Notes how the interior relative humidity in houses during winter affects the well-being and health of the occupants. Describes a model developed to predict the average steady-state winter interior relative humidity in dwellings. Defines all required input variables and outlines methods for their quantification. A method for estimating the occupant moisture generation value other than the generic 'family of four' value has been created as pat of the model. Also, the ASHRAE equation for calculating the humidifier moisture load in dwellings has been enhanced by providing a table and a curve-fit equation for finding the monthly outside absolute humidity for more than 300 sites in the USA. In addition to the complete 'equation form' models, nomographs have been created for relative humidity prediction and load calculation, which provide a very convenient, yet accurate, method of solution.

KEYWORDS: Housing, USA, relative humidity, winter, humidity, calculating, models, absolute humidity, nomographs