Duct Testing Exemptions in Ekotrope

Ekotrope supports duct testing exemptions for both IECC (2009 and newer), and ANSI/RESNET 301. The various exemptions and how to model them in Ekotrope are explained below.

NOTE:  The below ANSI/RESNET 301 exemptions apply to homes rated under the rules of Addendum L, which apply to all homes permitted after July 1, 2019.  Homes permitted before July 1 2019 may use the prior RESNET exemption rules, which allows specifying ducts as tested with 0 leakage to outside if all ducts and air handlers are visibly verified to be within conditioned space.

NOTE:  MINHERS Addendum 47i allows for the "Duct Leakage Testing Not Required" exemption for homes permitted prior to Jan 1, 2021 that have building cavities used as ducts.  After that date, if building cavities are used as ducts, duct testing is required.

Exemption: Duct Leakage Testing Not Required

Both IECC and ANSI/RESNET 301 do not require the testing of ducts as long as the ducts, along with all air handlers, are 100% in the Conditioned Space Volume. When this exemption is utilized, the Distribution System Efficiency (DSE) of the Rated Home will be set to 0.88.

To model this in Ekotrope, choose the untested Distribution System type and choose the appropriate checkboxes in the Duct Testing Exemptions Section.

Homes permitted before July 1st, 2019 may continue to use the old leakage to outside exemption logic for the HERS calculation, which sets leakage outside to zero, by using Ekotrope v3.1.1 or before.

Exemption: Total Duct Leakage in Lieu of Duct Leakage to Outside Testing

ANSI/RESNET 301 allows for the Total Duct Leakage measurement to be used in place of Leakage to Outside testing  for confirmed, threshold or sampled ratings as long as certain requirements are met. Those requirements are different for dwellings and townhouses than for apartments. Each case is described below:

Dwellings and Townhouses

Requirements for Total Duct Leakage Testing instead of Leakage to Outside:

1. Ducts and air handler are entirely in the Infiltration Volume.

2. Blower door test is no greater than 3 ACH50.

3. No building cavities are used in place of ducting.

4. Total leakage must be no greater than 4 CFM/100SF or 40CFM for systems with two or less returns. If the system has three of more returns, the total leakage must be not greater than 6 CFM/200SF or 60CFM. 

When utilizing this exemption, the Leakage to Outside will be set to half of the measured Total Duct Leakage value.

To model confirmed ratings in Ekotrope, choose the tested Distribution System type, uncheck the “Leakage to Outside Tested?” box, and enter the measured Total Leakage. 

To model either a threshold or sampled rating, select the Threshold / Sampled option, uncheck the “Leakage to Outside Tested?” box, and enter the tested values. If a sampled rating is tested, put your measured value in both the Threshold and Field Test boxes. If a sampled rating that is not tested, then put the measured Total Duct Leakage in the Threshold Total Leakage, and 0 in the Field Test Total Leakage.

Attached Dwelling Units Only (i.e. Apartments)

ANSI/RESNET 301 does not require a duct Leakage to Outside test for attached dwelling units even if ducts are outside of conditioned space. Instead Leakage to Outside of the HERS Rated home can be estimated from the Total Duct Leakage based on the location of the ducts and equipment. Ekotrope will automatically estimate Leakage to Outside for the HERS rated home. You can see the estimated leakage to outside in the HERS Rated Home Summary report.

Modeling both confirmed ratings and threshold or sampled ratings can be done following the same steps for dwelling units and townhouse as shown above. Be sure to include what portion of the ducts (if any) are outside conditioned space.