When it comes to “kicking natural gas” and reducing a home’s carbon footprint, geothermal heating & cooling is the “gold standard.” But it’s extremely expensive to implement as a retrofit and still quite expensive on new construction.
My friend, Martin Voelker, a leader with the Colorado Renewable Energy Society, recently replaced his gas forced air heating system with geothermal, and the cost for drilling the 300-foot-deep wells in his backyard was $18,000, which included running the pipes into his house but didn’t include the heat pump itself. Even though such a project would garner a 30% rebate under the Inflation Reduction Act, that’s still a heavy lift for any homeowner.
I know of another home which installed geothermal pipes horizontally in their large backyard at far less cost.
New construction is more affordable, because you can have the wells drilled within the footprint of the future home while it’s still open ground. And if it’s an entire subdivision, such as the Geos Community in Arvada, the cost is reduced because all the wells can be drilled one after the other.
In that scenario, each home still has its own geothermal well, but what if you could drill a geothermal well that was extensive enough to feed multiple heat pumps in multiple buildings?
Those Harvard students may have known something the judges didn’t — that Eversource Gas, a Massachusetts utility, had already begun a “networked geothermal” demonstration project 17 miles west in Framingham. That project is featured at www.HEET.org, short for Home Energy Efficiency Team, which in 2017 started promoting the concept of gas utilities delivering 55º water instead of gas to multiple buildings from a grid of geothermal wells. (The above graphic is from their website.) Think of it as a 21st Century version of what Con Edison still does in NYC, which is to deliver steam from its central boilers to local buildings through pipes under Manhattan’s streets. But steam, unlike water, can’t be used in the summer for air conditioning.
A local vendor that I recommend for both geothermal and air source heat pumps is Sensible Heating and Cooling, (720) 876-7166.
How Does Geothermal Work?
Geothermal heating does not require the presence of a thermal feature such as a hot spring. In fact, if you dig down about 10 feet anywhere at our latitude, you’ll find that the soil temperature is about 55ºF year-round. Circulating a fluid through underground piping heats that liquid to 55º so a heat pump can then raise its temperature to 100º or so for heating purposes utilizing either radiant floor heating, baseboards or forced air.
Geothermal is far more efficient than an air-source heat pump system which takes in outdoor air as cold at 10 degrees below zero and works much harder to achieve the desired temperature for heating.
In the summer the 55º fluid from geothermal requires far less energy to be cooled further for air conditioning your home.
I came across a website that gives a great description of heat pumps, how they work, and why they are more efficient. Here’s the link for it.
Most Americans are accustomed to heating systems that generate heat using fossil fuels, wood, or electricity. But heat pumps don’t create heat, they move heat. Here’s how the process is explained on that website:
Heat pumps function similarly to refrigerators or air conditioners, which take warm air from one space and send it to another. In the winter, a heat pump transfers heat from the outdoors inside and, in the summer, it reverses this process.
There are two main types of heat pumps, and both can function as space heaters or coolers and as water heaters.
A ground-source (or “geothermal”) heat pump sends a mixture of water, antifreeze, and/or a refrigerant through a network of pipes buried below the frost line. As the liquid passes through the pipes, it absorbs the earth’s approximately 55-degree heat. The liquid is then drawn up into a compressor, which heats it further, creating a vapor. The heat pump then distributes the warm air through ducts or tubes throughout your home. In the summer, the heat pump reverses the process, taking warmth out of the house and transferring it to the earth.
An air-source heat pump extracts heat from the air rather than from the ground. It functions the same way, but because air temperature, unlike earth temperature, can get very cold, it has more work to do bringing up the temperature. As with a ground-source heat pump, a reversing valve inside the heat pump allows the same unit to function as an air conditioner in the summer. At right is an air source heat pump that was retrofitted into a ducted forced air heating/cooling system of one of my current listings in Golden.
It’s sad to see elected officials not taking the time to learn about new technology, especially technology that contributes to abating the effects of climate change.
Such is the story unfolding in the city of Arvada, where the city council — historically super friendly to developers — has bought into a false narrative by a developer/builder team that all-electric homes are not affordable or desired by today’s home buyers.
This is happening despite the fact that Arvada is itself home to a well known model of affordable all-electric homes in the Geos Community located west of Indiana Street and south of 72nd Avenue.
The Geos Community was partially built out several years ago without any natural gas lines. Home heating is by geothermal and air source heat pumps. Cooking is on induction cooktops. Heat pump water heaters provide the domestic hot water. Solar panels on each home provide all the electricity needed for these and other needs, making all 26 current homes “net zero energy.”
Before the Geos Community could be fully built out, its original developer was forced into selling due to a divorce settlement. Otherwise the remaining 250 homes — a mix of townhomes and single family homes — would have been built to the same net zero standard. The new developer had promised to do so, as described in a Nov. 17, 2020, post on MileHighCRE.com, but it reneged on that promise and is in the process of installing natural gas lines to the new homes, greatly annoying and angering the owners of the original 26 homes.
The fossil fuel industry duped all of us by promoting methane as a “natural and safe” gas for use in homes. This gas is highly heat-trapping (80-100 times more so than carbon dioxide), prone to explosion and causes many health issues (see Electric4Health.org). During the last decade Colorado added an average of 20,500 residential gas customers each year. BigPivots.com reports that our state now has 1.8 million residential gas customers. That trend needs to be reversed. There’s no need to keep building home reliant on natural gas.
Geos homeowners appealed to Arvada’s city council to deny the developer a permit for the gas lines, but the city declined to do so. The neighbors, however, are not giving up and have 267 signatures (including my own) on a petition to reverse that decision. The City of Arvada has advised the current Geos residents that this issue is closed.
Arvada should be proud that it is the home of the country’s first “geosolar” community which has, among other honors, been featured several times in the Metro Denver Green Homes Tour. I myself have produced narrated video tours of three Geos homes for that tour, which you can view here, here, and here.
As part of its COP 26 coverage this week in Glasgow, CNN will air a segment on Geos as a home building model to be emulated, essential for addressing climate change.
The Geos Community located southwest of Indiana Street and 72nd Avenue in Arvada is a shining example of what’s possible in net zero energy home construction.
All Geos homes are solar powered and have no natural gas service. Heating and cooling is provided by ground source or air source heat pumps. Water heaters utilize heat pumps, not gas, and all the homes and townhouses are built according to passive solar design standards.
Two Geos homes were on last fall’s Metro Denver Green Homes Tour, and you can view narrated video tours of them by clicking on that link.
Now a developer has bought the remaining land within the Geos Community but is intending to install natural gas service in all the homes they will build. Naturally, the current residents are quite upset about this turn of events and are hoping to convince the City of Arvada not to allow this diminution of the original intent of Geos to be a strictly net zero energy community.
Visit www.DiscoverGeos.comto appreciate this community’s net zero energy mission.
Rainer W Gerbatsch, a Geos resident, in an email to Linda Hoover, Senior Planner for the City of Arvada, expressed concern about the new developer’s plan to deviate from the community’s principles by installing natural gas in future homes. Here is Ms. Hoover’s emailed response:
Thank you for your strong interest in your community. I was forwarded your concerns regarding the new upcoming development in the GEOS Neighborhood and I will do my best to address your comments. The GEOS Development was approved 12 years ago. I took over as the staff planner for this project in 2014 when the previous planner left the City. When GEOS was approved, it was intended to be a sustainable community and Norbert Klebl tried for many many years to obtain the funding to make that happen. To date, the only homes constructed out there are on Block 10 which has a mix of the staggered “checkerboard” single family detached homes and townhome units. This totals approximately 38 units out of the 282 planned. While the existing homes have a number of sustainable features, SunStudios (Architect) and Laudick Engineering are telling us that marketing of this concept has been very difficult in part due to the economics of having a development without gas service and other unique features of this development, such as having custom designed mechanical heating systems, etcetera. Most of the larger home builders want developments that have gas service. As you may know, this development went through a bankruptcy last summer. The new owners are currently in the process of working with a new builder – Dream Finders Homes. As Dream Finders comes on board, they are planning on keeping many of Norbert’s original concepts, but wanting to make some adaptations to make it economically feasible. The lot layout which has the staggered checkerboard placement of single family detached homes in the middle of the block and townhome units on the ends of the block will remain as originally intended. As a result these homes will continue to have the same architecture and passive solar design. In addition, solar panels will be placed on the rooftops and appliances will be energy efficient. These new homes will follow the Building Code to construct energy efficient homes. The building codes adopted by the City already allow various paths/choices to construct very efficient (minimum energy code) all the way to net-zero buildings – the traditional codes were followed to build the first 38 units. It is my understanding that DreamFinders would prefer to have the project served by gas, but are still looking into the economics of this issue.
This development was and still is zoned PUD (Planned Unit Development) which has its own unique design requirements rather than following the standards in the City’s Land Development Code (LDC). The GEOS Design Book states that “architecture should strive for Energy Self-Sufficiency and the avoidance of Fossil Fuels.” It also identifies net zero homes as one of the intended goals (not requirements) and further clarifies that that “goal can be achieved by combining good solar orientation and good insulation with geothermal or solar thermal heat, and photovoltaics.” However, it is silent on the issue of gas service.
As a result, we would allow the development to be built without gas service (just as was done for the first phase of GEOS) provided alternatives were ensured. However, no restrictions were included in the Design Book or on the project approvals that prohibited gas service. Passive systems, energy efficient buildings, heat recovery ventilation are guidelines not requirements.
Sent 5/13/2021
Here is Rainer’s response to Ms. Hoover’s email:
I am familiar with the background of GEOS and the more recent events. Contrary to your statement that net-zero homes are difficult to sell, recent sales activity of homes in GEOS show just the opposite – there is high interest in these homes resulting in higher than expected returns for the seller and very short listing periods. It would appear that cited developer/builder statements are either uninformed or demonstrate an unwillingness to engage in construction practices that are a win-win situation for the builder, the buyer, and perhaps most importantly, the environment we all rely on. Also, I contacted and asked the architect whether he supported the cited developer/builder statements, and he responded that he did not.
Studies of completed net-zero buildings in Colorado (including GEOS) conducted by SWEEP also show that the initial cost of net-zero, all-electric homes at this time is on par with so-called traditional (polluting) construction. Net-zero construction represents a clear choice once future buyers understand that (1) these homes represent (already at this time) substantial yearly savings in energy use/expenditures (fossil fuel based energy costs will only increase as the cost of natural gas escalates based on the need to curtail and ultimately eliminate gas as a potent driver of climate change), and (2) eliminate health risks related to exposure to gas appliances and fossil-fuel burning heating devices that generate a variety of air pollutants which have been linked to cancer, decreased lung function, heart disease and a host more diseases. While these risks have been recognized for some time, they are finally receiving mainstream media attention. However, resolution is not possible without the engagement of all levels of government with developers/builders on more responsible construction practices. In summary, net-zero construction is currently superior to traditional construction because of reduction in emissions, elimination of health issues traced to fossil fuel based energy use in homes, and escalating future costs of fossil fuels, particularly natural gas.
GEOS’ prominence as a leader in de-carbonized and sustainable community living is recognized locally (we have been visited by members of sustainability committees of several Colorado towns), and nationwide (CNN’s chief environmental correspondent Bill Weir visited GEOS; CNN will be airing a nationwide broadcast on GEOS, highlighting its features as the model for home construction to achieve decarbonization and healthier interior air quality for residents). In that vein, responsible governments on all levels are preparing and committing to road maps with the goal to rapidly reduce emissions in home construction through elimination of fossil fuels, increased efficiency in appliance/lighting and heating/cooling, as well as the production of on-site renewable energy. In order to have an effective road map, commitments are required which mean nothing less than elimination of fossil fuel use in all new buildings. Consider that the IEA has just issued a special report; this statement stands out: Fatih Birol, the IEA’s executive director and one of the world’s foremost energy economists, told the Guardian: “If governments are serious about the climate crisis, there can be no new investments in oil, gas and coal, from now – from this year.”
It is 2021, and permitting a developer/builder team the inclusion of natural gas infrastructure for about 250 new homes, based on questionable developer/builder concerns of perceived marketability or economics, thereby locking in emissions for the life of the buildings, subjecting owners to health risks related to gas pollutants and escalating energy costs (not considering future mandated retrofits based on the trajectory of climate induced changes), is not responsible, sets the wrong signal and constitutes a serious setback in rising to the challenges of the climate crisis.
The City of Arvada has the opportunity and responsibility to address the climate crisis, facilitate the transition from fossil fuels to renewable energy, and protect the health of residents from natural gas pollutants. Both can be realized, simply and effectively, through rapid adoption of policies and building codes that support state and nationwide goals in emission reductions. We urge you to demonstrate your commitment to a sustainable future not only through elimination of the fossil fuel infrastructure for the next phase(s) of GEOS, but through a city-wide commitment to net-zero construction, fossil-fuel free construction.
As I write this, I have just completed shooting videos of the 15 homes on this year’s Metro Denver Green Homes Tour.
The tour, currently in its 25th year, takes place on the first Saturday in October. Normally, you would register for $10 and get a book describing the homes, along with a map. Armed with that, you create a self-guided tour of the homes which interest you. You’d have to complete your tour by 4pm that day, followed by a reception and expo.
Because of the pandemic, this year’s tour will be totally virtual, which is actually better because you’ll get a link to view detailed videos of every home on the tour and not miss any of them due to time constraints. We won’t release the URL for the tour until October, but when we do you’ll be able to take your time to view all 15 — and the virtual tour is free! I’ll publish that URL in my October 1st column.
Meanwhile, let me share one particular lesson that you will learn from viewing the 15 videos: that gas forced air furnaces, no matter how efficient, are obsolete.
One thing you learn really quickly in the sustainability arena is that America is far behind other countries when it comes to energy-efficient technology. That’s because our fossil fuel costs have always been lower than in Europe and Asia, specifically Germany and Japan, where you’ll find the most innovation and product development. Just look at this chart from statista.com of electricity costs in different countries:
Germany 33 cents/kWH, Japan 22 cents/kWH, United States 13 cents/kWH
With our cheap energy, higher standard of living and higher incomes, Americans have long been able to waste money and energy with abandon. The result has been to leave it to other countries to create more energy efficient and less costly products.
Since home heating and transportation are the most energy-intensive aspects of modern life, that’s where we have seen the greatest innovation abroad. We in America continue to play catch-up and hang on to old technology. Our continued use of gas furnaces is an example of hanging on to old technology.
For a long time, I thought that higher efficiency gas forced air furnaces was the direction we should go to reduce our carbon footprint. However, after viewing the videos of highly efficient net zero energy and even energy positive/carbon negative homes, I think you’ll agree that it is time to abandon altogether that method of heating our homes.
Carrier Hybrid Heat Pump
When Rita and I purchased our current home in 2012 and installed the maximum solar photovoltaic system allowed by Xcel Energy (10 kW), we looked into how we might heat our home using the free energy we were creating from the sun. That’s when we learned about and purchased the Carrier Hybrid Heat®system, which uses an air source heat pump paired with a gas furnace to heat our home in the winter and cool it in the summer. It looks just like a gas forced air furnace, but the gas flame only comes on when the outside air is below the temperature at which the heat pump can generate heat from outside air.
Although Carrier still sells its hybrid system, heat pump technology has advanced far enough that gas back-up is no longer needed in our region. However, since our hybrid furnace uses natural gas so seldom, we won’t replace it anytime soon.
When your gas forced air furnace needs replacing, don’t make the mistake of replacing it with a newer and better gas forced air furnace. Instead, look into the many alternative ways of heating your home, which you’ll learn about when those 15 video tours are released in October. (If you can’t wait, Google “heat pumps” and investigate the options.)
Solar thermal (Wikipedia link), using both flat panels and evacuated tubes, is another technology, typically augmented by electric and heat pump units, which can provide heating as well as domestic hot water. A few of the homes on this year’s tour have solar thermal systems.
Geothermal heating (link to vendor),present in other homes on the tour, takes advantage of the earth’s temperature below the surface. In our latitude that subsurface temperature is about 55°F year-round. It is extracted by running a liquid-filled loop 300 feet or so into the earth and using a heat pump to heat that 55-degree liquid for radiant floor or forced air heating, or using it at 55 degrees for cooling in the summer. That takes less energy than our air source heat pumps, which take much colder air from outside and extract heat from it in the winter, and can then cool your house (like A/C) in the summer.
The thing to remember about heat pumps is that they don’t create heat (such as from burning fossil fuels), they move heat. The difference between a traditional A/C system and a heat pump system is that a heat pump moves heat in two directions, not just one.
Blower door test during a home energy audit. Credit: Holtkamp Heating & A/C, Inc.
There is so much more to learn about efficient heating and cooling of your home. But first, to provide the highest return on investment (and lowest heating cost), you will want to improve your home’s insulation. A blower-door test (energy.gov link), conducted by an energy efficiency professional, identifies where the leaks are in your home, so they can be sealed. A heat recovery ventilator (HRV) (Wikipedia link) can then help you bring in fresh air without losing your home’s heat. (A heat exchanger within the HRV transfers the temperature of the outgoing air to the incoming air.)
Thermal mass (Wikipedia link) can play a big role in reducing the energy needed to heat a home. You’ll see thermal mass applications in many of this year’s videos. Concrete, brick, water and even dirt can function as a thermal mass to accumulate heat from the sun and then release it slowly after dark. (There is an example of a “climate battery” (vendor link) using dirt on this year’s tour.) With the proper roof overhang on south-facing windows, your thermal mass is shaded from the sun during summer months but exposed to the sun in the winter, when the sun is lower in the sky.
The best way to heat and cool your home may be different than the best way to heat and cool someone else’s home, and it’s hard to do justice to this subject in a single article.
Here are a couple vendors I’ve used who would, I’m sure, be happy to give you some free advice about the best heating system for your home.
Bill Lucas-Brown, owner, GB3 Energy – www.GB3energy.com, 970-846-4766 or bill@gb3energy.com. He sells and installs heat pump systems, but also does energy audits, including blower-door tests and will super-insulate your home as he did for my current home and for the Golden Real Estate office.
Dennis Brachfield, owner, About Saving Heat – 303-378-2348 or info@aboutsavingheat.com. Dennis does blower-door tests and will super-insulate your home, based on what the test reveals. He does not sell or install heat pumps or mini-splits, but he can refer you to someone and probably give you good advice about their applicability to your home. I have known Dennis for 30 years, and he has tested and insulation several homes for me.
Note: HomeAdvisors would be a reasonable choice for such a project. I have not used them, but I am impressed at their quality control regarding the vendors they work with. Did you know this national company is actually based in Golden? Originally called ServiceMagic. (888) 921-3034
For geothermal heating, see the link in the paragraph about geothermal heating for a vendor who sounds great to me, but whom I haven’t used.
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