Air Quality Guidelines Updated by ASHRAE and CDC

In order to improve air quality and help limit the spread of coronavirus, the American Society of Heating, Refrigeration, and Air-conditioning Engineers (ASHRAE) recommends more adjustments to the current Center for Disease (CDC) guidelines for the operation and control of HVAC systems. 

As offices slowly start to open, if you are a building owner or facility manager, make sure you are up to date on the current air quality recommendations so you can keep your workspace as safe as possible. 

What are the CDC Air Quality Guidelines? 

The current guidelines recommended by the CDC suggest building owners and facilities managers improve the engineering controls for their building ventilation systems to reduce disease transmission from airborne particles. This change largely impacts air quality in two ways: 

  1. Increases the percentage of outdoor air inside the building
  2. Increases ventilation rates

What Are Additional Recommendations by the ASHRAE? 

In addition to the CDC guidelines, ASHRAE also warns that unconditioned spaces can cause thermal stress to people and possibly lower their resistance to infection. To mitigate this risk and improve overall air quality, ASHRAE further directs facilities managers and business owners to consider the following:

  1. Flush the air in a building for two full hours prior to first expected occupancy 
  2. Flush the air in a building again for two full hours post-occupancy or after close

How Will These Changes Impact Your Building? 

With new information and guidelines from scientific, non-governmental, local, state, and federal sources, it is important for all facility owners or managers to consider a few effects these air quality recommendations may have on their buildings before implementing them. Based on the recommendations above, the biggest impact will be an increase in humidity. But, how bad is an increase in humidity? Based on recent research, it’s actually recommended to mollify the spread of CoVs, or coronaviruses. 

How Can Humid Air Slow Down Airborne Dispersal? 

A recent paper published in the American Society for Microbiology suggests maintaining relative humidity as high as 40 to 60 percent indoors can reduce the spread and survival of viral particles. The society’s latest paper on the topic indicates that relative humidity above 40 percent is detrimental to CoVs and can slow down airborne dispersal of a virus by encouraging larger droplet formation and infected particles, which are weighed down onto floors or surfaces more quickly and reduce aerosolization and spread distance

Why is Humidity Important? 

Increasing the use of outside air in a building during summer generally increases the relative and specific humidity. As the weather heats up, more moisture is retained in the air. But, at night the temperature drops, especially in your building’s unoccupied spaces, making the air less able to hold moisture. In short, while specific humidity remains the same, relative humidity increases. When relative humidity nears 100 percent or dew point, the air is considered saturated and condensation will form on even slightly cooler surfaces inside your building, including the foundation or cold exterior walls. 

According to ASHRAE Standard 8, occupied spaces should be controlled to limit the indoor humidity to a maximum dew point temperature of 60°F, a recommended comfort level dry-bulb temperature between 72°F and 78°F, and a maximum relative humidity level of roughly 60 percent.

What is the Risk of Not Monitoring Humidity? 

As mentioned above, humidity in a controlled space can be beneficial to the health and safety of employees. So, what happens when it’s uncontrolled? Not monitoring humidity properly can produce the following concerns for building owners and facility managers.

1. Growth of Mold and Mildew 

The risk of mold and mildew can occur without humidistats or humidity monitoring as mold and mildew can grow in conditions above 60% humidity.

2. Building and Property Damage

Depending on the construction type, a failure to monitor and control humidity can cause building and property damage. Electronic equipment, furniture, paper files, and merchandise are all examples of property that can be easily damaged if excess humidity is maintained. 

3. Energy Loss

Most buildings measure the humidity in only one space and when the dew point temperature increases above 60°F, building engineers will lower thermostats so that air conditioning systems run longer and remove excess moisture. This over-conditioning comes at a great energy cost.

A solution for this is to install a building automation system that should meet guidelines by using outside air based on sensing temperature, humidity, and occupancy in each individual zone, and redirecting air from partially occupied or unoccupied spaces to maximize ventilation in occupied zones and optimize energy savings. 

For More Information 

For more information on how to improve your air quality and regulate your office’s humidity level with a building automation system, contact us for a free energy audit!

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