Electrical Energy: What it is and how to measure it Rod Hinman Energy Efficiency Workshops, Spring 2009

Electricity 101 Volts – pressure pushing the electrons Amps (current) – flow of electrons Watts = Volts * Amps

Volts – pressure pushing the electrons

Amps (current) – flow of electrons

Watts = Volts * Amps

Electric Power: Watts “Power”, or how fast we are using energy Watts = Volts * Amps Also kilowatts (1 kW = 1000 W)

“Power”, or how fast we are using energy

Watts = Volts * Amps

Also kilowatts (1 kW = 1000 W)

AC / DC DC = “direct current” Examples: 12V car battery 35V solar panel AC = “alternating current” Example: 120V wall voltage

DC = “direct current”

Examples:

12V car battery

35V solar panel

AC = “alternating current”

Example:

120V wall voltage

Electricity 102 Energy – how we measure “useful work” that accomplishes a task Wash clothes Light the room during dinner Heat your tea Phone your mother Energy = (how fast using energy) * (how long) Energy = Watts * Time

Energy – how we measure “useful work” that accomplishes a task

Wash clothes

Light the room during dinner

Heat your tea

Phone your mother

Energy = (how fast using energy) * (how long)

Energy = Watts * Time

Energy: Units Watt-hour (Wh) Kilowatt-hour (kWh) 1 kWh = 1000 Wh = 10W * 100 hours = 100W * 10 hours * remember

Watt-hour (Wh)

Kilowatt-hour (kWh)

1 kWh = 1000 Wh = 10W * 100 hours = 100W * 10 hours

Why Measure or Audit? control

control

Measure your total use Read your meter Use special tools for real-time display Break consumption down by appliance Measurements Estimates

Measure your total use

Read your meter

Use special tools for real-time display

Break consumption down by appliance

Measurements

Estimates

Using HELCO Meter to Calculate Power Kh is a value printed on meter label: 3.6, 7.2, 14.4 Multiplier is printed on meter label, or = 1 if omitted Revolutions: number of revolutions of the wheel Seconds: # seconds that those revolutions took Example: 3.6 · 7.2 · 1 · (1 rev) /(10 sec) = 2.6 kW Power (kW) = 3.6 · Kh · multiplier · revolutions / seconds

Kh is a value printed on meter label: 3.6, 7.2, 14.4

Multiplier is printed on meter label, or = 1 if omitted

Revolutions: number of revolutions of the wheel

Seconds: # seconds that those revolutions took

Tools – Whole House Power Cost Monitor from Blue Line Innovations Reads dial or flashing light on HELCO meter Indoor real-time display encourages conservation Safe install But finicky setup

Power Cost Monitor from Blue Line Innovations

Reads dial or flashing light on HELCO meter

Indoor real-time display encourages conservation

Safe install

But finicky setup

Tools – Whole House The Energy Detective (TED) from Energy, Inc. Sensor unit in breaker box, electrician needed Indoor real-time display encourages conservation Accurate, even at low power usage Updates every second, both kW power and total kWh energy used Can connect a PC to log power draw over time

The Energy Detective (TED) from Energy, Inc.

Sensor unit in breaker box, electrician needed

Indoor real-time display encourages conservation

Accurate, even at low power usage

Updates every second, both kW power and total kWh energy used

Can connect a PC to log power draw over time

Individual Appliances with Whole-House Tools Turn off as many appliances as you can Unplug them or use breakers Especially devices that cycle: refrigerator, water heater, air conditioning Measure base power consumption in kW – clocks in your stove, etc. Turn on an appliance and measure total power consumption in kW Appliance power kW = total – base Turn off appliance and repeat with another one

Turn off as many appliances as you can

Unplug them or use breakers

Especially devices that cycle: refrigerator, water heater, air conditioning

Measure base power consumption in kW – clocks in your stove, etc.

Turn on an appliance and measure total power consumption in kW

Appliance power kW = total – base

Turn off appliance and repeat with another one

Tools – Individual Appliances Kill-A-Watt Watts Up Plug into wall, then plug appliance into device.

Kill-A-Watt

Watts Up

Plug into wall, then plug appliance into device.

Estimating Appliance Consumption Look on label for Watt or Amp rating Usually means peak: Turned fully on Under all operating conditions

Look on label for Watt or Amp rating

Usually means peak:

Turned fully on

Under all operating conditions

Estimating Appliance Consumption Printed Publications HELCO Energy Star Online energy calculators Home Energy Saver from Lawrence Berkeley National Labs (hes.lbl.gov) US DoE Office of Energy Efficiency and Renewable Energy (www1.eere.energy.gov/calculators/homes.html) Others

Printed Publications

HELCO

Energy Star

Online energy calculators

Home Energy Saver from Lawrence Berkeley National Labs (hes.lbl.gov)

US DoE Office of Energy Efficiency and Renewable Energy (www1.eere.energy.gov/calculators/homes.html)

Others

Example * $0.34/kWh was the effective residential rate for my bill spanning most of September and a couple of days in October 60 60 1000 8.3 label Coffee maker TED measurement HELCO pamphlet HELCO pamphlet “ Kill-A-Watt” measurement HELCO pamphlet Data Source 496.9 = $170 at $0.34/kWh Total 1.3 90 14 CFL 11.8 540 22 32” LCD HDTV “off” 43.2 180 240 32” LCD HDTV on 120.6 Refrigerator 260.0 4500 Hot Water Heater kWh/mo. = W*H/1000 Hours in use/mo. Watts = V*A (usually 120V) Amps Appliance

Other Examples Room Air Conditioner 500-1000W Desktop Computer 60-400W Laptop Computer 10-30W Toaster Oven 1600W Incandescent Lamp 60-100W Pool pump 1000W

Room Air Conditioner 500-1000W

Desktop Computer 60-400W

Laptop Computer 10-30W

Toaster Oven 1600W

Incandescent Lamp 60-100W

Pool pump 1000W

Photo Credits Water pressure by “pbo31”, Bubbling water by “just having some fun” on Flikr Fire hose by dmuth on Flikr, Faucet: City of Grapevine, Texas CFL by Outsanity Photos on Flikr Green clock by Catherine on Flikr Product photos from company web sites Others by Guy Toyama and Rod Hinman

Water pressure by “pbo31”, Bubbling water by “just having some fun” on Flikr

Fire hose by dmuth on Flikr, Faucet: City of Grapevine, Texas

CFL by Outsanity Photos on Flikr

Green clock by Catherine on Flikr

Product photos from company web sites

Others by Guy Toyama and Rod Hinman

Ways to Reduce Consumption Solar hot water heater: simple payback within 18 months after tax incentives Set A/C warmer; service the A/C unit Replace incandescent (halogen, too) with fluorescent lights Turn off/hibernate computer when not using Configure monitor to turn off, rather than use screen saver Turn off printer, especially laser printers

Solar hot water heater: simple payback within 18 months after tax incentives

Set A/C warmer; service the A/C unit

Replace incandescent (halogen, too) with fluorescent lights

Turn off/hibernate computer when not using

Configure monitor to turn off, rather than use screen saver

Turn off printer, especially laser printers

AC Power Watts = Volts * Amps Note: power is not constant, but is always one direction

Units comparison =kiloWatt · Hour = 100 kWh * Hour * 100 hours kiloWatts 1 kW Electricity = Miles = 600 miles * Hour * 10 hours Miles Hour 60 mph Distance Quantity * Time Rate Measurement

Reading Your Meter Read left to right Dials spin opposite directions (driven by gears) If hand between two numbers, pick lower If hand on a number, pick it if the next hand has passed zero, otherwise pick one less. Example from HECO site: 13924 kWh

Read left to right

Dials spin opposite directions (driven by gears)

If hand between two numbers, pick lower

If hand on a number, pick it if the next hand has passed zero, otherwise pick one less.

Example from HECO site: 13924 kWh

Reading Your Meter: Digital with Net Energy Metering Screen 3: consumption Screen 6: production (when meter spinning backwards) Screen 7: net kWh with initial value set to 50,000 = 50000 + (screen 3) – (screen 6) {note rounding error}

Screen 3: consumption

Screen 6: production (when meter spinning backwards)

Screen 7: net kWh with initial value set to 50,000

= 50000 + (screen 3) – (screen 6) {note rounding error}

Auditing Break down your usage by appliance Measure or estimate how much energy used Start with largest users

Break down your usage by appliance

Measure or estimate how much energy used

Start with largest users

Automotive Mileage Meter ScanGaugeII Displays instantaneous and trip MPG Plugs in under dashboard Also records other operating parameters

ScanGaugeII

Displays instantaneous and trip MPG

Plugs in under dashboard

Also records other operating parameters