Green Heat and Air Conditioning
From: Fred H Olson (
Date: Fri, 16 May 2003 09:25:02 -0600 (MDT)
Cat Barron Oak Village Commons Austin, TX <ccbarron [at]>
is the author of the message below. 
It was posted by Fred the Cohousing-L list manager <fholson [at]> 
because the message included an attachment.
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Here's some info on ground-source ("geothermal") heat pumps, which may
be interesting to some cohousing groups looking for more efficient


Cat Barron
Oak Village Commons
Austin, TX

Info from John D. Manning, PE, Beardsley Design Associates (addr at end)

First of all, kudos to everyone who spoke out in the recent issues of BIG
GREEN (Big Green Digest - 05/05/03) regarding Ground Source aka geothermal
heat pumps, it is that passion that will drive the changes we are all
striving for....  

I would like to convey my take on this, if nothing else, interesting
technology.  Since 1982, I have lived with a system, installed hundreds of
systems, sold material on well over a thousand installations, and designed
scores of systems, and prior to becoming a geojunky, I received the UTC
Design Achievement Award for Heat Pump Design while working at Carrier
Corporation.  So although I continue to be a student of the technology, the
"scar tissue" I have acquired in the past 25 years has provided me with a
perspective that is at least a well-founded bias....

To characterize geothermal heat pump systems with a brief discussion about
COP's and electric generation efficiency is like trying to describe your
mother as "a woman with gray hair"... I don't even know your mother, but I
am sure that description does not do her justice.

The geothermal technology is truly multi-dimensional, however, before I
embark on a treatise to fully describe the technology and it's place in the
marketplace, I would like to support the concept that it is better to reduce
demand then to discuss the most efficient heat/cool source.  As an example,
the Cambria (GOLD - LEED 2.0) Project reflects an approach that reduced
demand (compared to typical office space the square feet per ton was about
650 vs 350-400 sq feet per ton for a typical similar office).  This demand
reduction was accomplished through the architectural elements of
incorporating day lighting, efficient artificial lighting controls, and a
raised floor air distribution system to name just a few.  However, this
reduced demand allowed the geothermal system to be downsized and the entire
mechanical system was installed for $11/sq foot (without any of those
exorbitant utility rebates).  So let's talk economics....


Perhaps the biggest myth about geothermal is that it does not reflect a good
economic choice without rebates...  Personally, I am not a big fan of
rebates, because they do create an artificial market, where the investments
of many businessmen and women are at the mercy and subject to the whims of
utility companies.  Fortunately, the utility landscape has changed and today
the most common rebate/incentives are managed state-wide through a more long
term approach through organizations such as the New York State Energy
Research Authority (NYSERDA), which is currently offering a pre-qualified
rebate of $800/ton.

When discussing economics, it is important to separate the residential
market from the commercial market.  The HVAC industry in the residential
market is plagued with a constantly degrading commodity mentality.  There is
extreme variation across the country, with Florida being an example of how
low it can go.  Air conditioning systems with electric resistance heat are
being installed for as little as $400 a ton.  And in that market I know
several contractors who are successful at selling geothermal systems in the
residential market albeit at a much higher price tag.

Within, the residential Market there is also a great disparity in the
economic realities.  Most markets do not have experienced contractors who
can price a job with the experience that would allow them to make money
without a whole lot of "contingencies" built in.  However, I am familiar
with contractors who have installed thousands of systems.  For example, in
Oklahoma, I am familiar with a contractor who is changing out air source
heat pumps for $4995 for a 3-ton system, including the loop field and heat
pump, and he is making money.  

The geothermal "do-it yourself" market is an un-tapped opportunity.  I have
helped dozens of homeowners, who, with access to a backhoe, were able to
install systems for $5-7,000.  The development of "Stab" fittings and
non-pressurized flow centers has allowed the geothermal technology to be
installed almost as easily as installing a washer and dryer (including
plumbing and electric hook-ups).

Consequently, it is very difficult to make blanket statements about the
economic justification of geothermal HVAC Systems in the residential market.

The commercial market, although very diverse, has a more consistent level of
quality and pricing.  At the low-end of the spectrum are the gas-electric
rooftop equipment/systems, while 4-pipe VAV systems dominate the high end.
The typical range for a commercial HVAC System is $8 to $20 per square foot,
with local market conditions affecting it up or down.  In the past 3 years,
all the geothermal projects that I have designed and were installed, fell in
the range of $10 to $16.50 per square foot, prior to any rebate.  The
projects included a dormitory, office building, several schools and a
doctor's office.  Rebates provided a discount from $2-$4 per square foot.
So, I can emphatically state that geothermal is directly competitive with
comparable commercially available technology, and anything the architect can
do to reduce the load will manifest itself with an even more competitive
geothermal option.

But there are many horror stories out there.... Such as a project that went
to bid and the result was a geothermal system that came in at $36/sq foot,
obviously blew the budget...  I would suggest that engineers who elect to
design a geothermal project without the benefit of experience are doing a
disservice to their client.  The danger of poor design is not only a higher
first cost, but also operating costs that are way out of line.  I actually
performed an energy audit on a facility with a geothermal system, and it
turned out that the circulating pump was consuming more energy then all the
heat pumps combined, the engineer should have been "Tarred & Feathered".
The conventional engineering mantra of "2X + 1" can kill a good design
before it even gets off the drawing table.  Let's go beyond economics....


A comment was made as to "How could geothermal heat pumps have lower
maintenance costs then regular DX systems that use the same components?"
There are two very significant differences in the stress that is experienced
by the identical components in two different applications.

The first is the inherent pressure ratios differences associated with
air-cooled condensers vs. water-cooled condensers, and the fact that the
stress on the compressor is directly related to pressure ratio.  An
air-cooled DX system will condense at temperatures 25 to 35 degrees above
the air temperature, while a water-cooled condenser will be 12 to 15 degrees
above the water temperature.  Additionally, for a given air conditioning
load, the temperature of the fluid in the ground loop is considerably cooler
then the air temperature, further reducing the stress on the compressor.

Secondly, when compared to an air-source heat pump, there are no defrost
cycles on a water source heat pump.  Consequently, the same components will
experience significantly different stress levels, thus increasing the
inherent life expectancy for a compressor in a water source heat pump.  But
what about comfort....


Ideally, in the heating mode for forced air systems, the perfect supply air
temperature is one that feels warm to the touch, but not so warm as to cause
excessive air stratification.  Two extreme examples of an uncomfortable
supply air temperature are an air-source heat pump that can supply air at
such a cool temperature that it can feel drafty and a conventional furnace
that can supply heated air at temperatures as high as 140, which will cause
stratification and a sense of having a warm head, but cold feet.  A
geothermal water source heat pump supplies air at a temperature between 95 &
105, which is ideal.

Perhaps the most comfortable form of heat is in-floor radiant heat, which a
water-to-water heat pump can deliver at extremely high efficiencies.  A COP
of 5.0 is easily achieved when producing water at a temperature of 80-90

One of the keys to comfortable cooling is humidity management.  Cooling
without enough dehumidification can result in a clammy feeling, which is
certainly uncomfortable.  Water source heat pumps have excellent sensible
heat ratios, and as a result of a consistent loop temperature can be sized
closer to the load requirements, which minimizes the negative effects of
short cycling.  How can we be comfortable if we are damaging our


Using Carbon Dioxide emissions as the key parameter of gauging environmental
impact, and comparing the New York State Average CO2 emissions per KWH of
.957 lbs/KWH to the embodied CO2 for natural gas of 117 lbs/Mbtu a
comparison of geothermal to conventional HVAC systems can be made.  With an
average COP of 4.0 and a 40% improvement in cooling performance and a
Natural Gas combustion efficiency of 82% (and adding fan energy impact of
5.8 lb/Mbtu, which is typically overlooked) a CO2 emission reduction of
47.7% is easily obtained.  Being located in Rochester Gas & Electric Service
Territory would result in a 62.4% reduction.  And the ultimate goal would be
to source the electricity from a renewable source and eliminate CO2
emissions by 100%.

As we as a society become better at producing electricity a geothermal
installation that is "plugged into the grid" will continue to improve in
environmental performance, as opposed to an on site fossil burning
technology, which will lock the facility into a given emissions level for
the life of the system/facility.


Show me an architect who appreciates not having to hide outdoor equipment or
try and make a chimney look good and I will show you an architect who likes
geothermal heat pumps.  Numerous historical renovation projects have
benefited from the use of geothermal heat pumps because of being able to
maintain much of the original character of the building.  As I am writing
this, Auburn Memorial City Hall is an example of such a project.  For 70
years, the employees of the City of Auburn did not have air-conditioning,
not even a window AC Unit.  Currently a geothermal system is being
installed, and by the time the heat of the summer arrives the system will be
operational with no visible sign of the system.  The citizens of Auburn will
be pleased that they are not only efficiently keeping the facility
comfortable, but it is being accomplished without compromising the visual
appeal of the building.


Geothermal heat pump systems offer an incredible opportunity, but not just
on one front.  From simple economics, to comfort, to excellent reliability,
to reducing our environmental impact, etc., this technology is commercially
available and is applicable on virtually all types of applications,
including underground electrical vaults, to ice rinks, to office buildings,
to schools, to historical projects, to low income housing, to hospitals to
name just a few.  

I look forward to hearing/reading your comments.

Respectfully submitted,

John D. Manning, PE
Beardsley Design Associates
64 South St; Auburn, NY 13021
P: 315-253-7301 / F: 315-253-7306

There are in fact four very different stumbling blocks in the way of
grasping the truth, which hinder every man however learned, and scarcely
allow anyone to win a clear title to wisdom, namely, the example of weak and
unworthy authority, longstanding custom, the feeling of the ignorant crowd,
and the hiding of our own ignorance while making a display of our apparent
-- Roger Bacon

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