ENERGY STRATEGY: STAPLES CONDUCTS “ECO-TREASURE HUNTS” AT ITS FULFILLMENT CENTERS. THESE THREE-DAY ENERGY AND WATER AUDITS INVOLVE
FACILITY STAFF AND ENERGY MANAGEMENT EXPERTS. SEE THEIR PLAYBOOK AND
CHECK OUT MORE SAVINGS STRATEGIES AT EERE.ENERGY.GOV.
in the same spot as the original tank.
These units can be tucked away in utility
closets, basements, attics, or even outside.
Most water heaters receive little
upkeep and consequently have to be
replaced at the first sign of failure. Rather
than a total replacement, individual parts
of a tankless heater can be exchanged to
extend its life, says Houston.
“The heat exchanger is the most
important component,” Fleming notes. “A
total flush is needed periodically, which
could be annually or every three to five
years depending on water hardness.”
The chamber of tankless units that use
flash heating should also be cleaned or
descaled, Stebbins recommends.
Periodic flushing should be done once
a quarter or every year depending on
water quality, says Houston. You can use
inexpensive products such as vinegar or
a lime-and-rust remover. You should also
perform a full drain.
Clean vents and ensure there’s no
debris, particularly if the return is
positioned near other exhaust vents,
Fleming advises. You can also use
compressed air for any buildup on the fan
3 Reasons to Switch to Tankless Water Heating continued from page 11
For gas units, schedule burner check
and evaluate the vent for cracks as a safety
precaution, Houston recommends.
Some facilities have oversized water
heaters in the first place. Tankless can be
scaled to your actual water demand.
“You don’t replace a water heater with
a tankless unit based on the original
storage capacity – you size the tankless
model based on your hot water demand,”
Sizing evaluates a number of factors,
says Houston. Look at the number of
fixtures that use hot water, their gallons
per minute rate, and peak demand. You
also need to know the groundwater
temperature coming in through your pipes,
which affects how much energy is needed
to raise the temperature to the setpoint.
Installing a tankless heater as close as
possible to the point of end use is best
as less energy will be lost as water is
transported throughout your building.
Otherwise, you need a recirculation pump
and line, which will keep the water at
the correct temperature, says Fleming.
You can also add a timer and aquastat for
For gas units, anticipate a slightly larger
fuel bill, particularly if your hot water
demand was never satisfied with your
“For example, you may currently have a
199,000 BTU water heater but are always
short on water. It could take a 380,000
BTU tankless unit to meet your demand
fully,” says Fleming.
You may also need to expand the size of
your incoming gas line, Stebbins suggests,
though gas companies typically offer deep
discounts to help you with upgrades.
Vents are another consideration as
tankless heaters use concentric vents to
dissipate carbon monoxide rather than a
standard V vent, Fleming says.
“Electric units are simpler to retrofit
as there are no venting requirements,
though you might need to increase the
size of your breaker in the main panel and
have a larger electrical feed wire running
to the unit in many applications,” says
Lastly, shop around for installation
costs, stresses Houston. The plumbing
technician should also have familiarity
with these units, otherwise improper
installation could negate future savings.
Jennie Morton jennie.morton@buildings.
com is senior editor of BUILDINGS.
In pursuit of the SunShot Initia-
tive’s goal to drive the cost of
solar-generated electricity down
to 6 cents per k Wh, the DOE’s National
Renewable Energy Laboratory (NREL)
has designed a new solar cell that con-
verts electricity at 45.7% efficiency.
With one of the highest photovoltaic
research cell efficiencies ever achieved,
the new design incorporates an extra
absorber layer to achieve the boost in
efficiency and is designed to receive more
than 1,000 suns of concentrated sunlight.
The solar cell can be used in a concentrator photovoltaic system, allowing more
light to be converted to electricity and enabling the high efficiency rate. While the
maximum efficiency was measured at 234
High Performance Solar Concentrator Developed
suns concentration, the system performed
nearly as well under higher concentrations, demonstrating 45.2% efficiency at
700 suns concentration. The cell is currently being sent to an external accredited
laboratory for confirmation of the tests.
A NEW SOLAR CELL can convert electricity at 45.7% efficiency, one of the highest photovoltaic
cell efficiencies obtained in research so far.