COVID-19 | BUILDING MAINTENANCE A weekly maintenance programme will help ensure heating systems work as they should when the building is reactivated assessment they might give a range, rather than an exact number but any indication of a change in water quality is important during a shutdown, when there are fewer people and less use on site, he says. Heat interface unit keep-warm modes and thermostat heating profiles enabled for one hour a day should ensure sufficient circulation throughout the network and tertiary heating systems, says Valletta. If this isnt feasible, the furthest rooms on each floor should have hot water enabled at least once a week to ensure network water is circulated to the outermost points. The longer the period between circulations, the longer the hot water draws should last for, to ensure suitable circulation is achieved, he says. If the electricity supply to the building hasnt been established on a new site, systems may have to be drained, so as much water as possible is removed. When the site commences, the system should undergo filling, pressure testing, cleaning, flushing and, if required, chlorination, as biofilms can develop on wetted pipework exposed to oxygen. Legionella risk should also be considered in the potable water system, he says, as legionella can develop in stagnant systems. Heat gain from the surroundings can elevate the water temperature and provide a more suitable environment for legionella growth. To alleviate this, hot and cold taps should, ideally, be run at least once a week to induce flow in the potable water system. This can be done in tandem with running the hot water to induce network circulation. If this is not possible, then a legionella risk assessment will need to be carried out post-shutdown, with regards to opening taps to protect those working on site, he says. Controls To help prevent unnecessary energy use, and to reduce overheads during a shutdown or partial closure, its important to identify areas of non-critical operation and adjust building controls. Jo Harris, lead author of CIBSE Guide M, advises applying a risk- based approach to maintenance tasks. For example, in unoccupied buildings emergency lighting routines can be risk-assessed, and the three-monthly checks can be postponed and rechecked when reoccupied. Its important to protect your maintenance staff too, so the least amount of time they can be in work, the better, she says. To protect building fabric while reducing energy, Harris advises maintaining air movement inside buildings, but with reduced air-flowrates from air handling units (AHUs). Set them to a building fabric protection setting not a comfort temperature for occupants so they are not heating and cooling, she says. Its about keeping buildings ventilated, but not making the chillers or boilers run unnecessarily, because you dont need to comfort cool. When occupant numbers are reduced, fewer contaminants would be circulating in the space, so fan coil maintenance in offices could be carried out and then suspended until occupants return, adds Harris. CJ Key guidance: CIBSE Guide M Maintenance Engineering and Management chapters on maintenance strategies and operational risk management procedures BESA SFG20 Planned maintenance maintaining statutory/insurance requirements and building security BESA SFG20 Core Plus identifying the tasks required to maintain statutory compliance; the SFG20 Service Model identies critical and routine tasks BESA SFG30 Mothballing and reactivation a step-by- MAINTENANCE AND REACTIVATION Baxi Heating recommends implementing a weekly maintenance programme to ensure heating systems work as they should when buildings are reactivated: Carry out a visual inspection of plant once a week Allow the domestic hot water to reach pasteurisation temperature (60oC) for one hour once a week to prevent bacteria forming Keep moving parts, such as pumps, operating for 10 minutes once a week to help prevent seizing. Most control systems will build this into their strategy 24 hours before reactivating the building, bring the hot-water system back up to 60C; open all the outlets until they reach at least 55C to ensure all stagnant water is removed; carry out microbiological sampling to ensure there is no contamination of the hot water supply; chlorinate the hot-water system to remove legionella, if needed. step process for maintaining critical services during low-occupancy periods, including passive re protection systems; refrigerant gases; electrical and gas service safety checks; ventilation hygiene; systems and lifts Health & Safety Executive Legionnaires disease Part 2: The control of legionella bacteria in hot and cold water systems (HSG274 Part 2) Water Supply (Water Fittings) Regulations BSRIA BG50 Water treatment for closed heating and cooling systems BSRIA BG29 Pre-commission cleaning of pipework systems CIBSE Knowledge Series KS21 guidance on competency and competency management. 20 May 2020 www.cibsejournal.com CIBSE May 2020 pp18-20 FM Covid-19.indd 20 24/04/2020 16:55