Exam 3 Essays (33 points)
Please save a copy of this document and type your answers beneath each question. Keep
the present format. Resave and rename the file with your last name at the beginning of
the filename (i.e., Smith Exam 3 Essays), and submit it as an attachment to the dropbox.
1. What are 6 things you could do personally to contribute to more efficient water
use? (3 points)
ANS: I will not wash my clothes everyday; I will wait for a week to wash my clothes. I
will take a quick shower instead of taking a bath. When I washing the vegetables, I will
not keep turning the faucet on, I will just save a bowl of water to wash them. After
washing the vegetables, I can use that water to irrigate my plants, and it can reuse water. I
will close the faucets when I am washing my face. Also, I will use as less as dishes to do
cooking, because it can save water to not wash that many dishes.
2. Compare and contrast active and passive solar energy. Consider factors such as
energy efficiency, cost, and other factors. What purposes and conditions are they
each best utilized?
ANS: A passive solar energy is about absorbing and restoring the energy directly, and the
energy efficient is the house faces direct to the sun and get the solar energy. Walls, floors
of concrete, adobe, brick, stone, and salt- treated timber, and water in metal or plastic can
store much energy to supply the heat during a day. Usually, with a good design of passive
solar system, it should be the cheapest way to apply heat for a house, for example, this
system costs extra 5-10 % to the construction cost, but the life-cycle cost of operating
such a house is 30-40 % lower, so it will pay back for the construction cost and save our
resources. There are some disadvantages of using passive solar energy, if the building or
house is blocking by trees and could not get the solar energy, then this system is not
working for it. An active energy is about absorbing the solar energy from the sun by
pumping a heat- absorbing fluid through a special collector which put on the roof to face
the sun to get energy. Some of the heat can be used directly, or it can be stored and we
can use it when we use it, also an active solar collector can supply hot water too. Same
with the passive solar heating system, the active one is also need to work in the sunny
areas, if not they could not work. Although it is a very good way to heat water by the
active solar heating system, but it costs a lot to do that, and it is hard to maintain the
requirements, and the unappealing appearance.