Door blower test

[eclecticcottage]

We recently had a door blower test here at the Cottage. Someone I know has a relative that works for an HVAC company so I picked them for the free NYSERDA test. Previously I wasn't so sure I wanted to do it, it seemed a bit like a sales tool (which it still is). I'm a little meh about having all the specs and info fed into an NYS program, but we felt we needed to do the test and free is about the cost we wanted to pay for it.

So, the result...was...6,000 CFM movement. We have some serious sealing to do. Some places were expected, but we found a few we were surprised by, especially the trim by the front door (not around the door itself, but the trim against the wall). No big shock that we're drafty, this place was meant to be a summer cottage originally...

Anyone else have one done on an older (smaller) house? I'm just curious what other folks numbers were like.

 

[woodgeek]

Wowsers.

My 1960 split level, with 2250 sq ft was prob ~5000 CFM50 when I bought it, and you could feel the wind blowing through sometimes, even on our very sheltered site. Somehow you have more air leakage than my old barn with a third of the square footage!

I found ~10 sq ft of openings from the framing to my attic. You prob have a bigger amount of leakage area. Imagine having 3-4 windows wide open all winter. That is what you have now.

On the other hand, this is really great news. My energy bill was ~50% air leakage, and it was easy to fix most of that DIY. My guess is that if you explore you attic and basement you will find the culprit (look for 10-20 sq ft of opening) without too much effort. It is prob a soffit or hung ceiling open to the attic, or a place where all the wall framing stud cavities connect to the attic, or the attic and basement.

If you get it figured out, a couple weekends DIY could drop your winter heating bill 50%.

My advice...if you look around the interior of the house you will find little drafts...window/door trim, outlets, cracks around stairs. I would ignore them for now. I suspect that the framing of your house is a highway for outside air. Fixing the giant holes you will find in the attic and basement will stop much of the flow into the little leaks all over the place.

There are a lot of great how-to instructions out there if you just google 'airsealing' and read around awhile.

 

[woodgeek]

Some more numbers, you can convert the flow rate @ 50Pa, CFM50 to Air Changes per Hour @50 Pa, ACH50. If we assume your 700 sq ft house has 9' ceilings, that is 6300 cu ft of volume. Your ACH50 is ~55. The worst old houses are usually ~20. Median houses in the US are ~10. Energy star houses are ~5.

Are you sure about the CFM50 number?

 

[Wildo]

Wow that is quite the flow. Air sealing will really help you save some major $ and cut down dramatically on the amount of wood you will go through. Our house's first test was 3800cfm after I had spent many hours air sealing over our first two winters. We had about 19,000cf of air space which meant we were changing the air every 5 minutes or so. After we had spray foam put in this summer it cut back to 850 cfm or 1 change every 20 minutes, what a difference it made. We would have burned half a cord by now, but cooking dinner has done all the work except for one burn to remove dampness and maybe five burns from the monitor for morning comfort.

If you but the great stuff pro 14 gun and a case of cans for it and a case of caulk you'll will see a very rapid payback and a huge difference in comfort.

I would hate to know what my air changes were before I started sealing at my house.

 

[eclecticcottage]

We're waiting to get the actual report back with the recommendations, he said it would be at least a week. I am sure about the number though.

No basement, we're on a slab. We don't have roof overhangs (they are basically wind catchers up here, seems none of the old cottages had them although I do see newer built places with them) so there's not much in the way of soffits although we did find a few spots up there to deal with.

We've been sealing up the spots we found on the first test. If they come back to do any work, they will have to do another (also free) so that should be a good test of our efforts.

We heat exclusively with wood with the exception of using the VF as a backup when it gets either really cold or if we are away for long enough that the stove burns down.

My only "fear" with doing this is that the Republic is going to be too much stove for the space, especially in shoulder season...except we need the burn times. We did scope out BK stoves last week when we happened to drive past a dealer with them on a daytrip. The problem is the 30's (Ashford, Sirroco) have a BIGGER firebox than the Republic, but the 20's might not have enough burn time. We've managed to still be ok so far with daytime solar gain and small evening fires. This season will be a good test of our abilities to run the stove and keep a balance. We hardly brushed anything from the stack when we cleaned after last season, I don't want to have to run the stove so low that we get buildup but I don't want to cook either.

We know we'll never be at 1000 or some low number, but I'd like to cut it in half at least, Mr Eclectic is aiming for more like 2000.

Some of the biggest areas were around the door trim, below another door and along the top of a wall where our livingroom (addition) meets the original cottage structure. We're working on a way to seal the ceiling/wall there now. Also, place we bought the stove from that installed it balled up our ceiling when they cut it to run the pipe so we have some damage repair to do there as well which is allowing air infiltration.

 

[woodgeek]

I got my place from ~5000 CFM50 down to 2660 (measured) DIY, and then I had a pro airsealing job that was very extensive, that got me down to ~1900. My ACH50 is now ~6 or so.

AS for your fear that you will have too much heat in the shoulder seasons.....you can always crack a window.

By soffits I meant 'drop soffits' in the interior where the ceiling line changes height.

Do you have an accessible attic?

 

[eclecticcottage]

Yes, we actually have two seperate attics, one above the original cottage and one above the living room (addition). The main cottage attic isn't a big issue, but we do have a spot where the addition meets the old structure that is a big issue, there was at least a 2" gap in one part. Unfortunately along the way the one side of the addition dropped a bit and now part of the framing is a little lower than the ceiling (structurally, the foundation and sill have been repaired, but we didn't jack it up because we didn't notice the minor drop and now it's just going to be like that) so we're going to have to box in along that wall and just seal the box (basically make a little mini-soffit).

 

[Wildo]

The more you seal the more you will save The satisfaction value of keeping my family warmer was the biggest reward for me.

 

[Ashful]

What happens when their blower is determined to be of insufficient horsepower?

 

[Wildo]

What happens when their blower is determined to be of insufficient horsepower?

You know you got it all.

 

[woodgeek]

What happens when their blower is determined to be of insufficient horsepower?

If the blower is too small to get the house to 50Pa, they measure the CFM at a lower pressure, scale it according to a formula and call the resulting CFM50 an 'estimate'. IIRC, most blower doors do not go much above 5-6000.

 

[tigger]

I had mine done about 3 weeks ago. Cape house about 1900 sq ft. We measured around 3200 cfm. I am scheduled to have the air sealing and insulation done on Nov. 3-4. I was told that after the work the house should come in around 1500-1800cfm. This plus my new blaze king and I. Reallllllly looking forward to this winter.

 

[Ashful]

If the blower is too small to get the house to 50Pa, they measure the CFM at a lower pressure, scale it according to a formula and call the resulting CFM50 an 'estimate'. IIRC, most blower doors do not go much above 5-6000.

Probably a lost cause, but it might be fun to have this place tested. I've already done a good bit to tighten it up, but I'm sure the numbers are still horrendous. I don't suppose PA has any of the free programs I see advertised for New England?

 

[jebatty]

Blower door would be interesting. Haven't pursued because I have done a lot to seal up the house and only burn 4 cords of aspen during our heating season with some very cold/windy periods into the -30'sF and lower. Average January temp is right around 0-5F. Plus, with the wood stove in the living room doing the heating, I need some air leaks for makeup air. Occasionally have to crack a window to get extra air.

 

[woodgeek]

Probably a lost cause, but it might be fun to have this place tested. I've already done a good bit to tighten it up, but I'm sure the numbers are still horrendous. I don't suppose PA has any of the free programs I see advertised for New England?

Looks like the low-interest-loan program I used came to end in 2013.
(broken link removed to http://www.energyworksnow.com/residential)
It might get restarted again in the future, PA does its incentives 'on and off' based upon fed and state funding, unlike MA, CT and NJ that just fill a pot of money from customer elec bills. It is actually seen as a model program around the country, and has been around for awhile.

My energy auditor was Bob Stoy in Newtown Square: (broken link removed)
He was an odd duck, and took a while to prepare a report, but it was well done. (I think when the above program was going, everyone was too busy.) I suspect it has slowed down a bit now....don't know what Bob would want for a full audit...blower, IR, complete visual inspection, prob a few hundred. Even if you plan to do your improvements DIY, his report would provide a v useful roadmap on where to focus your attention.

I had the work done by: http://www.orangeenergysolutions.com/ They did an ok job, and were a nice mix of competent and not gold-plated, if you know what I mean. They eff'ed up a couple small things (not uncommon in a big complex project) but made them right in the end.

In my case, I think the whole pro job saves me $400-500/yr, and cost me $5k. The DoE gave me a 0% 10 year loan, so the 10 year payback is not so bad, esp if I figure better 'comfort' and IAQ. In your case, I suspect there would be more low hanging fruit, and you could get a decent payback (<5 years), but you might consider that not attractive too depending on how you figure opportunity costs.

 

[Ashful]

Good info, as always, woodgeek. However my priorities are skewed by cosmetics and time. I have an enormous amount of 1980's or 1990's stucco applied over original 1770's stucco, and the bond is starting to fail. It will be a $30k job, and I need to get on it soon, before stucco starts raining down from 4 stories up. Likewise, I have several old windows with sill rot, and I'm tackling those in conjunction with each room I renovate. The choice of which room to renovate is a compromise between the urgency of the window situation, and our desires for which rooms inside get done first.

Each window rebuild tightens up the fitting of the sash, although I chose to forgo adding weatherstripping, as I hate messing with historically significant details. I am adding custom-made mahogany storm windows to each window, which drastically improves radiation loss (actually better than any of my new low-E windows in the new part of the house), and helps cut down on draft to a moderate degree. I am also adding interlocking metal weatherstripping to the doors, as I get to those rooms with exterior doors, which makes a very big difference. We can actually see light pouring in around and under several of the original doors.

 

[woodgeek]

Understood over here at maintenance deferred manor. The cfm50 number is prob not as useful as having a trained guy crawl all over the place with a flashlight to find big air holes in the framing, which would help the OP. In your stone place, I suspect you are pretty airtight except for doors and windows, and it sounds like you have those covered. But for a few hundred, he might find a bypass you could fix in an afternoon, if such holes exist.

I am a fan of low-E storms on my wood windows. My IR measurements suggest I am getting a respectable U ~ 0.35 with 1960 primary windows in place (better than most replacement windows).

 

[sloeffle]

Plus, with the wood stove in the living room doing the heating, I need some air leaks for makeup air. Occasionally have to crack a window to get extra air.

I am with Jim, a little bit of leakage does not bug me too much. What is the lowest CFM number that you can have and not need an HRV ?

 

[woodgeek]

You never need an HRV, you would just need to add some ventilation.

The figure I heard is that you start to get excess winter humidity when your ACH50 gets to the ~3 range, which is 95% lower than the OP, 80% lower than my house when I bought it, and still 40% lower than I have achieved to date. I still run a (small) humidifier in the winter.

I suspect that Jim is in the 3-5 range. Very few US homes are that low.

So you are right, the financial case for retrofit airsealing to <3 in a cold climate is not there....diminishing returns on energy savings, and additional costs for ventilation equipment.

Still, the advantages are great.....easy humidity control summer and winter (+ health effects), soundproofing, low dust and outdoor pollutants inside, fewer bugs coming in from outside, etc. Feels like a whole new house almost.

Note: while I get enough air in the winter due to stack effect, but I need a little more air in the other 3 seasons than would leak in with the windows closed. I have previously just cracked a window, now I have a $40 timer on one bathroom fan to run 50% duty cycle (about 50 cfm average). I'll shut that off in the winter.