Fine EE folks,

I've got to go the ALTERNATIVE COMPLIANCE PATH for ASHRAE 62.2, and I need help with the NATURAL INFILTRATION CREDIT.  Either ...

  • Tables where these have been worked out for different "n-factor" locations.
  • a calculation or formula for how to derive these myself.

Please see the attachment for an example.  And yes, I've reached out to the Energy Trust in Ore. about this.  No response so far.

TIA!

Views: 167

Reply to This

Replies to This Discussion

No attachment? What version of 62.2?

With that said, I don't much care for the credit - size to recommended & then tune it down with timers as much is overkill

http://thehtrc.com/2014/aci-great-ventilation-debate

Hey Sean, the 2007 version.  Example below.  

If you have thoughts on where tables like these might reside, or how I can calculate & create these myself, I'm totally game.

Thank you!

Melissa, there's a lot wrapped up in your question.

Is Energy Trust of Oregon somehow involved in your project? The reason I ask is because the table you posted would only be valid for the specific version of 62.2 that it was designed for (which should have been disclosed in the footnotes if not on the table itself). In particular, the way the infiltration credit is handled in 62.2 completely changed between 2010 and 2013. Then in 2016 it changed again.

That table is simply a shortcut for converting CFM50 to ACH-nat based on an assumed n-factor (and an unspecified average ceiling height, since ACH is based on volume.)  You can do the same thing more accurately with energy modeling software, which instead uses the Sherman-Grimsrud formula to convert from ACH50 to ACH-nat. The S-G formula involves several steps and thus is best done in software. For example, REM and Right-J will take your CFM50 input and convert that to ACH-nat or CFM-nat. No one should be using n-factors any longer!

Once you convert the blower door result to CFM-nat (infiltration), the credit under 62.2 depends on which version you're dealing with. For example, in 2010, the formula "7.5 CFM per occupant (# bedrooms + 1) + 1% of floor area" assumes a baseline infiltration credit of 2% of floor area, so you can only take infiltration credit to the extent that the blower door result (as CFM-nat) exceeds the 2% baseline. In 2013, the baseline credit was removed and the floor area component increased to 3%, so the infiltration credit is no longer optional, lest you end up over-ventilating with respect to what the standard requires.

NOTE: Residential Energy Dynamics website (http://www.residentialenergydynamics.com/) provides handy 50-Pascal-to-natural conversion tools for all versions of ASHRAE-62.2 since 2010.

Lastly, what exactly did you mean by 'alternative compliance path?

UPDATE: I just saw your update that you're working with ASHRAE 62.2-2007. Wow! To my knowledge, the residential i-codes didn't even require whole-house ventilation when that version of 62.2 was in effect! So it doesn't seem logical that any code currently in effect would refer back to that version of 62.2.

Also, I'm not sure if the 2007 version allowed for an infiltration credit. But I don't have a copy so perhaps someone else will chime in who can clarify how 2007 dealt with the infiltration credit.

Thanks, Dave.  You're always a source for nuanced answers.  

Yes, 2007.  It's a legacy version of LEED, and that's the referenced ASHRAE standard.  I think I got what I need from Energy Trust.  They're not my client, but they've been helpful in snapping the pieces together with this.  

FYI - They turned me onto the Wayback Time Machine - a Google archive with billions of old web pages that've ever been launched.  Just Google it.

RSS

Latest Activity

Michael Dunseith posted a status
yesterday
CEE posted a blog post
Friday
Sean Lintow Sr replied to Chris Bellanca's discussion Overheating garage
"There are only two methods - block the heat before it gets in & exhaust what gets in Blocking -…"
Friday
John White posted photos
Friday
John White posted a blog post
Friday
Rob Madden posted a discussion

E&O Insurance

Any recommendations for a good E&O and general liability insurance carrier for energy…See More
Thursday
John Redmond added a discussion to the group Energy Auditing Equipment for Sale, Trade or to Purchase
Thumbnail

Flir I7 Infrared Camera (Barely Used)

I have been away from this site for a while, so my apologies if this is supposed to be posted…See More
Thursday
John Redmond joined allen p tanner's group
Thumbnail

Energy Auditing Equipment for Sale, Trade or to Purchase

Discuss the pros and cons of the equipment you are interested in prior to purchase. Post equipment…See More
Thursday
Hannah Wood liked Quinn Korzeniecki's discussion Application Period for 2018 Energy Auditor (EA) and Quality Control Inspector (QCI) Pilots Now Open
Thursday
Quinn Korzeniecki posted a discussion

Application Period for 2018 Energy Auditor (EA) and Quality Control Inspector (QCI) Pilots Now Open

We need you!Applications are now being accepted to participate in the 2018 Energy Auditor (EA) and…See More
Thursday
Quinn Korzeniecki added a discussion to the group Building Performance Institute (BPI)
Thumbnail

Application Period for 2018 Energy Auditor (EA) and Quality Control Inspector (QCI) Pilots Now Open

We need you!Applications are now being accepted to participate in the 2018 Energy Auditor (EA) and…See More
Thursday
David Butler replied to Chris Bellanca's discussion Overheating garage
"Easy... insulate the attic ceiling. I'm not sure how much good it would do to air seal a…"
Thursday
Chris Bellanca posted a discussion

Overheating garage

Hi all, I'm looking for potential solutions to a problem at a client's house.  The south facing 2…See More
Thursday
Landon added a discussion to the group Energy Auditing Equipment for Sale, Trade or to Purchase
Thumbnail

Brand new retrotec blower door system $3000

Hi, I’ve got a brand new blower door system from retrotec that I got 2 months ago, and never got…See More
Thursday
John Redmond posted discussions
Thursday
David Holtzclaw replied to David Holtzclaw's discussion GSHP for domestic hot water
"Thanks John & Bill. Bill your experience is one reason why I wanted a larger heat pump with…"
Thursday
Diane Chojnowski posted events
Wednesday
Rob commented on Bob Krell's group Healthy Indoors (IAQ)
"Hello, Has anyone tried custom filtering of window AC units? Specifically concerned with…"
Wednesday
Michael Dunseith's 2 photos were featured
Wednesday
Franco Oyuela commented on Perry Ning's blog post Warnings About Portable Air Conditioners
"Here are the top five benefits of owning a portable air conditioner: 1. Low Price – All…"
Wednesday

Photos

  • Add Photos
  • View All

© 2018   Created by Home Performance Coalition (HPC)   Powered by

Badges  |  Report an Issue  |  Terms of Service