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Is the Humidity Level in Your Building Causing Tenant Discomfort?…

Written by Gary Giambatista, VP Operations, Control Temp Mechanical Services
([email protected])

Humidity control systems add or remove water vapor from indoor air to stay within proper humidity ranges.  Humidity control is important for three reasons:

  1. It is a large factor in people’s thermal comfort.
  2. Excess moisture in a building can lead to mold and mildew, causing problems for indoor air quality.
  3. It is a large energy user. Dehumidification alone can be a quarter to a third of cooling energy in humid climates or seasons. (However, humidifying does not tend to be a large energy load, even in dry climates or seasons.)

Understanding Relative Humidity (RH)
The ratio of water vapor in the air to the maximum amount of water vapor the air can hold at a set temperature is expressed as relative humidity (RH).  For example, a RH of 30% means that the air contains 30% of the moisture it can possibly hold at that temperature.  When air can hold no more moisture at a given temperature (i.e. the RH is 100%), the air is said to be saturated.
As air temperature increases, its capacity to hold moisture also increases, so if air temperature rises and its moisture content remains the same, the RH decreases.

Air usually contains water vapor, the amount depending primarily on the temperature of the air, so as the air temperature falls, the maximum amount of water the air can hold also falls.

The Most Common Problems Caused by Poor Indoor Humidity
Low Humidity Can Cause:

  • Static electricity
  • Dry, itchy skin and hair
  • Susceptibility to colds and respiratory illness
  • Viruses and germs thrive
  • Damage to wood furniture and floors, furniture split and crack
  • Paint can chip
  • Electronics can get damaged

High Humidity Can Cause:

  • Mold growth
  • Wet insulation
  • Rot on woodwork
  • Muggy conditions
  • Sleep discomfort

Optimizing Your A/C System to Control Humidity
An efficient air conditioning system will help to remove unwanted moisture in your building.  However, to do this, your equipment and ductwork must be sized and installed correctly.  Appropriately sized systems have sufficient capacity, run times, and ample airflow to humidify or dehumidify your building.   A custom-designed and installed HVAC system for your building keeps you more comfortable.  It can also save you money in the process.  Dehumidifying your building a little more in the summer allows you to set the temperature on your thermostat a few degrees higher which could produce energy savings.

There are no simple solutions to humidity control.  You need an experienced HVAC company to evaluate your system design.  Control Temp Mechanical Services can assist you with evaluation and corrective actions to resolve your humidification issues.

For more information, call us at 800-358-9904 or visit