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close this bookAppropriate Community Technology - A Training Manual (Peace Corps; 1982; 685 pages)
View the documentThe Farallones Institute Rural Center
View the documentCHP International, INC.
View the documentPreface
View the documentAcknowledgments
View the documentIntroduction
Open this folder and view contentsPhase I: Introduction to training
Open this folder and view contentsPhase II: Earthen construction and fuel-saving cookstoves
Open this folder and view contentsPhase III: Pedal/treadle power
close this folderPhase IV: Solar water heaters
View the documentPhase IV Calendar
View the documentSession 1. The role of the volunteer in development: international development part 2: the green revolution: successes and failures
View the documentSession 2. Introduction to solar water heaters
View the documentSession 3. Assessing community water needs and uses
View the documentSession 4. Introduction to solar water heating: determining hot water demand
View the documentSession 5. Plumbing a solar water heater
View the documentSession 6. Sizing a solar water heater
View the documentSession 7. Demonstrating a technical concept
View the documentSession 8. Shade mapping and solar siting
View the documentSession 9. Design of solar water heaters.
View the documentSession 10. Construction of solar water heaters
View the documentSession 11. Multi-media standard first aid
View the documentSession 12. Wind technology
View the documentSession 13. Volunteer in development part 2: women in development
View the documentSession 14. House design in four climates
View the documentSession 15. Presentation of solar water heaters
Open this folder and view contentsPhase V: Solar agricultural dryers
Open this folder and view contentsPhase VI: Concluding the program: The energy fair
Open this folder and view contentsAppendices

Session 4. Introduction to solar water heating: determining hot water demand

Total time:

2 hours


* To collect and calculate data regarding estimated levels of daily hot water use


* To compare different levels of hot water use in the United States to probable hot water consumption and needs in host countries


* To discuss the possible uses of solar-heated water in host countries


* Attachment IV-4-A, "Hot Water Volume and Temperature Data Collection Sheet"


* Design Criteria list from Session 2


Hot water source and for each group: 1 liter calibrated metric containers, large (8 liter or 2 gallon) wash basins, Celsius thermometers, newsprint and felt-tip pens

Trainer Notes

You may want to select one or two participants to assist as co-facilitators for this session. If so, review the session procedures with them and plan their involvement. Their involvement might include: gathering and distributing materials, facilitation of discussions and assisting the other participants with calculations. If this option is followed, set aside time after the session for feedback on their facilitation skills.


Step 1. (10 minutes)
Post the session objectives and briefly outline the activities.

Step 2. (10 minutes)
Have participants review the list of design criteria for solar hot water devices developed during Session 2.

Trainer Notes

Try to generate new ideas for additions or modifications to the list.

It is important that the criteria list include: inlet temperature, insolation rate, percent possible sunshine and efficiencies and volumes.

Step 3. (5 minutes)
Note the criteria that are related to water temperature, volume, use and the kind of consumer and explain that the session's activities will focus on these areas.

Step 4. (5 minutes)
List three categories of consumers: heavy, light and low (or non-users).

Trainer Notes

Ask for examples in each category:

* Heavy: industrial use, convenience-oriented urban family
* Light: conservation-minded family, etc.
* Low: poor rural family, backpacking, etc.

Point out that there will be overlap in each category.

Step 5. (5 minutes)
Distribute Attachment IV-4-A, "Hot Water Volume Temperature Data Collection Sheet." Explain the data collection activity and have participants form work groups of 2 or 3.

Trainer Notes

* Explain that each work group will select a consumer type from one of the categories listed and collect data on the estimated amount of hot water used per day by the hypothetical user.

* Data should be collected in at least three areas (e.g., hand washing, dishwashing, bathing, etc.). Post the instructions to help clarify the activity.

* Questions about the data collection procedure will probably arise (e.g., "Do we have to take a shower and collect the water?"). Explain that where possible, people should collect the water as it is used. If it is not feasible, as in the case of a shower, an estimate of the water needed should be made.

* Be sure there is no confusion on how to fill out the data collection sheet.

* At this point, a co-facilitator/s may assist work groups who need clarification.

Step 6.(45 minutes)
Have work groups collect and calculate data.

Step 7. (10 minutes)
Reconvene the large group and have a representative from each work group report their findings and discuss methods used to obtain the data.

Step 8. (20 minutes)
Facilitate a discussion of water use customs and patterns in host countries as compared with the United States.

Trainer Notes

For reference during this discussion, post the following information about average consumption of hot water in the U. S.:

* Heavy consumer: 60 - 80 liters per day
* Light or conserving consumer: 30 - 50 liters per day
* Host country person: 0 - 80 liters per day

You should provide further focus for this discussion by asking and/or and/or posting on newsprint the following questions:

* How do water consumption rates and patterns in host countries compare with those of the U.S.?

* In rural villages in which there has never been hot water, will there be a need or desire for hot water?

* What are some specific, potential uses for solar water heating devices in host countries?

Step 9. (10 minutes)
Explain that the information presented and ideas generated during this session will be used in conjunction with the data on insolation and climate to develop a sizing formula for use in the design of solar devices.

Explain that the information and ideas will also apply to the selection and design of solar-heated devices during this training program.


Step 1:
Fill out the following chart for one person's daily hot water use, recording the actual volume and temperature data where you can ant estimating where you need to do so. Decide among the group whether your measurements and estimates are for a non-conserving person, a conserving person, a city-dweller, a rural person, a camper, etc.

Hot Water

Volume Per Day (Liters)/Day

Temperature (ºC)










Dish wash & rinse


Sponge bath




Clothes wash & rinse










Step 2:
Decide how many people are in your hypothetical family of conservers, non-conservers, campers, etc. Multiply the total average volume Per person per day times the number of people in the family to find out the average daily family hot water usage (given in liters per day):

Total average volume per person per day

( ) Liters/Person Day

X Number of people in the family

x ( ) Persons

= Average daily family hot water use

( ) Liters/Day

NOTE: This information will be used in Session 6: Sizing a Solar Water Heater

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