Whole-Home Humidity Control
Whole-home dehumidification / humidification provided where appropriate by climate (target 40–50°F dewpoint).
Spec
Applies uniformly from Platinum upward.
Scope
Whole-home humidity management — dehumidification in cooling season, humidification in heating season, as appropriate to climate.
Requirements
- 01.
Install a whole-home dehumidifier (typically integrated with the HVAC return) sized for the dwelling.
- 02.
Target dewpoint range: 40-55°F (corresponds to ~30-50% RH at typical indoor temperatures).
- 03.
In cold-dry climates (Zones 6-8), add a whole-home humidifier to prevent winter RH dropping below 30%.
- 04.
Controls must be tied to the IAQ sensor required at Gold.
Documentation
Evidence the inspector / Institute will need.
- 01.
Dehumidifier (and humidifier where applicable) spec sheets showing pint/day capacity and integration.
- 02.
Photo of installed unit + control interface.
- 03.
Initial commissioning record showing RH/dewpoint readings in main living area.
Guidance
Why dehumidification is separate from AC
In hot-humid climates, a properly-sized AC removes humidity as a side effect of cooling — but only when it's running. During mild "shoulder" periods (May, October), the AC doesn't run enough to control humidity, and indoor RH can climb to 65-75%. A dedicated dehumidifier handles the gap.
Note
Mold growth becomes likely above 60% sustained RH on cool surfaces. Most building scientists recommend keeping RH between 30% (winter floor) and 50% (summer ceiling). Below 30% causes static, dry skin, increased respiratory infection; above 60% causes mold + dust mite growth.