1. Who let the Cold out? Chris Christensen & Michael Davis

2. The Background: –As students we live in somewhat less than new living accommodations. The windows are single paned and a noticeable amount of heat is lost through windows.

3. The Question: –Just how much heat is lost through the windows in a typical apartment at Canyon Terrace? –How much does that loss cost? –How much could be saved given a more efficient window situation?

4. Analysis: –We needed to find a few bits of data. Window Dimensions Pane thickness 2mm Width.8636 m Height 2.388 m Number of windows In each apartment 4 The total heat loss through the window will be calculated using A thermal circuit and the following assumptions: - Steady-state conditions - One-dimensional heat transfer - Constant properties - Negligible radiation effects - Air between glass is stagnant

5. L1 Air T∞,i = 25˚C hi = 5 W/m^2K Glass Air T∞,o = 5˚C ho = 25 W/m^2K Diagram of thermal circuit and calculations For a single pane: q = → q = =170.24 W

6. Diagram of thermal circuit and calculations For a double pane: q = = L1 L2 Air T∞,i = 25˚C hi = 5 W/m^2K Glass Air T∞,o = 5˚C ho = 25 W/m^2K = 49.2 W

7. Results: –Single pane window: q= 170.24 W –Double paned window: q= 49.2 W –Double paned w/ C0 2: q= 40.6 W At a rate of: –$9.43 per person every two weeks w/ single pane –Savings with double paned: 71% or $6.70, leaving $2.73 per person! –Savings with double paned w/ C0 2 : 76.2% or $7.18, leaving $2.25 per person!

8. Conclusions: Though there would be some cost associated, the loss in energy due to the inefficient windows that are currently used at Canyon Terrace would more than pay for the replacement of new double paned windows. Recommendations: The analysis on CO 2 was only to see if there might be any other neutral gas that might replace the gap between the panes for a more effective window. Though the analysis showed that it would be more effective, it is not much more. Therefore, our recommendation is that the replacement is well worth the cost to do so. The more realistic gas to insulate the window would be air.