MVHR vs Demand-Controlled Ventilation: Which One Is Best for Your Home?
Choosing the right ventilation system is a key decision in modern homebuilding, especially in airtight or energy-efficient homes. Two of the most common systems in Ireland today are MVHR (Mechanical Ventilation with Heat Recovery) and DCV (Demand-Controlled Ventilation).
But which one is better for your build — and your budget?
In this post, we break down the pros, cons, and differences between MVHR and DCV to help you make the right choice.
What Is MVHR and How Does It Work?
MVHR systems provide balanced, whole-house ventilation. They extract stale air from wet rooms (bathrooms, kitchens) and supply fresh, filtered air to living spaces — while recovering heat from outgoing air to warm incoming air.
✅ Key Benefits of MVHR
Recovers up to 90% of heat
Delivers consistent airflow 24/7
Ideal for airtight homes (Passive House, NZEB)
Filters out allergens, moisture, and pollutants
Reduces heating costs
❌ Potential Drawbacks
Higher upfront cost
Requires careful planning and ducting
Needs filter replacement and annual maintenance
💡 Ideal for: New builds, Passive Houses, NZEB homes, and airtight properties.
What Is DCV (Demand-Controlled Ventilation)?
DCV systems adjust airflow based on demand — typically using sensors to detect CO₂ or humidity. They are mostly extract-only systems and do not include heat recovery.
DCV is more common in retrofits and multi-family buildings due to its simpler setup.
✅ Key Benefits of DCV
Lower installation cost
Requires less ducting
Simple to retrofit
Energy efficient – ventilates only when needed
❌ Potential Drawbacks
No heat recovery → higher heating bills
No fresh air supply to living areas
Less effective in airtight homes
No air filtration
💡 Ideal for: Retrofits, smaller homes, and low-budget upgrades.
🆕 Important Update: MEV Recognised Under DEAP
The Sustainable Energy Authority of Ireland (SEAI) now recognises Mechanical Extract Ventilation (MEV) systems under the DEAP (Dwelling Energy Assessment Procedure) for BER (Building Energy Rating) calculations.
Key points:
MEV systems must provide continuous extract ventilation in wet rooms and use background ventilators in habitable rooms.
To qualify, systems must be properly sized, installed, and commissioned, with airflow rates measured and recorded.
Installers must provide a signed commissioning sheet demonstrating compliance with Part F airflow standards.
While DCV systems are not separately recognised, if a DCV operates as a fully compliant MEV setup — with continuous extract, background ventilators, proper flow rates, and full commissioning — it may still qualify under the MEV category in a BER assessment.
🔗 Learn more: SEAI DEAP Guidance
MVHR vs DCV — Side-by-Side Comparison
| Feature | MVHR | DCV |
|---|---|---|
| Air Supply | ✅ Yes (balanced) | ❌ No (extract only) |
| Heat Recovery | ✅ Up to 90% | ❌ None |
| Filtration | ✅ Yes | ❌ No |
| Best For | New builds, airtight homes | Retrofits, older homes |
| Install Complexity | Medium–High | Low–Medium |
| Cost | Higher upfront, long-term savings | Lower upfront, higher energy use |
| Maintenance | Filter changes | Minimal (sensor upkeep) |
Which Ventilation System Should You Choose?
If you’re building a new energy-efficient home, especially to NZEB or Passive House standards, MVHR is the clear winner. It improves indoor air quality, saves energy, and supports airtightness targets.
If you’re doing a retrofit or working with a limited budget, DCV may be a practical solution — but it comes with trade-offs in comfort and long-term efficiency.
✅ Final Advice
Ventilation is a long-term investment. The right system should match:
Your building type (new or retrofit)
Airtightness level
Budget and energy goals
👉 Need expert help choosing or installing the right ventilation system?
Contact Eco Vent Ireland for professional advice, system design, and installation of MVHR and DCV ventilation systems.
