How we keep cool in a tiny house during big heat

Elaina the cool cat blocks my workstation relief

Elaina the cool cat blocks my workstation relief

During the summer months in Portland, Oregon, air-conditioning was unnecessary. The temperature was typically around 80 degrees Fahrenheit (F) and rarely felt hot. The wool insulation in the tiny house combined with a fan to suck in the cool evening air was all that was required to stay within a tolerable temperature. However, now that the tiny house has moved south to the Central California Valley, the summer heat has been intense. We moved to Red Bluff, CA during the first week of May and quickly experienced high temps above 95 degrees F. In early June, one day exceeded 113 degrees F.

I quickly realized after a few days in our new climate that we needed to adapt. Our tiny house has a wonderful feeling of space with 10 windows, however, a sunny day can rapidly turn this benefit into a green-house effect. Further exacerbating the problem was the tiny house parking spot. In Red Bluff, CA the tiny house is parked directly in the sun and on a black asphalt driveway. To cool the house, I started drawing the window shades after mid morning to reflect sunlight. Also, to reduce solar gain in the loft, I mounted a nylon sun fabric to the outside of our skylight. Although, blocking sunlight and using a fan to circulate the air reduced the interior temp about 10 degrees F, this wasn’t quite enough to get the house down to a comfortable temp.

Exterior view of AC

Exterior view of AC

To meet our immediate need and to save the cats from another day of misery, I purchased a small window air-conditioner with good reviews. The model I purchased was a 5,000 BTU, 500 Watt, Frigidaire unit. Thankfully, this air-conditioner was inexpensive ($118) and easy to install with the provided insulating foam and a few added “L” brackets. The opening for my tiny house window is only about 18” wide but the air-conditioner with insulating foam fit easily. The unit is very stable with the “L” brackets and conserves space by protruding only about 5 inches beyond the exterior siding and less than 1 inch beyond the interior wall.

Initially, I was concerned that the energy consumption with this new appliance would skyrocket. After using the unit nearly constantly for about two months I’m happy to report that our electricity cost merely doubled from about $6/month to $11/month. In comparison, the central air conditioning and attic fan in my mother-in-law’s 2,500 sq ft home costs about $300/month to run. This cost is so prohibitive that my mother-in-law keeps her central air off. We have invited her to come over to the tiny house to cool down periodically. For example, during that 113 degree F day I mentioned earlier, we all hung out in the tiny house and relished the comfortable 70 degree F interior temp.

In summary, after six seasons in the tiny house spanning three distinct climates, I’ve learned how to adapt. Below are a few tips I’ve learned that can help keep a tiny house cool in the summer heat:

  • Trees are wonderful for blocking the sun and reducing the wind, so incorporate them into your parking space planning.
  • If possible, park on grass surfaces during the summer. Black asphalt surfaces can dramatically increase the heat.
  • Sun screen fabric is a great addition to the house and has the added benefit of greater privacy.
  • Tiny houses are easy to efficiently heat and cool so don’t worry about the added $5-10/month additional cost in maintaining a comfortable temperature.
Dang, our power billed doubled to $11! ;)

Dang, our power billed doubled to $11! ;)

6 thoughts on “How we keep cool in a tiny house during big heat

  1. Here’s how I keep my tiny house cool in over 35C heat:
    surround by grass
    lengthwise porch with roof
    only 3 windows in the house
    bamboo shade on the southern (long) edge of the porch
    bamboo shade on outside west facing window
    windows open at night, closed during the day (it cools down nicely here at night)
    keep the door closed as much as possible
    spray the roof of house and porch with hose a few times/day
    minimal cooking

    none of these adds to my electric bill!

    Glad to hear your move wen well!

  2. Those little air conditioners are really remarkable. My mother has one in her small home, and it cools the entire house despite the walls which one would assume would prevent it from reaching each area. Great tips for keeping cool without mechanical interference, too. Thanks!

    • Thanks for reading! I dug into my calculations a bit more and after a bit more time with this unit I’ve discovered a few things. First my price/KWH of electricity was off. It was still based on Portland, OR rates of 8 cents/KWH. California rates are more like 13 cents/KWH so my monthly cost would rise to about $18 not $11. Also, my temp estimate of 70 degrees was off. After a few more triple digit days I’ve realized that this unit cools about 30 degrees F from the outside temp. Although it felt like 70 degrees F directly in front of the unit the rest of the house was more likely in the mid 80s during the 113 degree F day mentioned in the post above. Sorry for any confusion! I’ll more carefully check my numbers and assumptions again when I go into tech details with only a qualitative effort…

      Cheers, L

  3. We just open all the skylights during the day. Plus we have plenty of windows carefully placed throughout the house for proper cross-ventilation.

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