We've been discussing this around the Saturn water cooler for a while now and figured an article was in order. Sound off and let us know what you think.

Questioning Worst-Case Combustion-Safety Testing

What new health-and-safety mandate will the home-energy community embrace next? We have worst-case combustion testing, the new lead regulations, the ASHRAE 62.2 ventilation standard, and new asbestos policies. Given the distraction from the energy-conservation mission and the high cost, I can’t help but wonder how these mandates relate to statistical risk and how effectively the prescribed testing and mitigation strategies reduce that risk?

Problems with the Current Reasoning

A new literature review by Lawrence Berkeley Laboratory (LBL) throws doubt on the value of worst-case combustion testing as part of home energy conservation programs. The literature review, titled: Assessment of Literature Related to Combustion Appliance Venting Systems, asserts that acute CO [carbon monoxide] poisoning from vented combustion appliances is extremely rare”. This paper also states the following: “Established methods for evaluating the safety of residential combustion appliance venting systems [worst-case combustion testing] produce results that are not directly related to risk”.

The Building Performance Institute (BPI) is known throughout the weatherization and home-performance industry for their emphasis on worst-case combustion testing of open-combustion appliances such as furnaces, boilers, space heaters, and water heaters. Worst-case combustion testing has driven an expensive, nationwide training-and-implementation initiative over the past 20 years.  It was designed to educate energy auditors, inspectors, and technicians about the assumed health risks of spillage and CO poisoning.

The Real Problems

The LBL report cites a Consumer Product Safety Commission (CPSC) study of the 184 total CO-related accidental home deaths in 2007. Ranges and ovens caused 4 deaths; water heaters caused 4 deaths; furnaces caused 28 deaths; and other heating systems including unventilated space heaters caused 34 deaths.

These statistics, and the fact that thousands of American homes still heat with unventilated space heaters, are reasons to question the “widespread menace of CO” purported within the home energy conservation community. These statistics don’t support either the risk claims or the mitigation imperatives that tens of thousands of energy specialists have studied, learned, and adopted.

Compare the home CO death statistics to the following deaths in homes during 2007:

  • approximately 15,000  falling deaths
  • 9,500 poisoning deaths
  • 3,700 fire deaths

I’m not suggesting that we discontinue combustion safety testing. I question whether the risk reduction (or lack of) merits the complexity and time investment of  the current worst-case testing procedure. If we want to make homes safer to offset possible unintended consequences of weatherization, why not attack the more statistically dangerous hazards: falls, poisoning, and fires?

Tags: CO, case, combustion, worst

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Replies to This Discussion

Playing devils advocate a little, but what if the dead client were your mother or child?
A little too close to home?
How difficult or expensive would it be for us to abandon natural draft appliances? ...compare that to the cost of this effort to deal with them.

Accidents do happen, but they are also random. This is not random, and it is not accidental. It is more like a sickness like polio or small pox. It can be terminated, but the first step should be to vaccinate the market. You do that by outlawing devices that expose civilians to the threat. Unvented and natural draft appliances should not be available in the market. Even if that step were taken, we need trained techs to deal with the devices in use now, likely for the next 3 decades.

Programs perpetuate the problems my excluding viable alternatives like high efficiency (85%?) vented devices and ductless splits.
We also need some reality introduced. If the heating plant is an oil boiler with an indirect or electric water heater, we can do can testing with our nose and eyes, we don't need to test that system or spend that time, unless we are using BPI standards. The standards should recognize situations where the testing is not necessary.

No question the WCC is the most time consuming and complex portion of a home performance assessment. As a result, I wonder how many are performed correctly, if at all, in the real world. That being said, while I can make a case, at test-in anyway, against spending time quantifying envelope leakage (the house is leaky, and needs mechanical ventilation, trust me), even duct leakage (it'll be at unacceptable levels, guaranteed), I think we're stuck with the WCC. It's a CYA issue, if nothing else.

It may be misleading to focus on the 184 deaths. I think a more relevant number would be how many people were sickened by CO. My research has lead me to believe many doctors can't diagnose the symptoms correctly. According to a trusted and authoritative website, mine, CO poisoning remains the leading cause of poisoning worldwide, and could easily be buried in the 9,500 figure noted.

I'm going to keep doing the damn thing, but would welcome any valid arguments that would convince me otherwise.

Darrell, I am confused by your last paragraph:  ‘I’m not suggesting that we discontinue combustion safety testing. I question whether the risk reduction (or lack of) merits the complexity and time investment of  the current worst-case testing procedure. If we want to make homes safer to offset possible unintended consequences of weatherization, why not attack the more statistically dangerous hazards: falls, poisoning, and fires?’

If you are not suggesting that we discontinue combustion safety testing, are you suggesting we start doing falls, poisoning, and fire assessments?

When quality weatherization work is done, the house will be substantially tighter.  This will not only lead to increased likely hood of combustion spillage, but also higher concentrations of those pollutants in the home.  If an incident does occur, the contractor and the agency or utility sponsoring the program can be held liable.  As we have heard many times before, ‘First Do No Harm’.

Paul, We're suggesting that combustion safety testing is unnecessarily complicated. We're using other hazards as a relative comparison of risk. We think that combustion safety testing, particularly worst-case CAZ, should be greatly simplified. Yes CO is a hazard. Yes the risk of CO is increased with air sealing. Do the complicated CO test procedures really mitigate that hazard? We think that the homes with the highest risk of CO poisoning can still be identified with simpler test procedures. Many of the replies at our Questioning WCC blog post have suggested simpler procedures that still, or perhaps better, identify homes with high risks for CO.

Your point of liability is well taken. Yes, air sealing may increase the risk of CO poisoning. But it also increases the risk of Radon poisoning. What to the standards say about that? In one of my replies to our Questioning WCC blog post I point out what a few standards say about Radon testing. I'm currently doing a home radon test. Total cost, $43. Air sealing increases the risk of Radon poisoning the same as CO poisoning. Aren't we incurring the same liability? How many lives can be saved with a simple $43 Radon test?


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