Posted by: Josh Lehner | June 30, 2021

The Fever is Broken

We made it back home just in time for the heat dome. The worst of it is over for the western part of the state while central and eastern Oregon have another day or two it looks like. But even then, the forecast calls for merely hot instead of extreme temperatures. It’s likely the risks have increased in terms of the impact from the current drought, and any fallout from this year’s wildfire season. While I know many of you found our office’s old post on air conditioning, I did want to share two charts this morning based on the new 2019 American Housing Survey data that was released last fall.

First, major metros on the West Coast have the lowest rate of AC usage in the country. If we combine the 2017 and 2019 AHS data (the metros rotate) Portland ranks 4th lowest out of the 35 in the data. One in five Portland households do not have AC, more than double the national share.

Second, a question I have seen pop up a number of times in recent days is why doesn’t the NW have more air conditioning? Shouldn’t AC be increasing noticeably due to climate change? As seen in the chart below, it very much is. In the past 15 years, Portland’s AC usage has basically doubled, going from 43% in 2002 to 79% in 2019. For much of the late 20th Century, Portland’s AC usage trailed the nation by about 40 percentage points. Today it is 13 percent. Seattle has gone from trailing the nation by 60-70% to “just” 47% today as AC usage has tripled in recent decades going from 15% in 2004 to 44% in 2019.

More importantly for the health of our neighbors and ourselves, the actual number of households without AC has fallen outright. Between 2002 and 2019, the number of households in the Portland region without AC declined by more than 250,000. It’s not just that new construction is boosting the AC figures (it does) but that older units are adding AC at the same time. The same overall pattern is seen in the fishing village up north, but starting from a much lower base of AC usage likely in part to being both on the water, and further north.


Responses

  1. I think the payback on a house with/without A/C justifies it’s installation more than an actual need. We’re still about a week a year on average when we really need A/C in houses.

  2. Josh, Thanks for some “hot” updates. 😉

    A/C is a deep subject. Let me just add some food for thought.

    In 2014-2015, my wife and I built a home in Sunriver, Oregon. Our home blew the doors off the rating scale to achieve Earth Advantage “Platinum” rating for energy efficiency and “green” construction.

    As you would imagine, the house is tight and well-insulated. But a part of the engineering was to create *distributed* mass (rather than a single “heat sink” such as a stone interior wall). That was achieved in large part by using *real* plaster for the walls. 5/8″ “rock” on all walls, as well as ceilings and two coats of plaster finish. Much, much “greener,” stronger, more massive and beautiful than (ugh!) drywall.

    The system of a DC-motor for forced air system and a high-end, carefully engineered, DC-motor ceiling fan above the stairwell run very low speed 24×7 to ensure that the interior air is well-mixed. High-tech, SIGA membranes prevent air and vapor leaks into the unconditioned, ventilated attic space. Deep eaves to shield sunlight during summer.

    Net result is we have no A/C, but the house rides a smooth wave of pleasant temperatures that averages out Sunriver’s wide (~35 to 45 degrees F.) daily temperature swings. And this is without using the tried and true method of opening windows during the cool nights and closing during the hot days.

    The “Dragonfly” has many other advanced engineering elements, as well.

    If you’re interested, I’ve posted some info and images at:
    https://home4jp.com/

    Stay cool!

    — Paul


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