Net Zero mission accomplished

One of my major goals for our home renovations has been achieving Net Zero, meaning our house produces as much energy as it consumes. As one might expect, producing as much energy as we consume yields energy bills of less than $0.  Today I consulted my energy meter and extracted the following data points for calendar year 2017:

  • Energy Produced: 9,288 kWh
  • Energy Consumed: 12,396 kWh
  • Energy Consumed by Auto: 3,216 kWh
  • Energy Consumed by Building: 9,180 kWh

For the purposes of measuring building consumption, I subtracted the auto consumption (measured by our chargepoint home charger) from total consumption. Since our building produced 108 kWh more than it consumed, I can claim the Net Zero goal as accomplished.

Our home and EV together consumed 1,500 kWh less in 2017 than 2016. Looking forward, I anticipate a similar reduction in 2018 because we were using space heaters for part of the house in Jan-Apr of 2017. The heat pump for that area is now installed. Also, the concrete basement and downstairs walls aren’t insulated yet. I have the insulation (XPS & poly-iso) standing by and it will be installed before the next heating season.

I don’t expect an substantial efficiency improvements after 2018. All our energy systems are super efficient, our insulation levels are super, and our energy surpluses (say hello to Energy Plus) will be consumed by our current and future EVs. Any further efficiency improvements would have no economic justification.

Reference points

  • Average home energy consumption: 23,000 kWh
  • Average auto energy consumption: 15,000 kWh
  • A super-insulated (aka: ultra efficient) home typically needs 1/5 the energy for HVAC.
  • On average, EVs consume  1/3 the energy of an ICE vehicle.

dumb questions

Straight from the department of Don’t Ask Questions You Don’t Want To Know Answers To comes today’s plumbing edition: “how much water could possibly be left in this pipe?!”

Is A Powerwall Worth It?

Primarily for economic reasons, I covered our roof with 10kW of solar panels. As a producer of electricity, it no longer made sense to pay a utility company for natural gas so the furnace was replaced with heat pumps and the water heater was replaced with a HPWH. The fireplace and chimney were anachronisms I was happy to get rid of. I removed all the gas lines and had PSE remove the leaky gas meter as well. From a safety perspective, ridding our home of combustion appliances was a big win.

While on the topic of safety, the Big One is coming. Our home was built in 1955, way before the Nisqually Quake and updated building codes. I’ve done a few seismic retrofits as suggested by the City. The most important thing, literally, is surviving the quake, so making sure our house doesn’t collapse is a good start. The next most important thing is potable drinking water. I warehouse a weeks worth. For lighting we have camping headlamps, Mr. Beam night lights around the house (with rechargeable AA batteries that last about a month) and outside, I’ve got solar LED lights attached to the house. They’re really nice when walking around the house at night and would suffice during a power outage.

What I don’t have is energy storage. For the safety of linemen, when the grid is down, so is my array. I want a Tesla Powerwall so I can operate off grid. For $6k, Tesla provides a 14kW battery and the transfer switch that enables off grid operation. In the summer, our array produces double what we use (including EV charging) so a single Powerwall could easily power our house, plus extension cords to the neighbors for their fridges, indefinitely. In mid-winter, with no visible sun and freezing temps we could drain a Powerwall in just two days. But after a winter disaster, we could turn the heat off, dress warm, and power the house for weeks. Or heat just one room. That’s a compelling use case, but I have yet to conclude that the potential losses from not having a battery (spoiled food, no lights, no cooking, no heat) during an outage outweigh the $6,200 price tag.

Lazy Basil

I’ve grown Basil on our windowsills for a few years. Version 3 is now growing in Utz Cheese Ball containers.

Basil plant, potted in a Utz Cheese Ball container
Basil in a 2-gallon Utz Cheese Ball container.

With flower pots, I used a moisture sensor and watered the plants a couple of times a week.

Version 2 of my window planters was less pretty but massively more functional gallon milk jugs. Their square shape provided far more volume in the same sill print. In that extra space, I also integrated some physics to reduce maintenance. I put an inch of gravel in the bottom of the jugs, a layer of fabric, and then filled the jug with potting soil. The fabric just keeps the soil out of the gravel. The gravel provides drainage when the soil gets saturated. As the soil dries, water wicks up from the gravel via capillary action and moistens the soil from below. When I can’t see water in the bottom, add some. It worked very well.

While v2 worked great for the plants, the gallon milk jugs were hard on the eyes. I watched for substitute containers. Last years make-the-walls-7-inches-deeper-project left us with 9″ deep window sills. That permitted use of containers in many more sizes and shapes.

Version 3 was born when the last jug of cheese balls was empty. I nipped off the top couple inches and assembled it the same way as v2. I dropped in a few basil plants and set them in my West window. They couldn’t be happier. Since I only have to water them every few weeks, I’m happy too. It’s time to buy more cheese balls!

EV: how much is 6kWh?

Our first Leaf was the 2013 model year. That was the year Nissan  boosted cold weather driving range by 20+ miles with the switch to heat pumps, for an estimated 85 total miles. While I was able to get 82 miles from one charge (summer hypermiling), in practice the range was quite a bit less. The worst case, mid-winter driving to and from work in the cold and dark, the range was closer to 50 miles. For Jen’s 32 mile round-trip commute, that mean charging the car every night.

On long trips, recharging an EV has the same level of friction as adding gas to an ICE. In the case of commuting, EV refueling is considerably more convenient:

EV

ICE
drive home drive to station
wait in line for pump
park near EV plug pull up to pump
negotiate payment
plug in plug in
wait for tank to fill
unplug (later) unplug
drive away

When the 2016 model year Leaf was released, the battery capacity increased from 24kWh to 30kWh, boosting the EPA rated range from 84 to 107 miles. That extra 23 miles was just enough to get us out to the ski resorts in the winter. It also made quite a difference in how often our Silver Leaf needed to recharge:

good neighbors

Today I heard my neighbors car alarm go off so I headed to a window. Then their other car’s alarm started going off too. Looking out the window, I could see both neighbors and their daughter, pushing buttons on their remotes to get the alarms to shut up.

Seizing the moment, I grabbed a broom and raced out the door towards them. While brandishing my broom high I screamed at them, “get away from my neighbors car.” Rhonda, their daughter, who had set off the first alarm was rendered utterly helpless. Apparently it’s much harder to dodge a broom waving maniac while busting a gut laughing. Who knew?

Smitty, upon hearing the first alarm, thought it was his car so he grabbed his keys and hit the alarm button to turn it off, which is why there was now two car alarms blaring. Rhonda had turned off the first alarm, but then Smitty’s started so she hit the alarm button again, turning it back on. I arrived in time to inject more confusion and transform it into a true comedy of errors.

Get them jollies while you can!

snowflake server

I’m in the middle of rebuilding my server. For years I provisioned one-off virtual machines for clients that needed custom solutions. Dedicated IPs for TLS (for shopping carts), custom coded extensions that turned a photo app into a shopping cart, email servers, etc. I’ve been maintaining those VMs for years while the cost of technical debt has been growing.

The base OS in the VMs is years old. As software gets upgraded, the state of the VMs slowly drift and the result is a snowflake server. Upgrades frequently break something. I monitor most services and usually get them fixed before anyone notices. Still. Even on conservative OSes like Debian and FreeBSD, stuff regularly breaks and manual intervention is required. And those manual fixes here and there contribute to the drift.

So I’m rearchitecting everything for composability and simplicity. HAproxy handles all the HTTP redirection and HTTPS termination. The certificate management is now completely automated with Let’s Encrypt and acme.sh. HAproxy routes the requests to the backend web servers. No longer do apache, lighttpd, and nginx handle SSL/TLS or URL manipulation. The web server configs are simpler and require fewer customizations.

Financial Literacy

A Freakonomics Radio podcast I just listened to, Everything You Always Wanted to Know About Money (But Were Afraid to Ask), stated that studies have shown that in the USA and in nearly every other country studied, the percentage of people who are financially literate is under 30%. That’s the bad news.

The good news was Harold Pollack’s “all the financial advice you’ll ever need fits on an index card” conversation. I took notes:

  1. save 20% of your income
  2. pay off your credit card bill in full every month
  3. max out 401k & other tax advantaged accounts
    1. it reduces your tax burden today
    2. matching employer contributions are free money
  4. never buy or sell individual stocks
  5. buy inexpensive and well diversified index and ETF funds
  6. make your financial advisor adhere to the fiduciary standard
  7. buy a home when you’re financially ready
    1. homes are something we use and consume
    2. when are we ready?
      1. have 20% in hand
      2. fixed rate 15/30 year mortgage
      3. still have reserves for home maintenance
  8. insurance: be protected against losses > your reserves
    1. get the largest deductible
  9. do what you can to support the social safety net
    1. bad stuff happens
    2. lots of people need help

Solar ROI update

I now have a full year of electric production and consumption measured. I also have the SCL rate updates for 2017 and 2018 so I have updated my solar ROI estimates. The significant change is that the Net Metering benefit has substantially increased due to:

  1. SCL electric rates are higher in Shoreline than Seattle.
  2. The 2017 and 2018 rate increases are 5.6% (estimated at 4%)
  3. An added RSA surcharge of 1.5%
  4. The coldest winter in 32 years
  5. More electricity use than I predicted.
    • I was still insulating deep into the heating season.
    • I guesstimated the kWh it would require to heat a 1955 house with heat pumps.
    • I installed a fast (level 2) charger for our Leaf. We were able to use it more, offsetting gasoline with electricity.
  6. The increased usage is all at the higher 0.14¢ price tier.

Reasons 1-4 weren’t known during my initial estimates. Reasons 5 and 6 were planned but their scale was unknown. I knew I’d be removing all natural gas appliances (furnace, water heater, fireplace) but I hadn’t yet decided whether to install tankless electric or a heat pump water heater. I hadn’t chosen the heat pumps for house heat yet so I didn’t know their HSPF. I also didn’t know how much more we’d be able to use the Leaf.

The net result is that I now estimate a 100% return on the solar array in the 6th year instead of the 8th year.

Notes

  • I did not include the cost of the heat pumps or the heat pump water heater. Those were efficiency upgrades that I’d have done anyway. If I were keeping natural gas, I’d have replaced the old 80% furnace with a 97% modulating furnace and the “well past its expected lifespan” gas water heater with a gas tankless. In both cases the costs are comparable and just like replacing the fridge, the efficiency increases have their own ROI schedule.

Solar 11-month update

On a typical “it rained every single day in April” month, we still managed to skate across the finish line at nearly at Net Zero:

April 2017 household energy
April 2017 household + auto energy budget

Last year I removed all the natural gas appliances and converted everything to electric heat pumps. I sized the 10kW array aiming for Net Zero during the calendar year. That would mean producing enough surplus during the summer to carry us through the winter. It looks like we’re going to miss this year:

2016-2017 household energy budget

Even though we’ll be banking surpluses in May, it won’t close that 7MWh deficit. Our household usage includes over 3MWh of car charging and this last winter was Seattle’s coldest in 32 years. The heat pumps were working overtime to keep the house warm.