Over the last several weeks we have been advising our customers and partners around the world how to best respond to the various challenges presented by the COVID-19 crisis. With a diverse customer base encompassing commercial/office buildings, retail, hotels, residential towers, clubs and hospitals, representing hundreds of sites spread across 18 countries, we have monitored and analysed an equally diverse range of site configurations and requirements.
EP&T’s team of experienced engineers and analysts have observed recurring themes across our customer base over this period, and have compiled a high-level summary of our observations. By reinforcing some of the best practice measures to be considered in response to this unprecedented health crisis, we hope we can in some way assist the many Portfolio Managers, Sustainability Managers, Chief Engineers, Facilities Managers, HVAC Professionals, Mechanical and BMS Contractors, building occupants and personnel all working hard to provide a safe and efficient building environment. As additional insights become available, our intention is to share these also.
As Federal and State Governments across the globe have imposed restrictions so that the chain of transmission can be broken, temporary changes in lifestyle have been introduced. Many hotels have experienced a significant drop in occupancy, shopping centers have seen a reduction in traffic, and as employees transition to working from home, commercial/office building utilisation has decreased.
These changes combine to affect the way we consume energy. As the significance of restrictions has increased, we have seen a corresponding shift in energy consumption patterns and peak loads. Some buildings have undergone a partial and/or temporary shutdown, each site inevitably presenting its own unique challenges and hence, opportunities. As Tony Gleeson, CEO of AIRAH (Australian Institute of Refrigeration, Air conditioning and Heating) observes; ‘…modern buildings are not designed to be shut down for extended periods’.
ASHRAE (The American Society of Heating, Refrigerating and Air-Conditioning Engineers), with a membership of 57,000 across 132 countries, believe that HVAC systems in most non-medical buildings play a minimal role in the transmission of infectious diseases, including COVID-19.
International professional engineering association CIBSE (Chartered Institution of Building Services Engineers) state that while very little literature is available, it is possible that coronavirus can be spread via air conditioning systems. While the impact of HVAC systems on the spread of the disease and corresponding transmission routes will become clearer as further scientifically approved information becomes available, evidence that the disease can be lethal and is easily transmittable is unambiguous.
A list of precautionary measures relating to HVAC systems, also endorsed by the likes of AIRAH, CIBSE, ASHRAE and REHVA (The Federation of European Heating, Ventilation and Air Conditioning Associations), includes:
- Maximise outside air supply to individual zones and increase ventilation rates (use caution in highly polluted areas and during extreme ambient conditions). Reduced occupancy does help increase the effective dilution ventilation per person.
- Toilet exhaust systems can be left on 24/7 (to reduce faecal-oral transmission risks).
- Minimise the use of rotary heat exchangers, including enthalpy wheels, as these can transport particles (contaminants) from exhaust air to supply side through leaks. This is especially relevant in cases of poor design and maintenance activities.
- Temporarily disable demand-controlled ventilation (DCV) to minimise recirculation.
- Where possible, use more window airing.
- Further open min OA dampers to eliminate recirculation. In the mild weather, this need not affect thermal comfort or humidity, but should be revisited come Winters in the Southern Hemisphere and Summers in Northern Hemisphere.
- Avoid central recirculation by closing recirculation dampers. FCUs, for example, use local recirculation and where relevant can be turned off. If they can’t be turned off, clean them frequently.
- Improve air filtration (by using HEPA certified filters or the highest grade compatible with the filter rack). Ensure the edges of filters are sealed to limit air bypassing through the corners.
- Keep some ventilation assets running longer or at higher speed to increase ventilation rate and air change rates inside the buildings.
- Consider portable room air cleaners with HEPA filters. When in use, placed them close to the ‘breathing zone’.
- Consider UVGI (ultraviolet germicidal irradiation), protecting occupants from infection, particularly in high-risk spaces such as waiting rooms, prisons and shelters.
- According to REHVA, humidification doesn’t have any practical impact on the virus under the thermal comfort temperature and humidity ranges. It is susceptible only to a very high relative humidity (RH) above 80% and a temperature above 30°C.
Some of these health measures have energy consumption implications, and therefore should be considered in combination with further measures to minimise energy consumption on a site-specific basis.
- Adjust temperature setpoints to ‘unoccupied’ levels and expand the dead-bands when a floor or zone is unoccupied. Operate the HVAC on those floors for only a couple of hours every day. This is required to eliminate problems like humidity levels affecting paints and carpets, smells, moulds, etc. when air conditioning is not operating.
- Update the cooling demand calculations to ensure the unoccupied spaces are not calling the plant to operate periodically. On days when outside air humidity is low, you would be better off enabling economy cycles on these floors in the early hours of the day.
- In buildings with multilevel carparks, some levels can temporarily be closed and tenants/patrons can be advised to park on certain levels in the available slots rather than their designated spots.
- Increase the chilled water supply temperature setpoints. This is particularly helpful in buildings situated in the southern hemisphere as they can make use of economy cycles and free cooling.
- Restrict the number of available lifts, especially in buildings where occupancy levels are less than 25%.
- Inspect for leaking taps and toilets especially in tenant spaces.
- Review mechanical drawings to check the availability of floor isolation dampers and check whether select spaces can be isolated.
- For hotels, check the possibility of letting rooms on a selection of designated levels, allowing other levels to be temporarily shut off. These can be reactivated as occupancy increases.
- Given cooler weather conditions in the Southern Hemisphere, we recommend setting the outside air lockout to 20°C. This will assist to extend the period prior to calling the plant and with it reduce energy consumption.
- Turn off/dim the lighting on ‘unoccupied’ floors and their common areas (other than emergency lighting).
- Consider amending time schedules to start the plant 30 minutes prior to commencement of core business hours.
- Preventative maintenance activities, water treatment and cleaning, and scheduled inspections and testing should continue as normal to ensure continuity of operations and cleanliness.
In Australia, NABERS ratings for most buildings would not be affected, as despite an increase in tenants working from home, with a valid lease in place most spaces would still be considered as ‘ready for occupation’.
A ruling released by New South Wales Office of Environment and Heritage (OEH) on 23rd March 2020, states that some additional issues are likely to arise in the coming days and weeks which might not have been captured yet. To address these, NABERS have formed a ‘Taskforce’ to assess the extension and inclusion of additional provisions in recognition that buildings and associated equipment may not be operating at full capacity.
EP&T’s review of our customers consumption data concludes that due to some tenants working from home, energy consumption is likely to reduce and ratings will be positively affected although only for an unknown period.
Every building presents its own unique combination of health and efficiency challenges and opportunities. The suggestions described are generic in nature and should be considered in the specific context of the purpose, technology, configuration, occupancy, climate and other attributes of each building and building site.
EP&T’s Engineers and Analysts are dedicated to providing detailed intelligence, insight and advice to customers around the world as they seek to adapt to the changes presented by the crisis. Commitment to partnership with our customers has never been more important. Building owners and/or building management professionals can contact EP&T via firstname.lastname@example.org.