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How do we determine if we should we opt for round or rectangular section ventilation ducts in our MVHR system?
Last Updated: 4 December 2025Round ductwork is generally the superior default choice because its circular shape provides the lowest air resistance, ensuring higher efficiency, lower energy use (SFP), and quieter operation, which complies with UK building regulations like Approved Documents F, L, and E. Rectangular ducts are a necessary compromise only when spatial constraints, such as shallow ceiling voids,...
What are the most effective mechanical ventilation strategies for controlling indoor relative humidity when external humidity levels are higher in UK residential properties?
Last Updated: 4 December 2025Mechanical ventilation with heat recovery combined with central dehumidification (MVHRcd) is the most effective method identified, as it can substantially reduce indoor relative humidity below high ambient outdoor levels. Standard MVHR systems are limited by high external humidity, but MVHRcd achieved 37% indoor relative humidity against 72% ambient outdoor relative humidity in one study. Five...
What is the Homes (Fitness for Human Habitation) Act 2018 (HFA 2018)?
Last Updated: 1 December 2025Definition and Explanation The Homes (Fitness for Human Habitation) Act 2018 (HFA 2018) amends the Landlord and Tenant Act 1985 to require that all rented residential properties in England are fit for human habitation at the beginning of the tenancy and remain so throughout. This Act provides tenants with a direct and more accessible legal...
How to Check CO2 Levels in Your Home
Last Updated: 27 November 2025To check CO₂ levels in your home, use a reliable indoor air quality monitor like the VENTI PICO, which measures CO₂, humidity, and temperature. Place the device at head height away from windows or vents, and aim to maintain CO₂ concentrations below 800 ppm for optimal air quality. Regularly ventilate high-occupancy rooms and consider installing mechanical ventilation systems for long-term...
What is the relationship between CO2 levels and cognitive performance?
Last Updated: 27 November 2025Research has shown that elevated levels of carbon dioxide (CO2) can negatively impact cognitive performance. In the UK, studies reveal that reducing CO2 concentrations from 5000 ppm to 1000 ppm improves cognitive abilities by up to 15% in tasks like word recognition and reaction time. Enhanced ventilation is key to maintaining optimal CO2 levels for...
What is the minimum heat cell efficiency change from the amended Approved Document L?
Last Updated: 27 November 2025The amended Approved Document L (ADL) in the UK has increased the minimum heat cell efficiency for Mechanical Ventilation with Heat Recovery (MVHR) systems from 70% to 73%. This change aims to enhance energy efficiency in new and existing buildings, promoting better indoor air quality and reduced energy consumption across the United Kingdom. The drive...
What is the minimum ventilation rate needed for a dining room?
Last Updated: 27 November 2025In the UK, ventilation requirements for residential dwellings, including dining rooms, are primarily governed by Approved Document F: Ventilation of the Building Regulations. Dining rooms are generally considered “habitable rooms” and require a combination of whole-dwelling, background, and purge ventilation to ensure adequate air quality and occupant well-being. Understanding UK Ventilation Standards for Your Dining...
If my old windows had trickle vents, must my new windows also have them?
Last Updated: 27 November 2025Yes, if your old windows had trickle vents, the new windows should ideally also include them UNLESS a suitable alternative ventilation system is installed. This is to ensure adequate indoor air quality and prevent issues such as condensation. However, if a Mechanical Ventilation with Heat Recovery (MVHR) system is employed, trickle vents will not be necessary. In fact, they SHOULD...
Do Front Doors in the UK Need Trickle Vents?
Last Updated: 27 November 2025While the regulations do not explicitly mandate that all external doors must have trickle vents, they do imply that if a door leads to a habitable space, it should contribute to the overall ventilation strategy of the building. This is particularly relevant for front doors, which often serve as the main entrance to a dwelling and can significantly impact the...
What is Interstitial Condensation?
Last Updated: 27 November 2025Definition and Mechanism Interstitial Condensation refers to the formation of liquid water within the hidden layers of a building element (such as a wall, roof, or floor assembly), rather than on the visible internal surface. It occurs when warm, moist internal air penetrates the structure and cools below its Dew Point Temperature. At this point,...