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  1. Gary Kristensen
    December 6, 2017 @ 8:25 am

    A list of questions was emailed to me and I wanted readers to hear my respons:

    Thank you for all your input. There is a bunch of stuff to explore in your questions. Particularly, I too would love to do a little more exploration of the more typical older Portland home seen close in with a basement and various configurations of that. That is now on the list for a future blog post. In my recent experience, homes with basements and a level above are performing similar to two story homes if the ducts for both properties are in conditioned space. For that reason, I think the tests I ran in this blog post mostly apply. I will address a couple of your other questions as well and also point out where things might apply or might be different:

    1. Refrigerators are not included in the Home Energy Score.

    2. It is my experience that mini split ductless heat pumps do not change the score when compared to a similar efficiency forced air furnace with ducts in the conditioned space, but I have not yet tested that directly. I will put that on the list to test. What I do see is that newer mini splits are extremely efficient and difficult to beat with another type of furnace.

    3. Wood stoves and fireplaces are not considered with the Home Energy Score.

    4. Air sealing is something that I did explore in the blog post and will affect the typical close-in Portland home similar to my test. Air sealing has the biggest influence when the home has more stories.

    5. The type of insulation is not something that the Home Energy Score models directly. What the computer models is R-value. Different types of insulation have different R-values and different derate factors. For example, spray foam has high R-values per inch, does not lose effectiveness over time, and also acts as an air sealant technique. Air seal and R-Value are two different factors and both factors that I tested in that blog post. I did not explore reflective radiant barrier in the attic, but I know from experience will have the greatest effect on the Home Energy Score when the home has air conditioning and ducts in the unconditioned attic.

    6. In the blog post, I did explore changing the windows and the coatings on the windows and this factor will affect the typical close-in Portland home similar to my test. The way that the home energy score treats storm windows is just by assuming they are an extra window pane. Double pane versus single pane was also explored in the blog.

    7. The Home Energy Score software does not have a function for tankless water heater specifically. What it does have is a way to input the efficiency. Typical tankless water heaters are about 80% efficient or better when a gas storage water heater is typically about 55% efficient. The Home Energy Score software does calculate solar photovoltaic, but not solar thermal hot water. The water heater has a lower influence on a Home Energy Score, but it becomes more important to the score with more bedrooms or a home with an inefficient hot water heater to begin with (software calculates more occupants using hot water).

    Hopefully that helps and we can continue the conversation.


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