Moisture In The Home

Many seemingly innocent sources create significant water vapor in homes. Note from the table that building materials emit 40 quarts per day of moisture into a home the first year after the home is built. An unvented gas range contributes more to indoor moisture load than showering and bathing.

Try to create a list of common household moisture sources, and then rank them for importance. Take into consideration the following list of moisture sources:

  • Running an unvented kerosene or gas fired space heater — each gallon of fuel burned creates about 7.5 pints of water vapor.

  • Cooking a gas range without using a ducted range hood (to the exterior) — each burner produces between 1 and 2 pints per hour.

  • Storing firewood indoors — a cord of green firewood creates about 3.5 pints of water per day.

  • Air drying clothes inside — each load of wash creates about 5 pints of water during drying.

  • Showering — a 10-minute shower creates about 1 pint of water.

  • Cooking without pot lids — about 1/6 pint per person per meal.

  • Washing floors — about 4 pints per room.

  • Watering plants — all the water is poured into house plants eventually evaporates into the room.

  • Pets — pets, and people, create about 1 pint of water per 50 lbs of body weight per day.

  • Hand washing dishes, including rinsing — about 1/3 pint per person per meal.

  • Faucet aerators — 0.02 pints per minute.

[

Common Household Moisture Sources1

su_table]

Moisture source

 

Estimated amount
(pints)

Bathing

 

0.12/standard
size bath

shower (excludes
towels and spillage)

 

.52/5-minute
shower

Clothes washing
(automatic, lid closed, standpipe discharge)

 

0+/load
(usually nil)

 

[/su_table]

 

Bathing

su_table]

Clothes drying

 

vented outdoor

0+/load
(usually nil)

 

not vented outdoors,
or indoor line drying

 

4.68 to 6.18/load
(more if gas dryer)

 

Combustion
(unvented kerosene space heater)

 

7.6/gallon of
kerosene burned

 

[/su_table]

 

Clothes drying

vented outdoors ………………………………………………………………………..0+/load (usually nil)

not vented outdoors, or indoor line drying ………………………………….4.68 to 6.18/load (more if gas dryer)

Combustion (unvented kerosene space heater) …………………………..7.6/gallon of kerosene burned

Cooking

breakfast (family of four, average) ……………………………………………….0.35 (plus 0.58 if cooking with gas)

lunch (family of four, average) …………………………………………………….0.53 (plus 0.68 if cooking with gas)

dinner (family of four, average) ……………………………………………………1.22 (plus 1.58 if cooking with gas)

simmer at 203°F, 10 minutes, 6-inch pan ………………………………………less than 0.01 if covered, 0.13 if uncovered

boil 10 minutes, 6-inch pan ………………………………………………………….0.48 if covered, 0.57 if uncovered

Dishwashing

breakfast (family of four, average) ………………………………………………..0.21

lunch (family of four, average) ……………………………………………………..0.16

dinner (family of four, average) …………………………………………………….0.68

Firewood storage indoors (cord of green firewood) ………………………400 to 800/6 months

Floor mopping …………………………………………………………………………….0.03/square foot

Gas range pilot light (each) ………………………………………………………….0.37 or less/day

House plants (five to seven average plants) …………………………………0.86 to 0.96/day

Humidifiers …………………………………………………………………………………0 to 120+/day (2.08 average/hour)

Respiration and perspiration (family of four, average) ………………….0.44/hour (family of four, average)

Refrigerator defrost …………………………………………………………………….1 .03/day (average)

Saunas, steambaths, and whirlpools ……………………………………………0 to 2.7+/hour

Combustion exhaust gas backdrafting or spillage ………………………..0 to 6,720+/year

Evaporation from building materials

seasonal ……………………………………………………………………………………..6.33 to 16.91/average day

new construction …………………………………………………………………………10+/average day

Ground moisture migration ………………………………………………………….0 to 105/day

Seasonal high outdoor humidity …………………………………………………..64 to 249+/day

 

1Minnesota Extension Service, University of Minnesota. Adapted from Home Moisture Problems, by the Minnesota Department of Public Service; and Moisture and Home Energy Conservation, by the National Center for Appropriate Technology. Prepared with the support of the U.S. Department of Energy.

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