Anyone ever get an energy assessment or inspection to get increased heat efficiency?

[woodgeek]

I am definitely making my house tight - since the tyveking, the indoor bugs have decreased dramatically (considering it's summer time). We'll see in the next month or so as it cools off if they flood indoors.

So now I'm wondering - how should I introduce fresh air in the winter? Opening a window will dry out my house (unless I humidify, which I might do anyway). An HRV system is too expensive...

I tend be unclear, sorry. Your natural air exchanges are highest in the winter--that is when your air will be 'freshest', because the stack is a maximum. When the air outside is the same temp as inside, if there is no wind, there is no fresh air either. I had some CO from a boiler last year, and it was a small source for months. The alarm went off only after the outside temps were hovering around 70F for more than 2 days.

So, don't bother cracking a window in the winter--you will likely have enough fresh air then. IF you knew your house was really tight (a big IF), then yuou might want to crack a window spring and fall (or leave a bath fan running) for fresh air (w/o an energy penalty).

As for hill-william ACH estimation, I looked at my house volume (18000 cf), and I figured that if I was ACH=0.3 (my target), then my '3 gallon/day' humidifier should boost my indoor RH by 10% over what it would be without. At ACH=0.6, it would only bump me 5% on RH. So, if you can run a honking big humidifier, and barely tell with a good/trusted hygrometer, then you are not yet 'too tight'. Of course, I do this in the dead of winter, cuz I only care about my ACH nat at my mean winter stack effect driving.

 

[joefrompa]

"So, if you can run a honking big humidifier, and barely tell with a good/trusted hygrometer, then you are not yet ‘too tight’" - huh?

In other words - if I run a significant humidifier in my home and have a humidity meter (hehehe, dumbed that down) in my house and it barely moves, then I'm getting enough ventilation through natural means because the humidity is running fairly stable.

However, if my house starts to get humid (I'm guessing a rise of 10%?) - then it's not ventilating that moisture very well and it might be "too tight"

...

Last thing - I would only crack a window if my I notice my stove has a tough time drafting AND if I want the fresh air to come in in the stove room.

I actually have a theory that a cracked window in my stove room MAY help spread more heat through the rest of my house. Crazy, I know.

 

[woodgeek]

Basically. Sorry to back into this stuff a post at a time....ACH=0.3 is a common level of minimum ventilation recommended for residential property. If you had an airtight house (e.g a super tight green house), you would size the HRV/ERV to provide something like 0.3 air changes per hour. In my case, since my house volume is ~18,000 cubic feet, that is 18000 (cf/change)*0.3 (change/hr)/60 (min/hr) = 90 cfm. So, even when it is 70F out, I can run a bathroom fan and get a 'code' amount of fresh air. Of course, most houses in the US have stack driven flow >0.3 ACH most of the time (except the hours when the temp diff and wind are both small), so it was never an issue.

A lot of folks think the 0.3 number is a little generous. If your house is lacking major pollution sources (e.g. smokers) and has a lot of square footage per person, 0.2 is likely plenty, in my case that is only 60 cfm. My current ACH in the winter is still well above that line, so I can still save energy by additional airsealing, without risk of killing my indoor IAQ. In mild weather, however, I am likely below 0.2 much of the time, because of reduced stack effect. That is, if I have an ACH of 0.5 when the temp outside is 20°F (50° differential), then I have 0.2 ACH when the diff is ±20°F (50 or 90F outside), or <0.2ACH whenever the temp outside is between 50-90°F. So I bought a blower, filter and filter box to supply ~60cfm filtered fresh air into my house, planning to run it from Apr-Oct. This would also maintain a small positive pressure to keep allergens out, and flood my wall cavities with dehumidified air during the AC season, which sounds good to me. Technically, this is fixing something that isn't broke (i.e. there is no evidence of our IAQ being poor), but my wife and I have wicked hayfever, so a filtered fresh air supply helps that and covers the hypothetical IAQ problem. I'll install it before the spring pollens.

Radon is a complex issue--I haven't checked it, but should. It does depend on the relative pressure--in the winter you are sucking air into your basement (mining radon) and in the heat of the summer you are pushing air out your basement. I'll check it soon.

On the humidifier, I worked out that ~4300cf of 100RH air at 70°F contains 1 gallon of water (as vapor). Evaporating 3 gal from my humidifier can humidify 3*4300 = 13000 cf of dry air to 100% RH, or could raise the RH of 130000 cf of humid air by 10%RH. If hypothetically my 3 gal/day humidifier only raises the RH in my house by 10% (say, after 24 hours of running, relative the RH the day before), then apparently I have 130000 cf of air entering and exiting my house every day to carry the water away so effectively. This huge amount of air corresponds to 90 cfm * 1440 min/day, or about 0.3 ACH in my case.

When I bought my house, I could never humidify it in the winter. I could run a big humidifier flat out (forget it maintaining a setpoint) and got no benefit I could detect with a meter, let alone feel! I now know that I was at 1.3ACH, and my 1.5 gallon/day humidifer would, theoretically, boost my indoor humidity by only 1.15%.

Bottom line: houses that are hard to humidify in the winter are leaky sieves (you can still put a humidifier in the bedrooms). Houses that are built tight (very low ACH) often don't need winter humidification at all. When I got to the point of seeing a measurable RH rise when I ran my 'whole house' humidifier, I knew I was getting close--and I could use the humidifier to estimate my wintertime ACH.

 

[jharkin]

My PM box is getting flooded with requests for a pointer to the Massachusetts program so here you guys go:

The state program is called Mass Save. Its funded by the big utilities and administered through a 3rd party company called Conservation Services Group.

First step is to call up and request a free energy assessment. This has all the info:
http://www.masssave.com/residential...assessments/what-is-a-home-energy-assessment/

 

[sesmith]

We had an energy audit done on our house this summer. It's an old (1840's) timber frame farmhouse with a couple of conventionally framed additions. I've upgraded insulation, put in vapor barriers where I could, and replaced the windows and doors as I've remodeled it over the last 30 years that we've owned it. We're putting in a geothermal system this fall, so I wanted the energy audit info to help with sizing the unit. The blower door test showed air leakage of about 1 ACH, if you do the conversion from cfm 50. Fairly leaky as I suspected, but not terrible for a very old house. One area where the tech thought I could make a difference, was sealing the rim joint area (there's nothing I can really get to in the roof area or crawlspace over part of the house...both are pretty well insulated w/cellulose), though he said payback would be questionable if I had to pay someone else to foam it.

So yesterday, I sealed the conventionally framed rim areas with 2" blue-board foamed in place around the perimeter of each piece (using low expansion great stuff), and then I sealed around the inside edge of each piece with the regular great stuff foam. On the timber frame rim area, I just foam sealed the timber to sub floor joint and all joints and cracks where the rafters joined the sill beam, and any other areas where there seemed to be any leakage. I also sealed any penetrations from the cellar to the upper floor. One thing I noticed when I was partly done, and most of the major leak areas were sealed, was that my dehumidifier stopped running. It was a rainy, windy day, and normally the dehumidifier would be running 24/7 just to keep the old cellar at around 70% humidity under those conditions. So I'm guessing all this time, I was dehumidifying the outdoors mostly! Since I did the sealing yesterday, I'm more likely to find the dehumidifier off than on, and humidity is running about 65% down there at the present, and the cellar has a totally different feel to it...still windy, crappy and rainy outside. I'm pretty happy with my $160 investment in materials, at this point...should have done it years ago. So, if you are also dehumidifying a cellar, sealing it has other paybacks over just savings in heating and cooling as dehumidifiers aren't exactly cheap to run.

One last note. I have 4 can lights in my kitchen. They are rated for direct contact to insulation and have fiberglass and a healthy layer of cellulose over them, so leakage is probably minimal. I saw a display of Cree brand LED can light conversions at my local HD yesterday for $25 ea, so I picked up one to try. I'm totally sold. It's a solid unit, so once it's in, the only area for leakage should be around the lip of the fixture. If you wanted to be anal, I guess you could caulk it in place. They also are dimable and use around 10 watts instead of the 75 watt incandescents I had in them (I had never switched these to cfl's because they're on dimmers). The new light seems to be brighter, but doesn't have that stark, LED looking type of light. I think I'll pick up 3 more.

 

[laynes69]

When we had an energy audit done, they said our NACH was .8. Our home is at least 150 years old, which records were destroyed in a flood years ago. There were new homes built down the road where they said they had more air infiltration. The areas you were talking about was where the floor joists met the beam correct? I foamed the cracks then placed fiberglass batts in the cavities. I like your idea better. One of my largest leaks is the boulder walls of the basement, but also our bilco doors. Does anyone have ideas on sealing a bilco door? I would like to see our home down in the .4-.5 range. There's 2 problem areas that need to be addressed here but one is a new addition and the other a gut and remodel. Airsealing the attic and working in the basement has made a world of difference. We also dropped about 30 a month going with cfl lighting.

 

[semipro]

For those that live in Virginia, the state is offering a $250 rebate on home energy testing through the DMME. Our test, a shell evaluation including blower door and thermal imaging cost $350. It should end up costing us a net of $100.

We just had ours done. I quickly addressed some of the easy-to-fix air leaks and I swear our house already feels less drafty.

 

[jharkin]

Update....

The insulation contractors for MassSave - Anderson Insulation of Abington MA - were at my place today doing the work. These guys are good... we noticed a few things that the auditor mixed up (spec called for insulating slopes from the top... yet I have no open attic above the slope !) but they found ways around all the issues.

A couple of the walls they were going to blow turned out to have some insulation so they ended up only blowing one 15ft section. On the other hand in the attic they are going to do more than was speced - I managed to make an access for them to get into some closed off attic space over my dining room so they are going to blow cellulose over the thin FG up there.


More reports tomorrow after they finish up...

 

[jharkin]

The insulation job is done.

We found all but one wall on the first floor was already blown in. So they cellulose dense packed that one remaining wall.

In the attic, they dense packed the kneewall floors and attic floor above the addition (7in ~ R 24). Blocked the slopes with FG and dense packed them (5 in+ the furring strips for a thermal break, R18+) - which also packed the flat. then the put 2in polyiso on the kneewals and access area (R14). As they were going they air sealed everything tight, including sealing the chimney chase with flashing and fire caulk and damming the chimney in rock wool so they could insulate up to it.

My slopes are now a sealed hot roof - I know that is controversial( especially with the old house preservation folks) but we found that they had been stuffed with kimsul 50 years ago and weren't well vented anyway and that didn't cause any water damage so Im betting this wont either. And if we have reason to be concerned in the future everything we did is easily reversible unlike spray foam (they can pull the plugs and vacuum out the cellulose for renovations).

The also put in baffles and blew over existing FG in the dining room ceiling, probably bringing that area up to R40+

No we just wait for the MassSave inspector to come check the work, then the gas company pays the rebate to the contractor and I get billed for the difference which will end up under 30% of the total job cost!

 

[jimbom]

Jeremy, Good looking project. My opinion is this type of effort is the most energy efficient thing we can do in the USA to reduce unnecessary energy waste. Congratulations.

 

[jharkin]

Dig this one back up again.


You guys might find this (not) amusing. Yesterday the MassSave quality control inspector came to evaluate the work done by the insulation contractors. This guy was not impressed.

#1 he found that all the dense packed cathedral ceiling bays were not - most bays were light and fluffy and a few left empty(!) He also went around with an IR camera and found all kinds of voids in the walls. They just used one center hole to blow in, no fill tubes or anything and missed a lot.

#2 they missed most of the air sealing around the transitions from the rigid foam to the cellulose bays.


#3 He was upset that they insulated over my recessed lights. The cans are IC rated, and the contractors asked that before doing the work, but the QC guy insists that its not safe to insulate any can even if its IC. I actually argued the point - "The manufacturer rates these for insulation contact up to 65watts, and Ive even under-lamped them with 10watt LEDs and you still think its a risk???" yup. And urged me to watch and if I see any flickering lights to throw the breaker and call them back asap. The guy really thought my house would just spontaneously combust!

They are going to have the contractors come back and take the insulation out and redo it. What a waste.

UGH.


I'm also really annoyed at the contractors - who were really nice guys and seemed to know what they were doing - apparently didn't do half of what they said.

I'm further annoyed that the original energy evaluator the sent didn't have the IR camera. We might have made better choices on what walls to blow into than just guessing based on sticking coat-hangers behind some outlets feeling for insulation.

 

[semipro]

I guess you're lucky the QC guy came by. Maybe the work will get done correctly now.

I just installed some dense-packed cellulose in our house and don't see how you could get it right without using a fill tube. Its difficult enough with one.

That is strange about the can lights though. Seems that with the IC rating, the under-lamping with LEDs, and the built in thermal protection you'd be pretty safe.

 

[jharkin]

That is strange about the can lights though. Seems that with the IC rating, the under-lamping with LEDs, and the built in thermal protection you'd be pretty safe.

Agree. I think the chance of fire is pretty close to zero. Even using the design wattage those things have a massive safety factor built in, not to mention the thermal cutoffs.

If these things were so dangerous when used as deigned, Cooper would have been sued out of existence years ago. I suspect most fires form recessed lights are people over lamping and insulating non-IC units. This state program is just being paranoid of lawsuits.

 

[jharkin]

Digging this one up yet again for a report on the results.

#1 - Turns out the inspector was a boob. the contractors put in a bit less insulation so as not to blow out my old walls. He made them pump in more, and they exploded my ceilings in two rooms UGH. But they did fix it on their dime.

More importantly I am seeing results! :
December 2010 gas bill - 187 therm
December 2011 gas bill - 80 therm.

Now, this year is mild and Ive been burning wood more days but that alone wont explain the 57% decrease in the bill.

 

[peakbagger]

I just had my work done this week. They sprayed a lot of foam and did a nice job sealing up a future spare bedroom as well as dealt with some air leaks. It was painful to see them seal off my gable end vents, but with a couple of inches on the inside of the roof sheathing, the roof is not going to see a lot of heat coming from the house to cause Ice dams. Its on a north facing roof with 2 rows of ice and water shield so I am not really worried but its still tough after all the work to keep a cold roof. The biggest pain was hauling all my accumulated junk out of my attic so they could do their work. The also spray the sills and the boxes, I expect that is where I am going to see the biggest impact as there were definitely air leaks.

I am waiting for an inspection. One issue is that the foam was sprayed on a cold day and there are some spots where the foam pulled away from the roof joists. I am going to see if I can get the inspector to require the contractor to do some touch up in those spots. if not I will keep en eye out for a sale on spray foam and DIY.

 

[begreen]

We get the first phase of the audit on Monday. This is paid for by the power company. If it looks like there are opportunities for some significant energy savings they may then authorize a FLIR and blower door test.

 

[billb3]

Had the Mass Save free audit a while back and (town takes forever to issue permits) the insulator guys finally showed up.
Sealed the attic and didn't help with the suction test that much, but they found that near the kitchen exhaust fan which I always thought I was doing a lousy job of sealing up for the Winter was a big empty spot behind a cabinet that was acting like a chimney going right up into the attic. Guys were fairly impressed with what I had already done especially such an old house and built rather poorly. They blew in 6 inches of cellulose on top of my fiberglass batts. I would have preferred more batts than a mix, but it works.

 

[schlot]

Definitely check with your utility company about this. Many do a basic audit for free, and some provide money to do the improvements they recommend.