With the UK Government closing non-essential shops and community spaces, and enforcing a work-from-home model for approximately 54% of the UK, commercial spaces are in a state of flux. Only essential spaces remain open, with the majority closing coupled with uncertainty on when they’ll reopen.
Anthesis’ Chief Engineer, Mark Hawker, provides guidance on how businesses, both operating and preparing to close, can support the ongoing fight against COVID-19 through the introduction of certain building control measures.
Operating and Using Building Services
To reduce the opportunity for viruses and bacteria to proliferate within the building during operation, we recommend considering the following:
- Increase Air Supply and Exhaust Ventilation – Increasing the volume of air moving through the building will prevent concentrations of stale air building up with a bacterial or viral load, by diluting it out with fresh air. If your filters haven’t been changed for a while, and are showing a distinct differential pressure, then it would be worth considering changing filters if feasible. Exhaust ventilation from toilets should be kept on 24/7.
- Air Recirculation Systems – Heat reclaim systems that are purely thermal and make no use of recirculated air, can be left on. However, any system that uses recirculation, or where there is a risk that virus/bacteria can stick to the transmission media (e.g. thermal wheels), should be switched off to prevent stale air with a bacterial or viral load being reintroduced within the building.
- Open a Window – Opening windows where practical will increase the amount of fresh air in the building, further diluting out stale air with a bacterial or viral load.
- High-Quality Clean Air Filters – High-quality fan/filter units with High-Efficiency Particulate Air (HEPA) filters will remove bacteria and viruses from the air, reducing the load. Typically, portable filters (which can be hired) will cover a space of around 10m2.
- Ultraviolet Systems – Ultraviolet systems are available for installation into heating and ventilation ductwork to kill viruses and bacteria. However, if airflow is maintained and recirculation is eliminated, then the incoming air should be clean, so the benefit may be minimal.
- Restrooms – Previous work by the World Health Organisation (WHO) on SARS-COV-2 showed that flushing a toilet caused a plume of fine water spray to form above the bowl. To minimise the risk of spray, it is good practice to keep the toilet lid down when flushing, avoid using high-speed hand-driers and keep the extraction fan on 24/7.
Things That Won’t Help
Unfortunately, COVID-19, like SARS-COV-2, is not particularly sensitive to temperature (>30°C) or humidity (>80%) in the normal range. On that basis, changing temperatures on heating or air condition or humidity levels won’t particularly help.
There has been some commentary recommending cleaning ventilation ducts to avoid transmission via ventilation systems. Duct cleaning is not effective against room-to-room infection because the ventilation system is not a contamination source if the space is well ventilated with fresh air and any routes to recirculation have been decommissioned.
Changing filters will have little benefit unless they are blocked as typical air filters will not capture bacteria or viruses as they are too small. However, if the filters are old and blocked, the increased flowrate will be a benefit.
Life Safety Systems
Life safety systems include any building systems required to protect life in the event of an emergency (e.g. fire, power outage or earthquake).
Typically, life safety systems include:
- Fire alarms (heat and smoke)
- Fire suppression systems (e.g. sprinklers)
- Lifts where they are the only way of an evacuating a high-rise building
- Ventilation systems where they are designed to manage smoke and fumes
- Generators where they are required to power the above
Closing Down a Building as a Consequence of COVID-19
- Leave the heating on and turn down the temperature to 10-14°C – 10°C for a building where you aren’t too worried about damp and mould in stock, and 14°C for a building where you are worried about damp and mould (e.g. textiles).
- Make sure all lighting and non-essential electrical equipment are turned off (not just on standby).
- Clean out any fridges or freezers, switch them off and leave the door open to prevent mould.
- Ensure all bins are emptied and cleaned.
- Fill up any water traps (toilet bowls, sinks etc) to maintain a seal against drainage.
- Leave toilet lids down.
- If service valves exist, isolate taps locally but leave mains water on to the heating system.
- Test any systems (particularly life safety systems (see life safety systems box)) that might be required whilst the building is unoccupied.
- As the building is unoccupied, there is a higher chance of break-ins. Take extra precautions to ensure anything that would attract a thief are removed, make sure all fire doors are closed, and set the alarm system (if fitted) as you leave.
- Many buildings have Building Management Systems (BMS) and can be remotely monitored via the internet and as a minimum have SMART gas and electricity meters. It is advisable to monitor energy consumption at closure and thereafter to make sure it remains as expected.
Reopening a Building after Closure for COVID-19
- Return the heating to its normal set points.
- Test any systems that are required (particularly life safety (see life safety systems box)) are still working.
- As vermin may have been able to get into the building, clean and wipe down all surfaces with an anti-bacterial cleaner.
- Employ a building services technician to sanitise hot and cold water systems with chlorine or similar, paying particular attention to showers. Un-isolate any closed legs, and flush both the hot & cold water systems until the water runs clear.
- Fill up any water traps (toilet bowls, sinks etc) to maintain a seal against drainage.
- Recommission any fridges to working temperature
- Check that light and emergency lighting are still working.
- Check that the fire alarm, CCTV, and security systems are all working.
References:
REHVA COVID-19 guidance document, March 17, 2020
WHO advice on SARS-COV-2, SARS-COV-1 and other flus
