What is an MVHR System and Why is Professional Design Essential?
What is MVHR?
Mechanical Ventilation with Heat Recovery (MVHR) is a system designed to provide continuous fresh air to your home while recovering heat from outgoing stale air. Unlike conventional ventilation, which often relies on natural air movement or simple extractor fans, MVHR ensures optimal indoor air quality and energy efficiency by balancing airflow and maintaining thermal comfort.
The Role of MVHR in Modern, Airtight Homes
Modern homes are built to be highly energy efficient, often with airtight construction. While this reduces heat loss, it also traps pollutants, moisture, and CO2 indoors. An MVHR system mitigates these issues by extracting stale air and supplying filtered fresh air, recovering up to 90% of the heat in the process. This is particularly vital for self-builders, architects, and homeowners aiming for low-energy or Passivhaus standards.
Why ‘One-Size-Fits-All’ Solutions Fail
MVHR is not a plug-and-play solution. Homes differ in size, layout, insulation, and occupancy patterns. Off-the-shelf systems often underperform, causing drafts, noise, and uneven ventilation. Professional design tailors airflow, ducting, and unit selection to your specific project, ensuring efficiency, comfort, and regulatory compliance.
The MVHR Design Process: A Step-by-Step Breakdown
Initial Consultation and Site Survey
A successful MVHR system begins with a thorough consultation and site survey. Professionals assess your building’s layout, review architectural drawings, and evaluate feasibility. This stage involves:
- Site assessment to determine ventilation requirements.
- Feasibility studies to ensure compatibility with building constraints.
- Detailed analysis of building drawings to plan optimal duct routes.
This step ensures the system integrates seamlessly with your home’s design and construction schedule.
Crucial Calculations: Airflow and Heat Loss
Accurate calculations are the backbone of an efficient MVHR system. Designers perform:
- Airflow calculations: Determining the required air changes per hour based on room volumes and occupancy.
- Heat loss calculations: Identifying where energy is lost and how heat recovery can be maximized.
- Compliance with Building Regulations Part F for ventilation.
- SAP assessment for energy performance and efficiency rating.
These calculations prevent underperformance, excess noise, and energy wastage.
System Layout and Ducting Design
Once calculations are complete, the next step is planning the system layout and ductwork:
- Creation of 2D and 3D schematics to visualise the system.
- Ductwork design using semi-rigid materials to reduce noise and pressure loss.
- Pressure loss calculations to ensure consistent airflow across all rooms.
Proper ducting design prevents inefficiencies, draughts, and noise problems, which are common in poorly designed installations.
Unit Selection and Specification
Selecting the right MVHR unit is critical for performance and comfort:
- Evaluating MVHR unit efficiency to meet your home’s heating requirements.
- Assessing noise performance for a quiet indoor environment.
- Considering Passivhaus-certified units for high-performance builds.
The right unit combined with well-designed ducting ensures a system that works quietly, efficiently, and reliably for years.
Building Regulations and Compliance: Ensuring Your Project is a Success
Understanding Building Regulations Part F (Ventilation)
Compliance with Part F of the UK Building Regulations is mandatory. This regulation governs ventilation to ensure adequate indoor air quality and energy efficiency. A professional designer ensures your MVHR system meets or exceeds these standards.
The Importance of a Competent Person and Certified Installers
Using certified installers guarantees the system is installed correctly and safely. Competent professionals ensure:
- Ducts are sealed and insulated correctly.
- Units are commissioned according to manufacturer specifications.
- Compliance with building control requirements.
Compliance Testing and Commissioning for Building Control Sign-Off
Before sign-off, the system must undergo testing and commissioning. This includes airflow verification, system balancing, and efficiency checks. Proper commissioning ensures the system performs as designed and satisfies building control authorities.
Common Pitfalls and How to Avoid Them
Poor Ducting Design and Its Impact on Performance and Noise
Incorrectly routed or undersized ducts cause reduced airflow, increased noise, and energy inefficiency. Early professional design avoids these issues.
Incorrectly Sized Units
A unit that is too small or too large for the building will fail to deliver comfort and efficiency. Accurate calculations and professional selection prevent oversizing or undersizing.
Skipping the Design Stage Entirely
Attempting a DIY or generic solution often leads to poor performance, higher running costs, and compliance issues. Investing in professional design ensures long-term savings and comfort.
FAQs About MVHR Design
What is the difference between MVHR and MEV?
- MVHR recovers heat from outgoing air, while MEV (Mechanical Extract Ventilation) simply extracts stale air without heat recovery.
How long does an MVHR design take?
- Depending on complexity, a professional MVHR design can take 2–6 weeks, including site surveys, calculations, and layout planning.
Can I design my own MVHR system?
- While technically possible, without proper training, it is difficult to ensure compliance, efficiency, and comfort. Professional design is strongly recommended.
How much does a professional MVHR design service cost?
- Costs vary by project size and complexity but generally range from £1,000 to £4,000 for complete design services.
Do I need MVHR in my new build?
- For airtight, energy-efficient, or Passivhaus-standard homes, MVHR is highly recommended to maintain indoor air quality and energy efficiency.
Ready to Start Your Project? Contact a UK Expert Today
If you are planning a new build, renovation, or self-build project, ensure your ventilation system is designed for maximum efficiency, comfort, and compliance. Contact our UK MVHR design experts today for a free consultation and take the first step toward a healthier, more energy-efficient home.