Solar space heating units tend to be less expensive than solar water heating units because
A) solar heating units can be passive and water heating units must be active.
B) it takes longer to heat air than water.
C) air has a lower density and is usually less expensive to move than water.
D) solar space heating units can be used only near the equator.
Question 2
Solar thermal systems would be inexpensive to build and most effective in heating
A) a cabin in Alaska in the winter.
B) a swimming pool in Arizona in the winter.
C) a home in South Dakota in the fall.
D) water in a home in Oregon in the spring.