Tim Palmer returns to the increasingly important matter of good air quality in energy efficient homes. Ventilation has a key role to play in creating comfortable, healthy properties
The focus on indoor air Quality (IAQ) has never been stronger. Local councils require air quality reports to be completed in most habitable areas while changes to local construction legislation puts responsibility on developers to ensure air to dwellings is filtered to increasingly higher standards. In new energy efficient houses, greater levels of airtightness can lead to poor indoor air quality and other, more visible impacts such as condensation damage and mould growth.
This is confirmed in a report by Professor Hazim Awabi at the University of Reading. The Future of Indoor Air Quality in UK Homes and its Impact on Health
forecasts that asthma could double by 2050 due to increasingly airtight homes. The research cites Mechanical Ventilation with Heat Recovery (MVHR) as the most cost-effective solution for achieving an energy efficient air exchange rate and a healthy environment for building occupants.(Pictured) "Vent-Axia offers a full set of MVHR solutions to meet all applications from one-bedroom apartments to light commercial projects" – Ian Mitchell, Vent-Axia product marketing manager – new build residential
Ian Mitchell, product marketing manager – new build residential at Vent-Axia, says: “With this in mind Vent-Axia offers a full set of MVHR solutions to meet all applications from one-bedroom apartments to light commercial projects, such as student accommodation. The Sentinel Kinetic range offers MVHR options with airflow from 15l/s to 200l/s allowing developers and households to benefit from the improved indoor air quality that MVHR systems bring.”(Pictured) Vent-Axia's Sentinel Kinetic range offers MVHR options with airflow from 15l/s to 200l/s
Jennifer Quinn, technical and marketing manager at Vortice adds: “Good mechanical ventilation systems are vital as our health depends upon good air quality. As far as the merits of the different systems are concerned, continuous mechanical extract, moving fresh air through the building, will give the best results. Heat recovery systems have the added benefit that they are an energy efficient option, re-using the energy contained within the stale air that it is extracting, by passing it over a heat exchanger and putting that warmth into the fresh air being introduced into the property. A Vortice MVHR system for a typical domestic property uses no more energy than a 60w light bulb.”
Titon senior technical manager Paul Cowell says that all the company’s MVHR units have been tested in accordance with the new EU regulations for ventilation units, which came into force on January 1 2016. “The company’s HRV Q Plus ‘Eco’ units are fully compliant and designed in accordance with the new regulations, offering a 100% airflow diverting Summer Bypass, as recognised and listed in the UK Product Characteristics Database (PCDB).”
Vortice says that good mechanical ventilation systems are vital as our health depends ongood air quality – increased airtightness in homes can lead to mould growth (pictured)
Cowell explains: “The purpose of the EU 1253 regulation is to improve energy use and the efficiency of ventilation units, while EU 1254 is to provide the methodology and presentation of the results of EU 1253. This latter process culminates in an energy label that is supplied with the ventilation unit, similar to the labels already in use on domestic appliances such as fridges and cookers. The new regulations will allow specifiers to evaluate the overall performance and energy use of a ventilation system, in turn leading to a more informed choice.”
While acknowledging that MVHR is the most effective ventilation strategy for homes built with high thermal values and airtightness, Andy Mudie, marketing and business development director at Nuaire, says Positive Input Ventilation (PIV) is the more effective retrofit solution.
“It works by providing a continuous supply of fresh, filtered air into the house through a fan mounted in the loft. The gently warmed input air enters the home through a ceiling diffuser, creating a positive pressure effect that reduces humidity levels and forces out air pollutants, improving indoor air quality and helping to minimise the entry of harmful Radon gas (see box). PIV will work without the need for any trickle ventilators down to an air permeability of 3m3
, ensuring an additional saving for the home owner.”(Pictured) When it comes to effective ventilation strategies, Nuaire says a Positive Input Ventilation system such as its Drimaster-Eco range is the best retrofit solution
Nuaire’s Drimaster-Eco range includes three models featuring a circular ceiling diffuser housing the system controls, allowing adjustments and commissioning to be carried out without having to enter the loft. Added controllability comes from remote sensors and controls that instruct the PIV system to respond accordingly to changing humidity and carbon levels.
The Royal College of Physicians recently published the report – Every breath we take: the lifelong impact of air pollution
– revealing how air quality affects health. In the report, it states that the relationship between indoor air pollution and health must be quantified.
Jennifer Quinn of Vortice says: “As far as product development is concerned, much attention has been focused on improving the filtration methods incorporated into fans, in particular heat recovery units – some with a fully filtered bypass. There are different grades of filters which reduce pollen spores, dust particles and fumes. They can be within the heat recovery units or separately boxed which helps if access to the unit is limited.”On demand ventilation
Vent-Axia’s Ian Mitchell says that the latest filtration systems are designed for on demand ventilation and MVHR units. “The new Vent-Axia Pure Air targets pollutants generated outside of the building by traffic and industrial processes and reducing these before supplying the air inside. Fitted to the intake airflow it incorporates two types of filtration: enhanced activated carbon which removes unpleasant odours and harmful gasses such as nitrogen dioxide, and particulate filters which can remove tiny airborne contaminants such as pollen, bacteria and even PM2.5 diesel particulates.”
Titon’s Cowell adds: “In urban areas where nitrogen dioxide is on the rise the addition of dedicated filters to an MVHR system can combat pollutants found in exhaust gases from diesel engines. Products such as the Trimbox NO2 Filter incorporate balanced flow technology to reduce NO2 to an acceptable mean concentration level while improving indoor air quality.”
Nuaire’s Andy Mudie says the company’s new Q-Aire Carbon Filter is specifically designed for urban homes and supports MVHR systems by ensuring air is properly filtered before entering the property. “It allows contractors to meet planning obligations when building homes and apartments in areas with high air pollution. It’s easily installed but also easy for home owners to maintain – effective maintenance is the only way to ensure the MVHR system works properly.”
Enjoy the silence
(Pictured) Envirovent will supply its Silent extract fans to approximately 3,400 homes per year as part of a contract with Redrow Homes
Envirovent will supply its Silent extract fans to approximately 3,400 homes per year and its Ozeo Mechanical Extract Ventilation (MEV) to around 600 apartments, as part of a contract with Redrow. Larry Soper, Envirovent’s technical training manager, says: “The Silent fans are suitable for wall or ceiling installations and are highly effective at solving ventilation problems in areas such as bathrooms, kitchens and laundry rooms. These extract fans extract maximum airflow, reducing the detrimental effects of high humidity in homes, while minimising noise levels. It’s enabled Redrow to standardise its specification in different plot types avoiding the need for centrifugal fans which not only reduces cost but minimises complexity of installation.
“The Ozeo MEV System being fitted into the apartments offers an energy efficient and costeffective alternative to installing multiple extract fans. Developed to meet the requirements of System 3 to meet Part F Building Regulations, it provides all-year-round, good indoor air quality, with very low energy consumption.”
Council UK figures report that up to 2,000 avoidable deaths occur each year through exposure to radon gas. Cavity Trays’ director John Shillabeer says: “Air quality will be compromised when building on contaminated land if measures are not taken to minimise or eliminate ground gas infiltration. A commonly overlooked ground gas entry route into the building envelope is the junction where the floor slab abuts the inner skin of the external cavity wall. This occurs all the way around the building at ground level and the smallest of cracks is sufficient to allow gases such as radon to feed into rooms. The crack is normally hidden and out of sight below the bottom edge of the skirting board, but it is via this junction that air quality can be compromised.
“This gas entry route can be closed using a combination of barriers and ventilation measures to evacuate the gas from under the floor slab. The barriers are usually cranked in profile and built in to the exterior cavity wall. Their profile extends inwardly to lap and seal with the oversite membrane, thus providing full footprint protection across the entire building. The elimination of contaminated land gas entering a building permits air quality to be optimised.”
Cavity Trays www.cavitytrays.com