SUSTAINABILITY BREATHING LIFE INTO A HOME
Every building needs a breath of fresh air, BMJ finds out about the shift towards energy efficient ‘pro-active’ ventilation.
B
y correctly ventilating a property, fresh external air is brought in airborne pollutants (including odours) are diluted and removed and excess humidity controlled. It 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.
“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.” says Penny Jones, Domus Ventilation’s marketing and product manager.
“Clearly opening a window is never going to achieve this, which is where mechanical ventilation steps in.”
Types of ventilation systems To achieve the levels of extraction required under Building Regulations, Jones says continuous Mechanical Extract Ventilation (MEV) and Mechanical Ventilation with Heat Recovery (MVHR) whole house ventilation systems are necessary in most cases. “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.”
“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.
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Key considerations
“All new homes can benefit from mechanical ventilation, but there are some aspects that it’s important for customers to consider when specifying a system and that you should bring up with them. Some of these will also impact what equipment to stock.”
• Size: Most MEV/MVHR units are now wall mounted within the heated envelope of the property; usually a cupboard. The size of the unit therefore needs to be compact, especially when it comes to height; the Domus Ventilation HRXE MVHR, for example, is just 507mm 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.
• Noise: nothing annoys a homeowner quite as much as being kept awake by a noisy appliance or building service. 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, recommend the use of an Anti-Vibration tray and duct sound attenuators to further reduce system noise; this is also a good upsell opportunity.
• Ducting: poor ducting impacts the air flow, sound and overall effectiveness of a system. Stock quality ducting that fits together to minimise air leakage. Also suggest 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. Some manufacturers enable you to combine both types of ducting through the use of special adaptors, for a versatile solution where lack of space or tight void areas are an issue.
• 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 come with filters to remove pollutants. If you are based in a city, then bringing this to customers’ attention is helpful. Continuous Mechanical Ventilation systems have never been so popular. Look at any of the property shows on TV these days and you can bet a mechanical ventilation system will be part of the house specification in one form or another. Consider expanding your ventilation range and knowledge from basic bathroom fans to mechanical ventilation to take advantage of this growth sector. BMJ
www.buildersmerchantsjournal.net November 2019
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