How can offices safely re-open after lockdown?

18th November 2020

Commercial buildings in the UK have been hit hard by the coronavirus pandemic.  As businesses were forced off their premises and into their homes back in March, some offices in London saw occupancy rates drop as low as 10% – a considerable change of use for buildings designed to host thousands of people and something we’ve never seen before in the modern built environment.

During times of low-occupancy and when bringing buildings back into regular use, employers and building managers must ensure that maintenance regimes are fit-for-purpose to safeguard against costly and potentially dangerous problems.

Safe building services

Complex office buildings of multiple occupancies cannot simply be ‘switched back on’ following a period of low usage.

Before occupants can be safely welcomed back, the building services must be recommissioned, with all relevant inspections and maintenance undertaken and settings modified to accommodate changes in occupancy, shift patterns and working practices.

Before change of use, the following services should be checked in accordance with government and legal guidelines:

  • Electrical safety – checks must be carried out by a qualified electrician under the 18th Edition of the IET Wiring Regulations (BS7671) and the Electricity at Work Regulations 1989.
  • Gas safety – Ensure all relevant gas safety inspections and maintenance have been carried out prior to restarting the system. Visit for more information.
  • Emergency systems – fire detection systems, emergency exits and emergency lights.
  • Access and security systems – review to reflect changes to occupancy and/or working hours.
  • Building Management Systems (BMS) – modify settings to ensure efficiency.
  • Ventilation – with increasing evidence for airborne transmission of Covid-19, steps should be taken to improve natural and mechanical ventilation in office buildings, with ventilation rates increased as much as is reasonably possible. Further guidance from CIBSE can be viewed here.
  • Water systems – Legionella is an increased risk during periods of low-usage and has been a huge concern for facilities managers over the lockdown period.

Legionella control

Manual flushing, even if carried out on a regular basis, does not replicate normal usage in large commercial buildings.  If appropriate sampling and treatment are not carried out water can stagnate and accumulate debris, such as sludge and biofilm, which only exacerbates microbial growth.

People in control of premises – including employers and facilities managers – have a legal duty under ACoP L8 to identify and control the risks of legionella in building water systems.

Prior to re-occupation, responsible parties must review their Legionella Risk Assessment and ensure that the appropriate maintenance and/or treatment have taken place to ensure occupant safety.

Contact Guardian Water Treatment to find out how our expert team can look after your building during periods of low usage and ensure a safe environment for re-occupation.

Further information and guidance can be viewed on the HSE’s Legionella website.