Is IECC 2021 and Easier Energy Code than IECC 2015?

On paper and in previous simulations we have ran on and the Reschexpert blog we found some locations to be almost unpassable with any amount of insulation using IECC 2021. However, we do believe that sometimes the Rescheck Software formats of Rescheck Web and Rescheck Desktop are calibrated on the fly to make the programs perform better. We can evidence by the fact that Rescheck Desktop is updated with new versions each year and Rescheck Web is routinely taken offline on holidays and weekends to make updates.

In this particular instance a jurisdiction had used the IECC 2015 energy code for Reschecks for quite a long time. Of course on the latest project we presented them they wanted a IECC 2021 Rescheck. We quickly went to work adjusting the Rescheck format and project to meet the IECC 2021 Rescheck codes. What we found was nothing short of astonishing.

IECC 2021 affects Rescheck, Comcheck, Manual J, Manual S, Manual D

The original Rescheck we created in IECC 2015 passed by 0.7%. When we entered the exact same data into Rescheck software using the IECC 2021 it now passed by 14.5%. It is noted on the Rescheck PDFs that the percentage of passing score does not indicate energy efficiency, but we still find this worthy of a Reschexpert blog post. This exact same Rescheck using IECC 2021 passed by 13.8% more than the IECC 2015 Rescheck using the same components. That is the main take away from our experiment.

The IECC does have additional energy packages that you must choose on the IECC 2021 Rescheck. So you have some choices in regards to updating your IECC 2015 Rescheck. Our client chose to use the enhanced HVAC. The total list of Efficiency Package Requirements in Rescheck 2021 is the following:

Enhanced Envelope Performance

Efficient HVAC Performance

Enhanced Service Water Heater Performance

Efficient Thermal Distribution Performance

Efficient Air Sealing and Ventilation Performance.

One option was required in this climate zone.

Overall comparing old Rescheck formats to new options is what we do on a daily basis. If you have a Rescheck that needs updated from IECC 2015 Rescheck to IECC 2018 Rescheck, or IECC 2021 Rescheck simply email us plans, jobsite address, and square footage to and we will get you taken care of.

Digiprove sealCopyright secured by Digiprove © 2022 Reschexpert Blog, Rescheck Podcast
software image
Author Rating
Aggregate Rating
no rating based on 0 votes
Software Name
Rescheck Web, Rescheck Desktop
Operating System
Windows, MAC, Linux, Android
Software Category
Energy Usage Estimator