Saturday, June 19, 2010

My Home Performance Test

While I owned, and competently operated a blower door, I of course applied it to my own house, typical, well-built, 1950's ranch-style. 

In this, apply my Insulation Math.

Here is the text of the Blower Door Test Certificate I produced:

Date: August 25, 2008

Baseline, My House

In a baseline test, all outside doors and windows are closed. If there are storm windows, they are closed. All interior doors are open. Fans and furnace are off.

Result: Airflow at test pressure (CFM50), 1330 CFM.

Results Commentary:
Desirable Air Exchange: Look at air changes per hour, ACH.
Consider ACH50, that at the minus fifty pascals test condition.
ACH50 = CFM50*60/House Volume
where house volume = 8 ft height times 986 sq ft floor area, 7888 cu ft. 
ACH50 = 1330*60/7888 = 10.1.
Compare this to a minimum value of eight for a healthy home. Some further reduction would be desirable. 

A reduction from ACH50 =10.1, to ACH50 = 8, is 280 CFM50. The value of that reduction, in annual heating cost, is 0.074 times change of CFM50, or $20 per year.

The estimated leakage under natural conditions (ACHnat) is approximately the result of dividing the test result by twenty. ACHnat = 10.1/20 = 0.506. Compare this number to a value of 0.35 to 0.5 for a healthy home. A target blower door test result is about 921 to 1315 cfm, for the target 0.35 to 0.5 ACHnat. A reduction of 280 CFM50, to 1050 CFM50, is a shift to ACHnat from 0.506, to 0.40. 

A 280 CFM50 change corresponds to 14 CFM at natural conditions. Compare that to accelerated fresh air exchange while running a bath fan. A good bath fan for a 100 sq ft bathroom will be rated at 80 CFM. If I ran that fan four hours a day, it would average 14 CFM.

I have a typical house, and this is a typical result. Nothing motivating. Just a sick feeling about wasted time and effort. It is a typical home performance test overall. No other step to assess the "science" of the personal comfort and health in a home, offered in the typical hopeful "holistic" baloney. No offer to look for hidden  problem areas with an infrared camera. No thought about Radon. No thought about control of relative humidity. No duct blaster test or furnace assessment competently at-offer, if not done by a rare professional home inspector or HVAC mechanic. Just the blower door show.

The commentary is above and beyond what most home owners receive. For most, there is nothing. A number might get written on a scrap of paper. It might appear in a report. There will be no offer of "fixing" anything. A particularly diligent tester might have tsk-tsk'd at a squealing window edge, and might have even done an impermanent and inappropriate repair, with a caulk tube. Anything serious is for another contractor, who will not likely see any of the tester's report.

If the testing is by an interest-conflicted blower of loose-fill insulation, repairs such as the so-often needed covering of attic floor pits, and bringing in an electrical contractor to deal with safety and convenience issues, will be precluded by immediate burial. In my area, that crook can then submit a fudged blower door report, and pad his bill with the rebate I would have been denied for my real, diligent, hard work. The home owner will then suffer  unsaved heating costs, for many years. This is a crime of the incentives programs that exalt home performance testing. The awful wrong-headedness is well illustrated in a flyer from Energy Trust of Oregon, perhaps from a national template for "training."

Weatherization Boot Camp will teach you how to:
Reduce uncontrolled air movement by installing blown insulation materials to correct density. 

What does that mean? For an attic floor without buried problems, it is absurd. For an attic floor with buried problems, it is criminal.

2016 Update
At 3/24/2106, add to this with goal of addressing IECC actions for 2018 revision, R402.4.1.2(old) R402.3.4(new) Testing Envelope Air Leakage. 

The building or dwelling unit shall be tested and verified as having an air leakage rate not exceeding five air changes per hour in Climate Zones 1 and 2, and not exceeding three changes per hour in Zones 3 and colder.  We talk of such "air changes," tending to forget such are for artificial conditions as if a home were subjected to static pressure everywhere outside the home, that of 20 MPH wind. The artificial condition is set by a "blower door" mounted in an exterior door, pushing air outward, at static head of 0.2 inches water column. The air flow through the fan for those conditions is about twenty times the rate of actual home fresh air exchange. 

I believe I am now below 5 ACH50, saving $50 per year in cost of make-up air, from accumulated home improvements. There was no possibility a blower door would have guided those improvements. I will own a blower door again someday, and will use it honestly. It will never be lied-about as guide and measure of weatherization. A blower door is useful only as verification of needed fresh air exchange, upon very rigorous completion of obvious improvements that tighten a home. If a controlled amount of air exchange is volunteered, as through continuous powered, regenerative heat exchange, a test may again have no value.

I am contributing to the 2018 IECC revision process as an unpaid volunteer, and hope to address applicability of rules, to existing homes, Chapter 5. Chapter 4 rules apply only to new homes unless referred into Chapter 5, and that referral for home sealing has not yet happened. That failure is associated with the continuing blower door madness that misguides weatherization. Important opportunities for sealing are found by sight, and should be addressed by each worker, not restrained by test-in, test-out foolishness. 

Proposed changes to the International Energy Conservation Code Of 2015, will be considered at the 2016 Committee Action Hearings, April 17-27, in Louisville, Kentucky. In my preparation  for this, I see a foolish continuing commitment to tighten our homes without limit, then needing to provide fan-driven fresh air.

I summarize thus, further exercising the Insulation Math for my 1000 sf home:

Each ACH50 for my home is 8000/60, 133 CFM50, and corresponds to makeup heat cost of $0.074*133 = $10 per year. The size of a hole that could carry this flow is 9.86/0.555 = 17.8 sq in, a circle 4.8" diameter.
Every ACH50 I may covet, could come through its 5" hole. 5" holes! No big deal. Driven by natural pressure differential without cost of electric power and with measurable increment of good health. The flow at natural pressure differential 133/20 = 7 cfm. is a small fraction of the flow of a bath fan.
Think about this please. Math is for fuel cost bumped up to truer cost at $2 per therm. It's a 1000 sf ft home in a moderate climate formerly 4400 65° HDD and already down to 4000 HDD with global warming. If in silliness I have tightened my home to 3 ACH50, from 0.5 ACHnat, I am paying  less for cost of heating the air from ambient to 65°F, to the tune of $10 * (10-3) = $70. Now I need to pay for the driven fresh air. Say it is 25 watts, continuous, six months per year. I will be erratic in regulating the system while mindful of opening windows more in mild weather. 25 watts *24 hr * 365/2 * KW/1000 watts *$0.11/KWH = $12 per year. Maybe the draw is closer to 100 watts. There are maintenance costs. I am not saving anything, really. I admit though, I have an unmentionable reason to be on this path. I have a radon problem largely solved by letting ample fresh air in at bedside windows at night, and will be happy to relax that some if I achieve a plan to exhaust stale air through-roof, via a sealed, conditioned crawl space. With this solution, I don't visibly and audibly display the radon problem. I think I have answers and not many problems. Silly people with blower doors know none of this. They think they know better. They cause us so much trouble and expense. We are made to feel guilty about opening windows a bit, letting in the evil coldness.

About that radon concern  I now monitor my house continuously with an affordable Corentium  Model QRI, a very nice Product of Norway . 

At Amazon $200 it isn't for everyone, but it is more affordable than I had hoped ever to find. It came to my attention in a post by friend Corbett Lunsford .

How to Test for Radon at Home: Proof Is Possible - YouTube

I thought I would observe readings for a couple of weeks, and then let my customers share it, but instead it has been recording away for three months now, and the long-term average has not held steady at 2.5 pCi/L.  It has drifted up now to 3.5 pCi/L, moving toward the action level of 4 pCi/L . I will continue to watch this for a few more months, before sharing the monitor. 

Where some say, and I accept, that radiation health consequences are random, there is no safe level of exposure to radon. I must take that further step to actively move crawl space radon up through my roof, maintaining the crawl space at static pressure less than that of rooms above. This is my plan, but it can't happen until I rebuild the crawl space access cut through the foundation, air tight. It's a big deal, but I must get it done next Summer. I still find a 100 watt 24/7 suck from the ground of my crawl space, absurd. A discharge duct through my new bathroom wet wall is in readiness. Now I need to create the draw through my kitchen floor, in a stalled remodel. My Winter project is construction of a half bath in a kitchen corner, enabled by near doubling of kitchen area, taking over a concrete porch. The exhaust down to the crawl space will be in that bathroom. There are many challenges and lots of expense in this that I will just now find means to bear. Challenges include powering DC-wired LED kitchen lights off-grid, with components not yet discovered. We must dare to persist in imagined best solutions, and then freely share them.