BSEE-JUL21-P12 Domus Ventilation_Layout 1 27/05/2021 14:20 Page 12
BSEE
AIR CONDITIONING, COOLING & VENTILATION
Breathing Life into a Home
With buildings becoming increasingly air tight in a drive to improve energy efficiency and lower carbon emissions, the need for ‘proactive’ ventilation has never been greater.
be hot and stuffy or damp from condensation, not only makes for an uncomfortable home environment but poor indoor air quality (IAQ) also has known links to allergies, asthma, lung cancer, chronic obstructive pulmonary disease, cardiovascular disease and even dementia.
B Ventilation Requirements
Building Regulations Approved Document F, which details the means of ventilation in new and materially altered properties, sets the minimum continuous extraction requirement for domestic properties at 13l/s from the kitchen, 8l/s from each bathroom/utility area and supply at the same rate. However, the regulations are being revised and it is expected that the minimum airflow to each bedroom will be increased to address concerns over insufficient ventilation in bedrooms overnight if doors are kept shut.
The revised Building Regulations will also make air tightness testing mandatory for all new build dwellings, with no exemptions for smaller developments, as was previously the case. Clearly opening a window is never going to achieve these increased levels of ventilation, which is where mechanical ventilation steps in.
Types of Ventilation Systems
To achieve the levels of extraction required under Building Regulations, Continuous Mechanical Extract Ventilation (MEV) and Continuous Mechanical Ventilation with Heat Recovery (MVHR) systems are necessary in most cases.
By Paul Williams, Domus Ventilation Product Manager
y correctly ventilating a property we not only bring in fresh external air to breath but we also dilute and remove airborne pollutants and control excess humidity. A poorly ventilated room, whether it
An MEV system actively extracts air from ‘wet rooms’ (kitchens, bathrooms, utility spaces) via ducting to a central ventilation unit which further ducts to an exhaust point. The systems are typically dual speed, providing low speed continuous trickle ventilation and high-speed boost flow. Replacement fresh air is drawn into the property via background ventilators located in the habitable rooms and through air leakage. Under the revised Building Regulations, extraction only systems such as MEVs will be expected to increase background ventilation from 2500mm² to 5000mm². Unlike MEV, MVHR systems combine supply and extract ventilation in one system. They work on the principle of extracting and re-using waste heat from wet rooms. MVHR systems efficiently temper the fresh air drawn into the building with heat attained from waste stale air using a heat exchanger; up to 95% of waste heat can be recovered by this mechanism. The filtered, pre- warmed air is then distributed around the home, effectively meeting part of the heating load in energy efficient dwellings.
Key Considerations
All new homes can benefit from mechanical ventilation, but there are some aspects that are important to consider when specifying a system, based on the nature and location of the property. Size: in larger properties, you have a far wider range of options in terms of the unit to use, where it’s located and how/where you run the ducting. In smaller properties, that choice is reduced. MEV/MVHR units are most commonly wall mounted within the heated envelope of the property, often in a cupboard. The size of the unit therefore needs to be compact, especially when it comes to height; the Domus Ventilation HRX- HERA, for example, is just 508mm in height. Where installation in a cupboard is not an option, then a ceiling void should be a consideration. Here the depth of the unit and weight are key factors. The Domus Ventilation HRX-aQ is the shallowest in the market place, measuring down to 199mm in depth and weighing from just 7.9kg, making it compact and light enough to be easily installed in the most restrictive of ceiling voids.
12 BUILDING SERVICES & ENVIRONMENTAL ENGINEER JUNE 2021
Noise: mechanical ventilation systems aren’t silent but they can be very quiet. Opt for a system that generates less than 24dBA (typically whisper quiet) at a distance of more than one meter away from the air valve. Also, consider the use of an Anti-Vibration tray and duct sound attenuators to further reduce system noise. Ducting: poor ducting (and that relates to the product quality, the duct run design and installation) impacts the air flow, sound and overall effectiveness of a system. Ensure quality ducting is used that fits together to minimise air leakage and avoid sharp bends which negatively impact air flow. Instead of traditional branch based ducting systems, you might want to consider using a Radial semi-rigid ducting system when fitting MVHR systems – especially good in small spaces. Radial systems allow each room vent to be served by single or twin duct runs which connect directly to the central distribution system, evenly splitting the air from the MVHR unit. Polluted areas: inner-cities have higher concentrations of pollution so bringing that air into a property may meet Building Regulations, but it’s not good for the inhabitants. Here an MVHR system is ideal as they are available with filters to remove pollutants. The Domus Ventilation NOX- FILT, for example, prevents up to 99.5% of NO² pollution from entering a home. There are two units in the range with the second one having the added benefit of a PM2.5 pre-filter.
Continuous Mechanical Ventilation systems have never been so popular. They have become an important means of addressing the issues borne out of making homes more air tight whilst also providing savings on energy bills due to the reduced heating demand but, most importantly, there’s a considerable benefit from improved IAQ that goes way beyond simply making a home a comfortable one: it needs to be a safe, healthy one also.
Domus Ventilation provides customers with a complete sustainable ventilation package to meet the most demanding of energy efficiency targets.
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