Old and drafty homes are so romantic – until you see the heating bill. One of our recent jobs on a particularly old house (we think it was built in the early 1900’s) is a perfect example of this. The house was so drafty the clients complained that they could hear the wind and traffic noise from outside very clearly. We suspected that outside air was seeping into the house through the walls, windows and doors. So, first we performed a blower door test to check the air infiltration throughout the house. To do this, a large fan sucked air out of the house to lower the inner air pressure, and then we could observe where exterior air was able to seep back in. What did we find? In short, the house ‘sucked’; with the exception of the attic there was no insulation in the entire house!
We began the renovation by filling the interior cavity of the exterior walls with densely packed recycled cellulose. (Where do you think all your Boston Globes end up?) The immediate observable result was that the house was much quieter and actually cooler during the hot summer day (it was summertime). And this was just the beginning! After the insulation was in place we re ran the blower door test again with much better results.
The rest of the project took a standard path: we installed rigid insulation, a drainage plane, and fiber cement siding on the exterior of the house. We used PVC trim boards, which added to the durability of the exterior and greatly extended the life-cycle of the paint job. We chose to replace eight windows that were leaking significant amounts of air. (The spring operated windows that are used in new construction and replacements today create a tighter seal than the sash weight style of previous generations.)
We also greatly improved the curb appeal of the home by tearing off the cracked front concrete porch and installing a beautiful mahogany porch along the entire front of the house. The new porch has mahogany rails, a front stair, and bead-board ceiling. We even included structure for a porch swing.
After the project was completed we performed a third blower door test and sent our results out to model the return on investment (ROI). We found that the ROI on the cellulose installation was a little over 3 years. The additional rigid exterior insulation gave us an additional 10% performance value. We excluded the cost of the new siding because the original siding (being almost 100 years old) was long past needing to be replaced, and the cost of painting it would have far exceeded the cost of re-siding. While I do not usually promote replacing windows as a first round source for energy savings (they have a 22 year ROI) I did feel that it was necessary to replace the sash weighs in order to reduce the volume of air leaking in. Even with the window ROI numbers, the total ROI on the insulation part of the project was just over 5 years. Plus, the client told us that the furnace comes on much less frequently than before which should extend it’s life. And that’s not to mention the comfort of a quiet, draft free home. This project is a prime example of the cost effectiveness of energy savings and building for durability.
Related Project: Evergreen
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