Heat Pump Results

After using a single stage heat pump for a year I have some results to share regarding the cost of cooling and reduction in natural gas. 

For heating, the time periods I’m reviewing are September 2020 through May 2021 which is before we got the heat pump and September 2021 through May 2022 which is using a heat pump. What I found was a 46% reduction in natural gas usage due to the heat pump, now down to 292 therms (about a quarter of a comparable home). 

Obviously this is an imperfect comparison due to weather differences, but I think it’s safe to say that the heat pump made a significant difference in natural gas use. I see two major advantages to reducing natural gas use – obviously there’s the emissions difference of 11.7lbs of CO2 per therm, but also isolation from the rapid increase in natural gas prices. 

I have the Emporia Vue Energy Meter watching the heat pump circuit to learn about costs. What I’ve learned about cooling is that we have 2 significant cooling months in Western Washington – July and August. Running a 4 ton heat pump to cool our house costs about $38/month at PSE Tier 2 rates those months. Other months are pretty trivial, for example September heat pump operation was less than $8, but also likely had some heating cost involved as in the past we used 9 therms of natural gas in September. 

So is a single stage heat pump a good idea in Western Washington? I think it depends on your goals – if you want to reduce natural gas and get affordable cooling it works great. If you want to eliminate natural gas use you’ll need a variable speed heat pump system.

Why I got a Heat Pump instead of AC

Interesting factoid (for those outside the Pacific NW) but the Seattle area is the least air conditioned major metro area, since I was young we’ve relied on fans bringing in cold air at night and room/window AC units the past decade. However the past few summer wildfires have seriously put a damper on the fans solution and the recent heat bubble pushed things over the edge. 

Of course AC isn’t great environmentally – it increases power consumption which in many cases means significant powerplant emissions and the refrigerants can be very powerful greenhouse gases if you have a leak. 

So instead I got a heat pump which is basically an AC with a reversing valve and all the same downsides of AC. I know that sounds bad, but hear me out for a second. The cool thing about a heat pump is it can generate heating and cooling – meaning that instead of burning natural gas in my furnace which emits 11.7lbs of CO2 per therm I can generate most of the home’s heat with zero emissions electricity. 

Note I said most of the home’s heat, for a few reasons I kept the existing high efficiency gas furnace. First off you need to know heat pumps come in a variety of types such as single stage, dual stage, and variable speed. I purchased a single stage unit which will efficiently heat the house when the outside temperature is at least 40 degrees, then the gas furnace will kick in. A cold climate variable speed heat pump would be able to heat my house in any Seattle weather but at significantly higher equipment cost than a single stage unit like I got. Variable speed is also more efficient, but looking at equipment cost vs operating cost savings it didn’t make a lot of sense in my case. 

The other issue is backup heat, we get a lot of power outages in my neighborhood and backing up a heat pump takes a large generator – so no matter what I’m not getting rid of fossil fuels entirely. On the other hand backing up a gas furnace has modest power requirements, we run that off an inverter connected to an EV. 

So in the end I didn’t completely eliminate the heating emissions, but I made a cost effective major reduction in emissions while getting some much needed cooling. I think that’s a good trade-off because that money can be used elsewhere for more significant emissions reductions. 

In case you wonder what my heat pump costs to run, so far I’m seeing a daily cost when it runs (which isn’t every day) of about 50¢ to $1.50 for the heat pump. In other terms, cooling in the PNW is pretty cheap. At the time I can’t yet compare to the gas furnace for heating, but later this winter I’ll have an update.

As for some heat pump shopping tips:

  • I suggest ensuring you get an Energy Star unit. Note Energy Star units also have $300 federal rebates which you may be eligible for. Also check with your utility for local rebates. 
  • My hope is a higher quality unit will be less likely to break and leak refrigerants. I got an American Standard which was top rated by Consumer Reports. Also expect annual maintenance on the heat pump to ensure it’s in good condition. 
  • I went with Arden Heating & Cooling after getting a referral from a neighbor and getting five quotes. I’d highly recommend them to anyone in the Seattle/Metro area. 

Plastic Recycling sucks…but I’m still excited for Ridwell

Usually when I’m writing a post I’m not conflicted. But in this case I feel funny that I have to admit that plastic recycling sucks and I’m still excited about doing plastic film recycling with Ridwell. 

So in case you haven’t heard plastic recycling is a disaster because there’s so many types of plastic, it degrades with each recycling, and recycling it costs more than making virgin plastic. So while you may think you’re recycling, it could also end up as landfill or incinerated. 

Yet I’m excited to have plastic film recycling with Ridwell. Plastic film is the thin flexible plastic used basically everywhere – plastic shopping bags, bubble wrap, air pillows, frozen food bags, bubble mailers (like amazon uses), dry cleaning bags, bread bags, etc. Plastic film is ubiquitous but difficult to recycle because it clogs sorting machines, gets contaminated, gets loose, and can be difficult to separate from paper. By collecting it separately Ridwell is able to bypass these issues and give it a second life as Trex decking.

Ridwell doesn’t just do plastic film but also clothes, styrofoam, batteries, and rotating categories. Last pick up we had filled a 60 bag of styrofoam, a 13 gallon bag of plastic film, and a handful of batteries. 

Ridwell does cost money (prices vary by area, $14/mo for us) and you could recycle these items without Ridwell for free, but at the expense of time. For example Styro Recycle will take styrofoam for free, but for me it’s an hour round trip and they’re only open weekdays when I’m working. Ideally Ridwell will help you cut down your trash bin size which may balance out the cost. 

Ridwell is in the Seattle/Eastside area now and going to PDX! Check it out from our link and get a free month. 


Solar Update and Q&A

Many of our friends and family have expressed an interest in solar power but given the expense wanted to let us be the guinea pigs for it. Now that its been 8 months I figure we have some real world experience to share.

Does it Really Work?
From January through June we produced 5680kwh. Typically these months produce 52% of the annual production, so we’re on course to produce 10900kwh this year (a bit above the annual average use for a PSE customer). This is about 10% more than the installer estimated, meaning our system will be even cheaper than we originally predicted this if overproduction continues. So short answer, yes, solar power does work even in rainy Seattle.

Any Problems?
So far not a one. It has dealt with feet of snow and windstorms without issue.

What About Maintenance?
Zero so far, the rain has been keeping them clean and our trees are far enough back that debris hasn’t been an issue.

I’ve also gotten many recurring questions, here’s some common questions and answers about solar power.

Is my roof orientation okay?
A southern facing roof is ideal, but ours is more east/west and we produce only about 5% less than our cousin’s system which is more south facing. I’d avoid solar for heavily shaded roofs and north facing roofs, but otherwise don’t let concerns about the roof get in the way of considering solar power.

Will my HOA Allow Solar?
As long as you own the roof (e.g. not a condo) legally an HOA cannot ban rooftop solar in Washington State (RCW 64.38.055). HOAs can reasonably limit aesthetics (e.g. banning tilt kits) but a homeowner does have the right to install solar power.

What about cloudy days?
When people think of solar they often think of being off-grid, but most residential solar power systems are actually grid tied with net metering. When the system overproduces the power is sent to the grid and you get credits, when it is nighttime or overcast you pull from the grid and use the credits or buy power when the credits are all used.

What about power outages?
Solar power systems actually turn off when the grid power is down to protect the lineworkers from being electrocuted. If you want to use solar power to address outages you’ll need batteries like the Powerwall and an automatic transfer switch.

What About Online Estimators like Project Sunroof?
Project Sunroof is an interesting Google service using satellite data to estimate roof solar potential. It is however just an estimate – it appears to underestimate my production potential by at least 20% and overestimated the cost of my system about $14000 too high. When you get a solar installation quote any reputable dealer will use a Suneye (or similar PV analyzer) to get better data to estimate production.

Two Easy Things To Cut Your Home Heating Bill and CO2

Home heating turns out to be a huge impact environmentally, heating a 2000sq foot home in the Seattle area can commonly range from $500-1700/year and 7000-17000lbs of CO2 annually. Needless to say modest improvements in efficiency can have major impacts.

While there’s huge, expensive projects you can undertake to cut these factors, there’s two simple things we did which cut our impact roughly by a quarter.

Below is a picture of our “new” (1980s) home gas use (we’re the blue line). In October things started to cool off here and you’ll notice we were running at the same gas use of an “efficient” neighbor, but since then we did just the two improvements below and now use 26% less natural gas than an “efficient” neighbor.

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Greener Home Heating

Home heating turns out to be an incredibly complex and regional issue – how much heating is needed, the practicality of heat pumps, and grid energy emissions vary significantly in the US. Not to forget your home variables – what services are available, ducting, current system efficiency, etc. Given that keep in mind there’s no one answer that works everywhere.

While home heating a complex and fairly mundane topic it deserves a lot of attention – some back of the napkin math suggests home heating and cooling in America is responsible for at least half a trillion pounds of CO2 annually.

We’re going to look at the three main categories of heating systems – electric resistive heaters, heat pumps, and gas furnaces.

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All About Home Battery Storage

What is Home Battery Storage?

Basically these are battery packs like used in EVs but for your home power. They can be used with or without solar, but the rebates only apply when used with solar.

Will Home Battery storage save me money?

It depends on your utility! For example if your utility charges time-of-use rates you can use the battery to run your house during high rate hours then charge the battery off-peak hours. Also if your utility doesn’t offer solar net metering it allows you to take full advantage of the solar power you generate.

But at least for major Western Washington utility users (PSE, Seattle City Light, and Tacoma Power) these aren’t a concern.

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