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The Top Articles in the Energy Vanguard Blog in 2021

The End Of The Year 2021

It’s the last day of the year, so let’s wrap it up with some lists.  Whether you missed some of the articles I wrote this year or are just curious about what other people were reading here, I’ve got three lists for you.  The first is the top 10 most-read articles I wrote in 2021.  The second is the top 10 most-read articles overall in 2021.  And the third is a list of another 10 articles I wrote in 2021 that I think would be worth your time.

Top 10 articles published in 2021

As I wrote in the 2021 wrap-up the other day, I published 53 articles before this one, so now I’m at 54 for the year.  That’s the most I’ve written since 2017.  Because the new ones are competing against 927 other articles that have some history, even the most popular article I wrote in 2021 didn’t crack the top 10 in overall pageviews for the year.  So, here are the 10 articles I wrote in 2021 that Google Analytics tells me were the most popular, along with where they ranked overall.

David Wasserman showing his hot water distribution system retrofit
David Wasserman showing his hot water distribution system retrofit (from article #10 below)
  1. Living With a Heat Pump Water Heater  (#13 overall)  With 27,000 pageviews and 120 comments, my heat pump water heater article was the most popular article I wrote this year.  And it’s been live for only three months.
  2. Where Should the Air Barrier Be Located?  (#23 overall)  I’m surprised this one’s number 2.  I figured one of my other hot water articles would be here.
  3. 2 Reasons to Avoid Most Electronic Air Cleaners  (#47 overall)  Perhaps my best IAQ article from the spring, written after learning to live in a pandemic that spreads through the air.
  4. Can an Exhaust Fan Control Humidity in a Spray Foam Attic?  (#64 overall)  I returned to this important topic with data from my own house.
  5. Heat Pumps, Auxiliary Heat, and Resilience  (#94 overall)  A followup to the #6 article of 2021 and the big freeze in Texas last February.
  6. Can a Heat Pump Work in Minnesota?  (#104 overall)  Spoiler:  Yes.  Gary Nelson does it in Minneapolis without built-in auxiliary heat.
  7. Bad Advice About Indoor Humidity in Cold Weather  (#111 overall)  Be careful taking advice on cranking up the humidity in your home in winter.  Health advice also needs to be compatible with building science.
  8. Why Your Hot Water Takes So Long  (#112 overall)  Hot water distribution systems have A LOT of room for improvement.
  9. How to Insulate a Short Attic Kneewall  (#119 overall)  Check your attic and fix this problem if you have it.
  10. A Hot Water System Retrofit for an Old House  (#129 overall)  A friend of mine cut the time to get hot water to his kitchen sink from more than a minute to about eight seconds.  Read how he did it here.

Top 10 articles overall in 2021

The Energy Vanguard Blog turns 12 years old in March, so the 53 previously published articles in 2021 are only about 5 percent of all the articles I’ve published here.  Without further ado, here are the 10 articles that got the most pageviews overall in 2021, with their date of publication in parentheses.

A pair-of-pants tee is great for air flow in a duct system
A pair-of-pants tee is great for air flow in a duct system  (from article #2 below)
  1. 4 Pitfalls of Spray Foam Insulation  (6/29/10 )  With 104,649 pageviews in 2021 alone, this article continues its dominance.  It’s been the overall number one in traffic every year but one.  It came in second in 2020 as the #4 article below took the top spot due to a pandemic-fueled search for information on filtration that year.
  2. My Undersized Ducted Mini-Split Heat Pump  (6/11/20)  Mini-splits and other types of heat pumps have been a really hot topic.
  3. What Happens When You Put a Plastic Vapor Barrier in Your Wall?  (4/24/14)  I had no idea this would become a perennial favorite, but here we are.  (If you’ve seen it recently, I apologize. The images got messed up in one of my two website moves, but they’re fixed now.)
  4. The Unintended Consequences of High-MERV Filters  (11/9/18)  Here’s the dirt on high-MERV filtration.
  5. 7 Things You May Not Know About Ceiling Fans  (7/11/18)  Good things every ceiling fan shopper and owner should know!
  6. Why Do Air Conditioning Vents Sweat?  (7/23/20)  Not an uncommon problem here in the Southeast in summer.
  7. What Happens to Air Flow in Ducts When Size Changes?  (10/29/18)  A continuation on my deep dive into ducts that started with my duct design series in 2017.
  8. An Easy Retrofit for Return Air From Bedrooms  (10/17/17)  Also part of my duct dive, but a little different.  This was a retrofit I did at the condo I used to live in.
  9. The #1 Reason Power Attic Ventilators Don’t Help  (5/29/14)  I’ve written a few articles on this topic, but this one gets the most traffic.
  10. The 2 Main Problems With Kitchen Ventilation  (9/4/18)  You probably can’t guess what the first one is.  Can you?

If you didn’t count along the way, that’s one article from 2010, two from 2014, one from 2017, four from 2018, and two from 2020.

10 other good articles from 2021

If I were to rank the articles I wrote in 2021, some of those that got the most traffic would be in the top 10.  But I’d also include some of the ones below.

When Is the humidity low enough to open the windows?
When Is the humidity low enough to open the windows?  (from article #7 below)
  1. Disruptive New Micro-Split Heat Pump Will Change the World  My April Fools’ Day article.
  2. Carbon Dioxide and the Air You Rebreathe  Here’s a nice table you can use to correlate the CO2 level in the indoor air with the amount of air that came out of other people’s lungs.
  3. 3 Ways to Get Cleaner Indoor Air With Filtration  More good IAQ advice.
  4. Does Poor Installation of Insulation Hurt R-Value?  I think the diagrams I came up with for this article (and the book) are really good.
  5. The 3 Safest Ways to Insulate the Top of the House  Based on a conversation I had with Kohta Ueno of Building Science Corporation.
  6. Why You Probably Need an ERV, Not an HRV  This definitely should be in the top 10 of the year.
  7. When Is the Humidity Low Enough to Open the Windows?  Good practical advice for people who live in humid climates.
  8. What I Got Wrong in Criticizing Fiberglass Batts  A look back at the trouble I got in with a manufacturer of fiberglass insulation in 2011.
  9. Building Your First House as an Owner-Builder  A look back at what I was doing 20 years ago.
  10. 3 Important Facts About Dew Point Temperature  An attempt to clear up some confusion about humidity and condensation.

And there you have it, a good look at what was popular in the Energy Vanguard Blog plus what I think also deserves your attention.  Well, I think it all deserves your attention, so you can click the links within each article and keep exploring.

Now, let’s end this year with a bang and make 2022 another of spreading building science knowledge far and wide.  We need it because, after two years of them being canceled, I want to go to Building Science Summer Camp and Possum Drop next year.


Allison A. Bailes III, PhD is a speaker, writer, building science consultant, and the founder of Energy Vanguard in Decatur, Georgia. He has a doctorate in physics and writes the Energy Vanguard Blog. He is also writing a book on building science. You can follow him on Twitter at @EnergyVanguard.


Related Articles

The 2021 Energy Vanguard Wrap-up

Top 10 Articles in the Energy Vanguard Blog in 2019

2013: A Look Back at the Year in Building Science


Photo by Caitlin H from, used under a Creative Commons license.


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This Post Has 3 Comments

  1. Thanks for the blog which I enjoy even though I can’t use the knowledge I gain.

    But why is there a pic of a canal boat going through a tunnel as the lead pic in this issue???

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