Tech Directions - December 2008 - (Page 20)

THINK GREEN Teach Students Smart Ways to Reduce Home Energy Use By Harry T. Roman htroman49@aol.com E NERGY conservation and reducing heat loss in buildings is a very powerful way to lower energy costs. Sometimes great savings can be realized with simple measures. This subject provides a great vehicle for teaching science content that is very relevant to everyone’s daily life—and ﬁnancial well-being. The Principles Involved I have found from my years of engineering experience that three simple rules will help with understanding how to save energy: • Heat always moves from a region of higher temperature to one of lower temperature; • Hot air rises; and, • Heat loss from a building depends greatly on the outside surface area of a structure. Let’s take the example of a sunroom, a room with lots of windows that generally faces south. During the day, sunlight pours into this room and warms it up, but by evening the room can grow very Harry T. Roman is an electrical engineer, inventor, writer, and strong supporter of technology education. cold because much heat escapes through the many glass windows. The remedies for this big heat loss: • Simply close the door to the sunroom after the peak sunshine hours of the day, generally around 2 P.M. • Make sure the windows are double pane or have heavy curtains that can be drawn over them to act as insulation. Insulation acts a barrier to heat ﬂow. An uninsulated sunroom or one with single-pane glass is just a conduit for costly heat to move from the warm interior of the home to the cooler outdoors. In fact, you can easily feel a draft in a house as warm air starts moving toward the sunroom and then out its windows. Engineers call this movement of air a temperature gradient. Anytime you can block a temperature gradient from moving, you will save energy. That draft will cost big dollars over a heating season. Each room of a house acts like a miniature sunroom, as heat ﬂows from the warm interior of the room, and the house, and naturally mi- grates via the temperature gradient to the nearest windows. The same strategy for saving heat in the sunroom applies to other rooms as well. Again, good, wellinsulated windows are important, as are curtains that can block the passage of heat. And closing doors in isolated parts of the house provides an easy step toward saving energy. Shape Makes a Difference Irregularly shaped houses, with large exposed surface areas, present a challenge when trying to prevent heat loss. Simple and symmetrical two-story homes are somewhat easier to save heat in than single-family, rambling ranch homes. The two-story home beneﬁts from the fact that heat rises, so some of the heat from the ﬁrst ﬂoor migrates up stairwells to the second ﬂoor. This “hot air rises” fact also makes it necessary to insulate attics and crawl spaces above the living area so heat will not excessively leak to them, then out through the roof of the house. The efﬁciency of heating a home and preventing heat loss has much to do with what energy engineers call the surface-to-volume ratio. A home with a large surface-to-volume ratio will be a hard home to heat and in which to prevent heat loss. In new 20 techdirections ◆ DECEMBER 2008

Table of Contents Feed for the Digital Edition of Tech Directions - December 2008

Tech Directions - December 2008 Contents Advertisers Index Technically Speaking Direct from Washington The Report Technology Today Technology’s Past Mastering Computers Digital Portfolios—Powerful Marketing Tool for Communication Students Choosing the Right CC Welding Unit—Student Success Depends on It Think Green—Increasing Awareness of Garbage and Recycling Think Green—Teach Students Smart Ways to Reduce Home Energy Use Go International! Build a Simplified Shortwave Receiver Mooresville Middle School Snags Web Site of the Month Gifts for Geeks More than Fun

Tech Directions - December 2008

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