The week has continued with sealing joints and taking blower door test points. Progress has been steady and it should just be a few more days until interior sealing is complete.
We also took some pictures with a thermal imaging camera to see temperature differences on the walls and roof.
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Below are the updated blower door test plots. So far we have reduced the infiltration by 800 cfm using ~60 tubes of caulk, taking just under 12 hours of labor. So, what is the significance of that 800 cfm reduction at 50Pa? Well, converted to more typical conditions it is an average of about 40 cfm air infiltration eliminated. That’s 40 cfm of uncontrolled, unconditioned air entering your home, forcing 40 cfm of conditioned air out. That 40 cfm of conditioned air is air for which you paid money and consumed energy to condition.
What is the economic and energy impact? Well, the 60 tubes of caulk at $4/tube is $240 and the 12 hours of labor at $20/hr is another $240. That’s a cost of $480 to drop the air infiltration by 40cfm. Uncontrolled air infiltration of 40cfm equates to a thermal energy impact on the house of ~1800kWh per year. Assuming an average COP of 2 for the heat pump to condition this 1800kWh load, would mean 900kWh of actual electricity would be used. At $0.12/kWh the 40cfm costs $108 worth of electricity per year. Bottom line, the extra cost to better seal the house will take less than 5 years to pay back. This is an improvement that goes with the lifetime of the house; a hundred years or more. There really is no excuse or reason for not having a well sealed home. You can put your money into improving efficiency by way of extra LOCAL material and labor (jobs) or EXPORT it to energy companies (few jobs).
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For the most part the seams being sealed look like the picture on the left, but in a few places you can see light through the cracks. The right picture shows a gap by a door. While each seam is being sealed no matter the appearance, thermal imaging is useful to see if there are any correlations between the type of seam and how leaky it might be. Chad Bowers from Creative Thermal Solutions, a company similar to ours helped us take infrared pictures of the house with their IR camera.
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Lately the weather has been fairly decent, which doesn’t really affect the interior work we are doing, but it is beneficial from a solar production standpoint. The solar system has been active for about 2 weeks now. Below are the daily solar and total cumulative solar produced each day.
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Here is the total cumulative solar production. The difference between the blue and red points is the amount of energy used for things such as running the blower door tests and using tools and lights. Total about 450kWh of electricity has been produced. That is enough to drive an electric car 2,250 miles; from Urbana to Los Angeles!
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In addition to the sealing work in the house, an electrician is running the interior electrical wiring. Interior layouts and finish are in the selection process. We will be measuring for the metal roof and exterior siding and getting that on order soon.
