One Family's Energy Evolution--How We Dropped our Utility Bills by 80%

Top red line is average cost/month for years '99-'03. Black line is average cost for years '04-'08. Bars at bottom are for individual years '09 - '13

In the year 2000, our family spent $2615 on our utility bill. For a family of five in a 2800 sq. ft. house we used on average 33.4 kilowatt hours (kwh) per day of electricity and 4.28 therms/day of natural gas. Our electricity consumption was almost twice that of the average household in our utility region (an area that includes most of California north of Los Angeles), though very close to the national household average. And our natural gas consumption was almost four times (!) that of the average household in our region. It was expensive! It was nuts.

We live in San Francisco where it never gets very hot or very cold. However, our house was built in 1935 with pretty much zero insulation. In 2000 most of the windows were original and single-paned and only a few walls had been insulated. We didn’t have air conditioning or electric heat, so no big electrical draws there, but when the wind blew and the fog rolled in, you could’ve flown a kite in the breeze down our hallway.

Looking back, I only hazily remember what we did to deal with that initial monster energy use. We put in a lot of fluorescent bulbs, got rid of an electric space heater, nagged the kids to turn off lights and stopped leaving outdoor lights on all night. That was also the year we got our first front-load washing machine and a new, more efficient refrigerator, both necessary replacements of dying ones. The next year our electricity use dropped nearly in half! Our natural gas use, however, was just about the same, and unfortunately that was the winter natural gas prices went through the roof in California.

Yellow lines are solar production. Bars are what we bought. Negative numbers mean we sold more than we bought that month.

Solar clothes dryer

The next year I paid more attention to our programmable thermostats, experimented with the house temperature dropping a few degrees at night, and began hanging my laundry outside to dry. That resulted in a 10% drop in therms. At the beginning of the following year, we had a big remodeling project that involved, among other things, replacing fourteen single-pane windows with double-pane ones and insulating the walls of about a third of our house. Our natural gas use dropped 25% the following year! In 2004, both electricity and natural gas consumption crept back up, as energy use is wont to do. We added more insulation to the attic (there was a minimal amount already), and, for the next four years, our natural gas ran about 2.5 therms a day and electricity around 21 kwh/day. Things had definitely improved. But energy prices had also crept up. Even though we were using a third less electricity and 40% less natural gas than in 2000, we were spending $2000 per year on energy. 

Red line=avg '99-'03. Black=avg '04-'08. Bars='09 - present

  

(Side note: another huge benefit of adding wall insulation and replacing single-pane windows with double-pane ones is that it makes the interior of the house much quieter, a big plus in a city with street noise.)

Solar panels east

 Then I started reading about climate and energy issues. That was the point we began to tackle energy efficiency and renewable energy in earnest. In 2009 we installed solar panels on our roof. Our roof breaks east-west and is partly shaded in the winter by a taller building directly south, so seven panels ended up facing east and eight faced west on the sunniest half of the roof. Not optimal, but so it goes. To deal with vampire loads, I went around like a maniac unplugging every unnecessary gadget and wall wart I could from wall sockets in every room of our house. (It’s amazing what gets plugged in and stays there, drawing power year after year for no benefit whatsoever!) I plugged our media equipment into a power strip and turned it off at night. I put in ultra low flow showerheads (1.5 gallons per minute). I bugged my kids about taking shorter showers and using towels at least twice before putting them in the wash. My oldest went off to college, so there was some less energy use, but I still had two active teens at home gobbling energy with showers, piles of laundry and electronic media gadgets.

Solar panels west

I turned down the heat. Boy did I get howls about that. I would point out to my kids that since they didn’t live Hawaii, they should expect to wear slippers and sweaters in the winter. This was not popular. I pointed out I wore wool and was willing to have the house even colder while home alone during the day. (Though I do admit it’s hard to sit still for any length of time in a house colder than 59 degrees.) Eventually we reached a compromise that 64 degrees was a reasonable ambient temperature when they were home. 

We had an energy audit by an energy efficiency company. Out of this we decided to have insulation blown into our uninsulated walls (over half the house), we had the attic sealed and more attic insulation installed, and we had the downstairs heating system optimized and its ductwork sealed. Later that year we also had six very leaky single-pane windows in my daughters’ bedrooms replaced. It was after this that I got brave enough to turn our inefficient upstairs heating system off entirely. (Luckily the laws of physics proved correct and heat really does rise.) 

The combination of all these actions dropped our electricity usage by one fifth, down to 14.4 kwh/day. On average we produced 11.7 kwh/day from our panels and bought 2.7 kwh/day from our utility. (In the summer we produce more electricity than we use and sell some back to our utility. In the winter we use more than we produce and so buy.) The insulation, heating system optimization, new windows, and cooler house temperatures made a dramatic impact on our natural gas use, which dropped by 40% to 1.7 therms per day. And yet there was more to do.

Solar hot water panels

The following year we installed a solar hot water system that dropped our natural gas another half therm/day. It went on the east-facing side of our roof, which is fine since most of our hot water use (showers, dishwasher, laundry) is in the morning. (Morning is also when electrical rates are cheaper.) Because the back up warming element of the solar hot water system is electric, it did bump up our electrical use an average of 2 kwh/day.

On demand hot water

The year after that, when remodeling our decrepit downstairs bathroom, we installed an on-demand hot water system to replace our downstairs hot water heater, decreasing both water and natural gas use. We are down, now, to an average of less than one therm of natural gas per day, but it does vary depending on how cold our winter temperatures are. For both electricity and natural gas we rarely use amounts above our baseline quantity, which keeps the energy we do buy at the lowest rate.

As we progressed along on our energy journey, we made a few step-level technology changes but, more importantly, we also made many, many little changes that added up in a big way. This is why I call it an evolution. It took time, experimentation, and a failure here and there to achieve our results, plus a willingness to change habits.

Solar hot water guts

Over the years energy prices have increased, more steeply-tiered electricity rates have been introduced, and the baseline quantity for both electricity and natural gas has shrunk. (The number of kilowatt-hours or therms included in the baseline rate—a number that both rate structures hinge on—varies in California per geographical area. Curiously, this baseline definition has shrunk more in San Francisco than in other parts of our utility provider’s district. It ends up being a mostly invisible, though I have to admit clever, form of rate hike.)

The result is that energy, especially electricity in San Francisco, is quite a bit more expensive than it was in 2000. I calculate that if in 2012 we’d used the same amount of electricity as back in 2000, we would’ve paid $2402. (Back in 2000 we paid $1350 for this energy.) And if we’d used an equivalent amount of natural gas, we would’ve paid $1680 at today’s rates. Put the two together, we would’ve paid $4082 for energy last year. That means we’ve dropped our energy bills from what we would’ve paid by $3581 a year, or 87%! 

What we’ve invested (after tax credits and incentives): solar PV $12,000; solar hot water $5600; wall insulation, more attic insulation, house sealing, HVAC duct sealing and optimization $8000; repairing decorative paint on walls after insulation blown in $800; on demand hot water $1200; new windows not part of remodel $6000; various light bulbs, low flow showerheads and power strips $400. Total $34,000. (Am not counting appliances or windows we had to replace anyway or insulation mandated by building code during various remodels.) I figure we’ve already recovered $15,000 of our investment in savings. If energy prices increase by only two percent per year, we’ll recover the rest in six years. If energy prices increase by three percent per year, we’ll recover it in five.

Also in 2008 we got rid of our minivan, leaving us just our 2004 Prius. Our annual gasoline purchases dropped from $2300 per year down to $1250. The average price for a gallon of gasoline in 2008 in the US was $3.16; in 2012 it was $3.63. That means we bought 728 gallons of gas in 2008 and 344 gallons in 2012. If we’d used as much gasoline in 2012 as in 2008, we would’ve spent roughly an additional $1400.

Of course the expense of owning a car is only partly the gasoline. All the other costs to operate it come to far more. Though our van was totally paid for by the time we offed it, if we’d kept it we would’ve spent an additional $500 on car insurance, $3000 on repair and maintenance (van was getting old and falling apart), $170 on car registration, $150 on tires, $200 on parking, tolls and the rare carwash. This comes to $5420/year in car expenses avoided.

Electric-assist grocery getter. Carries 5 bags uphill, no sweat!

Without the extra car we did spend about $220/year on City Carshare (car rental by the hour), and about $1200 on family transit. However, at least two-thirds of that transit cost would’ve happened even with a second car as I wouldn’t have wanted to drive my kids around much more than I ended up doing anyhow. Although my husband and I mostly travel around town by regular bicycle, because we live up a ginormous hill, we also spent $800/year to buy and maintain two electric bikes. (Initial cost + maintenance + 1 battery replacement for each bike at year 3, with this total amortized over six years.) And we now spend $360/year for a storage locker on the island where we go on vacation every summer to hold stuff we formerly hauled there annually in our van. So net, our yearly savings are $3640. On top of this, by our teens not getting driver’s licenses between the ages of 16 and 21, we’ve saved on average $2000 per kid per year, which adds up to $20,000 so far and counting. (Thanks, kids! The money went to your college tuition.) And also, no kids driving meant no kids crashing, which meant no shelling out-of-pocket to pay the deductible on insurance claims, no increases in car insurance rates due to accidents, etc.

What we learned on our energy evolution: cutting energy use in half the first time is pretty easy, especially if your use is high to begin with. The things that have the biggest bang for the buck are actually quite cheap—replacing incandescent bulbs with fluorescents (although at this point I would replace with LEDs,) attic insulation, unplugging useless stuff, unplugging second refrigerators, putting in power strips to deal with vampire load, and whenever you replace an appliance spending a few percent more to get the most energy-efficient one possible. And anytime you remodel, take advantage of open walls to insulate like crazy and put in the most efficient fixtures you can. (You will thank yourself later.) Cutting energy use in half the second time requires more investment, but if you take your savings from the first energy drop, you’ll have some money to play with. Cutting use in half the third time takes even more money per therm or kilowatt saved and has less monetary return unless you expect energy costs to keep rising (which I do.) 

But we are not done! Future goals are to install a ductless heat pump, deal with our drafty fireplace with some kind of insert, eventually replace all of our leaky single-pane windows, and, if we ever get our house tight enough, install a heat-exchange ventilator. With middle child now in college, we expect our vehicles miles travelled (VMT) to drop another 20 percent this year. Perhaps once we finish paying for college for all three kids (Done with one! Two left to go!) we’ll consider an electric car, but like everyone else I’m concerned about range issue for long trips. In addition, even minimal use of an electric car would raise our electricity consumption by at least a third, so we’d need to install more solar panels on our roof. If there were a medium-speed train that took less than ten hours to get from San Francisco to Seattle (heck, that’s only 80 mph—European trains do double that), I think we’d go car-free altogether and just rent a car when we needed to.