Introduction
Students will explore the differences between passive and active solar energy and conduct experiments demonstrating how thermal energy from the Sun can be efficiently harnessed and transferred. By studying thermal transfer, students will learn how passive solar design can help meet energy needs and improve energy efficiency.
Student Objectives
- Explore the difference between passive and active solar energy.
- Test and collect data on two different solar-heating models.
- Discuss real-world building and design cost-benefits.
Materials
For Solar Experiments: (for each group of 3-4 students)
- Shoebox or other cardboard container
- Black construction paper
- Clear plastic wrap or sheet protector
- Tape
- Small black cup or aluminum can
- Room temperature water
- Straw
- Probe thermometer
- Direct sunlight or a heat lamp
- Stopwatch or timer
- Flinn Scientific Kit (optional): Complete lab kit available here: Solar Ovens Kit
Procedure
Step 1: Introduction
Provide students with the Reading Activity and Investigation Instructions handout and have them work in pairs to read the “A Solar-Powered Bake-Off” story then answer the reflection questions. Have students share their answers and ask questions in a class discussion on passive vs. active solar energy. Alternatively, the teacher could read the story to the class and conduct a whole-class discussion on the reflection questions.
Step 2: Experiments
Divide the class into groups of 2-3 and have students follow the instructions on the lab sheet to conduct the passive vs. active solar energy experiments.
Step 3: Class Discussion
After completing the experiments and drawing conclusions, engage students in a class discussion, making real-world connections with the following discussion questions and features table:
- How are passive and active solar energy used to heat and cool real buildings?
- What are the cost-benefits of each?
- How could passive solar designs help in sustainable architecture?
- Where would each method be more effective (e.g. hot vs. cold climates)?
Passive and Active Solar Energy Features Table
| Feature | Passive Solar Energy | Active Solar Energy |
|---|---|---|
| Mechanical energy needed? | No | Yes |
| Energy collected? | Absorbed and stored | Uses mechanical devices to transfer energy |
| Example | Greenhouses, sunrooms | Solar water heaters, solar panels |
| Cost? | Cheaper (few materials) | More expensive (equipment required) |
| Maintenance? | Low (once built) | Higher (requires upkeep) |
Step 4: Extension Ideas
Have students modify the designs to improve heat absorption, and/or test with different materials (foil lining, different colors, etc.)
Active and Passive Solar Lab Answer Key
The Student Guide contains the Active and Passive Solar Lab – Student questions.
Reflection Questions Answer Key:
Question 1: (Example response): Mia used a passive solar method, letting the Sun’s heat naturally warm up her cookies inside a plastic-covered box. Jake used an active solar method, which included extra tools (mirrors and a fan) to make the cookies bake faster.
Question 2: (Example response): Mia’s method took longer because it didn’t use any devices to speed up the heating. The Sun’s energy had to slowly heat up the inside of her box, and the heat stayed mostly in one place.
Question 3: (Example response): Jake used reflective mirrors to focus even more sunlight on his cookies and a solar-powered fan to blow the warm air around. This made the oven warm up faster and spread the heat evenly.
Question 4: Answers will vary.
Hypothesis
(Example response): I think the active solar model will result in the greatest temperature change because the straw will help move the air like a fan and spread the heat more evenly inside the box.
Conclusion
Question 1: (Example response): The active solar method had the biggest temperature change. The water in the cup heated up more in the active setup than in the passive one.
Question 2: Answers will vary.