Jack Duffy

A comprehensive guide to getting the most out of your blower door system
Authored By: Sam Myers

A blower door system can do much more than tell you how much your building is leaking. It can also help you determine the location and severity of the leaks in different zones. There are also cases where you can use your blower door to determine if some ventilation systems are working properly. Knowing the tightness of a home and finding leaks is helpful to HERS Raters, BPI analysts, insulators and HVAC contractors. In this article we’ll introduce the blower door system and how it works for those who are new to the building performance industry. Then we’ll get into various methods to make your blower door work harder, impress your clients and increase the services you offer. 

Air Tightness: Why Do We Care?

The reason we care about air tightness in

When it comes to home energy performance, comfort, durability and health, the United States falls short in the ranks compared to other developed countries. This is based on the 35 years of experience that Colin Genge has in testing houses from coast to coast and from selling diagnostic tools to over 10,000 technicians who have tested millions more.

Duct leakage in existing homes can range from 12% to 35%.

Most American houses have poor quality flex duct running outside of the envelope into attics and/or crawlspaces and typically leak an average of about 20%. Some as high as 50%! Code for new houses allows roughly 12% leakage but most houses are not properly tested if they are tested at all. See The Compliance Project for details. These figures are also reflected in past DOE studies of homes built across the US. Older homes are generally much worse especially when duct tape and flex fail over

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

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

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

View the latest updates for rCloud.

Yes you can print your results via the rCloud portal. Just login to the rCloud web portal, find your report and you can save your report as a PDF to be printed.

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

500 Flow Chart

6000 flowchart