I would argue that as the envelope improves it takes less geo to cover the reduced load.  Where to stop work on improving the envelope and just pull the trigger is the trick.  It is a relationship between what it costs to heat the space vs. any other method.  If you improve the envelope to a point that it can be heated with an oil lamp, well......

Eric

Posted By gonegeo on 10 Jan 2011 04:19 PM
It would be great to see how a 2400 sq ft. cape or colonial gets from $8-11 btu/sq ft. to 1. Any articles or homes that have been documented for insulation techniques and materials? I don't think there is a lot of interest in igloos made of closed cell foam or geodesic domes in New England. And you are correct about retrofits. Geo does make sense.

Sure, there are lots of articles, lots of PassiveHouse compliant designs that are well-lit, & super-insulated, yet fairly conventional in look & floor plan (none of the igloos, tilted glass salt-boxes, foam domes of the 1970s & 1980s that you may be thinking of.) 

Better yet, the PassiveHouse design tools are now pretty refined and fine-tuned for the specific climates & insolation factors at this point.

Very few superinsulated houses rely on spray foam for a significant fraction of the insulation.  A combination of low-density EPS and cellulose or superfine new-school blown-fiberglass are more typical (better R/$), but spray foams are sometimes used extensively for air-sealing.

Polyurethane SIPs have been used successfully in PassiveHouse designs as well.

Some superinsulated home builders take it to the next step to meet annual Net Zero Energy by adding a bunch of rooftop solar PV, but that gets to be substantially more expensive than geo.  (Active solar inputs aren't necessary don't count toward the PassiveHouse rating anyway.)

This isn't pie-in-the sky or some sort of fantasy (anymore).  The insulation, air sealing & glazing upgrades it takes to get there is cost-neutral in many mixed heating/cooling climates, and less than the cost of geo for a code-minimum home in many ~7500heating-degree-day climates.  But it has to be planned in, and is climate & site-specific to keep costs bounded and performance maximized. 

The (~5500HDD climate) Urbana IL Passivehouse  only measures 1200' by PassiveHouse measuring methods (which only counts interior dimensions, and discounts basement floor area substantially)- might be more like 1500-1800' by US real estate measuring methods, which counts every square inch inside the exterior paint.  It's heated by resistance coils in ventilation air, but uses a fraction of the US average for electricity (all uses, not just heating.)  A single ton of geo would use more pumping energy than this house uses for space heating & ventilation combined, yet the estimated construction cost adder over a "conventional" design of similar was a similar in cost to a minimalist geo system. 

For somewhat bigger houses it's even easier, since the ratio of exterior surface to square footage of floor area is less.  Passivehouse is focus on ~2500' and under houses and making it cost-effective, but Net-Zero types have no problem with larger than average homes, and are apparently willing to go all out with the expense of geothermal + PV  or massive spray-foam too rather than nit-picking on R/$ the way the PassiveHouse folks do.  Making a  PassiveHouse  design Net-Zero would be typically cheaper than those who don't do the full analysis on where to spend the money to make it most cost-effective, rather than a trophy design for Net-Zero bragging rights.

"In older buildings, where the yearly heat requirement is high, and electricity costs are low, geothermal can be a bargain."
Eric,
What I tried to articulate is that where geo works it works. Regardless of the envelope. As you pointed out there are diminishing returns "Geothermal would save 2/3-3/4 of that or 250$ per year. On the other hand it would not matter, as most people would be happy with 367$ per year."
This of course is also true of insulation.
I think people sometimes overlook the heat system due to the "heat it with a candle" mentality in some new builds. As geo tax credits are so favorable, It can still be a valuable addition to a new home.
I don't know that we disagree at all in that; all should be evaluated with an eye toward cost v benefit. Or as you expressed it " The end goal is the lowest utility bill achievable for the smallest initial cost".
I will endeavor to express myself more effectively.

j

Dana, I don't see any New England traditional style homes in the articles, slides, and other links. Did I miss them? The homes that are shown are more modern looking and they are not typical of New England. Smaller windows or boxy looking homes. That said, I agree that there is a tradeoff between how much insulation and how tight before you balance cost with the heating/cooling system. First dollar cost vs. lower energy bills. If you have to pay 80% more to get the last 20% heat loss out of the house, is it worth it when the payback will be a long, long, time. If the home is so tight you can heat it with your breath, you may have some air quality issues to contend with. I have done retrofits where we ask the homeowner if they want to spend X dollars on insulation and sealing vs. getting another ton of geo? Most opt for the other ton. They don't want their home messed with outside or in. I have only seen a very few that have done deep retrofits and that was just luck that the home needed paint,siding, windows, and roof all at the same time. This was usually done when the home changed hands and not done with out of pocket cash. So there is idealism and realism at play here. Wouldn't it be nice is every new home was only 1Btu/ft/hdd? I agree.

Joe,
What is the smallest geothermal unit available? Do they go down to say a ½-3/4 of a ton for well insulated houses?
What strategy can be used to heat DHW year round? Remember in an efficient house, DHW is likely to use as much energy as heating so the system has to maximize that efficiency also.
I think what the geo guys need is an all in one unit, about a 1 ton that has an attached dhw tank and has a HRV built into it. One unit that does heat, cooling, fresh air and hot water. so it is a fast install once the ground loop is in.

Gonegeo,
What exactly a normal new England style home? On my street we have ranches, raised ranches, colonials, a salt box, a couple of capes and 1 modern style home. Most of what is being built nearby today are very cut up designs in the 3-5000 ft range. Can you make those houses Passive house? Probably not, the designs are too complex and there are 2 many thermal bridges inherent in that construction. If you want to build very efficient houses, there are some compromises required. Generally though they can look any way the builder wants them to look
If you start with a conventional design and try to adapt it, it is not going to work. These houses have to be designed and built from the ground up. My own half assed attempt at this yielded a very livable house that is around 1.4 btu/sf/hdd. IF I was doing it again, I think I could do a lot better. On the other hand I own a house that consumes about 18 million btu/s per year for heat and hot water and cooking and I used 2400 KWH of electricity in 12 months. Note this is for one person and a dog, clearly a family would be more energy usage
As far as building normal looking houses that are very energy efficient, look at:
http://www.kaplanthompson.com/index.php
For the comment about air quality, I assume this was in jest? Any tight well built house today will include a HRV or ERV, or other active ventilation strategy. Any HVAC company should be doing that, right?

Posted By gonegeo on 10 Jan 2011 06:29 PM
Dana, I don't see any New England traditional style homes in the articles, slides, and other links. Did I miss them? The homes that are shown are more modern looking and they are not typical of New England. Smaller windows or boxy looking homes. That said, I agree that there is a tradeoff between how much insulation and how tight before you balance cost with the heating/cooling system. First dollar cost vs. lower energy bills. If you have to pay 80% more to get the last 20% heat loss out of the house, is it worth it when the payback will be a long, long, time. If the home is so tight you can heat it with your breath, you may have some air quality issues to contend with. I have done retrofits where we ask the homeowner if they want to spend X dollars on insulation and sealing vs. getting another ton of geo? Most opt for the other ton. They don't want their home messed with outside or in. I have only seen a very few that have done deep retrofits and that was just luck that the home needed paint,siding, windows, and roof all at the same time. This was usually done when the home changed hands and not done with out of pocket cash. So there is idealism and realism at play here. Wouldn't it be nice is every new home was only 1Btu/ft/hdd? I agree.

The development in Belfast ME done with SIPS is pretty traditional New-England-ish (if a bit boxy). About any shape can be accommodated, but it makes detailing the air sealing and insulation.  Googling images of "PassiveHouse" or "PassivHaus" gets you more modern than traditional, but they're out there.

Issues with air-quality in tight homes is a non-starter where the PassiveHouse standard is concerned, since there is a minimum spec for ventilation air (and ALWAYS incorporates some form of heat recovery ventilation, and in some cases earth-tempering of incoming air.)  Counting on a leaky house with random inlets/exhuast locations is a far less reliable method of getting good indoor air quality.

It's that first ton, not the extra ton of geo that's most-expensive. The economics of retrofits are indeed different.  In a superinsulated house the design-conditions heat loss is typically well UNDER a ton.

The idealism of superinsulated new homes with heat loads ISN'T a pipe dream- it's as real as the designer/builder wants it to be.  But for the custom-home buyer, the economic tradeoffs in many/most parts of the US would favor highest-efficiency building envelopes over highest-efficiency mechanical systems. 

But on the realism side, I'm not anticipating that to be come the predominant way of building houses any time soon.  Something like 80% of the homes that will be in the US in 2050 are already built, and the paradigms for code minimums on air-sealing & insulation are a half-century behind the state of the art (as are most home builders & inspectors.)  The market for high-efficiency systems will continue to grow for decades.

Still, with tabula rasa in hand, running the PassiveHouse package and refining the design for optimal bang/buck is a good place to start, even if you DO end up with a "real" heating system in the end, not necessarily taking it the entire way to the standard.

Not to dodge the question Eric, but there are ~1ton systems in packaged units, 2 ton in 2 stage, fractional tonnage in console units and I haven't looked but am unaware in water to water in less than 2.5 ton.
With our low electric rates thinking in the direction you are on perhapsn an ASHP w/resistance heater and ASHP water heater work. A 1 ton geo isn't going to make a lot of hot water in a hurry soooo....
Oversize system with poor payback or pay more to operate (and here we are again)?

You guys know I tend to think of things in terms of my AO and my experience and from a contractor's perspective. The skinny on high end houses is that few builders or archetects really treat them any differently (remember I said my AO).....they continue to look at lowest bidder for heating and only seek out geo when customer demands it. Even when their client wants geo, they often ask if their "code-minimum guy" can duct it to cut costs.

The " building" we are discussing is little more than a pipe dream in mid MI. Try to get "cut-cost guys" to maxamize passive design.
Most recent product I bid that had the kind of bank to do it right, H/O was disinterested in energy expense but didn't want geo due to the size of standby generator (on the lawn of his 10K sf house).

j

Eric,

It appears your numbers are a bit off. The cost of propane hovers around $3.00 a gallon in NY. Many geo systems operate at 4.0 COP or higher - and actually perform that way in the real world. The only hard sell for geo is against. natural gas where the savings (in this area) comes in at about 40%. Just wait until cars start using LNG - price for natural gas to heat homes will jump like oil did in 2008. Switch now while you have the chance.

Paul
www.TotalGreenUS.com
DX Geothermal Specialists

If we are talking about costs ect. what is the average cost per square foot for the super envelope vs. the code standard house in any given market? Lets use 2500 0r 3000 square feet for avg. Then look at the cost of geo and returns on investment vs. the super envelope.
Eric

One thing about the "super envelope" eric is that it tends to be more "one-time expense" than geo. So cost can be spread out over more years.
I worry more about things like stale air and mold. Some do not address air changes correctly. Those that do find their returns diminished rapidly as "extra tightness" leads to extra btu requirements for exchange air.
Personally I think "super envelopes" like heat plants, have value that is enhanced or decreased by geography as well. Show me a mild climate with cheap electricity and I wont fret envelope or heat plant much at all.
j

Costs for increased insulation
I can only talk about my own house. It is not super insulated, but not bad.
I think the people pushing super insulation are a lot like the geo guys. They know that the concept is sound, but they can’t convince joe consumer to bite.

Paul, I mis remembered, I looked it up, I filled my propane tank 10 nov 2010 paid 1.91$ per gallon including tax. Previous fill was july of 2009, I paid 1.39$/gallon including tax. I own my own tank and can go 2-4 years between fillings depends on whether I feel like burning wood. I should have filled in august when it was 0.25$/gallon cheaper. I used 200 gallons of propane between fill ups (15 months apart) for heat, hot water and cooking. I also burned about ¾ cord of wood in a woodstove.

Measured the way we measure in the US 2240 ft^2 conditioned space
Total cost to build $181,300 not including land, including mortgage expenses

Difference between code min insulation and specs and what I built. It appraised fall 2009 for $256,000

Foundation I used poly steel ICF about a 3900$ differential with a straight concrete foundation insulated to code min. Additional 979$ underslab insulation 2” xps. I would have had to use 180$ worth of code min perimeter insulation anyway

Foundation increased cost 4699$ vs total code min

Walls are framed 2x6 OVE zip sheathing taped OVE construction saves 5-600$ in framing vs non ove construction.

Wall insulation exterior 1” polyisocyanate with seams taped with zip tape+ Interior ceiling 1” polyisocyanate insulation 1480$

Total calk and spray foam cost 410 dollars (some of this was fire block foam)

Wet spray cellulose + r 50 ceiling loose fill cellulose Plus 12” thick rim joist wet spray 3912$ installed

I don’t know what code min fiberglass would have been. Originally I estimated that materials costs would have been 1950 if I bought it, I am guessing ~1500$ in labor. I did get a quote from 2 spray foam contractors, they both wanted around 8000$ for walls, and ceilings to R30 open cell. Even though I asked for R50 in the ceiling the spray foam guys only bid it for r30 and had the balls to tell me r50 was a waste.

Windows and doors 9300$ I was only going to use casements so the ones I used vs the cheapest ones I found was about 3000$ Note: the highest quote I got for windows alone was 14000$ they were nice but way too much

Orienting the house due south was free. I cleared the lot to maximize solar gain in the winter, but leave tree cover to the east and west.

So increased costs for increased shell insulation 10,000$ +/- 200$ over code min with fairly cheap windows
Increased costs ~ 5.6% over code min to total build costs

HVAC costs for the house total 14,854$ this includes the following:
500 gallon buried propane tank + regulator plus gas piping
Munchkin T50 boiler + 50 gallon indirect dhw
Baseboard radiation
2 panel solar air heater
flat panel solar hot water heater with 80 gallon storage tank
Fantech Hrv
Wood stove(used) and stainless chimney

Posted By waterpirate on 12 Jan 2011 05:40 AM
If we are talking about costs ect. what is the average cost per square foot for the super envelope vs. the code standard house in any given market? Lets use 2500 0r 3000 square feet for avg. Then look at the cost of geo and returns on investment vs. the super envelope.
Eric

That depends entirely on the competence of the envelope designers & builders, but for a 2500' home in a 6000-7000HDD climate building to the PassiveHouse standard comes in at a 5- 15% construction cost adder (cost of a no-longer-necessary standard-efficiency heating system having been eliminated.)  Rolled into a 30 year mortgage the lower utility costs typically make it as-cheap or cheaper to buy/own on the total annualized cash-flow basis.

The bulk of the additional cost in a cost-sensitive PassiveHouse design will come from very high performance windows, foundation insulation, and additional framing costs for the fatter walls (to be able to use cheap insulation.)  I suppose it's possible to make that a 100% cost-adder if you cheaped out on the windows, and only used closed-cell polyurethane foam everywhere, but most designers wouldn't go there.

In temperate 4000HDD climates it can be cost-negative to build to the PassiveHouse standard compared code-min + standard efficiency heating, if you have decent designer, and a builder who understands high-efficiency envelopes.

Running a 25 year NPV analysis that includes maintenance costs it gets even harder to make an argument for high-efficiency mechanical systems vs. high-efficiency building envelope for new construction. (OK, a condensing gas/propane furnace is high efficiency, and pretty cheap up front, and even cheap to replace, there are times when that option can tip the balance.)

Code minimums for R-value are typically based on the MOST conservative 25 year present-value financials, for cost effectiveness, using the cheapest of construction methods/materials.  But a cost-conscious performance envelope design can still be NPV+ in a 25 year (or much less) time frame (even when high efficiency mechanicals are supporting the loads.)

Eric,
That's a pretty good breakdown, thanks. I wish everyone who built new would educate themselves on envelope v heat plant choices.
What you didn't mention that can impact long term equations is that your higher quality windows and doors may require less maintenace as well, further tilting things in your favor.

Unfortunately I live in an area where builders of homes had instant equity for a long time and 10%/yr appreciation. When propane was cheap folks cared little about their heat plant or insulation and moved every couple years building bigger homes.
Once propane shot to $2.50/gal and housing plunged they found themselves in large homes upside down in equity and paying 3 and 4 grand a year to heat the joint. While insulation can be added, those who did not walk away from these homes found the most bang for their buck was a geo system.
In the homes where folks did get foreclosed, the new owners want to be able to afford to heat the place and a geo system makes sense.
Others who are not distressed find the savings on the heating bill still make geo a great choice.

Of course my customers pay as little as 7.5 cents kwh so fuel costs are very lopsided.

So the lesson as always is "do your research" as one application may favor envelope, one may favor geo, one may favor gas........
j