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MVHR vs PIV vs MEV: Which Ventilation System is Right for My Home?

8 min read
Updated 5 January 2025

Choosing the best ventilation solution is a critical decision for every homeowner, architect, or builder. With options like Mechanical Ventilation with Heat Recovery (MVHR), Positive Input Ventilation (PIV), and Mechanical Extract Ventilation (MEV) on the market, understanding their differences and benefits can save you time, money, and future headaches.

Here's your straightforward guide to selecting the right system for your property.

Why is Proper Ventilation So Important?

A well-designed ventilation system is your first line of defence against damp, condensation, and mould—protecting both your family's health and your investment. Modern systems are more energy efficient and effective than ever, helping you meet Building Regulations Part F and comply with new legal requirements like Awaab's Law.

Understanding the Options

MVHR -- Mechanical Ventilation with Heat Recovery

How it Works: MVHR units continuously extract stale, moist air from wet rooms (kitchens, bathrooms) and supply fresh, filtered air to living spaces. The key? They recover up to 95% of the heat from outgoing air, drastically improving energy efficiency.

Best For: New builds and major renovations with good airtightness.

Key Benefits:

  • Whole-house fresh air
  • Dramatic energy savings
  • Superior condensation and mould control
  • Filtration of pollutants and allergens

Considerations:

  • Higher upfront installation cost
  • Requires professional design and setup

PIV -- Positive Input Ventilation

How it Works: PIV systems gently introduce fresh, filtered air—usually from the loft—into the property, gradually flushing out moist or stale air via existing trickle vents or gaps.

Best For: Retrofitting in older properties or where installation budget is limited.

Key Benefits:

  • Cost-effective upgrade for homes with chronic condensation
  • Simple installation, minimal disruption
  • Improved air quality and humidity control

Considerations:

  • Less control over heat retention than MVHR
  • May need combined with extract fans in high-moisture areas

MEV -- Mechanical Extract Ventilation

How it Works: Central MEV units provide continuous moisture removal from 'wet' rooms (bathroom, kitchen, utility) through ducted extract points, preventing condensation and odours.

Best For: Apartments or smaller homes; properties where installing MVHR is impractical.

Key Benefits:

  • Effective and reliable humidity control
  • Can be integrated with smart controls and sensors
  • Lower running costs compared to multiple standalone fans

Considerations:

  • Doesn't recover heat from extracted air
  • Supply air still relies on trickle vents or passive openings

Choosing the Right System: What to Consider

  • Property Type & Age -- Is your home a draft-free, new build or a solid-wall Victorian terrace?
  • Renovation Plans -- Are you planning extensive upgrades, or retrofitting in an occupied property?
  • Budget & Priorities -- Upfront investment vs. long-term energy savings and maintenance costs
  • Existing Issues -- Current problems with condensation, damp, or allergy triggers

System Comparison Table

| System | Best For | Key Advantages | Considerations |

|——--|———-|—————-|—————-|

| MVHR | New builds, airtight homes | Whole house airflow, heat recovery, top IAQ | Upfront cost, pro installation |

| PIV | Older homes, budget retrofits | Quick install, improved humidity | Less heat saving, may need extract fans |

| MEV | Apartments, extensions | Reliable extract, affordable | No heat recovery, supply vents required |

How Flexivent Can Help

We assess your property's unique footprint, needs, and priorities—designing and installing bespoke systems for optimum comfort, health, and regulatory compliance. Whether you're planning a renovation, struggling with condensation, or seeking top-tier air quality, we'll guide you to the perfect solution.

Book your free consultation with Flexivent today and breathe easy—whatever system you choose, your home's air is in expert hands!

Flexivent: Specialists in MVHR, PIV, MEV, and more. From design to commissioning and maintenance, we take care of healthy air, for every home and every budget.

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Written by Flexivent Team

Our team of NICEIC certified ventilation engineers has over 15 years of experience designing, installing, and maintaining domestic ventilation systems across the UK. We're passionate about helping homeowners and landlords create healthier, more comfortable living spaces.

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