Humidity Control

ASHRAE Humidity Control Design Guide

Sooner or later, every HVAC engineer, architect, building owner, contractor or maintenance professional comes up against the challenge of controlling humidity in a building. This 512-page book provides tools to meet that challenge. This file offered here provides a short sample of the book’s contents and its writing and illustrations, all generated by members of ASHRAE Technical Committee 1.12 - Moisture Management in Buildings. (The complete book is available in both printed and PDF format from the ASHRAE Bookstore.)

ASHRAE Guide for Buildings in Hot & Humid Climates

This guide is focused on climate-specific issues. It provides simple and practical suggestions to help professionals make better decisions about their buildings, and to make them more quickly. The book also provides a climate-specific overview of ASHRAE standards, guidelines, technical articles and Handbooks.

Controlling Dew Point Temperature Instead of RH

In the past humidity was controled using humidistats that measured the relative humidity of the air and turned mechanical equipment on or off to maintain a constant RH. Although that remains commion practice, increasingly the indoor air dew point temperature is being used to control systems, because it provides a more certain control of absolute humidity rather than the—well—relative control that depends on the always changing indoor air temperature.

The article explains some of the reasons and the benefits of controlling humidity based on dew point rather than RH.

The excerpt from ASHRAE Standard 62.1 (Ventilation and Indoor Air Quality) shows that ASHRAE standards have required humidity control based on dew point temperature since 2016.