Preparing to remobilise your building(s) after the lockdown for air and water systems – planning is key

Greg Davies

Greg Davies
Director of Market Development, Assurity Consulting
24th April 2020

Whether you have had nearly full, partially occupied or vacant properties, you will need to know it is safe for the return to work of your staff and others. For this you will also need a plan.

Already there are organisations advocating widespread treatment and cleaning of building services, as well as occupied spaces, being needed prior to re-occupation of everything from the ductwork distribution and waters systems to the hard surfaces and fittings. While some occupiers appear to be looking at doing nothing but a swift return to BAU. The reality for most is that something in between is going to be the best, most effective and most realistic answer.

Air systems

Re-optimising systems and confirming air quality and occupancy comfort conditions is the primary activity. Specifically, where systems have been altered to increase “fresh air” supply and extract or modified to reflect usage.

One of the unintended consequences of lockdown has been a dramatic reduction in vehicle movements, which, coupled with the prevailing weather recently, has seen an improvement in external air quality. This will also have helped in reducing the amount of external contaminants our air supply systems we have to deal with.

In relation to needing to now clean these systems (and kitchen extract systems notwithstanding), advice from REHVA (The Federation of European Heating, Ventilation and Air Conditioning associations) in their COVID-19 guidance document of the 3rd April 2020 states:

“Duct cleaning has no practical effect. There have been overreactive statements recommending to clean ventilation ducts in order to avoid SARS-CoV-2 transmission via ventilation systems. Duct cleaning is not effective against room-to-room infection because the ventilation system is not a contamination source if above guidance about heat recovery and recirculation is followed. Viruses attached to small particles will not deposit easily in ventilation ducts and normally will be carried out by the air flow anyhow.”

Confirm your air handling plant remains in good condition, check and replace filters as needed, make sure fans, heating/chilling batteries, terminal units and controls are operating properly and as a final assurance carry out an independent air quality survey.

You could also use the time to clean supply and extract grilles to remove any long-term build-up of dust and debris that will have accrued over time. This is likely to have been occurring for a lot longer than the lockdown, and while not directly linked to it will help aesthetically as people return to work

There is a relevant debate about the effect of heat and humidity on the endurance of SARS-CoV-2 virus particles but many mechanical ventilation systems have little direct control over humidity with no artificial humidification available as an option, and occupant comfort related to temperature control is a balance of priorities. Many workplaces rely on natural ventilation also, with only comfort cooling as a potential option to normal heating, so again very little that can be realistically changed.

Water systems

Just as with adjusting to managing ‘empty’ buildings, there is no blanket approach to managing re-occupation that will fit all circumstances or individual sites. Some buildings will have continued with their ongoing PPM schedule, amending it as necessary to address the risks; other sites may have simply been ‘abandoned’ and the water services left operational. Either way, you should review your written schemes/water safety plans ready for re-occupation to provide reassurance that it will prevent water-borne microbiological and other health related risks.

From a Legionella perspective, where dutyholders have had the ability to keep their systems operational and maintain or enhance their controls through etc. (and your management demonstrates control) it should be a return to normal (depending on re-occupation rates of course).

For others where some or all of the services have been out of use or isolated, they will need to be cleaned and disinfected prior to reoccupation. Reset controls for hot water systems and check they are achieving the right temperatures too.

Where you have showers or other high hazard spray outlets in place, cleaning and disinfecting these outlets just prior to returning the building to use would also be a sensible action.

For evaporative cooling towers and other process water systems, it will again be based on recent usage. If your systems have continued to be operational, nothing may change, on the other hand if they have been taken out of use then your start up procedures will have to be followed.

Drinking water provision through taps, vending machines, water dispensers or other systems needs careful management as some of these systems may not have been used for weeks. Proper cleaning, flushing, replenishment and/or replacement of consumables (or water for standalone units) could be needed. Where installed don’t forget about ice makers and other equipment of this type too.

Check your sanitation and drainage systems as well to make sure they are functioning correctly and appropriately free of blockages and contain water as required.

There are a number of organisations with commercial vested interests already offering cleaning and testing of systems, but be very careful how you consider these. Whether building services actually require cleaning in the first place is a point to consider (see above), but more importantly if you are going to test and consider cleaning, how and why are you going to do it?

Remember that random testing of any building service in isolation is of little or no value and you never get a good result from badly taken samples. For it to be of most benefit to you and the building occupants, sampling should form part of a wider independent assessment of your building systems and services to include, inspections, temperature profiling and documentation review so a fuller and more complete appraisal of the services takes place for full reassurance. The company providing this work need to be competent and experienced in providing it too.

In summary plan your remobilisation carefully:

  • Identify how you are going to re-occupy your premises and put in place the processes you need to be able to demonstrate your building services are operational and safe;
  • List your building systems and services based on their recent usage (BAU, partially used and/or mothballed);
  • Review any modified or changed risk assessments and update them;
  • Implement your re-start, cleaning, assessment and testing regimes as required;
  • Contact your specialist service partners early in the process, they are likely to be busy too!
  • Don’t sample building services in isolation or clean systems without a valid reason.
  • Seek independent advice to balance that of a contractor whose business is primarily providing ancillary services;
  • Document all your processes and procedures, especially anything that is new or different;
  • Remember to include social distancing and other COVID-19 control measures as part of your new management procedures;
  • Keep well and stay safe.