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Old 11-21-13, 09:42 AM   #341
AC_Hacker
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Location: Portland, OR
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Quote:
Originally Posted by michael View Post
Zip code 95460... We have a mild climate stabilized by the proximity of the Pacific Ocean and not hard on a heating system...
I went HERE and checked your Heating Degree Days. Not knowing any better, I chose the weather station at the Ukiah Municipal Airport. I used 68F as your base temp, that seems to be pretty commonly the case for most of the EcoRenovators.

Your HDD value came out to be 4886, which surprised me, as it is just a tad cooler than there in Portland... guess it must be an ocean current issue.

Anyway, as if you didn't already have enough data, here is how the average HDD from the last five years graphed out...


Also, your temperature data looks quite favorable...



Quote:
Originally Posted by michael View Post
The house has energy compliance heat loss calculations to predict how it's supposed to perform. They were part of the permitting process, and they predict 17k BTU/hr loss in the worst case.
Wow, pretty impressive that your local government is so advanced in their thinking. I thought Portland was on an energy jihad, but now I see that we have work to do.

Quote:
Originally Posted by michael View Post
The plans call for a geothermal heat pump to provide space heat, but that's another story.
Excellent!

I played around with the Carnot Efficiency equation, as it relates to heat pump COP curves, and I found out that heat pump efficiencies are more sensitive (in a favorable way) to small improvements in radiant floor efficiencies than fossil fueled systems may be.

> ...and they predict 17k BTU/hr loss in the worst case.

This is lovely.

I don't know what your typical solar exposure is, but this makes you a good candidate for solar.

It also opens up a good opportunity for ASHP-to-water providing heat for your slab. Your worst low air temperature is very ASHP-friendly.

It also puts you in the rare category of people (like me), who want to strangle every last efficiency possible out of their heating system and want to go GSHP. It may be good news or it may be bad news, but you are going to have trouble finding a commercial water-to-water GSHP that is small enough to heat your home most efficiently.

So don't forget where the Homemade Heat Pump Manifesto is.

On with the show...

Best,

-AC_Hacker

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Last edited by AC_Hacker; 11-21-13 at 10:00 AM..
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