Does anyone have any sources for savings estimates for wrapping ducts?

In particular - I am interested to know the performance difference between:

1/2" fiberglass wrap with no backing

2" fiberglass duct wrap with FSK Facing - seams taped

Thanks

Views: 551

Reply to This

Replies to This Discussion

Hi Craig,
I don't have materials to recommend, but I have considered different insulation values. When ducts are located in unconditioned spaces they first must be air sealed, foil tape of duct mastic or other approved solution. Then consider your climate, heating and or air conditioning. If those ducts are in a high loss/gain area, then consider them as wall area. Would you apply 1/2" of insulation to one of your walls? There is some give and take when deciding how much "R" you need, but in my cold climate, I would want them well insulated.

You can calculate the inside surface area, estimate the run time, and add in the delta T and it will give you the heat transfer. Each installation will be different.

Bud

Bud

Thanks Bud, I am good on the application of the job, just interested in the validation of the savings. Supposed I could just run a REM/Rate model for my avg housing stock and vary the insulation level of the ducts.

How does Rem handle the ductwork inside the walls? Can you tell the software how many feet of ducts you are insulating?

Let me know how much REM applies for savings. I run all of my calculations myself for the level of work I perform so have developed methods for getting my predicted loss to match what the customers actual spend. I actually see very few ducts in totally unconditioned spaces.

Bud

Here's an LBNL research report by Iain Walker, who tested 24 retrofitted duct systems in the Central Valley of CA.  Retrofits increased delivery efficiency by 64-76%, and reduced HVAC system energy by 18%, on average.  This is going from uninsulated to insulated and airtightened systems; not exactly what you're looking for, but probably the best you'll find of actual data.  Energy reductions varied substantially from house to house, and they suggest targeting homes with higher supply-side leakage to outside.  

http://cgec.ucdavis.edu/ACEEE/1994-96/1996/VOL01/147.PDF

Cheers!

Heat / cool load calculation software (Manual J) provides ability to run different scenarios for duct insulation levels and duct leakage into unconditioned spaces.

Be careful with two layers of insulation on ducts in humid spaces - could create condensate / mold problems

REM allows you to estimate the length of supply and return duct based on the size of the home and # of registers.  I have never done so, but it also allows you to directly enter the length.  On two new Energy Star Homes I measured the actual lengths and was within 1% both times.  A) 4000 sf home B) 1100 sf home.

Depends on where the ducts are located for the savings.  You will get no savings for conditioned space.  Still might be a good idea.  You get most in  a vented attic, some in an enclosed crawl space.  More for supply, less for returns.  Less still for panned body cavities.

Get the ducts out of the attic. Get them out of the crawl space and the unconditioned basement! Seal them up.

RSS

Featured Forum Discussions

Too many BTU's. Too much horsepower?

Started by Steve in General Forum. Last reply by Walter Ahlgrim 11 hours ago. 3 Replies

Stack/wind pressure and flow networks.

Started by Daniel James Grundy in Training. Last reply by Daniel James Grundy 15 hours ago. 5 Replies

BDT with vermiculite in hollow CMU walls?

Started by Brad Cook in General Forum. Last reply by John Nicholas 21 hours ago. 2 Replies

Strange IR Image

Started by Larry Nissman in General Forum. Last reply by Brad Cook Mar 9. 7 Replies

Videos

  • Add Videos
  • View All

Latest Activity

Colin de Paor is now a member of Home Energy Pros
1 hour ago
Walter Ahlgrim replied to Steve's discussion Too many BTU's. Too much horsepower?
"The 5 ton system you have is not 500 hp racecar engines they are 500 hp truck engines. The duct…"
11 hours ago
Daniel James Grundy replied to Daniel James Grundy's discussion Stack/wind pressure and flow networks.
"So I wanted to start with a basic who can help then go into more detail later. But yes find…"
15 hours ago
Daniel James Grundy replied to Daniel James Grundy's discussion Stack/wind pressure and flow networks.
"My tutor got back to me and while areas don't quite feel right a little to much assumptions…"
15 hours ago
Brennan Less replied to Daniel James Grundy's discussion Stack/wind pressure and flow networks.
"Daniel, I'm assuming you're trying to predict the airflows through the different openings…"
17 hours ago
Martin Newmark 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
19 hours ago
John Nicholas replied to Brad Cook's discussion BDT with vermiculite in hollow CMU walls?
"If the drywall is in good shape, you should have little worries about the 50pa depressurization…"
21 hours ago
tedkidd replied to Steve's discussion Too many BTU's. Too much horsepower?
"Does the house ever feel clammy? Do you have to keep the thermostat below 74 to be comfortable? Is…"
yesterday

Home Energy Pros

Welcome to Home Energy Pros – the unique digital community by and for those who work in the home energy performance arena.

Home Energy Pros was founded by the developers of Home Energy Saver Pro (supported by the U.S. Department of Energy) and brought to you in partnership with Home Energy magazine.  Home Energy Pros is sponsored by the Better Buildings Residential Network. Please honor our Guidelines

© 2017   Created by Lawrence Berkeley National Laboratory.   Powered by

Badges  |  Report an Issue  |  Terms of Service