If you want to address your attic without paying 10s of thousands of dollars, you can spend a weekend crawling around with caulk and canned foam and get a lot of them, and then buy some cellulose from a big box store and borrow their insulation blower to add insulation on top. Energy Star publishes a good how-to guide on that.

The fact that your double panes seem as cold as your single panes might be a result of air leaks around the windows. Interior or exterior storms would help that problem as well as helping your heat loss, although there might also be other ways to seal the air leaks if you can identify them.

Do you have a high-power range hood or other exhaust fan? That can be operated as a substitute for a blower door to help find air leaks. You can turn on all the exhaust fans at once if no one is powerful enough.

Do you have recessed ceiling lights? Those are notorious for air leakage, and could be a big part of the problem.

In your climate, air source heat pumps make a lot of sense. If you like the idea of radiant, you could consider a chiltrix air-to-water heat pump, and then put in radiant floors or ceilings. Except that if your labor rates for installing mini-splits are high, the labor rate for installing that system might be even worse, since it's an unusual one.

Chrs,

Considering the bid included $5k to remove the old insulation and "sanitize" the space, I think I might have to buy a great mask and DIY that. I'll check out Energy Star and other sources on sealing to learn about what needs it and where to look. Thanks for the idea. We only have a few can lights, so I definitely need to do some kind of test. We have a decent stovetop exhaust and some bathroom fans. I'm sure I could rig up a space fan tightly into a window, too. If I tape off the fireplaces and the obvious bottoms of doors, that might help tighten it up and draw more through the smaller openings.

Re: the dual and single pane being the same temp, all our windows are super tight. They're casements that seal all the way around with good strips. Storms aren't viable for us, for multiple reasons ranging from impracticality to snobbery (and that we have more door area glass than window).

Labor rates.... SKY high here. Bested probably only by the SF Bay Area. I love the idea of radiant floors (and what I have read suggests it's a better fit for our house than it would be for a tight and efficient one). Early indications are >$50k for the install, excluding the solar array and water storage, and a propane backup source. That has me leaning toward ASHPs for the savings and convenience of fast on/off.

Posted By Bob I on 05 Dec 2015 08:50 AM
AztecSD: you are missing the point. Whenever I mention air sealing, people start talking about insulation. They are not the same things and one does not replace the other. You could replace your R13 insulation with R100, but if you do not repair your air leaks, you will still be cold. You cannot guess where the air leaks are are or where they are not, you must use diagnostic tools, and you must reduce your infiltration.

That's right. Air sealing is a prerequisite to insulation. While cellulose is very air retardent even at low density (much more air retardent than blown fiberglass or mid-density fiberglass batts), it is not the same as air sealing.

Blowing a foot of cellulose over ducts and air handlers is fine during the heating season, but can create condensation in the insulation near the ducts themselves when the outdoor humidity levels are high. SoCal isn't nearly as humid as GA or FL, but it's still an issue. Bringing the ducts fully inside the pressure and insulation boundary of the house would be a better bet.

The single largest air leak in your house is probably the crawlspace, probably several times the leakage at all doors & windows combined. It's far easier to air seal the crawlspace walls from the outdoors than it is to air-seal the crawlspace ceiling from the rest of the house, and insulating those walls provides the thermal mass benefit of the soil below, which has a favorable temperature in your location.

Less obvious but still large air leaks are things like plumbing stack chases and electrical chases that go from the lower levels all the way to the attic. Electrical penetrations of studwall plates can also be big, expecially in uninsulated partition walls or exterior walls with low-density (or no) insulation. Sealing both the tops and bottom of these vertical leak channels is important for killing of the stack-effect drives.

This is true of the whole-house stack effect drives. A blower door test only tells you the size of the leak area, not the location, and location matters. Penetrations into the attic and penetrations into the vented crawlspace are orders of magnitude more important than leakage at the walls somewhere in the middle. The attic sounds like it's Swiss cheese with the duct and can-light penetrations (and the unstated flue & plumbing stack chases) but if I had to guess I'd hazard that the first-floor floor/crawlspace ceiling is equally as bad.

Some primers on the subject:

http://www.greenbuildingadvisor.com/air-leaks-waste-energy-and-rot-houses

http://www.energyvanguard.com/blog-building-science-HERS-BPI/bid/56102/The-3-Rules-of-Air-Sealing

http://www.builderonline.com/building/building-science/5-penetrations-that-provide-the-most-bang-for-your-air-sealing-buck_o

http://www.greenbuildingadvisor.com/blogs/dept/musings/getting-biggest-bang-your-air-sealing-buck

http://www.energystar.gov/ia/partners/bldrs_lenders_raters/downloads/TBC_Guide_062507.pdf

http://www.greenbuildingadvisor.com/blower-door-directed-air-sealing

http://www.greenbuildingadvisor.com/how-air-seal-attic-introduction

Caution, the numbers here need adjustment (but I doubt it will change the conclusion):

Let's say the house is at .29 ACH nat (sounds reasonable based on the ACH@50 and the climate), it's 50F outside and 70F inside. 44,000 cubic foot house. So 12,760 cubic feet/hour. .018*12760*20F = 4600 btu/hr. With an ASHP COP of 3, .45 Kwatts. Say the 50F outside is for half the day. So $2.21/day for the whole house air leakage. The areas of your attic floor (~60% of the house) that you can't seal from below and aren't reduced with 12" of cellulose (fairly effective at reducing air flow) might be as high as $.50/day and $100/year. What's the ROI if you spend $10K to save this?

This is the type of calculation your energy auditor should do.

Good math jonr.

It reminds me that the OP is looking for comfort sans a large capital investment.

We all want that.

But if you focus on comfort first and then hand him the bill, we have to forget about most of the options posed.

I agree, with lots of single pane/non Low-E glass, one needs to think seriously about MRT - just overheating the air to compensate isn't as comfortable.

OTOH, I don't agree with the small changes in air sealing in a mild climate -> comfort connection.

Thanks for the math a few posts up. I'll think about that and talk with our energy guy.

I'm skeptical of the effect from air sealing as well, but if I DIY it, it can't hurt. I'm also skeptical of the real difference from dual pane, given the infrared testing I've done. Likely it's a whole lot of small things that add up to a cold house.

Re: the glass, the windows are likely coated with something low E. They're tinted (wish they weren't), laminated, and when the sun goes through them, the heat seems lower than ordinary windows.

Maybe they are just tinted. At 68F inside, my low-E windows read 64F with the IR gun. (33F outside, double panes). As you found above, 6F in IR temp can be a "HUGE difference" in comfort.

Thermo says 68F now, walls are 64-66F, and windows are 58-59F.

Wow, that's a huge temp spread in vs out. It's possible I'm not heating enough (because why bother when propane is so expensive and it takes so much to make the house comfy?). So we never heat up the mass of the house at all, just the air for awhile. So our glass never gets warmer.

Air sealing something that leaky is by far the cheapest energy & comfort upgrade you can buy.

If you're not heating the place because it's not affordable it'll never be comfortable. You can make it more affordable by fixing the monster heat leaks. jonr has this one wrong, and I'm talking significan air leakage improvement, not "... small changes in air sealing..." Getting the nearly 6000 cfm/50 down to under 3000 cfm/50(or better yet, under 2000 CFM/50 so that it actually meets code) will make a difference in comfort. There's no way that it would cost anywhere near $10K to achieve that, unless you're air-sealing with gold leaf foils.

But the cold single pane glass generates convection drafts even in tight houses, making it feel chillier- it's more than just an MRT comfort issue. Heating with direct radiation is significantly more comfortable than heating with an on/off hot air furnace, and doesn't drive air leakage while running, and it would raise the MRT. But it's not cheap to install.

Skepticism about the comfort & efficiency benefits of air sealing or better windows is not well founded. These are fundamental. Many (or even most) houses in the upper midwest test under the current code-max 3ACH/50 before it was required by code, but because people figured out decades ago that even at the same temperature the tighter house was more comfortable. The higher comfort of double-pane windows was also noted by the occupants of homes with such glazing long before it became a code requirement.

Most low-E single panes are designed for rejecting solar gain, with a hard coat low-E coating on the exterior side only (usually looking like a light gray or light brown depending on the light & viewing angle.) A single pane with the low-E coating on the INTERIOR side would be more comfortable, since it reflects the infra red of warm mammalian bodies rigth back at them. This results in a somewhat lower glass temperature which can lead to more window condensation, but in your climate probably not much. It's not worth re-glazing them for that modest a comfort gain though, unless you re-sash to a high performance windows. But I suspect that what you have is less comfortable during the heating season than clear-glass, but more comfortable during the cooling season. Whatever glass that is, the single panes are an impediment to comfort. Cold glass generates convection drafts even in tight houses, making it feel chillier.

Dana, great insight. I hope this thread gets lots of hits in the future to benefit others.

It won't cost $10k if I DIY it. Probably more like $0.5k! It's awful work, tight spaces, lots of "stuff" up there, not to mention the misery of working around fiberglass. The smart thing would be to remove all the R-13 up there so I can see everything, clean it, seal it, and then re-insulate with something more lung/eye friendly.

And you are exactly right -- we're fine in the cooling season, barely "need" any a/c, can always cool the place off at night by ventilating.

I'm talking significant air leakage improvement, not "... small changes in air sealing..." Getting the nearly 6000 cfm/50 down to under 3000 cfm/50... will make a difference in comfort. There's no way that it would cost anywhere near $10K to achieve that,

Either a straw man attempt or Dana missed that I was running numbers for and referring to some additional air sealing in 60% of the ceiling area - nowhere near the whole house. And from what I understand from the OP, the quote WAS $10K. This small piece will have a small effect, nowhere near 50% of the entire house air flow. The ROI is ridiculous.

Seal the whole house DIY and yep, one will get a very different ROI number. I too recommend doing this.

I was saying that just adding cellulose on top without sealing first seemed suboptimal, even if it does add about $10k to the work.

Another diagnostic tool can be as simple as going down to the big box store and buying a number of sheets of 2 or 3" eps foam. Cover windows and / or walls in your main living area and see if it makes a difference.
When you are done with your tests, screw them to the underside of your vaulted ceiling, strap and apply drywall. One insulated vaulted ceiling.

In our area, we have several insulators that are setup to suck the insulation back out of a ceiling. We use them when doing major renos, like taking off a roof and adding a second storey. Might help and getting the main area air sealed.

I'm sure it would make a difference. We can feel the cold when near a window. Problem is we have as much french door glass as window glass.

No can do with insulating the vaulted areas. We have beams that would look awkwardly shallow (I know, purely aesthetic, but it is a critical component of this Spanish house, and would kill the resale).

The insulation is batts. No sucking them out. But at least they ball up nicely into bags!

When was the original portion of the house built?

1990

In 1990 they at least were installing R13s in the walls rather than R11s in 2x4 construction, which is an improvement in air-retardency slowing infiltration flows in the wall cavities.

Blowing cellulose over the tops of batts in the attic is fine, so you can just re-use the batts unless they're full of rat-poop or something. Overtopping with enough cellulose to bring the combined depth up to 10-12" isn't very difficult or expensive as a DIY-able project using a box-store rental blower, assuming box stores in your area carry cellulose. Plan-B would be to overtop it with a chunky denser blown fiberglass such as AttiCat, which is also DIY-able, and may be more available in your area. IRC code min for zone 3 is R38, which would take about 10.5-11" of combined depth. At box-store pricing AttiCat would run about 65 cents per square foot for R38, 50 cents per square foot for R30 (+R13 batts = R33). They'll usually throw in a day's rental on the blower if you buy enough for 400 square feet of R38.

jonr: I indeed missed the original quote number, which is off-the charts insane. If someone was quoting $10K for air sealing & insulation for only part of the attic there are probably much hungrier contractors out there than that! If not, you could probably fly someone out from MI for the weekend to do the job for the cost of just the air fare & motel expenses when the next Polar Vortex event hits! :-) )

Blow over cellulose and radiant floors.

They make full face respirators. I had one on today.

You can use cardboard to get the "feel" of better windows.

We work on many historic homes and manage to make everyone comfortable without knocking the house down and you don't have to get to NZEH standards to do it.

... and this one isn't even an historic home, just a poorly sealed 1990s house that LEAKS AIR as badly as an uninsulated 19th century antique!

A friend of mine with a blower door tracks the air leakage of houses he tests by the year they were built, with before & after air leakage rates on houses undergoing improvements. Most of these houses tested are in New England. Of those that initially leaked 6000 cfm or more, all but one were built prior to 1900.

The majority of houses on his chart built after 1900 tested at or under 4000 cfm initially, and improved after air sealing &/or insulating. Only a handful of the 20th cenury homes (out of a sample size of 20 or so) tested over 5000cfm, and one (built in 1902) tested over 6000 cfm.

The most dramatic improvements in a post-1900 houses on that chart were a house in Holderness NH built in 1975 that initially tested at 4000 cfm, that dropped to about 400 cfm after air sealing & insulation on a deep energy retrofit, followed by a house in Gloucester MA that initially tested at about 3500 cfm that ducked down to ~500 cfm after a deep energy retrofit. Clearly that's not where we're going with this house, but I have no doubt that beating this leaky sieve down to below 3000 cfm isn't rocket science or expensive, and that it will improve both comfort and energy efficiency.

His absolute worst-case house is one that he happens to own, a historical antique in sleepy Georgetown Maine (a former ship captain's home), with the original historic single-pane wood sashed windows (that are still there) and a quarried granite foundation not particularly well sealed to the large milled beam foundation sills. On first test it initially leaked about 9000 cfm, but after dense-packing the walls with cellulose and insulating the attic with cellulose it dropped to about 4300 cfm, with PLENTY of obvious air sealing tasks yet undone. I'm not sure how much of that work has been done since, or whether he has re-tested- the snapshot I have of his chart is from about 3 years ago when it's air tightness was just starting to be addressed. (I've even slept there- it's a kewl house!)

The house where he lives most of the year is a 1770s antique in Harvard MA, (revolutionary war vintage!) that started out at 4200 cfm, and dropped to 3500 cfm when the antique windows got tightened up. It has a lot of obvious work to be done too, but taking it very far is hampered by the fact that it's built with clapboards nailed directly onto the studs- no sheathing which becomes a serious moisture problem if simply insulated without gutting the antique interior.

And beyond air sealing & insulation, in all seriousness, no matter how architecturally significant those windows may seem, they're junk- performing well below current code min, and not worth owning (unless discomfort is somehow considered a virtue?) Surely at least SOME windows don't need to be operable to use the nighttime ventilation cooling strategy, and could be fitted with interior storms!

In that context, mine is ridiculously leaky. The guys who did the test are a very reputable, "new school" outfit, and the young owner is very thoughtful and seemed to know his stuff. Disappointing to learn this.

Windows... they are not leaking at all (they are, of course, an MRT issue because of the single pane). They are casements that close up super tight. They're (very) expensive wood customs built around 2006. Storms are not viable/acceptable anywhere due to the aesthetics, size of some, and because we have more glass in identical-style French doors than in windows.

I finally checked the skylights. At least THEY are dual pane. I see some weepholes at the bottoms that appear to allow air between the panes (evap?). No telling what their U-values are. I've looked into some others, very $, with U-values in the .28 range, but doubt they would fit our sizes exactly. Nothing is easy! Perhaps storms could be put up in there since we have fairly deep curbs.