Jack Duffy

  1. A Brief History of Retrotec’s Involvement with Home Performance

    In 1980 I calibrated the fledgling Retrotec Energy Innovations Ltd.’s blower door at the National Research Council (NRC) in Ottawa, Canada.  It used RPM and pressure drop to crudely measure flow.  Little did I know that what I learned from the head air flow scientist at NRC would result in a 38-year long career making Retrotec the largest calibrated door fan manufacturer in the World.

    Retrotec stands for retrofit technology, which means fixing houses after they’re built.  Our first blower doors were designed to perform energy audits on these houses using their in-house energy analysis software based on HOT2000.  It ran on a 32k pocket computer.   Currently known as Home Performance (HP), this application was promoted by Retrotec as a non- government funded business opportunity.  Eventually this resulted in the HP application being spun off as The Comfort Institute which was later absorbed by AeroSeal. 

    Retrotec

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  2. The RESNET 380 Standard

    As you may have heard, the RESNET 380 standard will replace RESNET Ch. 8 which dictates how raters test homes for envelope leakage, duct leakage, mechanical ventilation, and duct system air flows. Any home permitted on or after July, 1 2018 must be tested in accordance to the 380 Standard. The standard currently applies to all single-family homes as well as multifamily projects that are three stories or less. There are more updates coming for multifamily so make sure you are signed up to receive email updates from RESNET.

    Definitions

    One goal of the 380 standard is to improve consistency throughout the HERS process and to reduce the need for Raters to make judgement calls when taking measurements in the field. To help achieve this, the standard includes definitions for:

    • Conditioned Space Volume
    • Unconditioned Space Volume
    • Infiltration Volume
    • Conditioned Floor Area
    • ELA & other metrics

    Envelope

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  3. rCloud Releases & Updates

    Major Enhancements Are Right Around the Corner

    October Release

    • Feature 1: Completion of the ATTMA (Air Tightness Testing & Measurement Association) standard. This standard is primarily used in the United Kingdom but also used or referenced in 90 other countries. This standard has two types of test available: Single Direction Multi Point Test and Dual Direction Multi Point Test. A lot of the groundwork for ATTMA was completed in the September release (1.1.7) however due to time constraints and the size of the feature some functionality was pushed into the October release. The biggest piece of this feature to be added is to allow user input of the fan flow equation parameters received when a test fan is re-calibrated, and have these parameters be used in calculating flows.  The other functionality to be added will allow rCloud to gather the post test information about environmental conditions, store the additional data in the
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  4. rCloud

    View the latest updates for rCloud.

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  5. How do I know how many fans I need for a Blower Door or Enclosure Integrity Test?

    I have a Energy or Enclosure Integrity Test to perform.  How many fans do I need to properly run the test?  Do I have enough fans to run the test?

     

    We have created two tools to help you figure out how many fans you will need for your test. 

    Download either the Blower Door or Enclosure Integrity version of the Number of Fans Calculator

    Next, open the file in excel and "Enable Editing" when a security warning appears.

    Fill in all the fields highlighted in blue.  The number of fan results are highlighted in green.

     

    Here is what the Blower Door Number of Fans Calculator looks like:

     

    And this is what the Enclosure

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  6. Why does my Q4 result have such high uncertainty?

    You need to consider that there is a fundamental issue of uncertainty with using 4 Pa as a reference pressure. Just imagine, if there is even a 1 Pa fluctuation, due to so many possible sources that can cause pressure fluctuations as you know, the pressure measurement already has an uncertainty of +/- 25% error. Consider that for almost all airtightness testing standards across the world, the reference pressure for Flow results are either 50 Pa or 75 Pa.

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  7. What do the different pressures and flows shown in FanTestic represent?

    How does FanTestic calculate the pressures and flows that appear in the FanTestic UI and in the generated Word reports?

    The table in the report (and the onscreen data entry fields) containing data for each Set shows:

    • the “Induced pressure” and this is the pressure measured by the gauge (read automatically or entered by user) without correction for bias pressure.
    • the “Fan Pressure” for each Fan, and this is the pressure measured by the gauge. (read automatically or entered by user)
    • the “Flow” for each Fan, which is calculated using the Fan Pressure 
    • the “Total Flow” which is all the Flows added up, for all the Fans used, at that target point (will be the same as Flow if only one fan is used)
    • the “Corrected Flow” which is the Total Flow adjusted as required in the chosen Standard to account for air density 
      (air density corrections generally
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  8. If I uninstall FanTestic will I lose all my test data?

    Uninstalling FanTestic will NOT remove any of your test files or reports, it will only uninstall the program files. 

    It is generally a good practice to regularly back your test and report data to a different location.

    Uninstalling FanTestic will also NOT uninstall the DM-2 USB driver.  You should still be able to see it listed as installed in your Control Panel after you restart the computer.

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  9. Why does FanTestic not find my DM-2 gauge when I start an Auto Test?

    When I try to start an Auto Test or click Find Gauges button, I get a message saying no gauges were found.  Part of the error message says "Error 5: Access denied".

    Your computer is limiting access to the USB ports by programs.  In order for FanTestic to access the USB ports on your computer, you may have to "Run as Administrator".  You will need to follow the procedure outlined in the attached document, regardless of whether you have Administrator privileges on your computer. 

    This problem can be avoided if you have a DM32 by connecting the DM32 gauge using an Ethernet cable to connect the computer to the Network port on the gauge instead of using the USB cable.

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  10. How is EqLA calculated?

    For reference to equations for calculating results from a Blower Door test, you can refer to the ASTM E-779-10 standard.

    In engineering (fluid dynamics) terms, Bernoulli's equation is an energy balance equation that assumes incompressible fluid (e.g. air) at steady state through two points (e.g. through a building); The equation can be simplified to an orifice plate equation and applied to a Blower Door test.  We can calculate point #1 - the total leakage (EqLA or ELA) of a building, and point #2 - a known area (size of fan hole: Range configuration) by measuring via Blower Door system the airflow rate through these points at a specific induced building pressure (the reference pressure). 

    Induced building pressure is directly proportional to airflow rate through a building, and EqLA is directly proportional to airflow rate; so that a higher induced

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