Approximate cost
richardlion
| Posted in Green Building Techniques on
I’m looking to install Geothermal heat/ac in a commercial building in north NJ. I need the approx cost for a 12,000 sq. ft. single-story office building. I was inform 6 units, 4 wells but no specifics were given. I know its not all the info needed but i was hoping to get a high ballpark figure.
Thanks, Rich
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Richard,
The quick answer is the following: "More than any other heating system you can think of."
If you want a more specific number, talk to contractors.
Richard , More information needed . I can say one thing , 4 wells does not sound right . I have done several homes larger than 10,000 sq ft and none of those had a requirement of less than 8 vertical bore holes . Be very careful that you don't get shorted on holes . Heat exchange cannot be forced and you will end up in a disastrous situation .
I am in ocean County and can help if you wish . 732-581-3833
I'm also highly suspicious of only needing 4 wells.
The last job I saw priced for geothermal was a retrofit of an old 5500 SF house in NC (zone 3/4 border), about 6 months ago. That was 5 wells, and about $125K for the whole sheebang. Air source heat pumps were ~$40k less.
These days it's hard to recommend geothermal if there's any decent exposure for photovoltaic.
Richard,
Needless to say, the cost of a ground-source heat pump for a 12,000 square foot office building will be higher than the cost of such a system for a typical single-family home. Here is some information on costs for single-family homes.
In my article, Are Affordable Ground-Source Heat Pumps On the Horizon?, I wrote:
"One fan of the technology, Brian Clark Howard, has provided the following guideline to system costs: “In our book Geothermal HVAC, my co-author, Jay Egg, crunches the numbers for a typical homeowner, based on his 20+ years in the business. For a home geothermal system, he estimates the total installed cost at $42,000.”
"This estimate is similar to those made by two installers of ground-source heat pumps from Maine, Jeff Gagnon and Jim Godbout. In an episode of the Green Architects’ Lounge series on the GBA website, Gagnon estimated the cost of a residential GSHP system (including the cost of a drilled well) at $30,000 to $42,000, while Godbout gave an estimate of $40,000 to $50,000."
While the cost for a commercial and residential GSHP system may and probably will vary , it should not . Does it take more energy to heat a sq ft in a commercial building as opposed to a residential building ? No . Would one use different heat pumps dependent on application ? No . Will the commercial building require less energy based on usage patterns and average occupancy ? Yes . Will contractors charge a commercial entity more because it's a commercial building ? Quite probably . Is this honest ? No . Might a 12,000 sq ft office building need cooling in the winter ? Yes . Could the residential building require cooling in the winter ? Yes . Will most buildings of this size have similar controls ? Yes .
Attached are quotes for a project taking place at present . This is a 13,565 sq ft residential building , a bit larger than the 12,00 ft commercial space . It is also in NJ and in an area south where prices tend to be a bit lower , albeit not that much . Mind you it is a terrible building and unfortunately was built prior to any of the contractors bidding to have any influence on it's design . At almost 18 BTUh sq ft , it is less than optimal . Forgive me , I did everything I could . This homeowner insisted on hydronic radiant floors and low temp / high output baseboard . Our price has yet TBD because of constantly changing requests but should be around 200K in addition to the 2 attached quotes .
Is GSHP a good option in every area or building ? No . Are there better options ? Yes . Does anyone believe that the Earth where this heat is taken from is heated by the Sun ? That is another discussion .
Thanks, Richard.
So here are the three quotes:
Quote #1: $108,900
Quote #2: $ 89,500
Richard's quote: About $200,000
Here's a back-of-the-envelope comparison as a reality check: if a ductless minisplit costs $4,000 (installed), then $89,500 will buy you 22 ductless minisplits. That's one minisplit per 545 square feet.
Of course, that would be a ridiculous system, and I'm not recommending it. Just a simple cost comparison.
Martin ,
I would point out that those are 3 quotes that must be added together for a total of 398,400.00 . That is a quote from the well driller (89,500) , the HVAC contractor ( 108,900) , and ours to furnish and install the radiant tubing and baseboard and make sure all the stuff plays nice together . Although not mentioned on the HVAC contractor's quote , it does include balanced mechanical ventilation . So , all in , 15% of the project budget for HVAC as a whole . Actually right in line with what a properly designed A+ system should cost . You cannot get an A+ system for D grade prices . That's where the nightmares begin , as you are aware .
http://www.healthyheating.com/Thermal_Comfort_Working_Copy/comfort.htm#.VcoTjvkp8Zw
http://www.healthyheating.com/How-much-to-budget-for-HVAC-2.htm#.VcoTPfkp8Zw
Once again I state that there are much better options at present to heat and cool a home than GSHP
Richard,
Oops! I didn't read the quotes carefully. Thanks for the clarification.
So, the ground-source heat pump system will cost as much as 100 ductless minisplits.
One difference between a large commercial system and a small residential system is that sometimes people opt for fewer deeper wells on a large job--I've heard of going as deep as 1500'. That's of course beyond the capabilities of a typical drilling rig, so whether that makes any sense depends on the capabilities and pricing of different drilling companies in your area. But talking about the number of wells without specifying how deep doesn't mean much.
When you use an expensive HVAC system, the incentive to make a really good envelop to minimize the heating requirements is very strong. If you do that, the cost could be quite a bit lower than the scary quote that Richard shared ... but clearly it's going to be expensive no matter what.
Charlie is correct .Many people choose to have fewer deeper vertical bore holes drilled . Will it work ? Yes . What those drillers and contractors don't tell you , if they actually know , is that when you do that you increase the cost of pumping for the entire life of the system . Longer loops equal higher head and bigger pumps . One must be careful .
As pointed out in one of the links Martin shared , pump energy consumption is not included in Unit COP which is quite often not mentioned in the discussions . Again , the installing / designing sector may not even be aware of this . System COP can become a killer really fast .
Could be alot worse though . People could be in there that believe in the old rules of thumb . Could you imagine the disasters that would arise without a proper heat loss calc and careful modeling ? The less intelligent of my uncles would have said we require 406,950 BTUh at design . Luckily the smart ones outnumbered the lesser intellect . Too much glass in this house is what actually did it in .
I am still attempting to do ductless chilled / heated water system . That'll bring the cost down by about 100,000
We are all saying that ground-source is way too expensive, but in a large commercial project, there's a factor that could push you in that direction that doesn't apply for a residential system (yet). That's a big enough project that, at least in some regions, the utility will charge for peak demand as well as for the overall energy usage. The power draw of a large set of air source heat pumps is significantly peakier than a ground-source heat pump system: on a cold winter night, the heat demand is highest and the COP is the lowest. You might even need a backup heater kicking in. But a ground-source heat pump has the same COP during those times as it does any other time. And with a water-water system you can put in a water tank and use that to do some time shifting of the electric consumption to avoid coinciding with the other peak uses in the building. To really take advantage of that you would need to have some good controls. I expect that peak demand charges are going to increase. And more sophisticated systems that allow shifting the timing of HVAC electricity use will also become more common and will be good economic opportunities for building owners. A water-water ground source heat pump is a great system for taking advantage of those opportunities, as well as avoiding painful peak charges.
I agree Charlie . Those controls are no longer complicated either . Buffer tanks are required anyway , why not just upsize appropriately and only run the unit when rates are best . Air source has a long way to go .
Carbon dioxide would allow more temp range but the pressures associated with it are scary considering where I see the labor forces' knowledge level or attention span .
I just wish everyone did not make first cost such a big issue . Price is only ever an issue in the absence of value . We could all get the system COP much better by drilling more and shorter vertical bore holes . This would lessen the required head and pumping power immensely . But due to the first cost argument what I mostly see happening is drillers , contractors , homeowners making the wrong decision and going the opposite way , fewer deeper holes which as we know increases the amount of power required to get the heat transfer we need . I bet the utilities love getting more revenue every month forever .
GSHP's have got to enjoy a longer life also being located indoors as opposed to out in the weather . It's snowing , everyone get your shovel to keep our heating unit operating .
Richard, interesting idea about going to multiple shallower wells. Conceivably that could also drive first cost down if you got into the range of a smaller, simpler drilling rig. To get the savings on pumping energy, you need to then plumb them in parallel, so the flow rate is low in each and you get the total flow rate you need in the heat pump's heat exchanger. Do you use a manifold with a flow meter on each well in order to make sure the flows are balanced between them? How far do you think it makes sense to go in that direction? Down to 50' wells? 25'? Can you use a $200 hand-held power auger to drill the wells? Just kidding there ... but maybe a rig not that much larger.
I agree about CO2--both that it would be great in terms of efficiency, capability, and climate impact, and that on the other hand the necessary skill set for servicing might be hard to find. Ideally an advantage of a GSHP over a minisplit is that it comes charged and you don't need a refrigeration tech to install it. But it's not wise to count on that working out ideally!
I guess the balance point on number and depth of well would vary . Don't wanna drill so many that you're paying someone 1/4 of the time they are there moving equipment . Couple of 10 ton homes I've done required 8 - 1" x 305' . At 3.75 gpm with 30% solution , that's right around 4' head per 100 feet . 4 x 800' = 28' . 8 bore holes x 3.75 = 30 gpm (what the Bosch TW122 requires on source side) . 30 gpm at 28' is a hell of a pump or 2 that would pump 15 @ 28' in parallel . Either way , you're using some power there .
Now 12 wells would have been 2.5 gpm @ 10.2' head . 30gpm @ 10.2 is much easier in first cost and monthly consumption , 2 pumps each doing 15 gpm @ 10.2 is better yet .
All the systems I work on get 2 pipe reverse return Charlie , first fed last returned , basically self balancing .
Thanks Richard. Your example shows just how dramatic the improvement can be for a small change in the number of wells. Very interesting. The nonlinearity of pipe friction means that you get a factor of 3 improvement for a pretty small change in the configuration!
2 pipe reverse return should solve the problem I was worried about.