Understanding the Difference between EPA Crib Wood Testing and EPA Cordwood Testing

July 18, 2023
When assessing the environmental impact and emissions of wood-burning appliances, the United States Environmental Protection Agency (EPA) has established rigorous testing protocols. These protocols include two distinct methods: EPA crib wood testing and EPA cord wood testing.
Understanding the difference between these two testing methods is crucial for consumers, manufacturers, and regulators in ensuring the safety and efficiency of wood-burning appliances. This blog post will explore the disparities between EPA crib wood testing and EPA cordwood testing, highlighting their objectives, procedures, and significance.

EPA Crib Wood Testing Explained:

EPA crib wood testing is a standardized method to measure the emissions of wood-burning stoves and fireplace inserts. The test is conducted in a laboratory setting using a controlled environment. Crib wood testing aims to evaluate the appliance's performance when burning small, consistent wood samples (cribs) that are representative of the type of fuel commonly used in residential settings.
During EPA crib wood testing, the appliance is operated using the specific test fuel, and the emissions produced are captured and analyzed. This testing method focuses on quantifying particulate matter (PM), carbon monoxide (CO), and other harmful pollutants emitted during combustion. It helps determine the appliance's efficiency, the level of pollutants released, and compliance with EPA regulations.

EPA Cordwood Testing Explained:

On the other hand, EPA cordwood testing evaluates wood-burning appliances using whole pieces of wood, typically referred to as "cordwood." Cordwood represents the natural, irregularly shaped fuel used in real-world scenarios. Unlike crib wood testing, which utilizes consistent samples, cordwood testing involves burning different wood species, sizes, and moisture contents to simulate the variable conditions encountered during actual wood-burning operations.
During EPA cord wood testing, the appliance is subjected to various test conditions, including different burn rates, loadings, and operating modes. This method assesses the appliance's emissions when exposed to more realistic scenarios. It comprehensively evaluates the appliance's performance across different parameters, including heat output, combustion efficiency, and emissions of pollutants like PM, CO, and volatile organic compounds (VOCs).

Differences between Crib & Cord Wood Explained:

The difference between EPA crib wood testing and EPA cordwood testing is essential for several reasons. First, crib wood testing allows for controlled laboratory conditions, enabling precise measurements and repeatability. It provides a standardized assessment that helps manufacturers to design and optimize appliances for efficiency and reduced emissions. Second, cordwood testing addresses the real-world complexities associated with burning different types of wood, mimicking the variability of residential wood-burning operations. This testing method ensures that appliances perform well under realistic conditions, providing consumers with reliable information for informed decision-making.

Learn how testing standards have changed throughout the years

BTU Results using Crib Wood or Cord Wood Test Methods:

Due to the differences in test methods, the tested BTU output will also differ. Here is an example using Regency's F2500 model.
        Efficiency (HHV) Run Time (hr) Tested BTU Range
Model Cu.Ft. LBs of Wood Available BTUs Low High Low High Low High
F2500 2.3 27.6                251,160 76% 74% 9.6 2.7 14,944 50,349
F2500-1 2.3 16.1                146,510 80% 76% 6.6 2.9 13,580 29,795
Note: In the cordwood method, 12 lbs of wood/cu.ft. is loaded for each test. In the crib wood method, 7 lbs of wood/cu.ft. is loaded for each test. Available BTUs are calculated by multiplying the pounds of wood by an average heating value of 6,800 BTUs/lb.
As indicated in the above chart, the BTU output will vary significantly between the two test methods since the amount of wood loaded into the firebox is considerably less using the crib wood method. In addition, these methods still do not indicate real-life BTU potential since the stoves are not loaded to their maximum capacity.
In conclusion, both EPA crib wood testing and EPA cord wood testing play crucial roles in assessing the environmental impact and performance of wood-burning appliances. While crib wood testing provides a controlled and standardized evaluation, cordwood testing offers a more realistic representation of real-world burning scenarios. These testing methods complement each other, ensuring that wood-burning appliances meet regulatory standards, optimize efficiency, and minimize harmful emissions. By understanding the distinction between these two testing methods, consumers can make informed choices when selecting wood-burning appliances, contributing to a cleaner and more sustainable future.