Home Energy Conservation Exercise

Journal of Geoscience Education, Nov 2003 by Frey, Steven T, Moomaw, William R, Halstead, Judith A, Robinson, Caitlin W, Et al

In order to help them decide which modifications their company will recommend, we provide students with a list of information concerning the possible energy-conserving upgrades that can be made to a home (see Table 2). We also supply students with a list of building material costs (including installation) and R-values (see Table 3). We generated this list by visiting our local hardware store and consulting web resources such ad http://www.get-a-quote.net and http://www. ornl.gov. Finally, we provide a Material Budget Form (see Figure 3) for students to complete with information regarding the modifications they choose and their costs.

For some students, the multiple step calculations in this exercise can be somewhat daunting. To help guide them and reduce their anxiety we provide them with a worksheet for completing the calculations (see Figure 4) and a step-by-step strategy (see Table 4). When they have completed the calculations, we ask students to answer a set of questions (see Table 5) prior to handing in the Materials Budget Form and Calculation Worksheet.

CONCLUSIONS

Most student teams calculate a monthly energy savings on the order of 20 million btu as a result of the modifications that they choose, reducing total heat loss by approximately two thirds. This corresponds to a cost savings of $180 to $200 per heating month (with oil heat). We have found that the competitive nature of the exercise (teams competing against one another to produce the greatest savings in energy and cost) inspires the students to examine the various components of the house carefully and run a number of test calculations prior to deciding on a final set of modifications. During this process, students develop a familiarity with the mathematical equations that are involved in the exercise and begin to recognize patterns and think on a quantitative level. In the end, they develop a very good quantitative sense of the thermal efficiencies of various building materials and excellent strategies for preventing home heat loss. Moreover, they are confronted with the staggering amounts of energy and money that are wasted in heating the un-insulated home.

It is important for students to recognize that there are financial and logistic limitations with respect to incorporating energy efficient technologies and materials into pre-existing homes. We point this out to our students and emphasize the fact that there are other effective design elements that can be utilized in new home construction such as super-insulation (see www2.srp.gov./homeenergymanager/advisor/superin sul.html) and solar heat gain (see www.eren.doe.gov).

We recognize that the repetitive nature of the calculations in this exercise lend themselves to the use of a spreadsheet. In fact, we offer our students the opportunity for extra credit if they wish to copy their worksheet and incorporate it into spreadsheet format. However, due to the time constraint of our laboratory period (teaching students the use of a spreadsheet would require a significant amount of time) and the esoteric nature of spreadsheet calculations, we have not made this a general requirement of the assignment. Instead, we befieve that working through the calculations by hand gives students a better perspective of the types and sources of heat loss and their magnitudes. In addition, by using a standard worksheet, we are better able to assist the students during the course of the exercise. Instructors adopting this exercise may wish to have their students do a few calculations by hand using the worksheet in Figure 4, and then transfer their work to a spreadsheet to complete the calculations.