31 Oct 2017

Selecting the right ventilation system for your self-build project

Ensuring you have the correct ventilation for your property and lifestyle, whilst ensuring you meet Building Regulations, can appear daunting, says Callum Graham, Self-Build Estimator at Nuaire.

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Follow our top tips to designing a seamless ventilation system that will save energy and keep your home healthy.

1. Save energy and improve your indoor air quality with MVHR

As a British manufacturer with over 50 years of experience, Nuaire has seen many ventilation strategies rise and fall in popularity, but a trend that we are certain will continue is the growth in use of mechanical ventilation with heat recovery, or as it's also known, MVHR.

MVHR offers year-round, whole-home ventilation that will remove condensation and pollutants, whilst recovering heat, significantly improving the indoor air quality and reducing energy usage. These systems work by combining supply and extract in one unit. Moisture-laden, stale air is extracted from ‘wet’ areas, such as kitchens and bathrooms. The heat from this extracted air is recovered via a heat exchanger, and this tempered air is filtered and delivered to the living areas of the home creating a healthier living environment for the occupants.

2. Think ventilation from the start

When undertaking a self-build project, the earlier you can start planning your ventilation strategy, the more time and money you’ll save and the more likely the ventilation system’s location and ductwork will fit seamlessly around your property’s layout.

Work with your ventilation designer to plan the most efficient design. The first thing your designer will request is up-to-date floor plans, in AutoCAD .dwg format, which your architect can supply. These drawings will be accurately scaled and ideally the final revision, so the MVHR system and ductwork can be located around other services, ceiling joists and any unusual features that form part of your design.

If you think about the building services from inception, you’ll avoid boxing in your system or ducting at a later stage, or creating voids and bulkheads for services that weren’t in the original design.

3. Location, location, location

Another key consideration at the design stage is where your MVHR system will be located. It’s crucial to have access to the system for filter changes and general maintenance, as well as adjustments for commissioning. The size of the unit and the entry path to install it also need to be considered. The loft space is favourable but not always feasible. If you do loft-mount your MVHR system, ensure the loft hatch is large enough to fit the unit through. If you opt for a cupboard-mounted system, it will need to be supported on a solid structural wall; ideally a gable-end or solid brick structure for maximum strength and mass. Attaching an MVHR system to a lightweight partition wall can cause vibration noise, which is difficult to mitigate further down the line.

4. Do not underestimate ducting

Ducting is far from being an after-thought ancillary item. Correctly installed ducting will ensure your system performs as intended and ensure you comply with current Building Regulations. There will be preferred sizes of ducting to suit your chosen MVHR system, and your designer will both recommend the ducting and ancillaries and will design the ducting layout for you. Nuaire offers this hands-on design service using 3D REVIT MEP software to illustrate the ducting systems and components. It allows the designers to provide a complete service of design drawings, fan selection and ducting schedule tailored to the property, which assists project management and material control.

There are two options for ducting your MVHR system: branch or radial systems. A branch system uses flat or circular PVC or thermal ducting in straight runs, connected with tee-pieces which branch off and serve each individual room. The branch system is preferred by designers as it can be designed using their specialist software and, when installed, there is less chance of veering away from the intended design. It’s also cheaper and easier to commission.

A radial ducting system is semi-rigid ducting that connects to a manifold and runs in single ducts leading to each room. As the ducting is installed in long runs, there is more flexibility for the installer. However, the design can be more complex and careful consideration must be given to the length of duct-runs as these can affect MVHR system flow rates.

Ducting in MVHR systems carry warm air through them, and when they pass through unheated spaces – such as lofts and voids – condensation can form on the ductwork and cause water damage to your property. So, in order to avoid this potential damage and to meet Building Regulations, ducting that passes through unheated spaces must be insulated with an equivalent of at least 25mm of insulating material. Unlike other thermal ducting systems that fit around the PVC pipe, Nuaire’s award-winning Ductmaster Thermal offers a neat all-in-one solution that improves thermal efficiency and is light enough for one person to install. It uses a unique clip system to form an airtight seal, so there’s no need for messy tape and sealant. The LABC-approved range is also independently tested for airtightness by the BRE, for total peace of mind.

5. Keep the noise down

Modern, lightweight wall construction methods offer very little mass to absorb noise and vibration, so attaching a mechanical system to a structure that isn’t solid can often result in low-frequency noise and vibration in adjacent living and sleeping areas. Then you add ducting, which creates a path for noise to travel between rooms.

Attenuation is the answer here. MVHR systems are available with different forms of attenuation, from silencers that fit directly onto the system to more sophisticated all-in-one solutions that provide an acoustic enclosure to your unit and ducting connectors, as well as attenuation. Nuaire’s 1Z takes this concept a step further, acting as an acoustic enclosure, encasing the attenuator and duct connections, whilst supporting the internals on anti-vibration mounts to further isolate noise and vibration. All this comes in a sleek, white casing that neatens up, what can be, a fairly messy fix.

6. When things change, inform your designer

You’ve invested a great deal of time, money and energy by the time you start planning the building services of your new home. So don’t compromise on the design of your MVHR system. By working with a designer you can plan ahead to ensure your system gives you the best possible air quality and the highest energy savings. And, by informing your ventilation designer at the design stage and beyond of any changes to the layout or any particular features central to your design that may affect the balance of the MVHR system, they can plan ahead and ensure the amended design still offers the same system performance and meets Building Regulations.

Small changes, such as selecting a different air valve or grille to better suit your decor, can have an impact on system performance as they may not give the required ‘free area’ needed to meet the flow rates for your property. Floor plans can change and change again, meaning you may need to relocate your MVHR system or add extra duct runs and bends. Working with your designer will alleviate any headaches along the way and make sure the building control officer gives you that all-important sign-off.

Installation engineers must be trained and registered to test and commission ventilation systems on new-build homes. They are expected to provide ‘right-first-time’ installations so that commissioning is easy and occupants can be confident that their MVHR systems will perform efficiently. Nuaire offers free specialist training to installers to promote industry best practice. Look for similar schemes with your chosen ventilation manufacturer.

Finally, remember that a well-designed and well-balanced MVHR system will give you excellent indoor air quality; will prevent condensation dampness and will help you save energy. Work with your ventilation designer from the first stages of your design for the best possible results.

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