If you want to be sure your mechanical system is operating so it protects your health, the single best recommendation we can give you is to technically monitor and commission the mechanical system with health as your prime requirement.
If you are not familiar with commissioning, it is worth your time getting up to speed quickly. Commissioning is quality management for buildings by which you make sure your building is performing the way it was designed to. Commissioning in existing buildings is like going to the doctor for an annual check-up. It helps you catch things early, before your building ends up in ER, where you will spend 10 times as much fixing the problem.
Can we use the CO2 level in a space to estimate whether ventilation is good or bad 1?
Yes, this is a useful technique, although it has some limitations. Outdoor CO2 in Australia is about 450 ppm, and human breath increases this concentration. In well ventilation spaces, CO2 should stay below about 800-950 ppm. In poorly ventilated spaces CO2 can reach levels of 3000-5000 ppm. CO2 can be monitored with a smart and affordable monitor.
Surveying classrooms, offices etc. with a CO2 monitor can be useful to determine which ones may have the worst ventilation, and prioritizing actions there.
- If there are sources of such as cooking they must be turned off for testing
- The amount of exhaled respiratory aerosols increases CO2 greatly with singing and shouting.
1. Learn more here: FAQs on Protecting Yourself from COVID-19 Aerosol Transmission
Our Recommendations for Mechanical Systems:
- Increase the outdoor ventilation rate and minimise recirculation
- Supplement ventilation with local exhaust and high efficiency air filtration
- Schedule ventilation at least 2 hours before and after occupancy