Window U Value versus Insulation R Value Rescheck Case Study

Authored by Jobe Leonard of Rescheck.info and the Reschexpert blog.  He likes publishing case studies on Rescheck components to help others with their DIY energy reports.

Jobe Leonard Rescheck.info

Window U Value versus Insulation R Value Rescheck Case Study

This version of the Reschexpert blog is presented as a case study. It looks at differing Window U Value and Insulation R values in a real life scenario that can be seen every day. Thanks for reading the Reschexpert blog and we hope you enjoy this Rescheck Case Study

Let me set this Rescheck case study up for you. This particular project had two outcomes in Rescheck Web and Rescheck Desktop. This is a set of Rescheck Frequently asked Questions that shows what type of modifications can be made and why Rescheck.info offers modifications free of charge.

The first version of this Rescheck used R38 roof R19 Walls and .28 U Value Windows. This Rescheck passed the IECC 2015 Energy Code by 12%.

The second version of this Rescheck used R30 roof R13 Walls and .28 U Value Windows. This Rescheck passed IECC 2015 Energy Code by 1%

The final rendition of the Rescheck with updated window specs from the window manufacturer had R38 roof, R 19 walls, and U.30 windows. This version of the Rescheck exceeded the IECC 2015 by 10%.

Frequently asked questions about this type of Rescheck scenario are below.

Rescheck.info answers to these Rescheck case study questions are below, (In bold type):

Rescheck Web User:

Does it make much of a difference when we have 2 x 6 exterior walls instead of 2 x 4 exterior walls?

Is 1% Compliance good, not really or otherwise?

In what categories were we below par?

I really appreciate it. Thanks.

Rescheck.info Rescheck troubleshooting answer:

This version is the 2×6 version which is what your insulation quote shows. It passes by 12%+ which would be your better option.

Rescheck Web User:

Yeah, this is much better.

Is 12% Good?

Rescheck.info Rescheck troubleshooting answer:

12% is good. It means 12% better than the adopted energy code.

Rescheck Web User:

Last question. We use Titanium WindowSHGCUValue Ultra 3050 (3′ x 5′) Single Hung windows. They come with energy efficient Low E glass and are equipped with Argon gas. Do you think this is a good, adequate or poor choice in windows?

Rescheck.info Rescheck troubleshooting answer:

Yes, that is a great window option. I updated this report with the specs from the manufacturer’s website.

Rescheck Web User:

Ok. So, it is a great window. However, our score went down from 12% to 10%. That seems like we screwed ourselves a little bit. Do you agree?

Rescheck.info Rescheck troubleshooting answer:

No, the 2% should not matter. You home is very efficient and in the upper tiers of passing percentages we see on a daily basis.

The end result was the project passing by 10% was used. Rescheck.info can create a Rescheck for your for $79. It takes 4-6 hours and we offer free modification. To get started email pdf plans, jobsite address, and square footage to service@rescheck.info. The key to remember is that the score for passing a Rescheck is percentage above code. So a Rescheck passes by 1% still “exceeds energy code” by that percentage and the Rescheck is valid.