1. Home Insulation By: Jeff Krise

2. Introduction Analyze the rate of heat transfer from the attic to the interior of the home. Based on summer average temperatures in the attic with the home maintained at 21°C. This is to compare insulation thicknesses and possible monetary savings based on the energy transfer rate reduction by using better insulation. Home has an area of 121 m^2 with a length of 9.14 m and with of 13.24 m.

3. Heat transfer problem Find the exterior convection coefficient based on low velocity air (2m/s) moving in attic. h=.98 w/(m^2*K). At attic Temp of 45°C. Calculate the interior convective coefficient based on free convection. h=.1078 w/(m^2*K). At home temp of 21°C. Build Thermal circuit Calculate the energy transfer based on insulation of R-30 and R-38 (both have units of m^2*K/w). Compare results

4. Solution

5. Results For R-30 insulation q=71.93 w. For R-38 insulation q=60.037 w. Total energy savings is 11.89 watts. Based on 24 hr per day of these temperatures. Over the period of one month this is approximately 8.56 Kilowatt-hours. At current energy cost of 12 cents per kilowatt-hour this equates to a savings of 1.03 dollars per month.

6. Conclusion I would not recommend spending the amount of money it would take to add the extra 4 inches of insulation to the entire attic surface area to gain this small amount of energy savings per month.