Experiment #11 from Middle School Science with Vernier
Alternative energy sources are energy sources other than the nonrenewable fossil fuels—coal, petroleum, and natural gas. Solar energy, or energy from the sun, is one energy source alternative. A passive solar heating system uses no pumps, fans, or mechanical devices. Insulation and heat storage are important factors in such a system. A thermal mass is a material that absorbs and stores heat. Thermal masses can keep a home from heating or cooling too fast.