TECA Member Meetings

Relative humidity is a measure of moisture content in the air. Relative humidity is a comparison between the amount of moisture that is currently held, versus the absolute maximum that air can hold when it’s fully saturated at its current temperature and pressure.

People are sensitive to relative humidity, which is why it is considered when evaluating thermal comfort. It can impact the health of the building occupants, in particular, that of the deepest lung tissues where the oxygen absorbing, carbon dioxide releasing process occurs in the alveoli. Research shows that our body’s natural protection and immunity from infectious bacteria and viruses is reduced when relative humidity levels drift away from ideal conditions.

The relative humidity in a dwelling home can affect the health of the house itself. HVAC contractors can alter the relative humidity of a dwelling, primarily through ventilation, but this is minor in comparison to how the building is constructed, the number of occupants, and the activities within the building. Understanding the limits of a typical ventilation system and the conditions that cause relative humidity to overpower that system are critical for setting realistic expectations and not accepting fault for poor building design beyond the mechanical contractor’s control.

Balancing relative humidity in a dwelling is challenging, to further complicate the matter, consider that what is ideal for the occupants of the dwelling is not the same as what is ideal for the dwelling itself. David Hill will share his experience and first-hand knowledge to shine a light on this often misunderstood problem.