Regulated by RICS

Over the past weeks we’ve seen a lot of evolving advice emerge from the Government, HSE, CIBSE and REHVA in relation to making your mechanical ventilation systems as safe as can be when returning to work premises by minimising the risk of airborne virus particles circulating. Some of this advice is pretty vague and overly technical, so our Hollis building services experts are on hand to help you make sense of it. Here are some of our operational top tips to get your workplace ventilation systems running safely.

Maximise fresh air

Your ventilation systems may be set by dampers or fan speed to limit the amount of fresh air and increase energy efficiency. During this period, we recommend getting as much fresh air into your building as possible by commissioning dampers or variable speed drives and fans. This of course needs to be done by a specialist. If you have windows that open – use them.

Where your ventilation controls are linked to an air quality monitoring system, lower the threshold at which this operates. Extend the running hours of any time-controlled supply and extract systems by at least two hours before and after the nominal working day.

Keep filters clean

Soiling of filters can lead to reduced airflows, so ensure your building services maintenance provider is keeping the filtration clean. Consider upgrading your filtration to EPA or even HEPA standards to enhance the chances of capturing the virus on the filter media. Please note that maintenance engineers and contractors should be using COVID-19 specific risk assessments and wearing the appropriate PPE when working on exhaust ventilation systems during this time.

Minimise or eradicate the recirculation of air

Many older systems recirculate a proportion of the exhaust air, or pass the air through a heat exchanger, but recirculating air may allow airborne viruses to re-enter the occupied areas. During this time we suggest implementing a full fresh air strategy, bypassing the heat recovery components to avoid possible contamination of the fresh air supply.

Toilet extract

Typically these operate only during occupancy hours. To continually purge the air, run your toilet extract systems 24/7. Openable windows in toilets should be kept closed to ensure the toilet extract ventilation paths function. If you have older premises with no mechanical ventilation, then get those windows open.

Our experienced Mechanical and Electrical experts are on hand to provide further advice in relation to these requirements. Please get in touch with Colin Edgar or Stephen Lemmon if you would like to discuss.

Get up to speed with the full guidance from the Government, REHVA and CIBSE here:

The Government:



Download pdf