I've been reading the posts in the geo forum and learning from the experts. Now my family is about to do a gut renovation of our house in Sunnyside, Queens NY. We are wondering if geothermal could be a good option.
The house is semidetached, about 3500 sq ft total, with a cellar, 2 floors, and an insulated attic used as a bedroom. We will be adding insulation and updating windows/doors per the suggestions in many posts here. We're also looking to add radiant floor heating.
Should we stick with a high efficiency nat gas boiler, or consider a geothermal heating system. We have a yard of about 30'x50', would vertical loops be possible if we got the geothermal loop?
Also, we're not sure about cooling. Because of landmark issues, air source heat pumps are not allowed. Window units are loud and ugly and inefficient(?). Or we can just use fans and brave the heat. Geothermal might be a good option here.
I haven't seen posts regarding installation in cities here. Is that possible at all? Does anyone have experience in NYC (queens, not manhattan), or know of some ball park prices?
Thank you for your help,
Ivan

At current NYC gas & electricity prices it would be very hard to rationalize the very substantial upfront cost of geo.  It's a much easier argument in places with 12 cent electricity with only oil or propane as their heating fuel options.

In nearby CT residential geo averages about $9K USD/ton, and a 3500' house at current code-min R/U could easily be pushing 4 tons.  (On this forum we've seen references to quoted systems of  ~$11K/ton in MA.)  I'd be very surprised if geo were cheaper on L.I. than in CT or MA.

In a full-gut rehab you may have options for economically bringing  that to under 3 tons, maybe even under 2 if you spring for U0.20 triple-panes and extensive exterior foam sheathing & air sealing, etc. as part of a deep-energy retrofit. Surf through the Nyserda site to see what the various envelope upgrade subsidies. are.  With condensing gas as an option you may end up with much lower operating costs by spending the $30-40K on more substantial R & U values for deep energy retrofit than spending it on geo.  It's usually cheaper to make big envelope efficiency changes all in one go rather than a bit here, a bit there, especially when there is subsidy for going big.

A full-gut rehab presents a building-efficiency opportunity that comes along at most once every half-century, and usually much longer.  Consider this carefully before plowing the cash into highest efficiency heat pump technology that would save at-best a few hundred/year compared to condensing gas. 

Also, if you go with geo it's better bang/buck to go with air distribution of the heat rather than radiant floors, since you'd need the ducting to support cooling.  Radiant is a signficant cost adder, and if you're going all out on the building envelope the bump in creature comfort you get from radiant isn't nearly what it is in a lesser-insulated drafty house with 2x the heat load.

Ductless air source heat pumps are FAR quieter than window-shakers or cube-on-slab outdoor units that typify ASHP, but there's no getting around the fact that the outdoor units would most likely be visible from some angle.  Compressor units on all inverter-drive ductless heat pumps are quieter than the venting on many power-vented condensing boilers, since they all use scroll compressors rather than old-school reciprocating compressors, and the fans are variable speed DC drive motors (no 60hz hum.)  Whether there's a way to comply with "landmark issues" depends on exactly what those requirements are.

thank you so much for the quick and very helpful reply Dana1! I will read through the links/docs you gave.

Geothermal if possible in your location would give you A/C

Ghermal would give you AC, and yes it's possible, but I'm skeptical of payback.
I don't know what this sentance means; "Also, we're not sure about cooling. Because of landmark issues, air source heat pumps are not allowed."
Does this mean you can't have anything outside? If that's the case mini splits are out.
Is there a possibility to roof mount a condenser?
If you are to do radiant flooring the geo might get more attractive as that would be included in the 30% tax credit.
Open loop might be an option if we can dump in storm drain.
Lots to think about.
j

Installation of HVAC equipment in rear/front yards would require a public meeting; we will go to a hearing to see if we can get approval. Roof wouldn't work either because the steep pitch exposes both sides to the public.
Thanks for pointing out the 30% tax credit that could be applied to the radiant setup as well. I would like to explore the geo option a bit more if that's the only way to get AC. Do you guys know of any geothermal installers/contractors who services the NYC area? I am having no luck at all finding one.
Thank you again for the help!

Dunno any. Sorry.

Is there no place to conceal a condenser. Condensers sure look nicer than a bunch of window shakers sticking outta a house.

Mini-splits are usually concealable via shrubbery, since they project only foot or so from the house, and in a full-gut you can run the line-sets inside rather than in an exterior conduit that looks a bit like a rain-gutter down-spout (as is commonly done in retrofits on fully-finished houses.) They can also be mounted under the edge of porches, concealed by latticework, etc.

eg:  http://www.cozyworld.ca/ductless-he...-deck.html

There is a list of installers in NY on this site

I went through this evolution a couple years ago for a remote consult client on LI. He came to me with geo bids exceeding $100k for 9+ tons capacity on a 5000+ SF home.

I drilled down into NYC natural gas and electricity rates and talked him out of geo in favor of modulating condensing gas boiler for heat and hot water and moderately high efficiency ducted split straight cool AC systems for cooling. He invested the up front savings in sprayfoam and air sealing that cut load almost in half.

He had a couple acres and no issues with outdoor equipment

That said, I have to figure you aren't the only one on your block to have / want AC, so there must be a way to locate the outdoor equipment in keeping with "landmark", whatever that is.

Minisplits are small, quiet, and highly efficient, though they lack the airflow flexibility of a fully ducted conventional system. That said, they are likely an excellent cooling solution for a moderate cooling climate such as NYC where it is probably OK if the odd pantry, walk in closet or bathroom hits 80*F a few times per year.

That was a quote for 9 tons at over $11K/ton? Ouch! (That leaves quite a sum on the table for load reduction!)

A key part to Ivan's financial analysis is that it's already being planned as a full-gut rehab, which means the envelope improvements can be more extensive and cheaper than a retrofit on a fully-finished & occupied house. And since there is likely to be substantial NYSERDA money subsidizing the whole-hog approach, it may even come out the same or cheaper than a more modest effort (as was the case on a deep energy retrofit I've been advising on locally, which is getting it's final blower door test this week.)

Agreed.

Subsidies do REALLY warp the market.

My consult was essentially new construction, wrapping a great big new house around part of an old small one...probably had something to do with Byzantine planning / zoning / permitting procedures rooted in old northeast nanny states.

Pricing was high owing to proximity to NYC, I'm sure.

One bidder wanted just under $120k for a DX geo...custom built, no AHRI cert and with a high glide refrigerant not likely to be found on 1 service truck out of 100.

Another was using sample gas bills with very low consumption to create the impression that NG costs $2+ per therm, when reality was half that for consumption amounts likely in a home with gas heat and hot water.

Posted By engineer on 05 Sep 2012 10:43 AM


Subsidies do REALLY warp the market.

It does indeed!  In MA you end up with competing subsidies for geo, load reduction, and site-production power with solar panels all with different time-windows closing, to help keep the accounting & financial analysis of a project like this crystal clear. 

My friend with the DER project in MA may get another ~$4K in subsidy if the final blower door test clears a higher level of air tightness, specified in cfm per sq.ft of exterior surface @ 50 pascals rather than just the specified max ACH/50, which is also required.  That prospect induced him to use more closed-cell foam than I would have, and it may or may not pay off on the subsidy end if it fails, and would NEVER pay off on the additional reduction in utility costs, even though the whole project would even un-subsidized over the lifecycle of the building, but not in short-years. 

Luckily (?) the shading factors were too severe to bother with the photovoltaic subsidy angle on this one. (And it was his questions about adding some solar thermal + PV that initiated my involvement with the project.)

It will be interesting to hear of the CC foam gives him the desired airtightness.

It used to be gospel with me that CC is more airtight than OC, and I'm sure the actual foam material is much tighter, but what I'm seeing in the field is that since CC expands less, there are more likely to be voids, particularly in congested or tight areas where the installer couldn't get a good spray angle or view for complete coverage. CC is pricier, so installer is less likely to let fly with bulk in hopes of catching the voids through sheer mass.

In addition, CC seems more vulnerable to shrinkage cracking if the installer fails to maintain required temperatures of the A+B components enroute to the nozzle.

This is not to say I don't like CC - it is in my own home and does well, and I like the added strength it confers on my roof assembly.

My mom has 2 KSF of completely flat roof in MA - it is a mystery to me how the house survived the 3' of snow in February 1978, but we had a fine time. That roof may be a primo spot for a great whacking PV array

Given the amount of air sealing already done via other methods on this project attributing it's total air-tightness to any one measure would be a mistake. Both the exterior rigid foam and the housewrap were detailed as air-barriers.

They opted for cc foam between the roof rafters and in some of the studwalls despite my recommendation that they use o.c. foam or cellulose- nervous about the antique broad plank sheathing in some sections, but most of the cavity fill was cellulose. Quotes on dense-packed cellulose for the rafter bays were coming in higher than even cc foam from the lowest-cost bidders. They did a decent job of it even though I was pretty nervous about anybody who would price-cut so deeply. No shrinkage or gaps were apparent 20+ days after installation. There's an air-sealed detailed membrane between the roof deck and ~7" of reclaimed roofing iso, staggered seams between layers and between the top layer of iso and the (unvented) nailer deck. Total whole-assembly R on the roof is pushing ~R60, and bit over R60 in one dormered section.

The building is configured as three 3br apartments- Manual-J on the highest-loss unit came in a bit shy of 15KBTU/hr, and it wouldn't surprise me if reality was closer to 12K. HVAC is a single mini-split per unit + ERV with the supply feeding the larger living/dining space as the mini-split head, exhaust from all other rooms. (w/jump ducts for pressure balance).

But this has gone way off-thread. I suspect this project will show up on the National Grid website ( https://www.powerofaction.com/der/ ) by next spring with some of the details, but maybe not.

thank you for the additional thoughts! even though this has gone off thread, I think the suggestions are very relevant for me. Please point me to a different (sub)forum if that's more appropriate.
The biggest conclusion I draw so far from reading this thread and many others is that planning is really first order, and best done by a professional. How do I go about finding a good energy engineer/consultant to do the proper calculations? Do you know any one servicing the NYC area? We already have plans of the house (post renovation), including elevations. can the consultation could be done remotely with these plans?

Designing a deep energy retrofit is one thing, implementing one is best done with contractors & consultants who have had some experience with them.  Poke around the NYSERDA site or call them. They have sponsored & documented many DERs, and have developed contractor-training guidelines, etc. but pay attention to the subsidy for DER vs. PV/other if best bang/buck is going to be a driving factor.  But the fact that you're going full-gut on the rehab means that some aspects of a DER will never be cheaper than right now.

I'd be surprised if folks at NYSERDA couldn't refer you to experienced consultants & contractors working those issues in the NYC area.  Even if not a full DER, those same consultants could give you a breakdown of what is/isn't a no-brainer type of upgrade for the long term that will pay for itself in comfort & reduced energy use no matter which way you go on the HVAC end.

Planning is important; so too is testing. Testing verifies the implementation You want to find and fix air leaks before the sheetrock goes up. You want to be sure whatever HVAC system you deploy is properly charged, has minimal duct leakage (if applicable) and delivers the right amount of air to each room. There are any number of other trades and assemblies needing quality control before their work is covered up.

I can work remotely with plans and provide support via teleconferences, evaluating competing bids, products etc. on a straight hourly basis. Not speaking for Dana, but he might do the same and be even better suited than I - closer and more attuned to current techniques in your climate zone.

A key objective is not to get hoodwinked by any number of one trick pony vendors hawking miracle energy conservation products that inevitably fall far short of promised or implied results.

Posted By engineer on 06 Sep 2012 01:11 AM
It will be interesting to hear of the CC foam gives him the desired airtightness.

It's preliminary, but this 3-story + full basement building tested out at 530cfm/50.  (So low that the test crew photographed the reading on the display to include in their records as verification that it wasn't a typo.) 

The hurdle required on the leakage/square foot of exterior surface spec to get the additional subsidy pencils out at 620cfm/50, so it looks like he made it well withing the margin of testing error.  The final test by the utility's crew will take place any day now- not sure if it's this week or next- the preliminary test was to have a chance to rectify any overshoot if possible (since there is a few grand hanging in the balance.)

Not too bad for a plank-sheathed circa 1905 house with brick foundation.