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.