What is Accuracy?

ASHRAE Standard 41.3, Standard Methods For Pressure Measurement, defines accuracy as “the degree of conformity of an indicated value to an accepted standard value, or true value.” In other words, how well do the values shown on your measurement device compared to the true value?

Accuracy is the critical currency in our industry, ensuring that both you and your client can always trust important building performance test results. Unfortunately, some pressure gauge manufacturers sacrifice accuracy in their short cuts to create new functionality, even hiding their product’s deficiencies with vague or made-up accuracy measures not consistent with industry standards.

At TEC, we take measurement accuracy very seriously. We never cut corners in product design by bundling components that reduce the precision or accuracy of the measurement. In fact, we believe that all of your pressure measurements should be accurate and that you can trust your gauge to meet the accuracy requirements for all performance testing standards worldwide. This attention to detail has translated into tens of thousands of gauges in the hands of contractors, energy raters, auditors and construction crews around the world.

When Accuracy Matters

TEC has developed two information sheets to help you make an informed decision when it comes to the diagnostic tools you use in your business. When does accuracy matter? All the time.

Standards Information

To further help you, below are the accuracy requirements of two of the most used airtightness testing standards in the United States which are referenced in our Guide to Wireless Pressure Gauges and our Gauge Comparison Sheet. The standard is very clear in that each and every reading needs to meet the accuracy requirement – not some, or an average of the readings – all of the readings. The DG-700 Pressure and Flow Gauge meets and exceeds the requirements of these standards.

RESNET Standard

“Pressure gauges shall measure pressure differences with a resolution of 0.1 Pa and have an accuracy of +/- 1% of reading or 0.5Pa, whichever is greater. Blower door and associated pressure testing instruments shall be tested annually for calibration by the HERS Rating Provider or Certified Rater.” Mortgage Industry National Home Energy Rating Systems Standards, section 802.9. Read more in Chapter 8.

USACE Standard

“Pressure gauges must be digital with a resolution of 0.1 Pa and accurate to within +/- 1% of reading or +/-0.25 Pa, whichever is greater, and must have a means of adjustable time averaging to compensate for wind. Pressure gauges shall have their calibration checked and accuracy verified minimum every two years (or sooner, based on the gauge manufacturer’s recommendations) against a National Institute of Standards and Technology (NIST) traceable standard over at least 16 pressures from at least +250 to -250 Pa or to the greatest pressure used during a test.” US Army Corps of Engineers Air Leakage Test Protocol for Building Envelopes, section 4.4. Read more in Chapter 4.

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