The focus of retrofitting is often on improving energy efficiency — through better insulation, sealing gaps, and upgrading heating systems. But there’s another critical factor that can’t be overlooked: ventilation.
Without proper airflow, a tightly sealed home can trap moisture, pollutants, and stale air, leading to problems like damp, mould, and poor indoor air quality.
To explore this essential aspect of retrofitting, we spoke with Michael Zohouri, founder of The Retrofitters. “Ventilation is just as important as insulation in a retrofit project,” Michael explains. “You can’t have a truly energy-efficient home without balancing airtightness with healthy airflow. It’s about creating spaces that are efficient but also healthy and comfortable for the people living in them.”
Here’s how construction professionals can get ventilation right in retrofitted homes, ensuring energy efficiency and comfort go hand in hand.
Why Ventilation Matters in Retrofitted Homes
Retrofitting aims to reduce heat loss by improving insulation, upgrading windows, and sealing gaps. While these measures are essential for cutting energy bills and reducing carbon footprints, they can unintentionally restrict airflow, leading to:
Moisture Build-Up: Everyday activities such as cooking, showering, and even breathing generate humidity. Without adequate ventilation, this moisture becomes trapped, leading to condensation and mould growth. In England, estimates suggest that between 4% and 27% of homes are affected by damp and mould, highlighting the importance of proper airflow.
Poor Air Quality: Pollutants from cleaning products, furniture, and cooking fumes can accumulate in a sealed home, leading to discomfort or even health issues.
Stuffy Interiors: Stale, stagnant air can make rooms feel uncomfortable, even when the temperature is well-regulated.
Proper ventilation addresses these issues by maintaining airflow, regulating humidity, and ensuring clean, fresh air circulates throughout the home. This is particularly important in retrofitted homes where the balance between airtightness and ventilation is crucial.
Key Ventilation Strategies for Retrofitted Homes
Balancing airtightness with proper airflow is essential to prevent issues like damp, condensation, and poor air quality. Here are some practical strategies to ensure ventilation is done right in retrofitted homes.
Assess the Existing Ventilation System
Before starting a retrofit, it’s essential to evaluate the home’s current ventilation setup. Many older homes rely on natural ventilation—air flowing through gaps around windows, doors, and chimneys. When these gaps are sealed as part of retrofitting, the natural airflow disappears, and mechanical systems must take its place.
What to Look For:
- Signs of damp or condensation on walls, ceilings, or windows.
- Rooms prone to poor airflow, such as bathrooms, kitchens, or basements.
- Existing vents or extractor fans that may be outdated or inefficient.
Michael’s Tip: “Before sealing up a home, understand how it currently “breathes.” A good retrofit plan accounts for what’s already there and includes solutions to replace natural airflow with something more controlled.”
Incorporate Mechanical Ventilation
Mechanical Ventilation with Heat Recovery (MVHR) systems are a good option for ventilation in retrofitted homes. These systems extract stale air while recovering the heat, which is then used to warm incoming fresh air. This makes them both energy-efficient and effective in maintaining good air quality.
Benefits of MVHR Systems:
- Provide consistent fresh air while retaining heat, reducing energy waste.
- Filter out allergens, dust, and pollutants, improving indoor air quality.
- Work seamlessly with airtight homes, ensuring healthy airflow without compromising efficiency.
Installation Best Practices: Position MVHR units in central areas like hallways or utility rooms to minimise ducting distances. Insulate the ducts to prevent heat loss and ensure the system runs quietly.
Use Localised Ventilation Solutions
Not every retrofit requires a full MVHR system. For smaller projects or where budget constraints exist, localised solutions like extractor fans in kitchens and bathrooms can provide adequate ventilation.
Modern extractor fans are more energy-efficient and can be equipped with humidity sensors or timers for improved performance. These targeted solutions focus on areas where moisture and pollutants are most likely to accumulate, ensuring problem spots are managed effectively.
Pro Tip: Opt for Energy-Related Products (ERP) compliant fans to ensure they meet high standards for efficiency and performance. For retrofitted kitchens, consider cooker hoods that extract air externally rather than recirculating it.
Ensure a Balanced Approach
Ventilation is about balance. Removing stale air is essential, but too much ventilation can lead to heat loss, which undermines the energy savings achieved through retrofitting. The key is calculating the right ventilation rate for the home. This depends on factors such as the size of the property, the number of occupants, and the level of insulation.
Michael’s Insight: “Every home is different. A one-size-fits-all approach doesn’t work with ventilation. It’s about understanding the property and tailoring solutions to ensure it’s both efficient and comfortable.”
Common Pitfalls to Avoid
Skipping Ventilation During Insulation Upgrades: Retrofitting without considering ventilation can lead to damp, mould, and poor air quality. Always include ventilation in the retrofit plan.
Installing Poorly Designed Systems: Incorrectly sized or poorly installed ventilation systems can be noisy, inefficient, and fail to maintain air quality. Work with experienced professionals to avoid costly mistakes.
Neglecting Maintenance: Even the best ventilation systems need regular upkeep. Filters should be cleaned or replaced, and ducts checked for blockages to keep the system running efficiently.
Ventilation and Building Regulations
In the UK, building regulations require adequate ventilation in all homes, including retrofitted properties. Part F of the Building Regulations sets out standards for:
- Minimum airflow rates for different types of spaces.
- Requirements for mechanical ventilation systems, including noise levels and energy efficiency.
- Guidelines to maintain air quality in highly insulated homes.
Meeting compliance helps avoid legal issues and keeps the retrofit within required standards. It also provides better results for homeowners, creating safer and healthier living spaces.
The Role of Construction Professionals
Construction professionals play a key role in ensuring ventilation is done right. By considering airflow early in the retrofit process, they can:
- Integrate energy-efficient solutions like MVHR systems.
- Strike the right balance between airtightness and ventilation.
- Educate homeowners on the importance of ventilation and how to maintain their systems.
Michael Zohouri of The Retrofitters highlights the importance of this step: “Good ventilation doesn’t just happen — it’s planned. By taking a proactive approach, we can create homes that are energy-efficient, healthier, and more comfortable for the people living in them.”
Creating Energy-Efficient and Healthy Homes
Ventilation is a crucial yet often overlooked part of retrofitting. Without it, the advantages of insulation and airtightness can be ruined by problems like damp, mould, and poor air quality. Using smart ventilation strategies helps make retrofitted homes healthier, more comfortable, and as energy-efficient as planned.
Good ventilation isn’t just about meeting technical needs — it’s about creating homes people enjoy living in. With a thoughtful and balanced approach, we can create a future where energy savings and healthy living work together.