In the Field with Neil: RESNET Chapter 8 Blower Door Numbers

In July 2013 – Florida changed; some say for the better – others not so much so.  Never the less, change has occurred. For raters working in Florida, it means that we now have the option in how we perform blower door testing.  In the past, it was a requirement that for a registered rating – a multipoint test was needed.  Now we can do a single point. (For me personally, I like the multipoint test.  All the hard work is done; I only need to gather a few building pressures and corresponding flows.  I get more info about the building enclosure.  But this is for another blurb.)

So what does RESNET chapter 8 say…

802.1 ON-SITE INSPECTION PROTOCOL

There are three acceptable airtightness test procedures:

802.1.1 Single-point test: Measuring air leakage one time at a single pressure difference as described in section 802.5

802.1.2 Multi-point test: Measuring air leakage at multiple induced pressures differences as described in section 802.6

802.1.3 Repeated single-point test: The test is similar to the single point test, but the test is done multiple times for improved accuracy and estimating uncertainty as described in section 802.7

 

What are the highlights of each test process?

(Note that the house setup is identical no matter which test procedure you use – the difference is in the pressures and flows taken from the blower door.)

Let’s look at 802.5  Single-point test.

  1. Determine the baseline range – Fan sealed, record 5 different pressures (10 second average minimum) of house wrt outside. Find the difference between the highest and lowest values – This sets the Level of Accuracy.
  2. Determine the Pre-test baseline pressure – Average these 5 readings just taken may be used (or use baseline feature of meter – 10 second min).
  3. Determine the unadjusted building pressure and flow at 50 pascals – the building pressure to the nearest 0.1 pascal and the flow to the nearest cfm.  Also record inside/outside temperatures, fan/meter models/serial numbers, fan configuration and type of test (pressurize/depressurize).
  4. Perform calculations to determine corrected CFM50.  See the RESNET Standard section 802.5.9 for that process.  Or my suggestion is to download the FREE EnergyConservatory Tectite 4.0 (wifi) software.  You can select this test type and just input your numbers and out pops the result and you can save it for later viewing – like when the QA person comes around and asks to see your files…just saying.
  5. If you are using EnergyGauge USA (of course), enter the building pressure and corrected fan flow as shown. Click on Calculate/Post and it will do the calculations needed.

august

Now let’s look at 802.6  Multi-point test.

  1. Determine the Pre-test baseline pressure – Measure the house wrt outside using the 10 second average minimum (or use baseline feature of meter – 10 second min). Fan sealed during this step.
  2. Determine the unadjusted building pressures and flows– Take and record a minimum of 7 additional unadjusted building pressure and nominal fan flow measurements at target induced pressures which are approximately equally-spaced between 60 Pa (or the highest achievable induced building pressure) and 15 Pa. The building pressures to the nearest 0.1 pascal and the flows to the nearest cfm.  Also record inside/outside temperatures, fan/meter models/serial numbers, fan configuration and type of test (pressurize/depressurize).
  3. Determine the Post-test baseline pressure – Measure the house wrt outside using the 10 second average minimum (or use baseline feature of meter – 10 second min). Fan sealed during this step
  4. Complete steps #4 & #5 above.
  • Note: the current version of EnergyGauge USA doesn’t do the required adjustments to the as measured building pressures and flows – therefore download the FREE EnergyConservatory Tectite 4.0 (wifi) software; it will perform all the calculations needed.

Lastly look at 802.7  Repeated single-point test.

  1. Determine the Pre-test baseline pressure – Average these 5 readings just taken may be used (or use baseline feature of meter – 10 second min).
  2. Determine the unadjusted building pressure and flow at 50 pascals – the building pressure to the nearest 0.1 pascal and the flow to the nearest cfm.  Also record inside/outside temperatures, fan/meter models/serial numbers, fan configuration and type of test (pressurize/depressurize).
  3. Repeat steps #1 & #2 a minimum of 5 times.
  4. Calculate the Average Nominal CFM50 by summing the individual nominal CFM50 readings and dividing by the number of readings.
  5. Perform calculations to determine corrected CFM50.  See the RESNET Standard section 802.7.9 for that process or use the FREE EnergyConservatory Tectite 4.0 (wifi) software. If you are using EnergyGauge USA, enter the building pressure and corrected fan flow. Click on Calculate/Post and it will do the calculations needed.

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