
You just had a Portland Home Energy Score done (Hopefully by A Quality Measurement) on your home and you’re wondering how the assessor knew the R-value for the insulation hidden in the walls. The answer is that the assessor does not know; rather, he/she estimates the value based on the best available evidence. Remember that Portland’s Home Energy Score is a low-cost “energy assessment” and not a more detailed “energy audit”.
An assessor usually relies on information from various sources to evaluate a home’s insulation. Such information is typically provided by the homeowner, through labels on the electrical panel, by examination of exposed areas, or by probing around outlets to evaluate the amount and condition of the insulation. Absent such information, the assessor can check the building code requirements when the home was built. In most cases, it is necessary to adjust the insulation R-value downward due to age and condition.
Here is a handy table provided to all approved Portland Home Energy Score assessors that shows code minimums for insulation over time within in the City of Portland.

It is interesting to see how insulation codes have increased through time. It is surprising that vaulted ceilings did not require insulation until 1983. Also, it is surprising that insulation codes have not changed in the last 25 years.
Did I leave anything out or do you want to join in the conversation? Let me know in the comments below.
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Thanks for reading,
Gary F. Kristensen, Owner
April 23, 2018 @ 5:09 pm
Thank you for posting this awesome article.
I’m a long time reader but I’ve never been compelled to leave a comment.
May 29, 2018 @ 7:55 pm
Thank you very much for the insiteful content.
I have shared it on my facebook page.
October 6, 2020 @ 5:58 pm
It’s good to know that the codes and regulations for insulation haven’t changed much in the last 25 years or so. My parents want to reinsulate their home so that it looks much better. That way, they can be sure that the winter cold won’t affect their energy efficiency that much.