Consider two air barriers, interior and exterior. I agree with tape and gaskets vs caulk and spray foam and Zip sheathing or other taped rigid barriers vs house wrap. Also look out for the things that make ACH50 inaccurate as to actual air infiltration (like room pressurization/depressurization).

To give you guys some follow up as to what happened since we went out Tuesday to meet with the builder and homeowner and insulator/air sealer.
Talked to builder about heat pump vs gas and that there would be high bills regardless of what system was in place because it has nothing to do with the system, the size is the same whether its gas or electric.
Had the insulator/sealer perform a blower door test and use a FLIR camera, while the insulator claimed the home was built to code, it was more than 7 ACH, they calculated the home on an over 40,000(i think they used 44K but I can't remember for sure) cubic foot volume which showed a 6.8 ACH, when we measured everything we came to less than 36,000 cubic foot volume after vaults and such were accounted for, which put the home way over the 7 ACH allowed by code. The insulator had sealed a few can lights as I mentioned in the first post before our meeting this week and that brought the leakage down a bit. After using the FLIR camera,the homeowner, builder and insulator found that the recessed lighting in the dining room was also leaking like crazy and they admited it should have been sealed better. They are going back to the house to adjust and reseal many locations in the attic and other areas as best as possible. We showed the homeowner and builder our Manual J and Manual D calculations that the ductwork and system were sized appropriatly and the builder has agreed to use better practices and methods from framing to insulation to air sealing on future homes as well as looking into HRV systems.

In the end while the customer was unhappy, it sounds like it is getting resolved and that while the utility costs were higher than projected, they would have been astronomically higher with a propane furnace. This home had less than $110 total utility costs during the summer months and im sure heating will get down to a low managable number as well once the air sealing is performed.

While it's true that 7 ACH/50 meets code under IRC2009, that's something of a "So what?" to somebody who was paying the freight for being better than code on most aspects. The 7ACH/50 hurdle barely higher than a stripe on the floor, and even 3ACH/50 is pretty damned easy to hit (which is why it made it into IRC 2012 without a lot of whining.) Even as retrofit it's usually possible to get there without breaking the bank, and that's probably an appropriate target, one that should leave the customer satisfied (but not elated.)

Given the current state of heat pump technology it's hard to find any rationale for buying ( propane or oil-fired space heating systems (or even replacing the equipment when it's nearing end-of-life), but it sure is an easy straw-man target for making the a case for the high up front cost of ground source heat pumps, eh?


The more complicated math is in the PV-solar + air-source heat pumps vs. ground source/no-PV type arguments, especially in US climate zone 4 or lower. Last week I reviewed three proposals for 15kw of rooftop PV for some friends- the high mark was $4.25/watt, the low $3.71watt, and the average was $4/watt. And that is still quite a bit above the Q4 2013 weighted national average (that includes utility scale PV) at $2.59/watt. In even a code-min house and a ducted air source heat pump hitting in the mid-2s for an annualized COP you'd have to do the math on the lifecycle costs of the various alternatives. In some hotter more competitive markets in the US rooftop residential PV is coming in under $2 before any subsidies are applied, and it's widely believed by industry analysts (including utility companies and financial institutions: http://www.businessinsider.com/citi-the-age-of-renewables-is-beginning--2014-3 ) that the national average will be buck-fifty a watt for rooftop residential (and about a buck a watt for utility scale) before Y2020. In new construction where the roof angles relative to site can still be adjusted, this could make it tough for continued traction on GSHP in some markets. Without the influences of subsidies (for any of it) a 3-ton GreenSpeed coupled with $1.50/watt rooftop PV could start to look pretty good against GSHP in a US zone 3 or 4 climate.

Dana, I certainly agree is some areas there, but in my zone with our 300 days per year of clouds, there is not a lot of solar available. I also am not very knowledgeable of solar but here is what I know.
In oregon, I was quoted a 4KW system for my home, cost was around $15K installed, we are normally higher than national average for all installs, Heat pumps, solar, you name it. That system would produce around $350 per year of electricity and there was maybe enough room to put another 1-2KW on my roof at best, so just for comparison sake, its $20K for 6KW on the roof that would produce around $500 per year of electricity(no math here, just guesstimates) for a system with a 20 year usable life, this shows a 40 year payback before tax credits and savings, which are similar to geo but a little higher.
Now compare my house cost of a normal heating system, around $10K, for a geo it could be done for around $22K, or a $12K difference
$20K solar gives $500 per year in electricity
$12K geo gives over $500 per year in savings and receives credits on the full 22K amount, not just the 12K upgrade cost.
Heating is needed and also provides benefits of no outdoor heat pump noise, possibility of water generation, no new loop needed when replacement comes and a 25 year life.
So how does geo not compete? I can certainly understand areas like Phoenix where my parents live and they have a 4KW system that provides just about all of their power needs and only cost around $12K and a geo would be expensive, but not in my neck of the woods.

Portland OR is not dramatically worse than New England for annual PV return, but the exact location matters:

http://www.nrel.gov/gis/images/eere_pv/national_photovoltaic_2012-01.jpg

On new construction (as opposed to your retrofit) the amount of available PV real estate can be designed in or out. The fact that you can only fit 4kw onto your house isn't relevant to the new-construction discussion. I'd only be able to fit ~1.8 kw on to my roof, and shading factors would limit me to only ~60% of the theoretical output, but who cares? In a new construction even on the same plot I'd be able to fit more than 10kw onto a house of the same size (different shape, and different roof lines) and with shading factors that only robbed me of 25% rather than 40% of the potential output.

At $3.75 /watt for your 4kw system it's higher than the recent national average, but more than 2x the anticipated nat'l avg. for Y2020. (And about 2x the 2014 all-in unsubsidized price in parts of TX, if the wonks at GreentechMedia can be believed, and I think they can.)

I've yet to see ANY pre-subsidy GSHP system quote that came in as low as $22K but OK. I'm not sure how the "...receives credits on the full 22K amount, not just the 12K upgrade cost." factors into anything at all, since we're talking bare-naked unsubsidized pricing. Credits for what?

An inverter-drive GreenSpeed doesn't have the objectionable outdoor compressor noise issue mentioned- it has a continuously variable speed scroll compressor and varaible speed DC blower. Cruising along at low speed (where it will be most of the time, being a fully modulating system) the sound level is 58dbA- there are some refrigerators out there louder that that. It's rated HSPF is in the 11-13 range (depending on air-handler options), and would come in about $6-8K less than the $22K GSHP example. It's still more expensive than the $10K brand-X heat pump system example, at some presumed HSPF less than 10 (IIRC an HSPF of 7 would still be code-legal, but hopefully most would do better than that, call it 9.).

But the difference in upfront cost between the better-class ducted air source heat pump and GSHP still buys 4-5kw of grid tied PV at the projected unsubsidized Y2020 price of PV(or the 2014 unsubsidized price in a few select US locations).

The delta in annual energy use between the GreenSpeed and a pretty-good GSHP would still be there, but the question then becomes whether the annual output of another 4-5kw of PV would be less or more than the energy-use delta. Again, location and climate will affect both the average operating efficiency of the GreenSpeed and the output of the PV. But it's not a slam dunk.

But sure, at current 2014 pricing for everything it's possible to get a better return with GSHP in a low-sun higher than average PV cost market if you can really buy the GSHP at $22K(instead of the $35-60K New England system pricing). I'm saying that in 5 years that may not be the case due to the crashing price of PV- you have to do the math. In 2014 you still have to do the math due to the competing subsidies for PV (which varies a lot by location) and GSHP (which also varies.)

So I'm still at my original statement which was:

"In new construction where the roof angles relative to site can still be adjusted, this could make it tough for continued traction on GSHP in some markets. Without the influences of subsidies (for any of it) a 3-ton GreenSpeed coupled with $1.50/watt rooftop PV could start to look pretty good against GSHP in a US zone 3 or 4 climate."

I didn't say "all markets", or "on any random house retrofit", and it was predicated on "$1.50/watt rooftop PV ", not last week's quoted price for PV in a marginal (but not terrible) location.

Eric; thanks for the blow by blow how to do it discussion. For those of us who aren't builders, this gives us a place to start by handing this to a builder. Then say " I am speccing a house that is better than the upcoming average house; I want an ACH50 est at 2 or better. Then get 3 or more bids. If a builder doesn't know any of the jargon, he can learn on his own. You shouldn't have to teach him. Many tract builders are hitting these goals on production homes built for much lower prices/sf than custom.

Posted By McFish on 02 Apr 2014 11:50 PM
Eric; thanks for the blow by blow how to do it discussion. For those of us who aren't builders, this gives us a place to start by handing this to a builder. Then say " I am speccing a house that is better than the upcoming average house; I want an ACH50 est at 2 or better. Then get 3 or more bids. If a builder doesn't know any of the jargon, he can learn on his own. You shouldn't have to teach him. Many tract builders are hitting these goals on production homes built for much lower prices/sf than custom.

There's a learning curve to hitting under 2ACH/50, and even though that's do-able without a lot of expense, all the subcontractors need to be on board with it, and penalized for failure to attend to their part of the details. 

The Canadian R2000 spec is 1.5ACH/50, and while reasonable to hit, only makes financial sense when the rest of the house is also getting onto 2x code-min.

The IRC 2012 code max of 3ACH/50 is an easier target, can usually be met without expensive remedial effort if the place was built with ANY awareness of air sealing- it's primarily about not building-in any big holes or thermal bypasses. From an energy use point of view the difference between 2ACH/50 and 3ACH/50 isn't huge, and you don't want to be spending much of a premium on air tightness unless you are committing to much better than code performance spec for everything else.

The other piece of the puzzle is that the metric we are discussing- ACH50 relates to house volume, while it is the external surface area that the house leaks occur from. If you take 2 houses, one is 10X10X 10 ft high and one that is 50X50X50 the first has 1000 cubic ft of volume and 600 ft2 of surface area so the surface area to cubic ft is 0.60 in the second case the cubic feet are 125,000 and the Sf surface area = 15,000 for a ratio of 0.12. The bigger house is much easier to get to 2 ACH50 than the small one. Since most of us don’t live in 6 sided cubes, the longer and skinnier the house is, the more surface area to cubic feet there is. So basically a ranch is harder than a colonial of the same size to get to the same number, and the smaller the house, the harder it is to get to the same number. Fortunately small houses tend not to have so many corners, penetrations, and intersecting roof planes so are easier to airseal (usually). Cheers, Eric

Dana, plainly you and I are in different parts of the country, it seems my area is lower cost for GSHP than yours and my area is higher for solar than it is for yours. But when you make blanket statements about solar with a greenspeed being the end all system you are not correct. Have you ever heard a greenspeed run? I have. I also install lots of the Trane XV20i which is quieter than a greenspeed and personally I would not want the noise of either in my backyard. You are also forgetting to factor in lifecycle costs and the longevity of the geothermal system vs an air source. From what I have heard, and you are certainly more knowledgable but many parts of a PV system have a 10 year life like the invertor? Thats what the guy quoting my system told me but I also assume the lifespan of these parts is getting better. Also while you may think that all houses can be designed for solar, they can't. Many homes here have large trees surrounding them that would kill the output of the PV system. The home I am building(if I am lucky) in the next 6 months for myself doesn't even qualify for any solar incentives because of the shading of the property. Roof lines also would have cost a ton more to redesign and engineer because when I started the plans I told them I wanted solar, they responded with "if you want more roof area we need to redesign the house and you will be paying more for trusses" so yes in theory you can desgin for solar, but not all roof designs have no additional costs on new construction.
Geo Vs Solar is really a case by case basis an homes, maybe in 2020 geo will need incentives but we are not talking about the future right now, we are talking about today and whats better.
You are also not factoring in that lets say you have a 15KW system(making up numbers here) and a greenspeed, yet with a geo and geo water heating(water heating is a large load and when I can make 100% of a houses water with a 4 COP average geo water heating system this really cuts down on load) you only need a 12KW system.
Which would you prefer if they were the same cost? Geo with 12KW solar or Greenspeed with 15KW solar? Which has a better lifecycle cost, which is the quietest. Geo. There are to many factors to argue in generalities over the internet.

I will agree "it could start to look good" but I don't think its there yet, and 2020 is still a long ways away. AZ or FL, thats a different story :-)

At $3.75 /watt for your 4kw system it's higher than the recent national average, but more than 2x the anticipated nat'l avg. for Y2020.

They are installing 2.7kW systems in Indio, CA for $23,000. What does that do for the national average?

Indio is southern CA right? Peterson/Dean is offering 2.88 KW systems installed for $9,993 on their website as of today. A little comparison shopping is valuable. Get 3 bids.

It may be a case of marketing 'approved' contractors to association homeowners.

Posted By ICFHybrid on 18 Apr 2014 11:44 PM

At $3.75 /watt for your 4kw system it's higher than the recent national average, but more than 2x the anticipated nat'l avg. for Y2020.

They are installing 2.7kW systems in Indio, CA for $23,000. What does that do for the national average?

At $8.5K/watt are you sure they are actually being installed? That was the price point more than 6-7years ago.  I've not seen a quote over $4.25/watt this year (and that was for high-efficiency PV with a 3-phase 208V inverter).  I'm dubious that many people are going to sign the purchace and sale agreement at that price point, since it's nearly 3x the going rate, despite the high prices in CA.  In 2013 CA rooftop grid tied pricing averaged about $5/watt, which was a bit higher than the national average.

Given that there aren't that many suckers (even in Indio)  I'm going to go out on a limb and say that the effect of that on the national average is zero- systems sold at that price in 2014 would be a 4-sigma outlier.

Today's price is just one point on a rapidly falling curve.  It's not just solar-cheerleaders with green pom-poms saying so- investment bankers are.  Citi-Group analyst are not starry eyed green dreamers- they're bankers. They recently published their projections plotting installed price logarithmically against a logarithmic scale of # of installation with projected numbers at different year-markers going forward.  They are projecting $1.12 all-in (no subsidy) pricing for residential rooftop by Y2020:




Note that PJ & E (a large CA utility) alone passed the 100,000 systems mark just within their ratepayer base earilier this month, and that's only 1/4 of all roof-top systems in the US, whic is consistent with the $3-4 projected in that curve (reading the logarithmic scale without the reference lines is a bit tough.)   The installed base of rooftop solar in the US is doulbling roughly every 2.2 years. If we're at about 400,000 installed systems in early Q2 2014 we should be beyond the 1,000,000 mark by 2017 when the federal tax subsidy steps down to  10% from it's current 30%.  If anything the Citi Group analysis is too conservative (but that
is as it should be with bankers, eh?)

Even more recently the Sanford Bernstein analysts plotted energy prices by source with a linear $/MMBTU price axis, which doesn't scale well enough to get the fine detail of what the price projections are, but it gives a better gut feel to just how precipitous the price velocity trend has been since Y2006:



The analysts at Sanford Berstein believe that the lifecycle cost of energy for PV will be cheaper than all other energy sources before Y2025, and that the low cost of PV energy will begin to drive broader energy price deflation sometime before Y2030.

Whatever the price of rooftop solar is in your neighborhood today, it'll likely be half that before Y2020, and under a buck a watt by Y2025.  The D.O.E. Sun Shot prize goes to the first PV installer who puts in more than 5000 residential scale grid tied system for under a buck a watt prior to Y2015, and another 1000 systems before Y2016.   I'm not sure if there will be any winners, but it's not as crazy a contests as I would have thought even 3 years ago. I've heard rumor of sub $2 PV in Texas, and the price in Germany in Q4/2013 was under $2.  There is very little doubt but that those price points will be met, and sooner than most of us had ever thought possible.

So, good luck to whomever is selling the $8.50/watt systems in Idio, but also good luck to those in Y2020 still trying to make the case for GSHP primarily on efficiency. (Or even now, since savvy buyers won't lose out much in extra utility bills going with lower efficiency heat pumps by just waiting 2-3 years before buying into PV at a steep discount from today's prices.)  Expect a real land-rush of a crunch to cash in on the 30% tax credit before the 2017 step back- but don't expect PV installations to slow for more than a couple of seasons after that (if at all) as everyone else becomes aware at just what a bargain buck-a-watt PV really is compared to what they're paying monthly to the utility. (Handled poorly by regulators it could be a real rough ride for the utilities and the non-PV-owning ratepayers too.)

At $8.5K/watt are you sure they are actually being installed? That was the price point more than 6-7years ago.  I've not seen a quote over $4.25/watt this year (and that was for high-efficiency PV with a 3-phase 208V inverter).  I'm dubious that many people are going to sign the purchace and sale agreement at that price point, since it's nearly 3x the going rate, despite the high prices in CA.  In 2013 CA rooftop grid tied pricing averaged about $5/watt, which was a bit higher than the national average.

I just received a quote for my new house for Solar, literally 30 minutes ago.
4KW system $4.85 per watt with projected TSRF of .84 and 3,628 KWh per year.
5KW system $4.55 per watt
7KW System $4.35 per watt

If i could buy for $3.75 per watt I would certainly be putting a large system on my roof. Fortunatly, here in Oregon we have a $1 per watt installed incentive from a power co-op thing called the ETO plus up to a $6,000 state tax credit(taken over 4 years at $1,500 per year)
I can e-mail you the proposals if you don't believe me. I tried to attach them but I can't get them to be less than 100KB.
I also looked back into my e-mail and found it was not $15,000 for a 4KW system but can't find the actual price anymore in my e-mails, but that was for my current house and the pricing above is for my new construction home about 15 minutes away from my current house.

At $8.5K/watt are you sure they are actually being installed?

Oh yes. For that price you get an online account so you can show your friends how green you are.

Posted By SkyHeating on 21 Apr 2014 02:32 PM

At $8.5K/watt are you sure they are actually being installed? That was the price point more than 6-7years ago.  I've not seen a quote over $4.25/watt this year (and that was for high-efficiency PV with a 3-phase 208V inverter).  I'm dubious that many people are going to sign the purchace and sale agreement at that price point, since it's nearly 3x the going rate, despite the high prices in CA.  In 2013 CA rooftop grid tied pricing averaged about $5/watt, which was a bit higher than the national average.

I just received a quote for my new house for Solar, literally 30 minutes ago.
4KW system $4.85 per watt with projected TSRF of .84 and 3,628 KWh per year.
5KW system $4.55 per watt
7KW System $4.35 per watt

If i could buy for $3.75 per watt I would certainly be putting a large system on my roof. Fortunatly, here in Oregon we have a $1 per watt installed incentive from a power co-op thing called the ETO plus up to a $6,000 state tax credit(taken over 4 years at $1,500 per year)
I can e-mail you the proposals if you don't believe me. I tried to attach them but I can't get them to be less than 100KB.
I also looked back into my e-mail and found it was not $15,000 for a 4KW system but can't find the actual price anymore in my e-mails, but that was for my current house and the pricing above is for my new construction home about 15 minutes away from my current house.

I believe those are real quotes- there is quite a range of pricing in the US, depending on local markets. But I also believe that in five years those same systems will be quoted at under two bucks, given that systems are already getting that cheap in locations where the market is competitive and the paperwork hurdles are streamlined.  In Germany they don't even have to pull a permit- a pre-certified installer puts it in, turns it on, and mails in the forms to the utility, city, and national agencies.  Some locations in Texas are already there too.  As the market develops the bureaucratic overhead, advertising & hand-holding costs fall, (currently accounting for over half of the cost in those $4.35-$4.85/watt quotes) and the stuff becomes ridiculously cheap, tracking the continued falling cost of the hardware.

But that $8.50/watt figure in Indio, CA is really something!

BTW: Greentechmedia (a reliable source of for the statics & analysis on this stuff) put this handy li'l graphic on one of their blog pieces today:



Note the nice linear trend line of the pricing (right side scale) since 2008, and the exponential rice of installations per year (left hand scale).  Even in 2008 the typical system price was $7.50/watt, (below the Indio pricing), and the national average for 2013 was in the same range that SkyHeating's quotes fell in Q2 2014.  But projecting forward to 2020 a $2/watt price point looks like a slam-dunk. (But analysts are projecting well below that mark due to streamlining/mainstreaming of the process in the US, combined with ramped up worldwide production using lower cost technology during that time frame.)

Late to the party but the blower door results for that house are quite high indicating poor framing, some major thermal bypasses or some sort of window, door sealing issue. I would guess their are some attic spaces open the the walls or major open seams in exterior sheathing. With that much leakage a thermal scan might look not bad, because their is so much leakage, smoke pencil or a hand scan might be better.

Typically I see newer houses in the 35-45k cubic feet around 2500 cfm50, 3500 is starting to get high. With no real effort a builder should be able to achieve that, spray foam the sill, foam windows doors and shut off any open chases to attic spaces.

I've done so many energy retrofits my memory is a bit hazy but it seems to me we once sealed a slightly open coal chute and saw a reduction of somewhere in the 500-750 cfm50 range? Since new houses typically dont have coal chutes you can extrapolate what that house has going on, that said the blower door guy could have an incorrect setup. Either way the builder really screwed it up.

No screw up by the blower door, we tested it with and then the insulator tested in and used a FLIR since normally all we do is duct testing. Both results were the same, just very leaky but it sounds like we got it resolved!