Energy Efficiency, Geothermal Heat Pumps and "Negawatts"

The lowest cost unit of energy is one that is not used

Douglas A. Dougherty, President and CEO, Geothermal Exchange Organization
January 24, 2013 | 36 Comments

A recent study by Ceres — "Practicing Risk-Aware Electricity Regulation: What Every State Regulator Needs to Know" — concluded that the least cost and least risk for future energy resources is energy efficiency. Indeed, the lowest cost unit of energy is one that is not used.

U.S. Buildings are Energy Gluttons

According to the U.S. Department of Energy (DOE), buildings are the largest single sector of total U.S. energy consumption. Indeed, the buildings sector accounted for a whopping 41% of primary energy use in 2010. The buildings sector consumes about one third more energy than either the industrial or the transportation sectors. And since 60% of energy used in buildings is for “thermal loads,” some 24% of all energy used in the nation is for space heating, cooling and water heating.

A unique renewable energy technology with vast potential for energy efficiency and savings stands ready to assist architects, engineers, developers, builders, facilities managers and homeowners dramatically reduce the thermal energy demands of buildings. That technology is the ground-source—or geothermal—heat pump (GHP).

High Efficiency GHPs Slash Energy Use

GHPs are today’s most efficient, “green” alternative to traditional heating and air conditioning equipment, offering significant environmental, economic and societal benefits. Using a concept called “geothermal exchange,” they tap the clean energy of the sun naturally stored in the near-surface of the earth, transferring this free heat to buildings in winter and back to the ground in summer.

They work by circulating water through a closed loop of durable, high-density polyethylene pipe installed either horizontally or vertically in the ground beside or even beneath a building. During the winter, GHPs transfer heat energy from the ground to buildings for warmth. In the summer, they provide cooling by rejecting unwanted heat from buildings back to the earth, while providing free hot water. This simple renewable energy concept has profound energy efficiency, cost and environmental implications.

According to the U.S. Environmental Protection Agency (EPA), “Geothermal heat pumps are among the most efficient and comfortable heating and cooling technologies currently available….,” and EPA’s Energy Star program website says that, “…qualified geothermal heat pumps are over 45 percent more energy efficient than standard options.”

EPA says that GHPs can reduce energy consumption — and corresponding emissions — up to 44% compared with conventional air-source heat pumps, and up to 72% compared with electric resistance heating with standard air-conditioning equipment. Recent advancements in GHP efficiencies only buttress these facts.

More importantly, says DOE, “The biggest benefit of GHPs is that they use 25% to 50% less electricity than conventional heating or cooling systems. This translates into a GHP using one unit of electricity to move three units of heat from the earth.” So while a standard electric heater or natural gas-fired combustion furnace can provide no more than 100% of the energy it uses, GHPs in heating mode can offer efficiencies of 400% percent and even more.

In cooling mode, GHPs have significantly higher energy efficiency ratings than competing air-source heat pump systems. A recent working paper by Western Farmers Electric Cooperative (Anadarko, OK) describes dramatic drops in efficiency for air-source heat pumps struggling in air temperatures exceeding 95° F on hot summer days. By comparison, efficiency degradation of GHPs under the same conditions is negligible.

GHPs Produce “Negawatts”

A typical 3-ton residential GHP can reduce summer peak electricity demand by approximately two kilowatts (kW). Take that times 500 homes equipped with GHPS, and you have a peak power demand reduction of a megawatt. That’s a megawatt of electricity NOT used, which creates what energy experts around the world have called a “Negawatt” since famed environmentalist and Rocky Mountain Institute founder Amory Lovins coined the term over two decades ago.

The idea of a Negawatt is cutting electricity consumption without necessarily reducing energy usage through energy efficiency. And given their efficiencies, one of the best ways to get there is to promote and install more GHPs across electrical power service territories.

Lovins said it best: “There isn't any demand for electricity for its own sake. What people want is the services it provides.… Nonetheless, most of our utilities have gotten into the habit of thinking they're in the kilowatt-hour business, so they should sell more.… For some reason, it's hard for them to get used to the idea that it's perfectly all right to sell less electricity, and so bring in less revenue, as long as costs go down more than revenues do.”

Electric Utilities Should Embrace GHPs

GHPs produce Negawatts, which have a higher value than any megawatt of costly power generation. Because of their technology, GHPs produce the thermal equivalent of a Negawatt at a fraction of installation cost compared to a megawatt of electricity produced by any renewable power source like wind, solar and biomass. And that doesn’t consider the fact that GHPs avoid the need for expensive transmission lines required by power plants, whether they be renewable, fossil- or nuclear-powered.

By providing essentially free renewable energy from the earth, GHPs can work wonders in lightening the load on our oft-strained electrical grid. This is especially true for those sweltering days with looming blackouts when consumer demand soars for air conditioning and power generation is maxed out. For electric utilities, geothermal heating and cooling reduces summer peak demand and actually builds load (and power sales) in the winter—while providing comfort levels that foster happy customers.

Another benefit of GHPs is carbon emission reduction. This is an especially important policy consideration as concerns grow about climate change caused by burning fossil fuels to produce electricity. According to Oak Ridge National Laboratory, one ton of GHP capacity over a 20-year operating cycle avoids CO₂emissions of 21 metric tonnes. A thousand homes would therefore reduce carbon emis-sions by 63,000 metric tonnes over a 20-year period.

Renewable Energy Policy Should Promote GHPs

Thirty states and the District of Columbia have enforceable Renewable Energy Portfolio Standards (REPS) that mandate a certain minimum share of electricity offered by utilities come from specified renewable resources. To date, only two of those states include the thermal load avoided by GHPs as renewable. All the others have definitions of “renewable” that state “energy generated” and exclude the term “thermal load avoided.”

States with REPS need to recognize the value of Negawatts and amend their standards to include the thermal load avoided by GHPs. Utilities should be allowed to receive credit for Negawatts, and in turn they should offer financial incentives for the installation of GHPs by their customers.

The socioeconomic benefits of producing Negawatts are too many to list here. Homeowners spend a majority of their energy costs to heat, cool, and produce hot water. A GHP can significantly cut that cost, and at the same time yield more disposable income. Innovative dealer payment options and utility on-bill financing programs can actually reduce monthly energy outlays while paying for GHP systems on the installment plan.

The Kaiser Foundation (Tulsa, OK) financially supports the installation of a GHPs in Habitat for Humanity homes in an effort to help break the cycle of poverty through energy efficiency. The average energy cost for such homes is less than a dollar a day. Both residential consumers and business owners alike can save energy and increase their bottom lines by utilizing GHP technologies.

And unlike the conventional heating and air conditioning industry, the GHP industry employs far more people than those working in factories and installation. That includes a nationwide network of drillers, drill rig equipment providers, and pipe and grout manufacturing workers, to name a few. Negawatts generated by GHP installations create thousands of jobs right here in the USA.

Our ability to use the earth for geothermal energy exchange is limitless. The technology is waiting to be used, and it’s proven to be the most energy efficient means to satisfy the thermal loads of buildings. Their geothermal exchange of renewable energy from the earth produces Negawatts, the cheapest units of energy produced and consumed. We must forge new public policies that recognize this fact, for the benefit of the environment, our economy, and the nation.

Lead image: Energy efficiency sketch via Shutterstock

36 Comments

Gary Richardson
February 5, 2013

Horizontal placement of heat storage coils may tweak out a few extra deg C if placed under heat-absorbing asphalt in direct sunlight with moisture barrier curtains extending down the surrounding edges to mitigate cold moisture penetration from outside the pavement into moisture absorbant thermal media within the thermal matrix.

Additionally, cold storage may gain similar benefits from opposite sourced locations (north-facing solar reflective/shaded surfaces with similar thermal media containment practices where applicable.

On vertical wells, zoned propagation via phase changed fillers to thermally isolated layers dynamically sensed after install and may be ongoing if intermittant vs continuous groundwater penetration is detected. The question is can the cost of filler, sensors, actuators and energy expended to trigger phase changing be less than the heat or cold stored. One key obstacle is integrating the technology into filler fabrication in one step. More expensive copper tubing may be preferred to transfer electricity to addressable actuators and also return an RF, RF/Optical signal from self-powered sensors via braided transmission media incorporated during tubing manufacture (in one step). The idea is to incorporate plug and play application of adaptive thermal/cold storage with upgradable apps downloaded to optimize operations further.

gideon goudsmit
February 4, 2013

Please keep in mind that geothermal is good for both cooling and heating, the combination is even preferred since warming up the source in summer helps to heat more efficiently in winter.
Giving a example in our house water temperature coming up after the winter is around 7 C. while we started out with 13 C now since we also cool the house passively in summer the temperature climbs back up due to the warm water being fed through the ground loop to 13 degrees. For a good use of the heat in the ground a distance of at least 15 ft is preferred but more is always better since it creates a larger heat or cold sink.
Our house has never been more comfortable since the geothermal heating and cooling was installed and the energy consumption has decreased by 50 %
We use a modular system from NIBE in Sweden that have been making geothermal heating since over 30 years but a few good american companies like Waterfurnace are also very experienced.
The system we installed has COP of 5.0 or very high but this high cop is only there if heating the water up to 40 C. once raised higher the COP drops COP is efficiency in other words for each 1 KW H put in to the system we get 5 Kw of heat out with a cop of 5.0
Floor heating is a must for a high cop since luke warm water of 40 C. can be used to heat the house

V. Bruce Stenswick
February 4, 2013

One thing that is not being mentioned here is the fact that we should get completely off of fossil fuels. In terms of CO2, each million BTU of natural gas is equivalent to about 6 gallons of gasoline. For many homeowners in northern climates, their carbon footprint from heating their home is probably close to equivalent to their carbon footprint from driving. If we ever start to take climate change seriously, ground source heat pumps will probably be the technology that prevails in the niche of home heating in northern climates.

Gary Richardson
February 4, 2013

The problem I hear with sealing up a house and increasing the R-value is in more damp environments mold growth becomes more of an issue. Even with heat/energy exchangers to transfer heat in and out of the intake or exhaust has to have it's filters changed/cleaned more often during damp weather.

John DAngelo
February 3, 2013

Byron,

I love your last sentence. We have been throwing good technology at bad design for over 100 years. That is since the utility companies where created. All they want to do is continue to have inefficient buildings built and have all of us "PLUG" into them to run that gas, electric, wood burning, or whatever heating device and have them meter the electric you need to run your other electrical needs. The GWHP is a good sell for them because 99% of people who get one can not afford solar electric after a GHP install.

Electric companies push GHP more than any other heat source because they know that when someone installs a GHP that are customers for life.

Yes, if a house is built with todays technology, best insulation, best windows, good sealing techniques,etc then a house only needs the smallest of heating system or cooling systems and sometimes a "convention" heating system is not even needed.

I have always said , you build a inefficient house, and pay for every increasing utility bills or you build a very efficient house and not only can you put in renewable energy provide for what little energy is needed to heat and cool that structure and not be a slave to the "system" the rest of your life.

byron zorzos
February 3, 2013

Many good points are raised here. It might be suggested at this point however to refer back to the Negawatt concept perhaps within the following context. In a building intended as a single family residence, that is designed and built to the most efficient standards available, using readily available building materials,heating loads can quite readily be reduced by 90% or better. Combine this with a design paradigm that reverts to "pre-McMansion" homebuilding where more people occupy less space ( roughly a four-fold increase in per capita sq.ft occupied post 1950s) and we have an energy consumption per capita of 2.5% present day values. (This may sound simplistic at first but do the math)
In a nutshell if homes were built to attainable energy-efficiency standards and to an appropriate size, there is not a GSHP that is readily available small enough to efficiently heat such a space.
GSHPs are indeed efficient, but let's not keep throwing good technology at bad design philosopy.

David Redding
February 2, 2013

For residential, small scale installs, regional contractors where there is that kind of uniformity underground, and the big aquifer in your area probably are contributing to this track record. It is not uncommon.

My point is, that the technology is not well understood, the industry is still learning from research, trial and error, and it seems many think this is the "silver bullet" for all locations everywhere....it part of "silver shotgun".

Ricky Hannah
February 2, 2013

The earth is one hell of a heat sink. I do not believe you can raise or lower the ground temperature when you drill 150-400 ft. wells unless you have spaced the wells too close together.

My 4 wells are 10 ft. apart here in east central Illinois. the bottom od my wells are in a 53 deg. water aquifer so the heat transfer is great. Granted if their is stone 150 ft. below the heat transfer would be slower and the wells might need to be closer to the 400 ft depth and or spread out more. The so called profesionals that design low or non-preforming systems need to go back to school on btu calculations or get out of the business. I had many choices for contractors in my area.

I choose the one that had been in the Geo thermal business for over 20 years with over 700 installs. Hire an experienced contractor. Do not purchase on price alone.

David Redding
February 1, 2013

Yes, the GSHP does, pump to and from, but over the year there is a net "add" of btu or "deduct" of btu to the ground. If those are widely out of balance, the earth surrounding the earth, will over time, rise in temperature. Interesting interest regarding poly tubing, however, it seems likely than an quake event would shear the underground piping, no matter the material. You are correct, an additional source/sink will alter heat balance equation, and is site analysis issue. Most GSHP are installed in static soil-temp condition, also most are closed loop, that is what I refer to. There is some good research in the latest few issues in the ASHRAE journal covering numerous GSHP issues.

Gary Richardson
February 1, 2013

@David-Redding,
The Ground Source Heat Pump does both pumping heat to and from the ground via the vapor compression unit. This reduces the amount of energy required to reach the desired btu.

http://en.wikipedia.org/wiki/Geothermal_heat_pump

My interest is to look deeper into designs of separate heat and cold storage sources with the use of heat insulatve and/or heat conductive fillers surrounding the heat-exchanger tubing. Also, knowing when to not use polyethylene tubing for an install (earthquake zones). These two factors are especially interesting for consideration in the pacific northwest because of wet climate sapping the ability to store heat seasonally and additionally to take advantage of the potentially cooler wet ground during summer months if this type of soil is available. The two types of source configurations I see are open vs closed sources. Some designers may have developed a bi-layer slurry that acts as either an oven or refridgerator to minimize losses (closed system) or increase conduction to tap sources available such as heat from under asphalt, cold from a nearby running stream.

David Redding
February 1, 2013

Not all electricity is generated with fossil fuel , but the majority is. The current wind portfolio is still pretty low nationally, I believe less than 5%. Certainly there are places that individuals can buy into a carbon-less power generation source (I also do it) But, as fully scalable option, it is does not quite pencil out. As far as Natural gas vs. coal, NG is cleaner, but not not at all carbonless and it is quite far from being so. I am not saying the GSHPs are a bad idea, in certain applications. There are other complications as well that are unrelated to the carbon and cost issue - these are mostly related to the constraints of the technology itself, and the lack of understanding of the technology. For example in the the pacific northwest, the GSHPs being installed in the commercial sector are having serious problems with heat balance in the ground loop. What this means is that because it is mild here, there is a mismatch of btu's being extracted from the ground in winter to that added in the summer. This causes the loop temperature to degrade over time, and the refrigeration compressors to 'cut out', and not function. In Minnesota and the midwest in general, the heat balance works out better, because there are more extremes, but careful attention must be paid to the heat balance. There is significant research being done with this problem sponsored by ASHRAE and other organizations. This is a tricky topic, because the degradation I am referring to usually takes 6-8 years to manifest itself, and the memory of the construction industry (at least on the design and construction side) is quite short. However, for the building owner, they begin to notice when all of the HVAC no longer works. I am not sure if this degradation occurs in the residential sector, (my professional expertise is in commercial projects) with large arrays of wells.

V. Bruce Stenswick
February 1, 2013

@DAVID-REDDING
Yes, but not all electricity is generated by using fossil fuels. The Minnesota legislature commissioned a study a few years ago on this, and it was found that the CO2 emissions for a house with a geothermal heat pump would actually be higher than using a furnace. I have heard this quoted many times as a reason not to put in a geothermal heat pump. There are two problems with this. First, it was a snapshot in time. As coal plants are retired and replaced with natural gas, and as more wind comes on line, the amount of CO2 produced by a geothermal heat pump decreases. At the time, the CO2 produced was not significantly higher than a high efficiency furnace. I do not remember the exact numbers. Suppose we get our act together and remove all carbon emissions from electricity generation, then anything that runs on electricity, whether it is electric cars or ground source heat pumps, will not produce CO2 either. Second, the report assumes a homeowner does nothing special. In Minnesota we have the option of paying extra to get "green" electricity. I buy all of my electricity from our local "WindSource" program, thus my heat pump emits far less carbon than the best furnace on the market.

David Redding
January 31, 2013

Another point, that adds to these ideas.

In most areas of the country, (really except the PNW), the electricity that is used to power the heat pumps is generated using fossil fuels. A common metric used is site-source energy, this is a DOE thing.

For example, electricity has a site-sources of about 3.34:1, meaning at the plant 3.34 energy units is burned to make 1 unit of electricity. That is often why houses in area that are heated with electricity have heating bills around 3x that of those heated by natural gas.

The big idea of GSHP is that they are 400% efficient when they have a "COP" of 4, some can get better. What happens then is that 400% efficiency is "washed away" by the site to source ratio of 3.4. So, for carbon, heat pumps sometimes don't pencil out especially when you talk about the money part of it.

There is quite bit of analysis that needs to go on for every situation. It is not hard, but it is complex.

Parker Thompson
January 31, 2013

@john-dangelo-175629
Yes, your electricity bills will go up with a GHP. But a dollar spent is a dollar spent on HVAC regardless what the fuel source is (propane, natural gas, electricity, etc). The major benefit of GHPs is that versus propane and electricity you are reducing that total dollar expense by 70%. So what's the difference if you are paying money to your electrical utility or your propane company? I've been to homes here in the Rockies that have frozen solid and had pipes burst because the propane company forgot to do a refill while the owners were out of town. So you can avoid that whole mess by installing a GHP.

In comparison to natural gas, you will only be reducing your dollars spent on HVAC by 30%. In most areas of the US GHPs rarely make economic sense when compared to natural gas furnaces in a retrofit scenario. New construction should always be considered for GHPs becuase you can take advantage of 30% federal tax credits on the distribution system (ducts & radiant) which are costs you will incur on that home no matter what type of HVAC you are installing. And there is less costs associated with landscaping if done during new construction.

You are right that insulation, windows, solar and siting are the most cost effective ways to reduce HVAC bills. But that's not always an option if you home was built in 1721 like fastcat445's home. If your goal is to completely zero out your emissions and utility bills then you should go solar.

I must also mention that we don't know what cost for fossil fuels will look like in a decade (or even next year!). So choosing a GHP will buffer you from spikes in those utility costs. Electricity rates don't fluctuate as dramatically as most fuel so you will gain a bit more price security in that regard.

Every home and person has differing needs. So we will all have to make educated decisions on a case by case basis. The bottom line is this: we need to promote all energy efficiency measures.

David Redding
January 31, 2013

Fastcat-Gary correct unit is Kw * h. It is a consumption value, often confused.

Also, keep in mind that the "heat pump" is a vapor-compression refrigeration machine that moves the Btu from one fluid body "air in house" to another fluid body, the "ground".

It is not merely using the "55 degrees" in the ground, which is often misunderstood.

gideon goudsmit
January 29, 2013

That is correct Gary 9000 Kw/h per year

V. Bruce Stenswick
January 29, 2013

Considerable discussion on how much electricity heat pumps use. My house was built in 1979, 2 x 4 walls, R-13. If I did not burn any wood, I would use about 7500 kwh each winter to heat my house. On our local utilities time-of-day plan, that works out to be equivalent to the best furnace available and natural gas costing about $3.50 per MMBtu. It is equivalent to about $4/MMBtu on the flat rate. I also pay extra to get wind generated electricity, and start a fire in the morning so the heat pump does not run much during the day. Off-peak rates are about $0.02/kwh and on-peak winter rates are about $0.11/kwh.

Gary Richardson
January 28, 2013

@fastcat445,
You mean 9,000 KW/H per year right?

gideon goudsmit
January 28, 2013

Hallo John the house was originally build in 1721 and completely rebuild in 1996 the 2 gas heaters needed to be replaced so that is when i decided to go for heat pumps 9000 kw per year at $ .11 ct per kw = $ 990 per year if i had to buy in. Most of the 9000 is consumed between octobre and march or in 5 months. Y The total pv array is 29000 wp and we get about 18000 kwh out of the solar array and another 8000 kwh out of the 2 skystreams Greetings

John DAngelo
January 28, 2013

Thanks for clearing this up.! Sounded like you where buying 9000 kW from the utility. You still never told us how large your PV array is.

So to run the two heat pumps is 750 kW per month. That is as about as much electric energy as the average American uses in their household without any heating costs.

If one where to buy that power at $.11/ kWh that would be about $1000 a month. AT $.12/kWh that is $35/MMBTU. Natural gas here in the USA would cost about half that. Seems to me that you spent an awful lot of money for renewables to operate two GHP when perhaps another fuel would have been less expensive. OF course you will never have to worry about increased utility bills! I find it interesting that you have a solar thermal system to heat your domestic hot water but not hot water to heat the house.

What type of heat did you have before installing the GHP or was this new construction? I am assuming it was new construction.

gideon goudsmit
January 28, 2013

Hallo John
it is 9000 KW per year that is consumed by the heat pumps ( 2 x )
we get no bill from the utility company but so far they paid us out for 9000 Kw per year and that resulted in a credit note of 900 € per year.
yes we have 400 squire meters of solar panels mostly 315 watt Sunpower panels , for the rest the house is very energy efficient with roof wall and floor insulation , all the lighting is led and hot water is made with 3 solar panels to heat a 100 gallon hot water storage .
In total we get 26000 Kw in from sun and wind and that is mostly used to heating the running of the house and for our electric car.

John DAngelo
January 27, 2013

fast cat

Thank you for the feedback. Is that 9000 kW a year or month? So yes your natural gas went down but your electric bill went UP. If you have renewable energy to offset that increase that is great, but as you well know it is far less expensive to NOT have a need for electricity than to have to generate it. All renewable energy equipment costs money as you know.

Natural gas is still one of the least expensive forms of energy to heat with here in the USA but I have no idea what your cost per MMBTU of natural gas i s in the Netherlands.

So even with TWO Skystream generators, and a solar 4000 Sq ft array (kW?- must be VERY large array as our 5 kW array is about 1000 sq ft.) you still have a $900 electric bill? WOW when was that 7700 sq foot house built? Seems like you use one heck of a lot of energy to heat your house. But if one's house is not well insulated, not facing south or in a site that i s shielded from the sun not much you can do but to have a higher than average energy bills.

gideon goudsmit
January 27, 2013

Hallo John our house is 7700 sq ft or 700 m2
We use 9000 kw more than before but use hardly any natural gas anymore , only for cooking. The money spend on energy is €7000 less or $ 10000 , that gives return on investment of roughly 24 % , since we generate all our electricity from solar 4000 sq ft and 2 skystream wind generators we feed back 9000 kwh less into the grid the feed in tariff in the Netherlands is $ 0,10 per kwh the total energy cost for heating and cooling is $ 900 per year

Gary Richardson
January 26, 2013

Excellent replies to this article!

Gerry Wootton
January 25, 2013

There's also a particular type of wood common in the Carolinas that has a peculiar buffering ability based on a phase change of the pitch in the wood that happens near 20 C - nice if you like the rustic look of exposed wood. It would be really neat if you could buy wallboard that does a similar thing.

Gerry Wootton
January 25, 2013

Of course heat pumps need energy to operate. But then so does your typical gas furnace. Motor efficiency is an important number - the difference between roughly equivalent gas furnaces with high efficiency variable speed motors and those without is quite substantial. Usually, when they state 'efficiency' they're only talking about natural gas consumption. Here's a good test - can you program you're programmable thermostat to disable the system during peak hours and still maintain a level of comfort? If not, better insulation and/or more passive thermal mass is the most cost effective solution. This can be done with additional heavy wallboard on acoustic lath(I learned this from sound studio design where you always need cooling but you rarely need heating). For new construction, the central load bearing wall should be masonry work(not wood framing).

Ricky Hannah
January 25, 2013

Rick Hannah Urbana, IL. Net Zero Plus home. 2552 sq. ft home with full basement built in 2010 with ICF walls. Regular Propane HAVC bid was $12,285.00 Ground Source Heat Pump bid of $22,000.00 for 4 ton system with four 150' deep wells reaching water at 53 deg. The $22,000.00 includes price of $1,000.00 per 150' hole. 30% federal tax credit of $6,600.00 Net extra investment of $3,115.00 after tax credit. Electric bill averaged $132.00 per month first 12 months with power at 11 cents per kwh. I had the GSHP oversized 31%. The two 5,000 watt heat strips never come on as I have had them disconnected since the system was installed. Best money I ever spent. Have winter thermostat set at 69 deg. and Summer of 76 deg. 10,810 watts of solar at cost of $24,500.00 after rebates and tax credits take care of all electrical needs plus enough for 12,000 miles per year of electric car driving.

Frank DiMauro
January 25, 2013

GHP is a great concept but we need to get the price down so that it matches normally installed units in the average size homes. I only use GHP in large homes or commercial units. Other comments right on the mark. Good envelope (SIP's a good idea) control of air quality by a good quality bath fan on a timer. Solar thermal for DHW and heating requirments. Photovoltaics for electricity use. Net Zero at a cost competetive with standard building cost. I do it and so can you. Keep up the good fight.

John DAngelo
January 25, 2013

fast cat, How much did your electric bill increase? I know that it did not decrease correct (unless you where heating with electric resistant heat to begin with) ? $41,000 for how many Sq feet of space conditioning?

John DAngelo
January 25, 2013

Geraldr has it right! That is what I am talking about!

John DAngelo
January 25, 2013

All a heat pump does is lower your propane or natural gas usage and RAISES your electric bill. When I read articles on how great ground heat pumps (GHP) are, NO one ever mentions that one simple fact, including this author. YOUR ELECTRIC BILL will go up when you install a heat pump. That said overall you will have a more efficient heating and cooling system, but the price is sky high. We had an esitimate in 2007 for a GHP for our 1600 Sq ft home for $28,000! I suspect that price today would be well over $30K. And after spending that money I would have to increase the size of my PV array to accommodate the extra electric costs which would bring the cost of a GHP to maybe $50,000.

Instead of a GHP I choose to update our windows, install more insulation, install a solar hot water system all for well under $30,000, obtain tax credits reduce my dependence on electric companies and LOWER my energy bills, not increase them forever. (electric costs will ONLY increase over time for people using DHP unless they own their electricity and you never will being tied to an electric meter)

The best way to heat and cool a house is not to simply plug in an expensive heating and cooling system but the insulate the heck out of your structure (new or old) and then use renewable energy to heat and cool that structure. The end game here is to not only save money, but to do it in an SUSTAINABLE way.

The best heating system in almost any building is low temperature radiant floor heating and the best AC is a downsized unit or no unit at all because your building envelope is so well insulated. Insulation is the key to providing heating and cooling systems that are very inexpensive and with the use of on site renewables can operate for free. Now that is the future of heating and cooling, not installing expensive GHP systems.

Gerry Meself
January 25, 2013

We are considering installing Geothermal, for environment and cost reasons; however we are concerned about the quality of our house AIR since it appears that all of the air we breathe will be cycled through long, flexible plastic pipes. I notice that Leeds and many green building methods seem to have downplayed INTERIOR AIR QUALITY. Does HDPE flexible hose off-gas as little as chemical industry used to say pthalates were safe? - thank you

Gerry Wootton
January 25, 2013

There's a very simple and basic principle: to a great extent the average ambient temperature is close to a comfortable level while the short term ambient temperature can be quite variable. By simply buffering an enclosure while isolating from ambient as much as possible, the enclosure can be kept at a temperature close to the average. The amount of additional energy then required is the amount needed to raise or lower the average interior temperature to the comfort level relative to the ambient average plus whatever is needed to offset inadequate buffer capacity and insulation losses. The secondary advantage of such a construction is that, as long as the time constant is more than 3 days, the energy needed to make adjustments can be purchased at off-peak rates. A ground water system is an expensive buffer as compared to internal thermal mass such as stone and concrete structures or rock cribs. Of course, insulation improves the cost efficiency of any buffering scheme. I own a triple brick house with interior rubble stone foundations which can ride out a heat wave or a cold snap for 3-5 days as long as windows and doors are kept closed. A good companion technology is an HVAC heat exchanger which minimizes the energy losses associated with admitting fresh air.
Not only is building HVAC a substantial portion of load, much of it is inefficient with a capital I.

gideon goudsmit
January 25, 2013

We installed water to water heat pumps in both our office and house and the comfort level has increased while the actual energy cost have halved. for the house 5 holes were drilled to 400 ft deep with close loop pipes and both the passive cooling and the active heating work very well.
The cost to do a installation like this for a total surface area of 700 M2 was a bit over € 30.000,00 0r $ 41.000,00 but the reduced energy cost give a good dividend on the investment besides the fact that our fossil fuel burn ( natural gas ) is finished

Frank Berry
January 25, 2013

Don't know much about heat pumps...understand they use the natural heat load in the earth to heat up/cool down. Easy to understand.

What's tough is what happens if a HDPE pipe breaks down 20'-150' in the ground? Is there a redundant ring placed to "take over"? Earth shifts constantly and subtly. I wonder about how often "initial tubing might be inclined "statistically" to break, get kinked etc.?

The physics are smart...how is the reality of install? And for residential or larger buildings..isn't vertical smarter than "larger horizontal lay-outs"? What guarantees do "drillers" give on the High Density PE tubing laid out?

Thanks-

V. Bruce Stenswick
January 25, 2013

I heat my house with one. They are the best thing since sliced bread. That being said, they are expensive due to a shortage of installers and a shortage of well-drillers. When I installed mine, vertical boreholes for the loop field were $1000 each in the Minneapolis-St. Paul area. The last time I checked they were $2500 each. 2.5 times as expensive in 11 years. Contractors also often put in system for houses one size too large. A homeowner should aim to have the heat pump max out about 70% of maximum load and use electric resistance heat to pick up the slack on the rare occasions that it is needed. Suppose your coldest temperature is -20, and you want your indoor temperature at 70, that is a 90 degree temperature differential. 70% of that is 63. 70 - 63 = 7. So you would want your heat pump to max out when the outdoor temperature is 7, and use a supplemental heat source when it is below that.

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Doug Doughtery

Doug is President and CEO of the Geothermal Exchange Organization, the "Voice of the U.S. Geothermal Heat Pump Industry." GEO is a non-profit trade group that represents the political and business interests of its member companies across...