Conservation
vs. Sacrifice
Outdated
Conservation Efforts
Why
is over 90% efficiency not nearly good enough?
The
300% to 400% Advantage of Ground-coupled Heat Pumps
Popular
But Misleading Terminology
Avoiding Your Own Private Permafrost
The 'Passive
Solar' Element to Ground-coupled Heating
An
'Active Solar' Element to Ground-coupled Heating
A Geography of Terms?
Ground-coupled
Heat Pumps Fit In Almost Anywhere
Air
Source Heat Pumps
Advantages
of Ground-coupled Space Conditioning Are Clear
___________________________________________________________________________
- This
webpage will focus on the world's most universally promising future
for heating and cooling of enclosed structures such as homes,
stores and offices through a ground-coupled application of heat
exchange technology. This webpage argues for fullest possible
adoption of the best space conditioning (heating/cooling) technology
available because current space conditioning systems that are
thought to be good are clearly not nearly good enough for the
long term future of our planet.
The
clear divisions of efficiency among existing heating and cooling
technologies will be reviewed as well as some location/climate considerations
regarding applicability of ground-coupled heat pump technology.
Resounding economic and environmental benefits will also be reviewed.
- There
is a lack
of uniform terminology in the industry that comes up much too
often to be ignored so an aspect of this recurrent problem is
presented here. Although the 'geoexchange' heat pump industry
still has an immature lexicon, the hardware itself is fully up
and running:
"Heat pump
technology is relatively mature; ... While further incremental
improvements in heat pump technology and performance are
possible, their impact on the performance of the heat pump
industry will not be a driving force in its development.
Therefore, the primary challenge is to develop the market,
rather than the technology." -EnerBuild Workshop,
May 14, 2002 (1)
Heat flows naturally from places of high temperature to places of
low temperature. Heat pumping reverses this natural flow and makes
warm places even warmer and cold places even colder. The production
of cold in appliances and in air conditioning systems is fully accepted
as mature and reliable technology. Unfortunately, due to outdated
perceptions and outdated customs, people are not yet willing to
fully trust heat pumps to heat their homes and offices even though
heat pumps reliably produce more heat than cold due to the motor
driving the pump.
"The
heat pump itself cannot be the problem, as it uses the same
equipment as a refrigeration system and operates with the
same temperature lifts. The only difference is the system
into which heat pumps have to be integrated." (Hermann
Halozan) (2)
Clearly, the challenge
to go from trusting heat pumps with our food to also trusting heat
pumps with our homes is one of education, persuasion, community
awareness and community action. I feel the pursuit of such things
is a worthy goal for this Geography website.
Back
to the top.
The
Problem
Hundreds of millions of people
in developing countries have rising expectations to attain the comforts
they see in Western civilization. Unfortunately, energy-intensive
Western civilization does not provide a viable model for its own
future much less provide a model for the entire planet. -- The earth's
ecosphere cannot well absorb several times the present burning of
fuels so that the world's people can enjoy westernized standards
of comfort and ease.
- Fortunately, Western
civilization is fully capable of setting a far better example
than it does now on how to achieve and preserve human comfort
without destroying the environment. This challenge is being addressed
on two main fronts:
-
- 1) Renewable
and nonpolluting energy sources such as wind, solar,
geothermal, waves and tides are fast becoming viable partners
in our energy supply systems.
-
- 2) Conservation,
from recycling aluminum cans to turning thermostats down in the
winter, from more fuel efficient cars and light bulbs to adding
insulation, from stricter building energy codes to environmental
education, and more, is already having a considerable impact on
reducing energy waste.
Back
to the top.
Conservation
vs. Sacrifice
Conservation of energy is not inseparably linked
to hardship. It is inseparably linked to efficiency.
Conservation of energy simply means using less energy to do whatever
we are doing. Technology, industry and education are fully capable
of bringing about a fundamental change in the way humanity views
and uses energy in the future.
Back
to the top.
Outdated
Conservation Efforts
Modern furnaces
installed in the USA must have an (A.F.U.E.) efficiency of at least
78%. (Before 1992 many furnaces had efficiencies
as low as 60%.) The best furnaces now available
boast up to 96.6% efficiency. This sounds good
but it is not nearly good enough. (3)
'Combined Heat and Power', commonly called cogeneration,
is a viable alternative to simply burning fuel to power industrial
needs and then discarding the heat. In the past, it was common for
factories with waste heat to sell this type of heat to heat homes
and offices and/or provide hot water. The practice fell into relative
disuse as energy became inexpensive and reliable home furnaces and
hot-water heaters became standard. The practice is making a laudable
comeback where this energy resource is available.(4)
'Decentralized Generation': Another form of cogeneration
is for utilities to generate electricity locally to displace electric
needs and then use the waste heat from electric generation power
plants to provide space heating and/or hot water. This both utilizes
potentially wasted heat and eliminates substantial portions of transformer
and transmission-line losses that utilities normally face. (5)
This technology can also be privatized for greenhouses or apartment
buildings or other operations that need considerable light and heat.
Some private residences also use this method to displace electric
costs. Although most decentralized generation is only about 85%
efficient due to its electrical emphasis, its great advantage comes
from conversion of about 30% of the fuel's energy into electricity
which is a far more valuable form of energy than heat.
If electricity is locally expensive, the electric savings alone
may recover the full cost of the fuel consumed. [Ontario Gov. OCETA
(6) also CIEEDAC (7)
. See Table 1 for efficiencies]
Back
to the top.
Why
is over 90% efficiency not nearly good enough?
Modern technology is
capable of so much more than simply burning fuel to get heat. There
is enough heat already available that can be concentrated into useful
intensity by means of mechanical devices called heat pumps. Once
installed, these reliable devices can also produce cold for summer
air conditioning. The payoff is neither small nor tardy. It is as
much as 400% efficient and payback on new construction can often
come in just a few years.
-
The
300% to 400% Advantage of Ground-coupled
Heat Pumps:
- A heat pump
is simply a device for concentrating existing heat mechanically
(rather than getting concentrated heat by burning chemically).
It works rather much like a water pump. A water pump can move
water uphill but it does not create the water it pumps --it needs
a source to pump water from and a place to send it. The same goes
for a heat pump. It can pump heat in or out of your home but it
needs a source of heat (source temperature) on one end and a place
to dump that heat on the other end (sink temperature).
-
Your household refrigerator
is a heat pump. It pumps the heat out of your refrigerator and then
dumps that same heat into your home. As the inside of your refrigerator
gets colder, the outside gets hotter. The refrigerator heat pump
can pump out so much heat that water freezes and you get ice cubes.
This technology is remarkably reliable --more reliable than almost
any furnace.
The neat thing about
ground-coupled heat pumps is that modern units move 3
or 4 times more heat
energy than the energy used to run them. In other words, a 1000-watt
ground-coupled (or geoexchange) heat pump can deliver the same amount
of heat as a 3000 or 4000 watt electric heater. A excellent
tutorial explaining heat pump applications can be found
online at Maritime Geothermal Ltd. (8).
It is both thorough and easy to understand. (This company does business
in the Canadian Maritime Provinces --check out its case studies.
For those entirely new to heat pumps, note the blue box under their
Table of Contents. Click on it and you get 49 questions and answers
contributed by The Electric Heating Institute of Indiana.)
Back
to the top.
Popular
But Misleading Terminology:
One shortcoming of the
Maritime Geothermal site is their 'slang use'
of geothermal. Geothermal
energy usually pertains to special places on the earth where such
energy is both intense and easily accessible --as in Iceland. In
Iceland, common water pumps move geothermally heated water into
buildings to heat them. No heat pump is needed. A heat pump
does not pump heated water, water pumps do that.
In all fairness, so
many people use the terminology 'geothermal heat pump' that Maritime
Geothermal may have felt it had no choice. But, most often, this
terminology does not fit.
Even the terminology 'Ground Source' in the name
of the International Ground Source Heat Pump Association
(9) is misleading.
This 'Ground Source' terminology also does not
fit.
Here's
why:
Both 'geothermal heat
pump' and 'ground source heat pump' terminology suggest that heat
pumps can simply keep taking heat from the earth. This is untrue
in the majority of highly suitable locations where heat pump technology
can and should be used. If you simply pump heat out of the ground
(ground-source the heat pump) where natural geothermal resources
are not adequate to replenish that heat, you soon develop "your
own private permafrost". This can happen in as little
as two years even with an oversized ground loop. In places where
substantial heating is needed, the earth simply cannot sustain
unreplaced extraction of geothermal heat year after year. Where
geothermal heat is weak, the earth rewarms itself too slowly to
engage in extractive 'heat mining' over a long period of time.
[
"... skimping on the ground loop..." "...what you
have is your own private permafrost..." (1)
from page 1 of Appendix C]
Back
to the top.
Avoiding
Your Own Private Permafrost:
In most locations, after pumping a lot
of heat out of the earth the heat MUST be replaced. In this sense
you are using the earth as a thermal bank account. It may be a big
enough thermal asset to get you through any one heating season but
come summer you need to help nature put that heat back. Although
the earth absorbs the sun's heat and geothermal conduction from
deep in the earth both help redeposit heat automatically, these
are simply not enough to maintain the heat balance. During the summer
months most heat pump applications air-condition --using the building
itself to collect heat to help rewarm the ground. During these months
the system truly becomes a 'building source' heat
pump rather than a 'ground source' heat pump.
Another essential factor
in avoiding your own private permafrost is to have a properly sized
ground loop system. If you are "skimping on
the ground loop "(1)
size, you will
have permafrost before a single heating season is over. Once this
happens, the heat pump's efficiency collapses for the remainder
of the heating season as the ground-source permafrost temperature
quickly plummets to deep sub zero temperatures --increasing the
'lift' load of the heat pump. Artificial permafrost was a recurrent
problem twenty years ago when people tried to derive heat only from
compact ground loop fields. This permafrost problem quite properly
discredited attempts at simplistic thermal mining of the earth where
geothermal activity is not strong. All credible installers have
learned to somewhat oversize ground loops and/or make provision
to reinject sufficient heat in the warm season.
Back
to the top.
The
'Passive Solar' Element to Ground-coupled Heating:
"GeoExchange heat pumps use the Earth's
energy storage capability to heat and cool buildings, and to provide
hot water. The earth is a huge energy storage device that absorbs
47% of the sun's energy -- more than 500 times more energy than
mankind needs every year -- in the form of clean, renewable energy.
GeoExchange heat pumps take this heat during the heating season
at an efficiency approaching or exceeding 400%, and return it during
the cooling season."(11)
Back
to the top.
An
'Active Solar' Element to Ground-coupled Heating:
Solar Assist:
Another way to help reheat the earth if you do not need to air condition
much in the summer months is to send low-grade solar heat under
your ground loop system through a separate pipe.
All you need to do is warm the earth some degrees above freezing
--even a heat collector inside(!) an attic that tends to overheat
in the summer can provide this sort of very low grade heat. This
is a simple and elegant way to store up summer's excess solar energy
for the winter months for the price of some foresight, some pipe,
some environmentally friendly antifreeze solution and a thermostatically
controlled circulation pump. This is as cheap as any 'active' solar
collection/storage system gets. More substantial systems are, of
course, available but may not be all that necessary.
Back
to the top.
A Geography of Terms?:
- Despite the use of
'ground source' in its name, The IGSHPA (9)
, readily uses the term 'GeoExchange' in its
literature. This terminology is both appealing and functional
but at the time of this writing, 'Geo Exchange' and 'Geoexchange'
together get only a third of the Google hits for 'Ground Source'.
-
- Another term (haunting
places like the Plastics Pipe Institute (10)
and student thesis papers) is 'ground-coupled'.
Although this is a most descriptive terminology for building heating
and cooling applications, 'ground-coupled' got a mere 2650 Google
hits in April, 2003. However, if you are going to study this matter,
this term is important for your lexicon of relevant words. The
most necessary collection of search words appears to be: (Yes,
there is a plug here for standardization of terms.)
- 1) Geothermal
Heat Pump ..............................(double-ugh)
2) Ground Source Heat Pump ...........................(one
ugh)
3) Groundwater Heat Pump ............................(sometimes)
4) Water-source Heat Pump ............................(sometimes)
5) Geoexchange Heat Pump .......................(great P.R.
image)
6) Ground-coupled Heat Pump ................(accurate and
specific)
The reason that the
last is most accurate is that even groundwater (#3) is absolutely
coupled to the ground temperature. In certain applications a 'water-source'
(#4) is simply chilled by a heat pump and then discarded. The most
common example is a drinking-fountain --the heat is extracted and
the bulk of cold (heat-depleted) water is discarded. But even this
water usually comes into the building at earth temperature. As for
Geoexchange (#5), I cannot find a single proper definition but it
applies to flowing streams or lakes and is easily applied to a cruise
ship named the Spirit of Columbia ( http://www.geo-exchange.ca/en/geosuccessstories.html
). It seems to be a 'selectively generic' term that applies to heat
pumping almost any thermal asset in the geosphere other than the
atmosphere which is called 'air source heat pumping'.
For a major growth
industry with a bright future, I hope this industry adopts defined
and universal terminology conventions sooner rather than later.
If the system is coupled to the ground in order to alternately provide
both heat source and heat sink
functions using a relatively stationary thermal mass, then the terminology
should indicate this, neither more nor less. I went with 'Ground-coupled'
for this webpage. The immaturity of current heat pump application
vocabulary came as quite a surprise.
Back
to the top.
-
Ground-coupled
Heat Pumps Fit In Almost Anywhere:
Using a ground-coupled heat pump to heat and cool your home or
business requires some land. If you have a lot of land you can
use a system where the ground loop is laid out
in a long trench, this is usually the easiest sort of ground loop
to install and works best in regions where land is cheap. Because
the working fluid is shown leaving the building
hot and returning cool, (blue) the system is shown in home-cooling
mode --it's summer.
(14)
If you don't have a lot of land the ground loop can double back
and forth to attain the necessary length (or form a grid which involves
an unfortunate number of connections). This dense type of application
is very common but is quite susceptible to permafrost development
if not properly sized and/or is not recharged with 'waste' air conditioning
heat or solar heat during the summer months.
Air
Source Heat Pumps:
Air source heat pumps
(whole-house air conditioners that can both heat or cool) are more
efficient than any ordinary furnaces by attaining 200% or more efficiency
--but they are not nearly as efficient as ground-coupled systems
because the atmosphere is, almost by definition, very cold when
you need to heat and very hot when you need to cool. This is not
a subtle point.
"At
times people confuse GeoExchange with Air Source Heat Pumps.
While both transfer energy, air source heat pumps try to
remove heat from the outside air and there is simply not
enough heat in that air during a Wisconsin winter."
(11)
"The ASHP [air source heat pump] is a tempting substitute
for the traditional heating and cooling systems. ... However,
once the honeymoon is over the homeowner must settle down
to life with an ASHP. Air, with its low heat capacity, is
not a good source of heat. The heating efficiency of an
ASHP decreases as the air temperature decreases, often requiring
supplemental heat from the electric strip heater. The defrost
cycle is also a kilowatt hog. The exterior units are exposed
to the elements and can be noisy with the high air flowrates
required for heat extraction. The attractive initial savings
are quickly eaten up by the reality of higher operational
costs."
"While
the equipment and installation costs for a GSHP [ground
source heat pump] system can be twice the cost of traditional
heating and cooling systems, there are two main advantages
over the ASHP; the earth is a stable temperature heat sink
and water is an excellent heat transfer fluid. Depending
on the geological formations, moisture content of soils,
and water table depth the GSHP can use the relatively constant
temperatures and high heat capacity of the earth as an efficient
medium for heat extraction and rejection."
"The
effect on the owner of a GSHP system is opposite that of
the ASHP. While initial investment is high, yearly energy
savings provide a payback in from 5 to 7 years over conventional
heating and cooling systems." (12)
The advantage of reversible
air conditioning systems (air source heat pumps) is clearly in the
low-overhead cost of installation. But this technology is not nearly
adequate to deliver heat in wintry climates. In mild climates where
only a little heat is needed, they can function reasonably well.
Although, this application of heat pump heating and cooling is simply
not nearly as efficient as geoexchange systems, where the need for
heating and cooling is minimal there may be little to gain by installing
a highly efficient but far more expensive geoexchange system.
Back
to the top.
Advantages
of Ground-coupled Space Conditioning Are Clear:
The landmark 1993 EPA
study, Space Conditioning: The Next Frontier, found that
geoexchange ('geothermal') systems are the most energy-efficient,
environmentally clean and cost effective space conditioning systems
available. Payback of installation costs can come in just 5 to 7
years -- often it is even less on new construction. [see (12) above]
The EPA study also found
that geoexchange heating and cooling systems can reduce energy consumption
by over 40% compared to air-source heat pumps.(13)
This study was based on field performance data available at the
time. It was true then and it is more true now since the installed
efficiency of geoexchange systems has significantly improved since
that time.
"The
U.S. General Accounting Office estimates that if GeoExchange systems
were installed nationwide, they could save several billion dollars
annually in energy costs and reduce pollution." (13)
Obviously,
the dollar amounts of potential savings are a fast-moving target.
However, the savings to the environment are potentially huge and
of incalculable value. Every pound of combustible fuel burned produces
anywhere from two to three pounds of carbon dioxide, CO2, a greenhouse
gas. As the world moves to reduce CO2, it is difficult to imagine
long term success without rethinking what is efficient heating and
cooling. 100% efficiency is not good enough. We need and can achieve
highly energy-leveraged heating and cooling from geoexchange heat
pumps.
Furthermore,
customer satisfaction with geoexchange systems is nearly fantastic.
"Surveys by utilities indicate a higher level of customer satisfaction
for GeoExchange systems than for conventional systems. Polls consistently
show that more than 95% of all GeoExchange customers would recommend
GeoExchange to a family member or friend.(13)
The
focus of this webpage is promotion of ground-coupled geoexchange
heat pumping for both heating and cooling of homes, schools and
businesses because it can be gainfully applied almost anywhere in
the temperate regions of the world. Society needs to become responsive
to the rather extreme and multiple benefits that ground-coupled
heating and cooling can deliver.
Back
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Use
your browser's BACK button to return to your last text position:
(1)
"EnerBuild
RTD Focus Workshop Thematic Group 3: Mechanical Heating"
(Copy and paste the above, including quotes, into Google.)
(2)
Herman Halozan (28
pages, an entire issue of a heat pump oriented magazine):
http://www.etis.net/common/tech/tech019/tech019.pdf
(3)
Carrier Corporation:
(site contains A.F.U.E. definition):
http:// www.residential.carrier.com/faq/brands-3.htm.
(4)
Combined Heat and Power Association
(UK, homepage):
http://www.chpa.co.uk/
(5) Decentralized Generation
(COGEN,
Europe, homepage):
http://www.cogen.org/publications/reports_and_studies.htm
(6) Ontario Government
Publication, OCETA:
http://www.oceta.on.ca/profiles/admic/admic_tech.html
(7) Canadian
Industrial Energy End-Use Data and Analysis Centre (40 page document):
http://www.cdea.ca/pdf/cogen_Potential_in_Canada.pdf
(8) Maritime Geothermal
Ltd:
http://www.nordicghp.com/mg/hpworks.htm
(9) International Ground
Source Heat Pump Association:
http://www.igshpa.okstate.edu/
(10) Plastics
pipe institute (3
pages):
http://www.plasticpipe.org/pubs/download/statemt/StateQ.pdf
(11)
Geothermal
Heating and Cooling Systems
[2003? ©?]
Booklet by the Wisconsin Geothermal Association.
(12)
Paul H. Gendron, P.E.
(7 pages):
http://www.hq.usace.army.mil/cemp/e/Et/resident.pdf
(13) Brief
summary of E.P.A. study Space
Conditioning, The Next Frontier :
http://www.geo-enterprises.com/plain/Benefits.htm
(14)
image:
Burkhard Sanner (8
pages):
http://www.ubeg.de/Downloads/GeothermalHeatPumps.pdf
(15) image: By "energy right"
(TVA):
http://www.energyright.com/heatpump/geothermal.htm
(16) image: Inst. of Geophysics,
Zurich:
http://www.gtr.geophys.ethz.ch/Projekte/ShallowGeothermics/shallow.html