Restarting hibernating HVAC systems

The Property Council of Australia, Facility Management Association (FMA) and the Australian Institute of Refrigeration, Air Conditioning and Heating (AIRAH) have called on building owners and facilities managers to commence careful planning for the safe reopening of commercial buildings and workplaces across Australia.

The advice comes as the national cabinet and state governments announce easing of COVID-19 restrictions.

“The time is right to take action to ensure a smooth transition for businesses to return to their workplace in the coming weeks,” says the joint statement.

The three organisations have encouraged their members to access Safe Work Australia’s comprehensive guidance on how businesses can plan a safe return to work.

“For building owners and building managers who have partially or completely shut down HVAC systems within your buildings (‘hibernating buildings’) during this period of restricted activity there are important safety considerations for you to address prior to re-opening your buildings to workers,” the statement says.

“Restarting HVAC systems in hibernating buildings can carry some significant risks including outbreaks of Legionella, reduced indoor air quality and damage to building systems. Precautions must be taken to avoid serious consequences.”

The statement provides information for building owners and facilities managers looking to prepare for the reopening of their commercial buildings. It also strongly recommends consulting a building services expert when restarting buildings after hibernation.

The FMA has a number of resources to support members reopening buildings here and the Property Council has summarised links to relevant guidance for building owners here.

Risk of Legionella and damage to building systems

Cooling towers and condenser water systems can experience significant issues when shut down. These include corrosion build-ups on system surfaces that haven’t been chemically treated, and dead legs in water systems, which may harbour Legionella. AIRAH has a suite of resources on cooling towers and Legionella prevention at

Internal air quality and mould issues

If ventilation systems have been shut down completely rather than operated at reduced levels, occupants returning to the building may face health risks associated with low indoor air quality and mould. Measures must be taken to identify and address these issues before they are reopened for business. For more information on HVAC hygiene, refer to AIRAH’s Best Practice Guideline.

Compliance problems

Essential safety and maintenance measures must be kept up-to-date, even if the building has been unoccupied, otherwise the statutory maintenance regime may be deemed non-compliant – and the building should not be occupied. AIRAH provides training on Essential Safety Measures. It has also recently published a revised edition of DA19 – HVAC&R Maintenance, which covers compliance maintenance.

“If a complex HVAC system has been shut down,” the statement says, “experts should be consulted to implement the correct start-up procedures, to check control settings, and to compare the system’s operation with commissioning baseline data.”

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