Trevor Hedman Kendall Hill

Assumptions:  Outside wall is exposed to convection due to wind.  Convection is approximated by flow over a flat plate.  Inside Wall temperature is constant at room temperature.  Radiation is neglected.

Measurements:  Outside temperature of 20 degrees F  Inside temperature of 70 degrees F  Outside wind speed of 8.8 mph used (monthly average)  The section parallel to the wind was measured to be 22’ long and 8’ high

Convection Coefficient Calculations

Thermal Circuit Analysis

Four Wall types were analyzed:  2x4 Stud wall with Stucco finish  Brick veneer wall  CMU  2x6 Stud wall with Stucco finish

1 st Wall: 2x4 Studs Composed of:  Stucco finish  Plywood sheathing  2x4 Douglas fir studs  Insulation (R-13)  Gypsum board

2 nd Wall: Brick Veneer Composed of:  Brick covering  Plywood sheathing  2x4 Studs  Insulation  Gypsum board

3 rd Wall: CMU Composed of:  Filled Cinder block  2x4 Studs  Insulation  Gypsum board

4 th Wall: 2x6 Stud Composed of:  Stucco Finish  Plywood sheathing  2x6 Studs  Insulation (R-19)  Gypsum board

Heat Transfer of each Wall BrickBatt Insulation Cork Mastic Expanded Polystyrene

Monthly Cost of each Wall

Conclusions:  2x4 Brick Wall and 2x6 stucco wall types are very similar when insulation of k=0.5 (typical batt insulation) is used  CMU wall has the highest thermal resistance for most k values and the best monthly savings. It costs more to begin with but will save you money in the long run.  At k values greater than 0.7 changing insulation type does significantly reduce heat transfer in walls. Don’t spend extra money to upgrade insulation unless the k value is less than 0.7.