Heating Houses in Hawaii (PT. 1)

It can get cold in Hawaii.  I know, I know.  I’ve been hearing it forever:

  • “My year in Hawaii we lived happily with no heat…”
  • “Winter is Not Coming”
  • “What do you mean, it’s cold?  You’re in Hawaii!”
  • “Do you even NEED walls?”

I live on the wet side of Waimea, north of Mauna Kea.  You know what “mauna kea” means, right?  It means “white mountain.”  You know why it’s white, right?  Because it snows sometimes.  Today’s news:

The last one is interesting.  It’s an “unseasonal” snowstorm.  Is it global weirding again?

So houses need heat.  Not all houses in Hawaii…if you live in Kailua-Kona, or Hilo, or Honolulu, you don’t need heat.  But some of us do, and how big a heating system?  Buying a heating system is like buying shave ice.  If you get the toddler size, you eat it up and are left wanting more.  You shoulda bought the big one, brah.  But if you get a bucket, you probably won’t be able to eat it all before it melts, so it’s a waste.

If a heating system is too small, it can’t keep up.  If it’s too big, it’s a waste of your money.  To right-size a heating system, I do heat loss calculations.  To do those, I collect data & measurements of the house, put it all in a model, and grab climate data from somewhere.  My software has some weather stations for me to choose from, but there’s a problem.  These are the Hawaiian weather stations available in my software.  I put the average annual Heating Degree Days (HDD) for each site next to them:

  • Barbers Point Naval Air Station (1 HDD)
  • Hilo International Airport (4 HDD)
  • Honolulu International Airport (0 HDD)
  • Kahului Airport (0 HDD)
  • Kaneohe Bay Marine Corps Air Station (0 HDD)
  • Kapalua (0 HDD)
  • Kona International Airport (0 HDD)
  • Lanai (16 HDD)
  • Lihue Airport (1 HDD)
  • Molokai (Amos) (4 HDD)

HDD are a measure of how much energy it will take to heat a house – the more HDD, the more energy.  For comparison, Barrow, Alaska has more than 19,000 HDD.  Minneapolis has more than 7000.  I live in Waimea on the Big Island and I can see the snow on the mountain from my house, so obviously none of these weather stations will give me good data to work with.

After some digging, I found the Hawaii State Climate Office, which put together some good numbers I can work with:

Those are average numbers of HDD per month, Jan-Dec.  Depending on where you are in Waimea, there are 600-800 annual HDD.  That’s quite different from Honolulu or Hilo.  After some MORE digging, I found a place that has 800 HDD and a weather station my software can use, and it’s…Daytona Beach.

I mentioned this to my mom, who used to live in Florida, and she said, “Oh yes, it gets very chilly in Daytona.”

People need to be warm and dry, because if they’re cold and damp they get sick.  The mold sets in.  Indoor air quality takes a nosedive, because you’re inside more and you closed up your house.

Next up, part 2: how to choose a heating system that you’ll be happy with for years to come, that does just what you need.  And what if it could ALSO give you air conditioning?  And dehumidify your house?

Are you looking for help with a heating system?  Let me help.  I’ll collect data, we’ll talk about what you need, and figure out what’s not too big, not too small, but juuuuust right – the Goldilocks Approach.  You’ll probably end up with something smaller than you thought, because bigger is not better.  It’ll also run more efficiently, saving you energy.

For more on Hawaii Island’s double-handful of climate zones, go here: https://www.hawaii-forest.com/koppens_climates/

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