Ventilation for Safety
Recent guidance from ASHRAE is to consider increasing ventilation rates to help protect against the transmission of COVID-19, and as a result, many are working to become familiar with an unfamiliar topic.
Minimum Ventilation Rates for Spaces
Ventilation is the intentional and controlled introduction of outdoor air into a space. It can improve air quality by diluting and displacing hazards, and also affects the temperature and humidity of a space and direction of air flow within the space.
Section 6 of ASHRAE Standard 62.1 provides minimum ventilation rates for spaces including classrooms, restaurant dining rooms, health clubs, and more. The rates consider contamination sources originating from building occupants and their activities, as well as from the building itself. This reference for determining outdoor airflow requirements illustrates how outdoor air rates vary with type of occupancy, density of occupants within the space, and the floor area of the space, and helps us to gain insight into increasing ventilation rates.
Clean, fresh air is generally a good thing, although outdoor source pollutants must be considered. Suggestions for increasing ventilation rates include:
- Check and clean your ventilation system.
- Increase total supply air, and outdoor air, by opening diffusers or adjusting dampers.
- Run systems longer. Temporarily scale back the use of energy conserving demand-controlled ventilation.
- Add hardware. An air-side economizer, for example, can bring cool, outside air into a building and distribute it.
If your building doesn’t have a ventilation system, opening windows and decreasing the number of occupants in the space are options, in addition to increasing natural ventilation through larger openings.
Measuring and monitoring airflow will allow you to understand your existing ventilation system, record changes as ventilation systems are adjusted and improved, and discover ventilation issues quickly, as they occur.
Standard airflow measurement techniques can be used for measuring outdoor air intake. Install air velocity and temperature probes at key points in your ventilation system to provide real-time feedback to your controller or control system. Get further assurance that target air volume is being added to/removed from a space by installing a Rooster™ Monitor for real-time display of air changes per hour (ACH). Unintended flow reversals can also be quickly detected with a B-Series bi-directional sensor to output airflow direction, along with air velocity and temperature, in real-time.
Measuring velocity in turbulent air can be simplified by using handheld visualization tools to disperse fog into the environment. When the airflow paths are understood, measurement tools can be deployed.
We are with you when you’re ready to begin your airflow improvements. Contact a Degree Controls representative to learn about our resources and airflow sensing and controls platforms.