Estimating Appliance and Home Electronic Energy Use
save electricity
in your home - help the environment and cut cost
bill
If you're
trying to
decide
whether to
invest in a
more
energy-efficient
appliance or
you'd like
to determine
your
electricity
loads, you
may want to
estimate
appliance
energy
consumption.
Formula for
Estimating
Energy
Consumption
You can use
this formula
to estimate
an
appliance's
energy use:
(Wattage ×
Hours Used
Per Day ÷
1000 = Daily
Kilowatt-hour
(kWh)
consumption
(1 kilowatt
(kW) = 1,000
Watts)
Multiply
this by the
number of
days you use
the
appliance
during the
year for the
annual
consumption.
You can then
calculate
the annual
cost to run
an appliance
by
multiplying
the kWh per
year by your
local
utility's
rate per kWh
consumed.
Note: To
estimate the
number of
hours that a
refrigerator
actually
operates at
its maximum
wattage,
divide the
total time
the
refrigerator
is plugged
in by three.
Refrigerators,
although
turned "on"
all the
time,
actually
cycle on and
off as
needed to
maintain
interior
temperatures.
You can usually find the wattage
of most appliances stamped on
the bottom or back of the
appliance, or on its nameplate.
The wattage listed is the
maximum power drawn by the
appliance. Since many appliances
have a range of settings (for
example, the volume on a radio),
the actual amount of power
consumed depends on the setting
used at any one time.
If
the wattage is not listed on the
appliance, you can still
estimate it by finding the
current draw (in amperes) and
multiplying that by the voltage
used by the appliance. Most
appliances in the United States
use 120 volts. Larger
appliances, such as clothes
dryers and electric cooktops,
use 240 volts. The amperes might
be stamped on the unit in place
of the wattage. If not, find a
clamp-on ammeter—an
electrician's tool that clamps
around one of the two wires on
the appliance—to measure the
current flowing through it. You
can obtain this type of ammeter
in stores that sell electrical
and electronic equipment. Take a
reading while the device is
running; this is the actual
amount of current being used at
that instant.
When measuring the current drawn
by a motor, note that the
meter will show about three
times more current in the first
second that the motor starts
than when it is running
smoothly.
Many appliances continue to draw
a small amount of power when
they are switched "off." These
"phantom loads" occur in most
appliances that use electricity,
such as VCRs, televisions,
stereos, computers, and kitchen
appliances. Most phantom loads
will increase the appliance's
energy consumption a few
watt-hours. These loads can be
avoided by unplugging the
appliance or using a power strip
and using the switch on the
power strip to cut all power to
the appliance.
Typical Wattages of Various
Appliances
Here are some examples of the
range of nameplate wattages for
various household appliances
(Unit: Watt):
Aquarium = 50–1210
Clock radio = 10
Coffee maker = 900–1200
Clothes washer = 350–500
Clothes dryer = 1800–5000
Dishwasher = 1200–2400
(using the drying feature
greatly increases energy
consumption)
Dehumidifier = 785
Electric blanket-
Single/Double = 60 / 100
Fans
Ceiling = 65–175
Window = 55–250
Furnace = 750
Whole house = 240–750
Hair dryer = 1200–1875
Heater (portable) =
750–1500
Clothes iron = 1000–1800
Microwave oven = 750–1100
Personal computer
CPU - awake / asleep =
120 / 30 or less
Monitor - awake / asleep
= 150 / 30 or less
Laptop = 50
Radio (stereo) =
70–400
Refrigerator
(frost-free, 16 cubic feet)
= 725
Televisions (color)
19" = 65–110
27" = 113
36" = 133
53"-61" Projection = 170
Flat screen = 120
Toaster = 800–1400
Toaster oven = 1225
VCR/DVD = 17–21 / 20–25
Vacuum cleaner = 1000–1440
Water heater (40 gallon)
= 4500–5500
Water pump (deep well)
= 250–1100
Water bed (with heater,
no cover) = 120–380
Home Electricity Energy Monitors
The basic figures contained
within a monthly or quarterly
electricity bill do not give you
much information as to where
your electricity is going - they
just tell you how much you have
used in total during that period
and how much totally you need to
pay. Therefore it is well worth
considering purchasing an
electricity usage monitor and
using it to see exactly where
all your hard-earned money is
going.
One great way to find out how
much electricity each of your
household appliances and
electronic devices uses is with
a wireless electricity
power/energy monitor, which
shows you in real time exactly
how much money your total home
or office electricity usage is
costing you. These monitors can
help you reduce your electricity
consumption by as much as 20%
simply by showing you what you
are using.
Sailwider-SmartPower is a developer and
manufacturer of electricity power
monitor and controlling system.
Most electricity energy monitors
in the market are uni-directional
(1-way) only, that means you can only
get energy consumption
information from the monitor.
The
bi-directional (2-way)
electricity power monitoring and
control system
from Sailwider-SmartPower makes
the user not only able to
monitor the electricity usage,
but also can easily remote control
the connected electrical
appliances wirelessly, providing great
convenience to electricity
efficiency management.
