong | Plan ducts and plant space early |
| Deep retrofit | Can be strong | Airtightness and fabric work matter |
| Light renovation | Project-specific | Check disruption and duct routes |
| Leaky older home | Often limited | Address fabric before relying on MVHR |
How MVHR relates to heat pump efficiency
A heat pump design starts with heat loss. Ventilation losses are part of that calculation. If a home has controlled ventilation with heat recovery, the heating demand may be lower than a similar home with uncontrolled ventilation losses.
That does not mean MVHR is installed only to make the heat pump smaller. It is mainly about fresh air, comfort and controlled heat recovery. The heating design simply needs to reflect the ventilation design accurately.
Do not forget overheating and summer comfort
Efficient homes can be warm in summer as well as winter. MVHR is not air conditioning, and it should not be sold as if it solves every overheating issue. Window strategy, shading, orientation, fabric, internal gains and night cooling can all matter.
For new and refurbished homes, overheating assessment methods such as CIBSE TM59 are often used by designers to assess risk. That is a reminder that comfort is broader than heating alone.
Plan ventilation, shading and heating together, especially on airtight homes with lots of glazing.
Frequently asked questions
Does MVHR heat the house?
MVHR is primarily a ventilation system. It recovers heat from outgoing stale air, but it does not replace the main heating system in a typical home.
Do I need MVHR with a heat pump?
Not automatically. MVHR can be a good fit in airtight, well insulated homes. The decision should be based on ventilation needs, duct routes, fabric quality and comfort goals.
Can MVHR help indoor air quality?
Yes, a well designed MVHR system can provide steady filtered fresh air and extract moisture and stale air. Filters and maintenance still matter for long-term performance.