Mechanical Extract Ventilation Systems (MEV & DCV)
A mechanical extract ventilation (MEV) system keeps your home fresh, dry, and energy-efficient. In essence, it continuously removes stale, moist air from “wet” rooms while drawing filtered air into living spaces through background vents. Moreover, demand control ventilation (DCV) adds smart sensors that automatically adjust airflow based on humidity or occupancy. Consequently, you enjoy cleaner indoor air, less condensation, and full compliance with TGD Part F (2019) and Part L (2022) of the Irish Building Regulations.
Why MEV / DCV Ventilation Matter for Irish Homes
Cleaner Indoor Air
Continuous extraction removes moisture, CO₂, and odours from bathrooms, kitchens, and utilities. As a result, rooms stay fresher and healthier all day.
Condensation & Mould Protection
Because MEV runs constantly, it prevents damp and mould even in airtight new builds.
Energy-Smart Operation
Unlike traditional fans, MEV avoids uncontrolled draughts. Furthermore, DCV ventilation systems use intelligent sensors to increase airflow only when needed—cutting unnecessary energy loss.
Guaranteed Compliance
Eco Vent designs each system to meet airflow, background ventilation, and commissioning standards under TGD Part F (2019), Part L (2022), and the NSAI Ventilation Validation Scheme (2025).
How a Mechanical Extract Ventilation System Works
In a typical mechanical ventilation system, a quiet fan extracts stale air from wet rooms, while background ventilators introduce fresh air into living areas. This creates a gentle, continuous airflow that protects the building fabric. Importantly, MEV runs 24/7—unlike intermittent extractor fans—so humidity never builds up.
Centralised vs Decentralised MEV
Centralised MEV (CMEV)
A single high-efficiency fan connects via ductwork to multiple rooms. It delivers steady airflow and operates quietly. Therefore, it suits most modern airtight homes.
Decentralised MEV (dMEV)
Alternatively, each wet room has its own low-energy fan. This approach is ideal for retrofits or smaller properties where full duct runs are impractical.
What Is Demand Control Ventilation?
Demand control ventilation (DCV) intelligently adjusts extract rates. When humidity or CO₂ levels rise, the fan ramps up; when the air is clear, it slows down automatically. Consequently, comfort improves while energy use drops.
- Smart humidity sensors: React instantly after showers or cooking.
- Energy efficiency: Reduces over-ventilation and heat loss.
- Low maintenance: No constant manual boosting required.
Compared with standard MEV, DCV systems offer the same reliability but deliver greater long-term savings.
Benefits of MEV
- Healthier indoor air quality throughout your home
- Reduced condensation and mould risk on cold surfaces
- Quiet, low-maintenance operation for lasting performance
Compliance with Irish Building Regulations
Ventilation (TGD Part F 2019)
Sets required extract rates for wet rooms, background ventilators (≥ 2,500 mm² EA per habitable room), and independent validation by an NSAI-certified professional.
Energy (TGD Part L 2022)
Defines airtightness backstops (≤ 5 m³/h·m² @ 50 Pa). Therefore, airtight homes need mechanical systems like MEV or MVHR to maintain air quality.
Validation
After commissioning, Eco Vent arranges independent validation per the NSAI Ventilation Validation Registration Scheme (Rev 8, 2025) to secure Building Control sign-off.
Our MEV / DCV Installation Process
- Assessment & Design – We survey your home, calculate ventilation rates, and design a compliant system with correctly sized vents.
- Installation – CMEV systems install within 1–2 days; dMEV is even quicker. Coordination with builders keeps timelines smooth.
- Commissioning & Balancing – Airflows are measured, balanced, and logged as required by Part F.
- Validation – An independent NSAI-certified validator confirms compliance, and you receive official documentation.
Note: If a system was not designed or installed by Eco Vent, we can still commission and report on it. However, design or installation faults remain the responsibility of the original contractor.
Is MEV or DCV Ventilation Right for Your Property?
Choose MEV/DCV when:
Choose MVHR when:
- You want efficient, low-maintenance ventilation
- Space or budget limits MVHR installation
- You’re retrofitting or upgrading an airtight dwelling
- You require both heat recovery and maximum energy savings
- Full supply and extract ductwork is workable
Typical Applications
- New-build homes and apartments
- Retrofits and extensions
- Rental or student housing
- Low-energy and NZEB dwellings
Costs & Long-Term Value
MEV and DCV systems represent a cost-effective way to protect your property and reduce energy bills. Because airflow adjusts automatically, fan energy and heat loss are kept to a minimum. Over time, this translates into lower running costs and better comfort—particularly under Part L 2022 airtightness standards.
Why Choose Eco Vent
- Irish Regulation Experts – We design strictly to Part F (2019) and Part L (2022).
- Certified Installers & Validators – All systems are verified through the NSAI Scheme 2025.
- Turnkey Service – From design to documentation, we manage compliance end-to-end.
- Nationwide Coverage – Professional support across Dublin and Ireland.
FAQs
What’s the difference between mechanical extract ventilation and a bathroom ventilation fan?
A standard bathroom fan is intermittent and room-specific. By contrast, mechanical extract ventilation (MEV) runs continuously and serves all wet rooms, ensuring whole-house moisture control and consistent IAQ.
Where should MEV systems be installed?
– Kitchen
– Bathrooms and shower rooms
– Utility room
– WCs/sanitary accommodation
How loud are MEV/DCV systems?
Properly installed systems are whisper-quiet; DCV units run slower most of the time, reducing noise further.
Do I still need a cooker hood with MEV?
Yes. Part F requires a separate kitchen boost extract of 13 l/s, excluding the cooker hood.
Is DCV worth the upgrade?
In many cases, yes—especially in airtight homes—because it maintains comfort and cuts operating costs.
Can MEV/DCV be installed in existing homes?
MEV is primarily used in new builds due to the need to incorporate ductwork within the building fabric. However, DCV systems are suitable for both new and existing buildings. When retrofitting as part of a major renovation where air permeability is below 5 m³/h.m², the system should be properly designed, installed, commissioned, and validated with documentation provided to the building owner.
Do I still need wall vents or window vents if I install MEV?
Yes — you still need a way for fresh air to enter the building.
A Mechanical Extract Ventilation (MEV) or Demand Controlled Ventilation (DCV) system continuously removes stale and humid air, but it doesn’t supply fresh air. For proper airflow balance, the system relies on wall vents, window trickle vents, or air inlets (usually in living rooms and bedrooms)
Get Compliant, Comfortable Ventilation Today
Breathe cleaner air and ensure full regulatory compliance with a custom-designed MEV/DCV system from Eco Vent.