Is MVHR Suitable for All Types of Property?
While MVHR systems could technically be installed in any building, they perform most effectively in properties with high airtightness levels (≤3 m³/hr/m² @50Pa). Recent UK research shows they still reduce carbon emissions compared to natural ventilation in moderately airtight homes (≤9 m³/hr/m²), but efficiency declines significantly in draughty properties. New builds and retrofits have distinct suitability profiles, with decentralised units often better for renovations.
Understanding MVHR’s Relationship with Airtightness
Mechanical Ventilation with Heat Recovery (MVHR) systems work by extracting stale air, recovering its heat, and supplying fresh filtered air. Their efficiency hinges on controlled airflow – something achievable only in sufficiently airtight buildings.
Ideal Scenarios (≤3 m³/hr/m² @50Pa):
- Passivhaus-standard homes or modern builds with meticulous sealing
- Delivers 90%+ heat recovery efficiency, slashing heating costs
- Maintains consistent indoor air quality without energy waste
Moderate Airtightness (4–9 m³/hr/m²):
- The Passivhaus Trust found MVHR still reduces emissions by 18–24% vs natural ventilation
- Requires careful system balancing to compensate for air leakage
Draughty Properties (>9 m³/hr/m²):
- Heat recovery becomes economically unviable
- Decentralised MEV systems often prove more practical
Property Type Breakdown
| Property Type | MVHR Suitability | Recommended System |
|---|---|---|
| New builds | High | Centralised (e.g., RESPIRO) |
| Retrofit/Extensions | Moderate | Decentralised (e.g., FLUXO) |
| Listed buildings | Low | Hybrid MEV/dMEV |
| Social housing refurbs | Variable | Room-by-room srMVHR |
Data sourced from UK airtightness testing trends (2023)
5 Critical Considerations for UK Properties
Air Permeability Testing:
- Mandatory for new builds under Part L regulations
- Retrofit projects require professional assessment (£300–£500)
System Sizing:
- Oversized units waste energy; undersized fail ventilation needs
- VENTI’s design service ensures 78% better compliance vs DIY installations
Renovation Realities:
- Ductless MVHR (AUREN) avoids destructive wall chasing
- Achieves 65–75% heat recovery in 1930s semis post-retrofit
Running Costs:
- Well-installed MVHR: £45–£60/year
- Natural ventilation heating loss: £220+/year (Energy Saving Trust)
Health Impacts:
- Reduces asthma triggers by 37% in mould-prone homes
- Filters 95% of PM2.5 particles during urban pollution episodes
When MVHR Isn’t the Answer
- Leaky period cottages: Prioritise envelope sealing before considering MVHR
- Temporary structures: MEV provides cheaper adequate ventilation
- High-humidity environments: Combine with humidity-sensitive extractors
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