Ventilation Cambridge: Extractor Fans, PIV and MVHR

Ventilation in Cambridge has two jobs: getting rid of moisture in winter and letting heat escape in summer. Flats and shared houses struggle with both, and over a third of Cambridge households live in flats.

Cambridge at a glance

Record heat: Cambridge University Botanic Garden recorded 38.7°C on 25 July 2019, confirmed by the Met Office as the highest UK temperature on record at the time. Source
Homes that are flats: 35.0% of Cambridge households lived in a flat in 2021, most of them (30.7%) in purpose-built blocks. Source

Winter moisture

Cooking, showers and drying clothes indoors put litres of water into the air every day. For Cambridge kitchens and bathrooms, Approved Document F lays down the lowest extract rates a fan should reach. Many older fans fall short. Replace them with humidity-controlled models that run on after the room is empty.

In shared houses with several people showering daily, the bathroom fan works hardest. A quiet, powerful fan with a long overrun pays for itself in reduced mould.

PIV and MVHR

Positive input ventilation suits houses and flats with general condensation. A loft or wall-mounted unit feeds in filtered air, pushing damp air out.

MVHR is common in newer Cambridge developments. Keep it running all year, and replace the filters at least annually. Many have a summer bypass that stops them warming incoming air on hot days.

Testing what you have

A simple tissue test at a fan grille shows whether it is pulling air at all. An installer can measure the actual extract rate with a flow meter and compare it with the Approved Document F minimum. Many fans that look fine turn out to move only a fraction of what they should, usually because of long or crushed ducting.

Summer heat

After the 38.7°C recorded at the Botanic Garden in 2019, summer ventilation matters too. Secure night ventilation, such as lockable window restrictors or vents, lets you cool the home overnight without leaving windows wide open.

Cambridge homes and what they need

Victorian gault brick and red brick terraces

Internal bathrooms added to old terraces need ducted fans. Check ducts run to outside, not into the loft.

Interwar and post-war semis in the northern and eastern suburbs

Replacement windows have made these tighter. Trickle vents and a PIV unit often solve condensation.

Recent developments on the city fringes

If your home has MVHR, find the unit and filters. Blocked filters are the main cause of poor performance.

Areas covered

Engineers who cover Cambridge work across areas including Chesterton, Romsey, Cherry Hinton, Trumpington, Arbury, Newnham, Histon, Girton, Great Shelford and Milton.

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Questions people in Cambridge ask

Can tenants ask for better fans?

Yes. Landlords must deal with damp and mould hazards, and working extraction is usually part of the fix. Ask in writing.

Is MVHR worth retrofitting?

Only if the house is being made airtight through major work. In a typical draughty house, good fans and PIV are better value.

Sources

Also nearby: Ventilation installation in Peterborough, Ventilation installation in Chelmsford, Ventilation installation in Luton, Ventilation installation in Norwich

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