What is the recommended humidity level for a house in Colorado when the inside temperature is 72 degrees?

You'll need a hygrometer (which measures relative humidity and is available at most hardware and home stores). The following list, supplied by the Minnesota Department of Public Service, is based on a double-glazed window and an indoor temperature of 70 degrees. You will notice that the lower the outdoor temperature, the lower the indoor humidity should be.

If outside temperature is 20 to 40 degrees, humidity indoors should not be more than 40 percent. If outside temperature is 10 to 20 degrees, humidity indoors should not be more than 35 percent. If outside temperature is 0 to 10 degrees, humidity indoors should not be more than 30 percent.

If outside temperature is 10-below to 0, humidity indoors should not be more than 25 percent. If outside temperature is 20-below to 10-below, humidity indoors should not be more than 20 percent. If outdoor temperature is lower than 20-below, inside humidity should not be more than 15 percent.

If you are building a home or remodeling, demand high-quality windows. They should have U-values of 0.35 or less. Such windows are less prone to cold-weather condensation and icing, which means that indoor humidity can be higher.