Happy New Year to all and congratulations to Diane Paterson
who answered the quiz question from two weeks ago correctly. For those of you
who did not read the Chronicle on the 22nd
of December, here is a summary of the question, which was used as a way to
explain the concept of payback period.
Our daughter’s bike trailer represents an investment in
energy efficiency in that it allows us to pedal her around town instead of
driving. The IRD mileage reimbursement rate for 2012 was 77 cents per
kilometre. (This takes into account all of the associated costs of driving:
petrol, insurance, WOF, repairs, etc.) For us, this means a round-trip to
centre city in are Subaru sets us back about $11.
The second-hand baby trailer cost $125, plus an additional
$60 for minor repairs. How many round trips from Castlecliff to city centre –
at a savings of $11 each – would it take to recoup the investment?
Diane wrote:
Hi Nelson,
Really enjoying your column
and coveting a home energy audit, should I be so fortunate!! By my reckoning it
will take you 17 round trips into town to recoup an investment of $185 on
Verti's baby trailer. $185/11 = 16 trips, $9 remainder.
I noticed you and the family
in town with the trailer before Christmas, so I guess you have made a start.
Happy New Year and warm
regards to all.
Di P
Payback period is usually expressed in units of time: weeks,
months, years. But in this case the unit was the number of driving trips
avoided. Probably the easiest way for anyone to see the potential savings made
possible through energy efficiency is to use the example of a compact
fluorescent light bulb.
A brief version of this ran months ago as a side bar with
this column, but at the current auspicious time of the dawning of a new year,
little Verti and I will use this opportunity to try to convince some readers to
resolve to change a light bulb in 2013.
Here goes.
A 25-watt compact fluorescent light bulb (CFL) emits the
same amount of light as a 100-watt incandescent bulb. This is a savings of 75%
every hour!
Good Idea
If you currently run one 100-watt incandescent for 10 hours
each day, you’ll use 1,000 watt hours (1 kilowatt hour - kWh), or one “unit” of
power as your electric bill probably says. Each unit costs around 28 cents.
Replacing that 100-watt incandescent with a 25-watt CFL
would mean you use 250 watt hours, or 0.25 kWh, per day, costing only 7 cents.
Therefore, your daily savings would be 21 cents by changing one light bulb.
CFLs cost $5 at most stores while incandescents cost $1. The
difference of $4 is the up front cost one must pay for long-term savings. The
question of the week is: How long will it take to pay back $4 at a daily
savings of 21 cents?
400 cents divided by 21 cents per day = 19 days. This is
child’s play, right Verti?
Bad Idea
Every proceeding 19 days you’ll save another $4, for an
annual savings of $76.84. Change two light bulbs and it doubles. Change three
and it triples. Change four…you get the picture.
Changing just five 100 watt incandescent light bulbs to 25
watt CFLs could save you $384.21. But there is a catch. You need to come up
with $25 to buy them. Is it worth it? Anyone resolved?
Helpful tip: I buy my CFLs at one of the major supermarkets
in town. Their ‘store brand’ of CFLs comes with a money back guarantee. I save
the bar code from the box and staple the receipt to it just in case a bulb does
not perform up to standard.
Peace, Estwing
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