Housebuilders: don’t rule out PIV

Andrew Sellman, Residential National Sales Director

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When a dwelling is designed with continuous mechanical ventilation the designer will typically opt for a design that contains either continuous mechanical extract (MEV), also known as System 3, or mechanical supply and extract with heat recovery (MVHR), also called System 4.  Various studies have found that continuously running mechanical ventilation will provide a higher level of indoor air quality than intermittent fans.

As well as being able to provide more traditional mechanical ventilation solutions, Nuaire is able to offer an alternative approach when heat recovery is not required. Our alternative approach is a strategy called is Positive Input Ventilation (PIV) which was invented by Nuaire back in the 1970s. It’s now installed in over 30,000 homes per year as a low-energy, low cost solution to combat condensation and indoor pollutants, and it’s suitability to new build ventilation is finally being recognised.

PIV can be a more cost effective and simple to install solution to ventilating houses than MEV and dMEV systems, whilst at the same time meeting the requirements of the building regulations by having a BBA certificate.  It works by drawing air from the loft, picking up free heat generated by solar gain within the loft and continuously supplying the air into the building through a diffuser on the central landing area. The air then mixes with the polluted air inside the property before dispersing  the pollutants out through natural leakage points within the building fabric.

The benefits of PIV are a continuous flow of clean, filtered, fresh air which will reduce indoor air pollutants, such as chemicals from cleaning, dustmite faeces and cooking gases, whilst at the same time removing external pollutants that would normally be pulled into the building using extract fans. PIV units are maintenance free for 5 years.

The cost benefits to the builder can be quite substantial when you consider that there is typically only one electrical connection and no penetrations through the fabric of the building. PIV will work without the need for any trickle ventilators down to an air permeability of 3m3h/m2 ensuring an additional saving for the house build.

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