| New
technology in earth coupled heating
and cooling systems are helping companies
save money
Design innovations in HVAC equipment
are breathing new life into a technology
that has been around for decades.
Earth coupled systems are revolutionizing
the way both commercial and residential
properties are heated and cooled.
Generally, heat rejection equipment,
such as cooling towers and chillers,
are installed on rooftops or on the
ground. Drawbacks to this equipment
include size, heat generation, vibration,
and most of all, noise. If the equipment
is placed on the roof, safe access
for maintenance is required and structural
reinforcement is often necessary.
Placing equipment on the ground can
also be problematic, because in some
areas, there may not be enough property
to place the equipment far enough
from the building and the neighbors,
so that noise will not be an issue.
Additionally, the costs associated
with the heating of buildings are
escalating. Due to rising oil and
gas prices, traditional fuel fired
equipment is becoming more costly
to operate. Maintenance and the venting
of gaseous emissions, such as carbon
monoxide, are also concerns with
fuel burning equipment.
The solution lies with “Earth
Coupled” heating and cooling
systems, which utilize the earth’s
natural resources to reject and store
heat. There are different installations
for this type of system; however
the geology of the New England area
lends itself to the “standing
column well” installation.
The well is six inches in diameter
and approximately 1,500 feet deep.
The pump is installed inside a four-inch
diameter induction tube that extends
down to the bottom of the well. PVC
or HDPE piping connects the earth
coupled system to the building’s
heating and cooling system. Well
water circulates from the well to
a plate and frame heat exchanger,
located in the building’s mechanical
room, and then back into the well.
A heat exchanger is used to keep
the well water and the building water
loop separate, so if the quality
of the well water is questionable,
the heating and cooling equipment
in the building is not susceptible
to any detrimental effects. In the
cooling season, the building system
rejects heat to the well water as
it passes through heat exchanger.
The well water returns to the well,
and as it travels down the depth
of the well, rejects heat to the
bedrock. By the time the water reaches
the bottom, it has been sufficiently
cooled. In the heating season, the
building water loop extracts heat
from the warmer well water, in just
the opposite process, to heat the
building. In an earth coupled system,
the heat is simply being moved- from
the earth to the interior space.
To measure the benefits of an earth
coupled system, we can assess comparatives
with industry standards. The Energy
Efficiency Ratio (EER), as defined
by the Federal Energy Management
Program is, “the measure of
the instantaneous energy efficiency
of room air conditioners; the cooling
capacity in Btu/hr divided by the
watts of power consumed…”.
Traditional air conditioning units
have an EER of 10, air-to-air heat
pumps can achieve an EER of 12, but
an earth coupled system will consistently
achieve EERs of 16 or higher. Unlike
air-to-air heat pumps, where the
efficiency of the unit in the heating
mode depends on the fluctuating outdoor
air temperature, the efficiency of
an earth coupled system is much more
consistent, since the well water
stays between 50 and 60 degrees year
round, and no supplemental electric
heat is required. In addition, earth
coupling reduces the emissions of
carbon monoxide and other greenhouse
gases by 30%, because no fossil fuel
is being burned to create heat. Replacing
bulky, noisy HVAC equipment with
an earth coupled design is easy on
the eyes and ears - it not only eliminates
large equipment eyesores, but it
also eradicates the fan noise associated
with heat rejection equipment.
Earth coupled systems have been
successfully implemented in Europe
and the United States. While the
energy efficiency of earth coupled
systems can result in paybacks of
5-10 years for residential and commercial
projects, for some projects an earth
coupled system is the system of choice
because it requires no outdoor equipment,
is virtually invisible and makes
absolutely no noise outside. We have
designed many earth coupled heating
and cooling systems including a mixed
use building that houses a professional
performing arts theatre and multi-tenant
office space in Harvard Sq., 70,000
s/f of converted mill buildings on
Harrison Ave. in Boston and several
high-end residences in urban and
suburban locations in Mass., Conn.
and Vermont. We have helped a number
of forward looking owners and developers
discover the environmental and economic
benefits of earth coupled systems.
In addition to significant savings
in fuel cost, maintenance costs can
be lowered by as much as 30% over “conventional” systems.
An earth coupled heat pump system
is an environmentally friendly, low
profile, low maintenance, energy
efficient, cost effective alternative
to fossil fuel burning systems with
a positive cash flow.
While there are no utility company “rebates” or
cost deferring grants available for
earth coupled heat pumps, the State
of Mass. has declared an earth coupled
heat pump system to be exempt from
sales tax. Not only that, but the
State Energy Code declares that energy
derived from the earth does not have
to be included in the energy budget
of a project when determining the
compliance of the project with the
State Energy Code.
There are lots of good reasons to
consider earth coupled heat pumps.
You don’t have to be a tofu
chewing, sandal wearing tree hugger
to like them, you only have to be
an intelligent, informed individual
with a strong desire to save money,
energy and the environment. |
