IT'S NOT THE HEAT!
IT'S THE HUMIDITY!

GOAL:
The student will understand the adverse effects of excess humidity and will recognize the importance of humidity control in the home.

OBJECTIVES:
The student will be able to:

1. Define humidity and explain its relationship to heat.

2. Describe the adverse effects of improper humidity levels.

3. List ways of controlling humidity in the home.

LESSON/INFORMATION:
Humidity refers to the amount of moisture in the air. Warm air is capable of holding much more moisture than cool air.

Relative humidity refers to the amount of moisture air holds in relation to the amount it could possibly hold at a given temperature. When the air reaches dew point, it is said to be saturated. This is when relative humidity reaches 100% and condensation occurs. Condensation shows up as small droplets of water. It forms on surfaces in the home that are cooler than air temperature. An outside example is dew on the grass in the morning.

Humidity is a major factor in Louisiana's weather and comfort level for several reasons:
1. As air is heated, it expands and has the ability to hold more moisture.

2. Moisture available from high rainfall and abundant natural water sources provide water vapor.

3. This mixture of heat and moisture results in an uncomfortably high humidity level for much of the year.

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Excess humidity in the home needs to be controlled. This is a problem especially in the summer months. Not only is excess humidity uncomfortable, but it also adds to the air conditioning load.

Excess humidity in the home can lead to odors, dampness, mold and mildew, fogged or sweating windows, and the decay of building materials.

Excess humidity in the home comes from two basic sources:
1. Infiltration of humid outside air.

2. Sources of humidity in the home.

ACTIVITY 1:
List ways that moist outside air leaks into your home.
____________________________________________

____________________________________________

____________________________________________

Some preventative moisture infiltration recommendations include:
- Use weatherstripping or caulking around doors and windows.
- Seal any other areas with joints or cracks that could allow air leaks.
- Limit trips in and out of the house in very humid weather.
- Reduce excess water around the home by eliminating areas where water can collect.
- Use vegetation to provide windbreaks.

What are some ways that excess moisture is produced in the home? The main problems result from moisture produced while bathing, cooking, and clothes drying. Warm, humid air can also collect in areas of the house that are not air conditioned. Use exhaust fans when cooking and taking a shower.

ACTIVITY 2:
Following is a list of items and habits that help keep moisture in the home at an acceptable level. Check off the good habits that you practice.

_____ I have and use a bathroom exhaust fan.

_____ I do not have a bathroom exhaust fan so I put a crack in the window when taking a bath or shower.

_____ I have and use an exhaust fan over the range.

_____ I cook with tight-fitting lids to retain moisture.

_____ I only use the dishwasher for full loads.

_____ I only use the dishwasher on the short wash/cool dry cycle.

_____ I have an exhaust vent on the clothes dryer that brings hot, moist air outside the home.

_____ I dry clothes outside on a clothesline when possible.

_____ I try to maintain good circulation throughout the house.

_____ I try to maintain good circulation in unconditioned areas of the house.

In addition to the above, another option is to use a dehumidifier that removes moisture by cooling air. The moisture condenses and drips into a collection pan. The dry air is then pushed back into the room. However, the returning air will be warmer.

By following some of the above practices, humidity in the house can be reduced. As less humidity means less heat retained, the air conditioning unit will not have to work as hard to cool and dehumidify the home.

Although it seldom happens in Louisiana, some families may have a problem with reduced humidity levels in the home during the winter months. Some types of heating systems overdry the air. This can cause discomfort. Moisture may be added to the air in the winter months by using a humidifier.

It is difficult to obtain the optimum humidity level in a home. The suggested level is about 45% relative humidity. At this percentage, occupants feel comfortable and most moisture problems can be avoided.

As it is difficult to determine the humidity level in the home, here is a list of guidelines that can help occupants know when there is too much or too little moisture in the home:
-- Too Much Moisture --
1. Skin feels damp or clammy.
2. Upholstery, walls, etc. feel damp.
3. Odors increase.
4. Odors may signal rot or mildew.
5. Wood may show signs of moisture damage.
6. Windows may fog on the outside.

-- Too Little Moisture --
1. Skin feels dry and itchy.
2. Surfaces, such as wood, may dry and crack.
3. Air that is too dry will not retain heat; thus it will feel cooler in the home.

RESOURCES:
Affordable Comfort - Louisiana Style: An Energy Savings Guide for Senior Citizens. Louisiana Department of Natural Resources, Baton Rouge, LA, n.d.

Moisture and Home Energy Conservation: How to Detect, Solve and Avoid Related Problems, U.S. Department of Energy, DOE/CE/15095-4, 1983.

INFORMATION CHECK
Choose the word or phrase that best completes the statement.

_____1. Humidity is
a. the same percentage as that for rain probability.
b. the air temperature plus water temperature.
c. the amount of moisture the air can hold.
d. the amount of heat the air can hold.

_____2. Humidity is a problem in Louisiana because of
a. high temperatures
b. abundant water
c. hard rains
d. a and b

_____3. Some of the excess humidity in the home comes from
a. infiltration from outside air
b. moisture vented out through the roof of the home
c. no air circulation in the home
d. a and b

_____4. High humidity inside the home (in Louisiana) will have the greatest adverse effect on the
a. heating system
b. water heater
c. air conditioner
d. none of the above

_____5. Other problems associated with high humidity include all of the following, except
a. odors
b. mold and mildew
c. drying of building materials
d. dampness

_____6. Moisture produced in the home comes from all of the following areas, except
a. bathroom steam
b. cooking steam
c. heated air
d. dryer exhaust

_____7. Bathroom, kitchen, and laundry exhaust fans should
a. not be used
b. be used only on cold days
c. be used to dispel humidity from inside the home
d. b and c

_____8. This removes moisture from air by cooling the air.
a. humidifier
b. vaporizer
c. dehumidifier
d. b and c

_____9. _____ is important in humidity control.
a. air circulation
b. exhaust fans
c. air conditioner
d. all of the above

_____10. Less humidity means less _____.
a. heat in the home
b. dampness in the air
c. air conditioning needed
d. all of the above

TEACHER'S NOTES
ACTIVITY 1:
Look for answers such as:
- Cracks around windows and doors.
- Cracks at wall or ceiling joints.
- Excess opening of doors and windows.
- Open exhaust or fireplace dampers.

ACTIVITY 2:
Student should check off the habits that he practices. This may lead to a discussion of how each of these habits does indeed reduce moisture levels inside the home.

DEFINITIONS:
1. Dehumidifier -
This is a machine that removes moisture from the air by cooling the air, causing the moisture to condense into water, and then collecting the excess water. Dryer and warmer air is then re-circulated into the room, and the collected water must be disposed of.

2. Relationship between heat and humidity -
The warmer the air, the more moisture it can hold. This is why cool air seldom feels damp. It cannot hold as much moisture as warm air.

3. Water vapor -
Water that has been evaporated and remains as small water molecules in the air. Excess water vapor or moisture is what causes high humidity.

ANSWERS TO INFORMATION CHECK:
1. c
2. d
3. a
4. c
5. b
6. c
7. c
8. c
9. d
10. d

Comments or questions to: TechAsmt@LA.GOV

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