The Attic Insulation Problem

This is a project started as an undergraduate research project involving Paul Martin of UW_Marathon County and two more students. It was eventually extended to a professional setting and published in a premier peer-reviewed journal by Paul and me. As an undergraduate project it was also presented at the Posters in the Rotunda event. Click here to see publication. This project originated fifteen years ago with the purchase of a home in Wisconsin and an effort to reduce the heating bill. One of the easiest places to slow the rate of heat loss from a house is through the ceiling into the attic space. It makes sense that adding more insulation will keep reducing the loss of heat. However, once the heat flux is fairly small, the marginal savings fails to offset the cost of additional insulation. The project we describe addresses these savings and costs by modeling the heat loss and developing a net savings function in terms of the depth of added insulation. Analysis of this savings function provides the optimal depth of insulation to add and the expected savings. Extensions of the basic project include accounting for air conditioning costs and also using present value accounting of future savings.