Priority Energy, Energy Code Assistance, IL

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The State of Illinois is transitioning to the stricter IECC 2021 energy code. Here are the Illinois cities that are following the updated code as of September: Chicago, Deerfield, Oak Park, Woodstock, and Elmhurst.

In some cities the permit date will determine which code you will need to meet, IECC 2018 or IECC 2021. 

The IECC 2021 requirements for Blower Door and Duct Tests are as follows:

  • Air leakage in the building envelope must not exceed 3 ACH50 for Blower Door tests.
  • All duct systems must be tested for air leakage, regardless of where they are located in the home. Ductwork within the conditioned space must meet 8 CFM/100 sq. ft., per IECC 2021 code.

Our 3 Step Path to Illinois Energy Code Compliance

The path to IECC 2018 compliance is a simple three step process:

  1. Design the home's envelope

  2. Design the mechanical systems

  3. Inspect and test the house

Priority Energy is a recognized and trusted Chicago-area company holding the following ICC certifications; Residential Energy Inspector and Plans Examiner, Property Maintenance and Housing Inspector, Mechanical Inspector and Building Inspector.  We are a one-stop-shop for meeting all of the IECC energy code requirements for residential and commercial construction in Illinois.

STEP ONE: Choose Prescriptive, Performance or ERI Path to IECC Compliance

IECC Prescriptive Path

Work with your architect to ensure your plans reflect IECC 2018 insulation values, which can be found on our Energy Code Facts page.

IECC Performance Path (Simulated Performance – IECC 2018 Section R405)

You must have an energy model completed for the home by utilizing RESCheck or REM/Rate software to pursue the Performance Path. The benefit of following the performance path is you can utilize tradeoffs between insulation and air tightness, which often results in a better performing home that can be built at a more competitive price.

ERI Path (Energy Rating Index – IECC 2018 Section R406)

The Energy Rating Index path can be accomplished by hiring Priority Energy as your HERS Rater to create your HERS Index. Much like the performance path, this will allow us to create a performance model (which takes in to account all aspects of the house) to identify the highest performing home at the best price. Under IECC 2018, any home that scores a 54 or less for climate zone 4 or 55 or less for climate zone 5, is found to be in compliance with IECC 2018. 

There are other benefits to creating the HERS Index, including:

  • In Illinois, a HERS Index is required to take advantage of most rebates offered through utility companies like COMED, NICOR, and AMEREN.

  • There is a 45L Federal Tax Credit available of $2,500 - $5,000 for builders of Energy Star and ZERH-certified homes. ed.

  • A HERS Score is a great way to market the energy efficiency of a home--it’s even on the MLS now in Illinois.

The RESNET-certified HERS Raters at Priority Energy will help determine your best strategy based on your goals and provide all necessary documentation for permitting.

STEP TWO: Have a Mechanical Sizing Completed For Your Home (IECC R403.7 – Equipment Sizing & Efficiency Rating)

With your path of compliance chosen and your building envelope decided upon, your next step is to procure an IECC-recognized mechanical sizing report. The most commonly-used reports for residential homes are an ACCA Manual J, ACCA Manual D, and ACCA Manual S report. In many instances, your mechanical contractor will offer to provide this report, but quite often, they are getting this sizing calculation from their equipment distributor for low or no cost. We recommend hiring a neutral third party to complete an unbiased recommendation.

A professional mechanical calculation report should include the following 3 components to be considered valid ACCA sizing:

ACCA Manual J

A complete Manual J will give you the total heating and cooling load (necessary for the ACCA Manual S – Equipment Selection) along with room-by-room loads (necessary for an accurate ACCA Manual D – Duct Design) so the installed system’s heating/cooling capacity can be appropriately distributed throughout the home to maximize comfort.

  • ACCA-approved software must be utilized for a manual J to be accurate. Click here for a list of approved software programs – Priority Energy utilizes the latest version of Wrightsoft Right J8 for all load calculations.

  • For complete details on what it takes to create an accurate Manual J, please see our HVAC Design & Testing - Residential page.

ACCA Manual S

A total block load created with the ACCA Manual J will provide the designer the total heat loss for heating, and the total heat gain (latent and sensible) for cooling. With the total heat load/gain, the designer will be able to select the exact furnace, AC/heat pump, and evaporator coil necessary to meet the home’s heating and cooling loads. This is required for permitting in the State of IL under the IECC 2018.

ACCA Manual D

An ACCA Manual D will give you a duct diagram from the furnace/air handler to the registers, including all ductwork, connections/fittings and registers. A duct system designed with ACCA-approved software will give you quiet airflow, extend the life of the furnace/AC, and decrease comfort complaints from the buyers/homeowners.

Click here to see a sample of a Mechanical Sizing Report as required for code compliance.

Priority Energy can provide ACCA Manual J/D/S reports within 48 hours (for an average 2,500 s.f. home). Our reports are accurate and priced competitively. Contact us to discuss your plans and get a quote today!

STEP THREE: Have All Required Inspections Completed

Under the IECC compliance codes, there are four inspections required:

     1. Air Barrier and Insulation Installation Inspection (IECC Table R402.4.1.1)

Depending on the village/town/city you’re building in, you may be required to have this inspection. The party who completes the inspection varies by where the home is being completed, so ask your builder or contact your city hall for specifics. Either way, this is a critical step to ensuring the home will meet the mandatory blower door test and occupancy requirements when completed. This will also help eliminate many future call backs related to comfort complaints and minimize building durability-related call backs (like drywall cracking and hardwood floor-related issues).

     2. IECC Duct Testing

     3. IECC Blower Door Test

     4. Home Ventilation Testing

All homes have to be provided with a ventilation system. Ventilation can be exhaust only (bath/kitchen fans with appropriate controls), supply only (intakes through the return ductwork of the furnace with appropriate controls), or balanced systems (ERV/HRVs). 

The system must meet the following requirements:

  • Meet or exceed a minimum ventilation rate of CFM total = 0.01CFA + 7.5(Nbr + 1) where the CFA = conditioned floor area and Nbr = number of bedrooms

  • Utilize ECM motors or meet a minimum ventilation efficacy

    • Fans <90 CFM = 1.4 CFM/watt

    • Fans=>90 CFM = 2.8 CFM/watt

    • Balanced HRVs/ERVs are an allowed exception and do not have to meet efficacy requirements.

Priority Energy can help you design, select and test your ventilation systems. Homes are being built tighter than ever, making this is a critical step to ensuring occupant safety and building durability.

See our Residential Ventilation Systems page for more information, or contact us to schedule an appointment.

Energy Code Facts

Priority Energy, Energy Code Facts, IL

With the adoption of the International Energy Conservation Code (IECC), home building and commercial construction has taken on an extra layer of complexity. The code is intended to increase the efficiency of the homes we’re building through added insulation, air sealing and other efficiency measures.

Blower Door Tests

Priority Energy, Blower Door Test, IL

Since 2012, blower door air leakage tests have become mandatory tests, regardless of the path chosen for compliance. The blower door test consists of a large fan installed in the opening of an exterior door of the home. With all doors, windows and other openings tightly closed, the fan will pull air out of the home to cause a depressurized condition to a difference of 50 Pascals, or 0.2 IWC with respect to the outside.

IECC Duct Testing

Priority Energy, IECC Duct Testing, IL

Since 2009, under the IECC Code, all ducts should be sealed, air handlers sealed, and duct tightness should be verified by a duct leakage test unless 100% of all ductwork is within the conditioned space. This means that any time you run a duct outside of the building envelope (in the attic, crawlspace, or garage, for example), the system must be tested.

IECC Energy Modeling

Priority Energy, IECC Energy Modeling, IL

An energy model, which is a computerized simulation of a home’s energy consumption, is used to compare energy-related components and test performance scenarios. This tool is especially helpful for predicting energy efficiency trade-offs, utility costs and the effects and payback of green energy solutions such as solar panels, photovoltaics, wind turbines and high-efficiency appliances.

  • Thank you again and you will be the first person I call if I need additional part or service from your company.
  • I just wanted to send this message to all you and say GREAT JOB!  We had a rough inspection today and passed for the Woodward Ave. house. The inspector told us "if every house I inspected looked like this one I would be out a job".

    Anonymous Builder
  • We were so impressed with the amount of information the Priority Energy technicians gave us during our ENERGY AUDIT.  If you are buying a house, I would strongly recommend having them do an energy audit on it, in addition to your usual home inspection.

  • Thanks for a super intelligent and deep seminar expertly handled by a staff which was a pleasure to be around. Lunch was superbly and subtly handled.

    A.S. Architect
  • I wanted to thank you for all of your extra time and energy during our BPI training over the last few weeks. You really helped put things in perspective. You are an awesome crew and your facility is a valuable resource for students and the community

    BPI Student, L.E.
  • There is much less dust in the house and the monthly gas and electric charges have been reduced by 10 to 15%.....I'm sure I will see greater savings over a twelve month period......thanks again.

    Aeroseal Client, R.N.
  • Just completed my BPI Field exam for my Quality Control Inspector (QCI) certification renewal at Priority Energy.
    Such a convenient and well-set-up training and test center with caring and knowledgeable staff and proctors! Thanks folks!


    P.R., Ottawa, IL
  • It's been cold here for the past few days and I really feel the difference in heating since the building was Aerosealed! My apartment is so much warmer now. Thank you Priority Energy!


    Miruna; Tenant at Country Manor Apartments, Peru, IL
  • Anytime I can be a reference for all the great work on my (new) house, please let me know.  Priority Energy is outstanding at what they do!

    Executive at Medline Industries, IL
  • I have a two story home built in the mid seventies. Lots of temperature fluctuation between the floors. The Aeroseal process dramatically increased the air flow to the second floor. Good experience. The company was very informative, answered a lot of questions.

    Vince from Oakbrook, IL
  • "It's been cold here for the past few days and I really feel the difference in heating since the Aeroseal, my apartment is so much warmer now. Thank you!"  

    MP from Peru, IL
  • Thank You so much for the super-fast turn around of our Manual J, D and S reprt for the Village of Glen Ellyn. Our original Manual J kept getting kicked back to us for corrections but your calculations/report got approved instantly-no questions asked and no more permit delays!

    Kim, Glen Ellyn, IL
  • Thank you. Truly. I appreciate you taking the time to clarify things for me and then going above and beyond to ensure that my CEUs are handled for our current RESNET cycle. You’ve always been kind to me and this is another shining example of that.

    Craig, HERS Rater, Batavia, IL
  • (Aeroseal) is a GREAT Product! Really made our townhouse more comfortable!

    Gordon; Chicago, IL
  • We are having less ice on roof since the Aeroseal duct sealing! Thanks!

    Bill; Downers Grove, IL
  • Duct sealing (with Aeroseal) was the smartest thing I ever did! Our home is sooooo much more comfortable! We were so very pleased with Priority Energy and their technicians!

    Richard; Lake Forest, IL
  • On to the Radon issue - Excellent results with Aeroseal!  From 5 + to a .4.  Before sealing like we discussed, I had warm air coming out of the sump basket with the furnace running. Even with the furnace running, it is still pulling air in now.

    Bill; Belvidere, IL
  • Pat was awesome and super helpful! We are experiencing weak air flow in the duct system of our 1950''s home and Pat gave us great recommendations to fix the problem when we do our remodel.

    David; Arlington Heights, IL
  • Already the house seems more balanced (since Aeroseal duct sealing yesterday) .. far end of house is getting more warm air flow!

    Bryan, November 2019, Chicago, IL
  • Priority Energy did a great job with an Aeroseal project for my home. The rooms are more comfortable and even throughout the house, including the far registers which never used to get significant airflow. Very honest and trustworthy

    Bryan, December 2019, Chicago, IL
  • I hired Priority to seal the ducts and air seal my home.  I have been very pleased with

    the results.  The personnel from this company are professional and quite competent.  I have literally saved

    Nelson, Lake Forest
  • Priority Energy did a great job with an Aeroseal project for my home. The rooms are more comfortable and even throughout the house, including the far registers which never used to get significant airflow.

    B. L., Chicago, IL Feb. 2020
  • Used Priority Energy to help insulate (Aeroseal) a property we purchased and could not have been happier.
    R. M., Lake Bluff, IL April 2020
  • Very knowledgeable and professional (Aeroseal) staff. I definitely highly recommend and would use again in the future for other services!

    D.F., Chicago, IL Feb. 2020
  • Employees were all very helpful and professional! Came out in a timely manner (to do our Duct Test). Would highly recommend this company!

    J. R. New Lenox, IL April 2020
  • I had Priority Energy analyze my older home for indoor air quality and comfort because I was having difficulty maintaining temperatures. They came out and discussed our options. We ended up sealing our ducts and installing a whole-house dehumidifier.

    D. L, Lake Zurich, IL Feb. 2019
  • Priority Energy did an aeroseal for our home. We have had issues with air flow in our kitchen (cold in the winter) and one bedroom upstairs (hot in the summer). After they were complete, there is such a stronger air flow from the vents, that it really makes a difference.

    J.J. Chicago, IL - November 2020
  • Excellent Service and Company to work with - highly recommended and professional!

    T. B. Chicago, IL - July 2020
  • Before we sealed our ductwork the rooms farthest from the furnace were always hotter or colder than the rest of the house. We felt an improvement in air flow to the kids rooms right away. 98% duct leak reduction!

    S. H. Glenview, IL - October 2020
  • The Energy Audit you did on last home was so helpful; we referred to it for years when we made home improvements. I'd like to have you do an audit on my new home now. B. A.

    B. A. Lake Forest Homeowner
  • "We were impressed with how well your technicians answered our questions and how quickly and neatly they performed our Aeroseal service. Our rooms are much warmer now that the duct leaks have been sealed! You have a great team."

    D.F. Palatine, IL
  • "You have a great Aeroseal team. We were impressed with how well they answered our questions and how quickly and neatly they performed our service. Our rooms are much warmer now that the duct leaks have been sealed!"  

    D.F., Homeowner in Palatine, IL
  • "We enjoyed meeting Dave, our Energy Auditor.  He was interesting, knowledgeable, and professional.  We appreciated all his time and effort." 

    S.B., Homeowner in Prospect Heights, IL
  • Priority Energy is an A+ company! I've been having issues with my house staying warm in the winter so I called them up and they came out right away. Kurt was so helpful and professional! He explained everything that was going on in my house and gave me  peace of mind.

    M.I., Homeowner in Norridge, IL
  • "The employees that showed up were friendly and took care to make sure they kept the house clean while performing the aeroseal job. They explained the procedure thoroughly, I would recommend this company A+."

    T.B., Elgin, IL
  • Excellent service and quality! (excerpt)

    R.N., Inverness, IL
  • "I had Priority energy clean and then aeroseal my supply ducts; what a great experience! Great communication, great technicians, and great overall customer service!

    M.G., Downers Grove, IL
  • The Duct Leakage assessment we had yesterday was extremely informative! I'm glad we had you come to our home.

    D.K. Homeowner, Chicago, IL
  • Anthony was brilliant and answered all my questions. Really appreciate his expertise on our energy audit!
    January 2023

    S.K., Chicago, IL
  • David was very professional, thorough, and easy to work with. He provided us with a clear, detailed report with helpful suggestions as to how to improve our home.

    C.S. Chicago, IL
  • I highly trust and recommend this company for their prompt response, punctuality, and honesty in the performance of their service.

    C. H. Chicago, IL

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