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how green is my shack?

Posted: Thu Aug 22, 2019 10:50 am
by JR.
I have long pursued energy efficiency for the old fashioned reasons (I'm cheap). Often suffering through cold in winter and hot in summer from limited spending on comfort. That was then.... over the last year I have made two major upgrades... last summer I put a new light colored tin roof on my house replacing the old black asphalt shingles. This year I upgraded to a modern high efficiency 2 ton heat pump.

Over the last few weeks we've had mid 90's daytime high temperatures and multiple heat advisories. Now for the good news, my electric bill reveals that I used 86% of the electricity that I did this same month last summer. This is with 24x7 air conditioning.

The dollar savings from reduced electricity bills would take longer than my life expectancy to break even, but I do have a nice new roof that doesn't leak and a far more comfortable house, while saving the planet. 8-)

JR

Re: how green is my shack?

Posted: Fri Aug 23, 2019 6:05 am
by terkio
Interesting for a hot place I know in Australia.
What is the heat sink of the heat pump ?
An outside air exchanger I presume.
Can a heat pump give an efficient air conditioning using water from a nearby creek ? At the cost of pumping water, though.

Re: how green is my shack?

Posted: Fri Aug 23, 2019 10:14 am
by JR.
terkio wrote:
Fri Aug 23, 2019 6:05 am
Interesting for a hot place I know in Australia.
What is the heat sink of the heat pump ?
An outside air exchanger I presume.
Yes... outdoor air.
Can a heat pump give an efficient air conditioning using water from a nearby creek ? At the cost of pumping water, though.
That is called ground based heat pump and I have a high enough water table that I could bury a heat sink (pipes) beneath my water table, that would be even more effective, but also much more expensive. :o You can bury ground based heat exchange pipes in dry ground too, but wet ground has even lower thermal resistance.

An old friend of mine has a water sourced heat pump exchanging house heat/cold into a deep water well drilled under his house. Doesn't get more efficient than that.

As it is I will not break even money wise on my 2 ton unit over my lifetime from reduced energy bills, but the modern air exchange heat pumps are more efficient than even a few years ago. Instead of cycling on/off at full tilt, it varies the compressor to regulate the temperature in the evaporator for most efficient transfer to room air.

I expect another significant saving for heating during the coming winter months compared to my previous (cheap) in wall heat pump. My house originally used in-wall resistance heaters.... so pretty large electric bills for winter heat. Several years ago I upgraded to an in-wall heat pump for the main room that was far better than the simple resistance heaters, but lower efficiency than my new modern unit.

JR

Re: how green is my shack?

Posted: Sun Feb 02, 2020 9:44 am
by JR.
My most recent electric bill showed 2/3 the energy consumption of the same month one year ago... This is a better payback than summer months, with the extra benefit that house is heated 24x7 not just in the daytime.

===

I have half considered getting a heat pump based clothes dryer when my current decades old dryer finally gives up the ghost. I am intrigued by the technology so asked my local appliance repair guy, and he has never seen or worked on one... Not surprising they are significantly more expensive than old technology dryers.

Bleeding edge technology is rarely the safe bet, while these have probably been around for a while elsewhere in the world.

JR

Re: how green is my shack?

Posted: Mon Feb 03, 2020 6:37 am
by mediatechnology
The elementary school a few hundred yards from me had geothermal wells installed in 2010.

I would be interested in talking with the building engineer responsible for the geothermal plant to see how its working out.

Re: how green is my shack?

Posted: Mon Feb 03, 2020 10:13 am
by JR.
mediatechnology wrote:
Mon Feb 03, 2020 6:37 am
The elementary school a few hundred yards from me had geothermal wells installed in 2010.

I would be interested in talking with the building engineer responsible for the geothermal plant to see how its working out.
Ground sourced heat pumps are very effective even up north where air source heat pumps can be challenged. I had a friend living in Atlanta with his heat pump pulling heat/cold from a deep water well under his house. It seems pretty logical to incorporate ground source heat pumps for any new home construction, where the ground heat exchange can be accomplished at the same time as digging a foundation. Out in the country if you have to dig a septic field, it seems like ground sourced heat exchange could share the same trenches (maybe?).

I have looked at ground sourced for an after the fact upgrade and it was too expensive for me to consider seriously, even though I live on low (wet) ground, so wouldn't have to dig very deep.

My appliance guy tried to explain to me how air source heat pumps don't work below 30'. I guess he is used to dealing with uninformed people. :lol: But he did make me look it up. Modern technology heat pumps like mine drop down to roughly 50% heat output capacity below 30'... Perhaps that explains why I went for an oversized 2 ton unit (I originally shopped for 75% of that), roughly 2x the capacity of my former thru-wall unit I replaced. That same reference didn't show the air source heat pump dropping to 0 heat output until -19' or something like that... Of course it gets problematic for the compressor running anywhere near that cold.

JR

Re: how green is my shack?

Posted: Wed Feb 19, 2020 4:32 pm
by JR.
Completely unexpected I got a home energy report from my electric utility... according to them my house uses 3% less energy than the 20% most efficient homes in my neighborhood.

This is not surprising to me, my energy bill shows 34% less energy consumption versus last year.

I like the new high tech heat pumps.

JR

Re: how green is my shack?

Posted: Wed Feb 19, 2020 8:32 pm
by mediatechnology
Do you have a smart meter?

Re: how green is my shack?

Posted: Wed Feb 19, 2020 11:09 pm
by JR.
mediatechnology wrote:
Wed Feb 19, 2020 8:32 pm
Do you have a smart meter?
Meter was replaced with some kind of high tech version a couple years ago, but not doing any tricks that I am aware of... it has a LCD display, but nothing intelligible to me on it.

JR

Re: how green is my shack?

Posted: Thu Feb 20, 2020 6:01 am
by mediatechnology
If your utility supports it you can read the meter and usage with either a wireless ZIgbee-based gizmo or your utility's portal.
I use a GE Nucleus (discontinued).
There is also Rainforest Automation.

I've found the Nucleus very helpful to monitor energy usage.

This is what the SmartMeter portal looks like. viewtopic.php?f=11&t=408&start=10#p5007