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Green Building News

Giant ‘Geothermal’ Community in the Works

Each of the 1,800 lots will have a ground-source heat pump for heating and cooling

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Norton Common in Louisville, Kentucky, is a mixed-use community where housing, schools, parks and stores are close to each other. Developers say the "Traditional Neighborhood Development" mimics the way villages used to be built.
Image Credit: Norton Commons
Norton Common in Louisville, Kentucky, is a mixed-use community where housing, schools, parks and stores are close to each other. Developers say the "Traditional Neighborhood Development" mimics the way villages used to be built.
Image Credit: Norton Commons
The South Village at Norton Commons will be matched by an even larger North Village where everyone will get a ground-source heat pump.
Image Credit: Norton Commons

Work is underway on an 1800-lot subdivision in Louisville, Kentucky, that according to its developers will be the largest community in the country that insists that every house must have a ground-source heat pump.

Builders who buy lots in the North Village of Norton Commons will have a free hand on what kind of houses they build, as long as they meet general architectural guidelines, but a ground-source heat pump for heating and cooling will be a requirement.

The project is a Traditional Neighborhood Development, a type of development which includes a variety of housing types and commercial buildings and is designed so people who live there can walk to many of their destinations.

Marilyn Patterson, director of marketing and general counsel for the development, said by telephone that there are a variety of advantages to requiring ground-source heat pumps, including better heating and cooling performance, greater efficiency than other options, and reduced environmental impact. A big part of the appeal is that no one living there will have to listen to a noisy outdoor compressor belonging to a neighbor with a conventional air-source heat pump.

In a news release, developers said well drilling has started for heat exchange tubing on the first 50 lots, and another 75 lots will be drilled in the spring. Construction could begin any time.

It will take 12 to 15 years to build out the entire North Village, she said. The 600-acre development already includes the South Village, with about 1,000 residential units, where ground-source heat pumps were not a requirement.

Houses will range in size and cost

Houses in the South Village range in size from 1,200 square feet to 8,000 square feet, and cost between $360,000 and $2 million, Patterson said. She expected the range to be similar in the North Village, but the first group of houses would probably be in the 2,200- to 2,500-square-foot range.

Requiring ground-source heat pumps makes the houses more expensive, adding from $4,500 for a smaller unit to as much as $15,000 for a large house, she said, but the 30 percent federal tax credit, good through the end of 2016, will take away some of the sting.

Builders will not be required to build to any particular efficiency level, Patterson said, although upgraded insulation packages and Energy Star appliances would probably be the norm. “The market demands they build efficient housing,” she said.

Developers also promote the idea that people who live in Norton Commons have a lot of what they need nearby: local stores, schools, and playgrounds in addition to housing. So driving won’t be as essential to life there as it is in many suburban settings.

“What could be greener than that?” she asked.


  1. JustHousing | | #1

    this is green building news?
    I'm not sure why this post belongs on GBA. Ground-source heat pumps are not in and of themselves "green." Using electricity for both heating and cooling isn't necessarily "green," especially if the generation source is coal-fired plants. According to the EIA, in 2013 93% of electricity produced in Kentucky was generated by coal.

    Requiring ground source heat pumps without requiring any level of building enclosure (or system) efficiency is a far cry from "green." I went to the website for the south village and the homes look attractive. They are expensive. There is no mention of efficiency whatsoever, although I did see a photo that shows the taped Zip sheathing on a home. But I also found this photo on a house advertised for sale. Note the date and time stamp (November 2014) and look at the windows and door glazing - looks like a lot of condensation to me.

    I pay for access to this site and expect to find reliable, valuable and accurate information. Please vet some of your posts a little more closely.

  2. GBA Editor
    Martin Holladay | | #2

    Response to Rachel Wagner
    GBA trusts its readers to be sophisticated enough to tell the difference between greenwashing and green building. This is a news story, accurately reported. Sometimes it's fun to throw out a few stories like this, to keep our readers on their toes and to await the reaction of our intelligent readers.

    I certainly agree with your conclusions.

    Rachel, I hope that you continue to read GBA and to share your comments.

  3. AntonioO | | #3

    Response to comment [1]
    If we're looking at the same photos, I think what your're calling window condensation could be paint over spray (onto a protective window film).

    But if I was the well driller for this development, I'd pay the developer a kickback for every well I was able to drill for these GSHPs. Is that too cynical?

  4. GBA Editor
    Martin Holladay | | #4

    Response to Antonio Oliver
    I agree that the photos are most likely showing paint overspray. The key detail in favor of your theory is the blue painters' tape.


  5. JustHousing | | #5

    nice work team!
    I agree with you, Antonio, about the paint overspray. I hadn't zoomed in. Thanks for catching that. I will limit my griping on this one to the requirement of GSHPs.

  6. AntonioO | | #6

    not a GSHP hater
    BTW, I'm not a huge skeptic of GSHPs. One of my neighbors has one in his new mansion. He has about 8800sf of living space including his basement, and his electric bill (at a rate of $0.12/kWh) for an all electric house is only about double my gas bill (at a rate of $0.97/therm). My gas is for heating only, and my 1954 built house is about 2600sf including heated basement space.

    For the record, his is the house that sticks out on the street.

  7. rjparker | | #7

    Geothermal Advantages
    Given inverter based air source heat pumps are just as efficient as today's geothermal units and cost much less, geothermal still has the advantage of quiet operation with the compressor and water to refrigerant coil heat exchanger tucked away in a sealed enclosure or in the basement. A geothermal is unlikely to need defrosting in the winter allowing even efficiency and heat output largely independent of the outside temperature. They will not degrade due to snow or freezing rain. What I wonder about is the impact on ground temperature when 1800 adjacent homes are absorbing heat in the winter and rejecting it in the summer.

  8. AlanB4 | | #8

    I have heard of cogen set up like this
    Generate electricity for the grid and use the waste heat for heating and hot water. They have the right idea, but perhaps ground source is not the best implementation. Maybe they will improve on the next one.

  9. user-1105327 | | #9

    lloyd alter must be grinding
    lloyd alter must be grinding his teeth at the article stating GSHPs are synonymous with geothermal energy

  10. Alex House | | #10

    1,800 homes in close
    1,800 homes in close proximity to each other and all extracting heat from the earth might very well unbalance the equation. The earth picks up the heat from insolation and a little house sucking up heat from a large patch of land can work but can the insolation levels over the entire development support the heating requirements of 1,800 homes? The math shouldn't be too complex, the big issue will be boundary lands and how the homes at the very center of the development fare.

    Slinky coil systems have run into this issue:

    If you were to apply the laws of thermodynamics to ground loop design, it would be clear that there is a limited amount of energy available from a given area of earth, and a limited amount of energy that the earth can absorb. Cramming in more pipe by using a slinky pit will have a number of effects:

    1. In heating mode, the loops compete with each other for the same thermal energy, interfering with each others ability to do the intended heat exchange. This results in very low temperatures in the loops in the centre of the pit, and lower overall loop temperatures. We’ve seen these loops running at 20deg F, abysmal performance. The earth is frozen and the moisture is crystallized, air pockets appear and the thermal conductivity nose dives. The system is forced to run on back-up heat, your operating costs go through the roof, and the high efficiency system you invested in becomes a black mark on our industry.

    I see this as a marketing gimmick, to get free publicity for the development and snag the true believers who are easily swayed by fads and gimmicks. The geo isn't the gimmick, it's the notion of an entire development which is the gimmick, especially when the land covenant leaves insulation levels open. The only unifying theme is geothermal heating, but standing alone this can be a curse or blessing.

  11. GBA Editor
    Martin Holladay | | #11

    Response to Erik Olofsson (Comment #9)
    This article did not report that "GSHPs are synonymous with geothermal energy." That's why we put "geothermal" in quotes in the headline. (Our headline is similar to one reading Kellogg's Announces That Sugar-Frosted Flakes Are "Healthy".)

    GBA has been fighting the use of the word "geothermal" to refer to ground-source heat pumps for many years. For example, see Geothermal Energy and Narrow Streets.

  12. Aaron Birkland | | #12

    Interesting experiment
    At first, I was thinking they were going for something like a 'district' setup with shared infrastructure (pumps, wells), but it looks like each house will have its own independent system.

    The density of houses looks fairly high. I know that some commercial installations of ground source heat pumps rely on huge arrays of densely packed vertical wells, but I don't think I've ever seen the same density for residential. As residential loads are so different (not so heavily biased toward cooling), it would be interesting to see how the loops behave over time. Temperature drift for very dense vertical fields is not unheard of, but that's usually temperature drift *up* due to cooling-heavy commercial-type loads.

    Summer heat pumped into the ground vs winter heat extracted may be fairly balanced for a house in Louisville.

    If they actually end up building this development according to plan, it would make a fascinating case study 20-30 years from now.

  13. vensonata | | #13

    Compare this to Drakes Landing community seasonal storage
    The community of Drakes Landing near Calgary Alberta , Canada. Is interesting to compare. They heat a 50 house community of "pretty good houses" by seasonal storage from solar thermal panels into ceramic tubes vertically 300 ft deep. It took about 3 years to "charge" the ground storage. But they have been 100% heat and DHW for the last 3 years. They are in a 9000Hdd area at latitude 51 on the Canadian prairie. IF they can do it there its possible in very cold northern climates. The webe site has live feed of their production and consumption, temperature in the ground storage etc. Quite the show! It was a subsidized effort but they say that it is economical with the experience they have gathered and are happy to share. Various delegations from around the world including Korea, are considering implementing the system. Check it out. Look up "Drakes Landing solar community"

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