|
Cost effectiveness
by U.S. Dept. of energy
|
Cost-Effectiveness Example |
|
Performance |
Base Modela |
Recommended Level |
Best Available |
Self-Closing |
|
Water Use Only |
|
Gallons per minute/cycle |
2.2 gpm |
2.0 gpm |
0.38 gpm |
0.25 gpcb |
|
Annual Water Use |
17,160 gallons |
15,600 gallons |
2,964 gallons |
3,900 gallons |
|
Annual Water Cost |
$69 |
$62 |
$12 |
$16 |
|
Lifetime Water Costc |
$585 |
$530 |
$100 |
$135 |
|
For Electric Water Heating |
|
Annual Energy Use |
1,014 kWh |
922 kWh |
175 kWh |
231 kWh |
|
Annual Energy Cost |
$61 |
$55 |
$11 |
$14 |
|
Lifetime Energy Costc |
$505 |
$460 |
$90 |
$115 |
|
Lifetime Energy and Water Cost Savings |
— |
$100 |
$900 |
$840 |
|
For Gas Water Heating |
|
Annual Energy Use |
53 therms |
48 therms |
9 therms |
12 therms |
|
Annual Energy Cost |
$32 |
$29 |
$5 |
$7 |
|
Lifetime Energy Costc |
$250 |
$230 |
$45 |
$60 |
|
Lifetime Energy and Water Cost Savings |
— |
$75 |
$690 |
$660 |
a - The flow rate of the Base Model just meets the current federal
standards for faucets, based on ASME standard test conditions.
b -Gallons per cycle. The duration of 1 cycle is based on the American
with Disabilities Act (ADA) specification of 10 seconds with a flow rate
of 1.5 gpm.
c - Lifetime Energy or Water Cost is the sum of the discounted value of
annual energy or water costs, based on average usage and an assumed
faucet life of 10 years. Future energy price trends and a discount rate
of 3.0% are based on federal guidelines (effective from April, 2004 to
March, 2005). Future water and waste-water treatment costs are
conservatively assumed to increase only at the rate of inflation.
Metric Conversion:
1 gallon = 3.8 liters
1 therm = 100,000Btu
= 29.3 kWh
= 105.5 MJ
1 psi = 6.9kPa
°F = (1.8 * °C) + 32
Cost-Effectiveness Assumptions: In a commercial facility, faucet use is
assumed to last for 1 minute, 30 times per day, and 260 days per year.
The faucet water temperature is assumed to average 80°F. For
self-closing faucets, each faucet use is assumed to require 2 on-cycles.
The assumed electricity and gas prices are $0.06/kWh and $0.60/therm,
the federal average energy prices in the U.S. The assumed combined water
and waste-water price is $4.00/1000 gallons.
for more information, visit www.hes.lbl.gov
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