What is the ideal relative humidity of a conditioned space?

• A. 40% - 60%
• B. 20% - 40%
• C. 60% - 80%
• D. 10% - 30%

Answer: (A)

Maintaining indoor humidity at a moderate level supports comfort and health. Relative humidity in a conditioned space should stay in a middle range so the air doesn’t feel too dry or too damp. If the air is too dry, people experience dry skin, irritated eyes and mucous membranes, and static electricity increases. If the air is too humid, surfaces can stay damp, mold and mildew can develop, and dust mites thrive, along with potential condensation and odor issues. A balanced, moderate range minimizes these problems, making the space comfortable for occupants and safer for the building and its contents.