This comprehensive reference was developed under ASHRAE research project 1047, and intended for "the designer who has to get it done by Friday." It covers the full range of dehumidification issues in commercial buildings, including load calculations, equipment alternatives (both desiccant and mechanical dehumidifiers), humidity sensors, controls and specific suggestions by type of building.

This article discusses, in general terms, how to go about keeping humidity under control in commercial buildings. The information is not specific to desiccant systems. It describes the mechanisms of common moisture-related problems in buildings, along with suggestions on how to avoid such difficulties.

The largest single load in any dehumidification system is excess moisture carried by the ventilation air. This article quantifies the annual ventilation dehumidification loads for 237 locations in the United States, and advocates the use of a new metric called the VLI, or Ventilation Load Index, to quantify and compare annual loads in different locations. The article received the ASHRAE "Best Journal Paper" award for 1997.

After ventilation, the second largest moisture load in most buildings is air infiltration. There is a common misperception that buildings built in recent years are more air-tight than in the past. This article shows measured values from a wide variety of commercial buildings, demonstrating beyond any doubt the magnitude and nature of the infiltration load.

In commercial buildings, the areas above dropped ceilings and other building cavities are often used as air ducts. Also, most commercial duct work is unsealed. Unsealed ducts and building cavities usually leak air in very large amounts, generating internal suction and increasing outdoor air infiltration. This paper explains and quantifies the problem, and provides suggestions to limit the moisture load it generates.

In many cases, a building owner's interest in dehumidification is prompted by some sort of moisture problem in the building envelope. Such problems are not always caused by a lack of dehumidification capacity. Often, air flows into building cavities and condenses on cold surfaces such as supply air duct work and chilled water piping. The HVAC designer can do a great deal to prevent such problems, as explained in clear terms by this article.

Some moisture problems in buildings can be solved with better dehumidification and better sealing of duct work. Others require a comprehensive understanding of the building envelope. This down-to-earth and entertaining article describes the most common moisture-related problems in buildings, why they occur, how to find them and what can be done to avoid them.