Does anyone have a calculation or guide you follow to de-rate the r-value of existing insulation?

I'm familiar with RESNET grading, but that seems to be for new installs and I can't find what the actual calculation would be - I'm assuming it's built into modeling software, but does anyone know what the actual adjustment factor on the R-value would be if rating something Grade II or Grade III?

I'm interested in this information both for batts and loose-fill. 

Any resources (even tangential) are greatly appreciated!

Tags: correction, derate, derating, factor, insulation, r-value

Views: 470

Reply to This

Replies to This Discussion

Page 7 & 8 of the old Technical standards have that info. (attached)

Attachments:

Ah, the table on batt insulation was what I was thinking of but couldn't find. Thanks!

You are welcome. Not sure what that did not make it into the new standards, but I still use it myself, as do many others I know.

I've attached the HES insulation derating page for illustration.

You can find an assessor or train to use their software. It is a simple certification.

homeenergyscore.gov

Attachments:

Attached HES insulation derating file. 

Attachments:

Check the California Installation Standards with a well thought out and researched listing of old insulation. 

Open batt or open fiber will wind wash in vary cold weather so the batt says R-30 and with IR its says R-10 test same spot with out wind and is R-30.    How do you deal with wind washing?  

I don't have a copy of the original BPI charts, but I believe our local utility has adopted the original charts and included some examples of insulation in various states. You can tell which portion of the attached was produced by the utility as they are have the logo attached. The following pages that do not have the logo are the original insulation rating charts that came from BPI.

Attachments:

RSS

Forum

Insulating Chilled/Cold Water Lines

Started by Sean Wiens in HVAC. Last reply by Sean Wiens yesterday. 10 Replies

Floor I joists and properly installed insulation

Started by Robin Henry in General Forum. Last reply by Brian Robinson on Thursday. 29 Replies

What's the Most Profitable HVAC Job for Your Company?

Started by Wayne Melancon in HVAC. Last reply by bebelyn accessdoors on Thursday. 5 Replies

Looking for a Rater in Sacramento Area

Started by Brian A McFadden in BPI. Last reply by Building Performance Institute Jan 14. 1 Reply

Hydronic System Critique

Started by Sean Wiens in HVAC. Last reply by Sean Wiens Jan 14. 8 Replies

Condensation Quick Fix

Started by Dan Antonioli in General Forum. Last reply by Sean Wiens Jan 13. 12 Replies

How many BTU required to heat air

Started by Sean Wiens in HVAC. Last reply by Sean Wiens Jan 9. 28 Replies

Denver Home Energy Score Pilot Evaluation Report

Started by Julie Saporito in General Forum. Last reply by Jacob Corvidae Jan 9. 8 Replies

Green Button Connect

Started by Rob Buchanan in General Forum. Last reply by Steve Schmidt Jan 6. 3 Replies

Latest Activity

Building Performance Journal posted a blog post

Dust-Control Strategies for Energy Upgrades

In the Winter 2019 issue (our last under the Home Energy name), author Cory Chovanec wrote an…See More
3 hours ago
Sydney G. Roberts liked Macie Melendez's blog post Re-introducing Myself as the Building Performance Journal’s Managing Editor
3 hours ago
Macie Melendez posted a blog post

Re-introducing Myself as the Building Performance Journal’s Managing Editor

I worked on the editorial staff of Home Energy magazine for nearly 7 years before I made the…See More
4 hours ago
Diane Chojnowski added a discussion to the group News & Announcements
12 hours ago
Luis Hernandez replied to Al Tibbs's discussion Energy Audit Book & Equipment in the group Energy Auditing Equipment for Sale, Trade or to Purchase
"Just resend it again just now. Please check your spam folder"
13 hours ago
Jose Macho commented on Chris Laumer-Giddens's blog post Near Perfect Air Tightness Measured in Contemporary Home
"My thinking is zip strip sheathing & tape would have been more cost effective which I have seen…"
yesterday
Al Tibbs replied to Al Tibbs's discussion Energy Audit Book & Equipment in the group Energy Auditing Equipment for Sale, Trade or to Purchase
"Never received your email? Send to altibbs@twc.com "
yesterday
Profile IconJay cooper and Zachary Ames joined Home Energy Pros Forum
yesterday
Sean Wiens replied to Sean Wiens's discussion Insulating Chilled/Cold Water Lines
"Just a follow up to Mark's post "cold waterlines in this space wont be exposed to outside…"
yesterday
Sean Wiens replied to Sean Wiens's discussion Insulating Chilled/Cold Water Lines
":-) - Guess I should not read so literal! That makes more sense."
yesterday
Building Performance Institute liked Kirsten Richnavsky's discussion New BPI Standard for Conducting Energy Audits Published as an ANSI Standard!
yesterday
Building Performance Institute liked Kirsten Richnavsky's discussion Breaking the link between unhealthy homes and unhealthy kids
yesterday

© 2020   Created by Building Performance Association   Powered by

Badges  |  Report an Issue  |  Terms of Service