What the Chicago energy code requires of a replacement window

Yes, it applies to you. Replacement windows in an existing Chicago home are subject to the city's energy code, and the code's exemption list does not cover them. The 2022 Chicago Energy Transformation Code sets a maximum window U-factor of 0.30 and a maximum solar heat gain coefficient of 0.40 for houses and residential buildings up to four stories. Storm windows and window film are exempt by name; replacing a window is not on that list. Here is the part that catches people. Most Chicago window replacements need no building permit, and the city states that skipping the permit does not skip the code. So the numbers bind on a job nobody inspects, nobody plan-reviews and nobody signs off. That makes the specification you sign the only place the requirement is really settled. Everything below is quoted from chicago.gov and from the adopting ordinance, read 2026-08-11.

The three numbers

For a residential building up to four stories above grade plane, Chicago's revised Table R402.1.2 sets these maximums. They are ceilings, not targets: a window may perform better than the number and may not perform worse.

What the table calls it	Chicago maximum	What it covers
Fenestration U-factor	0.30	Windows and glazed doors. The column excludes skylights
Skylight U-factor	0.55	Skylights only
Glazed fenestration SHGC	0.40	"The SHGC column applies to all glazed fenestration"

Source: the ordinance that adopted the 2022 Chicago Energy Transformation Code, SO2022-2008, Table R402.1.2, with the coverage notes from footnotes to Tables R402.1.2 and R402.1.3. Read on chicago.gov, 2026-08-11. The same three values appear a second time in Table R402.1.3, which is how we checked our own reading of the first one.

What the two numbers actually mean

Plain-English explanation rather than quoted code, flagged so you can tell the difference.

• U-factor is heat leaving. It measures how fast heat moves through the whole window assembly, glass and frame together. Lower is less heat lost. In a Chicago January that is the number doing the work.
• SHGC is sunlight coming in as heat. Solar heat gain coefficient measures how much of the sun's energy the window lets through. Lower means a cooler room in August.
• The SHGC cap is a ceiling only, and that has a trade-off. The code stops a window passing more solar heat than 0.40. It does not set a floor, so a very low SHGC unit is compliant too, and on a south-facing room that means giving up free winter heat. That is a design conversation to have with whoever is quoting, not a code question. Our reading, said as one.

Both values are properties of the specific unit you buy, published by the manufacturer for the whole assembly. We read no Chicago provision setting out how compliance gets documented on a job with no permit, so this page describes none. The rated numbers on the units are the only checkable evidence in the transaction, which is why writing them into the contract gets its own section below.

Which code, and since when

Chicago's energy code is the 2022 Chicago Energy Transformation Code, Title 14N of the Municipal Code, and it is based on the 2021 edition of the International Energy Conservation Code with local amendments. The city states its reach this way:

"The 2022 Chicago Energy Transformation Code, based on the 2021 edition of the International Energy Conservation Code, applies to projects where the first permit application is started on or after November 1, 2022. Additional requirements of this code will apply to projects where the first permit application is started on or after January 1, 2023."

The Department of Buildings put the same thing in an alert dated October 18, 2022 and updated October 31, 2022: "For building permit applications started on or after November 1, 2022, compliance with the 2022 Chicago Energy Transformation Code is mandatory, with limited exceptions for phased permitting and revision permits." That alert also identifies which pieces wait for the later date: "Certain provisions of the 2022 Chicago Energy Transformation Code, specified in Chapters C6 and R6, apply to projects where the building permit application is started on or after January 1, 2023."

Chicago sits in climate zone 5A for the purposes of this code, stated at Section C301.1 of the same ordinance. That is why the numbers here are colder-climate numbers and why a figure quoted from a national article about window ratings may not be the figure that governs your job.

Effective-date wording read at chicago.gov, 2026-08-11: the Chicago Energy Conservation Code page and the October 2022 Department of Buildings alert. Climate zone read in SO2022-2008.

An honest wrinkle in that wording

Read those two quotes closely and you will notice they are both written in terms of permit applications. Most window replacement in Chicago involves no permit application at all, so the sentence that switches the code on does not literally describe the ordinary job. That gap is real, and a page that did not mention it would be hiding something.

It does not change the answer, for a reason the city publishes elsewhere: an exemption from the permit is not an exemption from the codes, quoted in full two sections below. The permit application dates tell you which edition of the energy code a project is measured against. The obligation to meet the code comes from the code applying to the alteration in the first place, plus the city's statement that exempt work still complies. Chaining those two is our reading, labelled as our reading, and both links in the chain are quoted from the city.

Why a replacement window is subject, in four published steps

Nobody assembles this chain for homeowners, so here it is with each link quoted.

What the city publishes	Where	What it settles
"Alterations to an existing building or building system shall comply with the requirements of the code for new construction, without requiring the unaltered portions of the existing building or building system to comply with this code."	14N-R5-R503, revising R503.1	An alteration is measured against new-construction requirements
The exception list, which names storm windows and surface-applied window film and does not name window replacement	Same section, revising the exception to R503.1.1	Two neighbouring jobs are exempt by name. Replacing a window is not among them
"Replacement windows and doors installed under this permit must meet the U-value and solar heat gain requirements of the Chicago Energy Transformation Code."	Express Permit Program terms and conditions, window and door replacement	The city applies the code to replacement windows as a class, stated here for permitted work
"Section 14A-4-402 does not waive any applicable requirements of the Chicago Construction Codes or of the Municipal Code other than the requirement to obtain a building permit."	Guide to Building Permits, work not requiring a building permit	An exempt job is exempt from the paperwork, not from the code

Rows one and two read in SO2022-2008 on chicago.gov, rows three and four on chicago.gov directly, all 2026-08-11.

The exception list is worth reading in full, because its shape is the argument. Chicago's revised text: "Exception: The following alterations shall not be required to comply with the requirements for new construction provided that the energy use of the building is not increased: 1. Storm windows installed over existing fenestration. 2. Surface-applied window film installed on existing fenestration assemblies to reduce solar heat gain provided that the code does not require the glazing or fenestration assembly to be replaced." The remaining items, three through nine, deal with cavities, roofs and air barriers rather than windows.

A drafter who exempted storm windows and film by name, in the two entries that sit closest to window replacement, did not forget window replacement. It is not on the list because it is not exempt.

An exemption from the permit is not an exemption from the code

Chicago publishes that a building permit is not required for most window work. In a residential building up to four stories above grade the list covers "Repairing or replacing (in-kind) an exterior window or skylight in the existing opening" at any floor, and in any building it covers repairs, replacing glass in an existing sash, and storm windows. In-kind is defined by the city as new elements "of the same type, size, and shape". The full permit answer, including the landmark exception, is on do I need a permit.

Then, on the same page, the sentence that settles this one:

"Any work performed without a building permit, as allowed by Section 14A-4-402 of the Municipal Code, must still comply with all applicable requirements of the Chicago Construction Codes. Section 14A-4-402 does not waive any applicable requirements of the Chicago Construction Codes or of the Municipal Code other than the requirement to obtain a building permit."

The Chicago Energy Transformation Code is Title 14N of the Municipal Code and is published by the city under its construction codes. So a 0.30 U-factor and a 0.40 SHGC apply to a permit-exempt in-kind replacement in a bungalow exactly as they apply to a permitted job.

Our observation, not a code quotation: on an exempt job there is no plan review, no inspection and no certificate at the end. The requirement is real and the enforcement moment does not exist. Practically, that means the code protects you only to the degree your contract repeats it. A homeowner who never asks can be sold a unit that does not meet the city's own numbers and will never be told.

Which set of rules covers your building

The ordinance draws the line by occupancy group and by height:

"The residential provisions of the Chicago Energy Transformation Code apply to Group R-2, R-3, R-4, and R-5 occupancies with no more than four stories above grade plane."

Those letters are occupancy classifications defined elsewhere in the Chicago Construction Codes, which we did not read, so we do not translate them for you. The unambiguous half of the sentence is the height cap, and for Chicago's housing stock it does most of the work.

Your building	Which provisions	The numbers
Bungalow, two-flat, three-flat, greystone, small courtyard building, four stories or fewer	Residential provisions	0.30 U-factor, 0.40 SHGC, 0.55 for a skylight
Residential building over four stories above grade plane, including a condo unit in one	Commercial provisions, Table C402.4	Not established. We publish no figure. See below
An occupancy group the scope sentence does not name	Not the residential provisions	Not established here

Scope sentence read in SO2022-2008 on chicago.gov, 2026-08-11.

On tall buildings, we are stopping short deliberately. The ordinance revises Table C402.4, and that table did not come through when we extracted the text of the PDF. We have therefore not read the commercial U-factor and SHGC values at source, and this site's standing rule is that an unread figure does not get published. If you are in a building over four stories, get the value from Table C402.4 in the ordinance itself, or ask the Department of Buildings for your scope. Your association declaration is a separate question, and often the binding one.

You may not need any of this

This site is paid a referral fee when a homeowner asks to be matched with a window contractor, which is set out in full on how we make money. So it is worth being direct about the cases where the energy code is not a reason to buy anything.

• The code does not require you to replace a window you have not touched. Chicago's revised R501.1.1: "Except as specified in this chapter, this code shall not be used to require the removal, alteration or abandonment of, nor prevent the continued use and maintenance of, an existing building or building system lawfully in existence at the time of adoption of this code. Unaltered portions of the existing building or building system shall not be required to comply with this code." Old single-glazed sash, left in place, is lawful. Nobody can cite the energy code at you as a reason you must act.
• Storm windows are exempt from the performance numbers by name, and installing or removing one needs no building permit in any building at any height. Both statements are the city's. That makes an interior or exterior storm the one improvement on this page that sits outside both rulebooks.
• Surface-applied window film is also exempt by name, where it is applied to reduce solar heat gain and the code does not otherwise require the assembly to be replaced. Both exemptions carry the same condition, "provided that the energy use of the building is not increased".
• Repair and reglazing are different jobs. Repairing damage to an existing window and replacing glass in an existing sash are both on the city's no-permit list in any building. One failed unit is not evidence that a whole house needs replacing.

R501.1.1 read in SO2022-2008; exception list read in the same document; permit exemptions read at chicago.gov. All 2026-08-11.

What none of that tells you is whether replacing is the better decision for comfort, noise, operation or resale. It is not a code question, and this page does not pretend the code answers it.

These numbers stop at the city limits

If you are reading this from a near suburb, do not carry the 0.30 and 0.40 across the city limits. Illinois preempts local energy standards for residential buildings, and the preemption carries a short list of exceptions, one of them written as a population threshold. From 20 ILCS 3125/45(b):

"No unit of local government, including any home rule unit, may regulate energy efficient building standards for residential buildings in a manner that is either less or more stringent than the standards established pursuant to this Act; provided, however, that the following entities may regulate energy efficient building standards for residential or commercial buildings in a manner that is more stringent than the provisions contained in this Act: ... (iii) a municipality with a population of 1,000,000 or more."

We do not tell you which municipalities meet that population test, because we could not read a population figure for any Illinois municipality at a primary source. The Census Bureau API needs a key and its QuickFacts pages refused the request. Under this site's own rule an unattributable figure is deleted rather than published from memory, so the statutory test is quoted and the check against it is left to the reader. If your property is outside Chicago, ask that municipality whether it meets the test and which residential energy standard it enforces. The statute names other entities that may go more stringent, and we quote only the clause that decides this question rather than paraphrasing the rest. What is not in doubt is where the numbers above come from: Chicago adopted the Chicago Energy Transformation Code by ordinance, and they are quoted from it.

One more contrast worth knowing. The statewide provision at 20 ILCS 3125/20(c) exempts, among other things, "glass-only replacements in an existing sash and frame". It does not exempt full window replacement. So the direction of travel outside Chicago matches the direction inside it: swapping glass is treated differently from swapping the window.

Where the property is	Whose residential energy standard	What this site publishes
City of Chicago	Chicago's own Chicago Energy Transformation Code, adopted by ordinance	0.30 U-factor, 0.40 SHGC, up to four stories
Any other Illinois municipality	The state standard, which local government may not move in either direction, unless the municipality is one of the entities the statute excepts. Ask it which test it meets	No figure. We have not read the state values at source, and no population figure was sourced for any municipality

Both statutory provisions read at ilga.gov, 2026-08-11.

Landmark and historic buildings

Here is a place where we can show you exactly how far the published text goes and no further. On the commercial side the ordinance carries an explicit historic provision, at 14N-C5-C501.5, making a requirement not mandatory for historic buildings "provided that a report has been submitted to the building official and signed by a registered design professional demonstrating that compliance with that provision would threaten, degrade or destroy the historic form, fabric or function of the historic building".

The residential modification list does not contain an equivalent sentence. That does not prove there is no residential relief. Chicago adopts much of the residential chapter by reference and reprints only what it changes, and the underlying text is copyrighted and not published on chicago.gov, so we have not read it. What we will not do is tell you either way. If your building is a designated or proposed Chicago Landmark, or sits in a landmark district, the practical route is to ask the Historic Preservation Division before you order anything, because landmark review can constrain the window you are allowed to fit regardless of what the energy code would accept. The landmark side of the question is covered from the permits hub.

Turning the code into a purchase specification

On a permit-exempt job the code binds and nobody checks, so the useful move is to make the numbers part of what you are buying. The list below is our practical reading, not city instruction, and it is labelled that way.

• Put both numbers in the contract, not the brochure. Write that every unit supplied has a rated U-factor of 0.30 or lower and a rated SHGC of 0.40 or lower, and that skylights are 0.55 or lower.
• Ask for the ratings per unit, in writing, before deposit. Different lines, glass packages and grid options from the same manufacturer perform differently, so a brand name is not an answer.
• Say what happens if a substitution arrives. Product changes between order and delivery are ordinary. Agree in advance that a substitute unit meets the same two numbers.
• Check the ratings again at delivery, before installation. The rated values travel with the unit. After the sticker is removed and the trim goes on, you are relying on paperwork.
• Ask which figure the quote was priced against. A quote built around a unit that does not meet 0.30 is a cheaper quote for a different product, and comparing it to a compliant one is not a like-for-like comparison. The Express Permit Program page covers the parallel problem on permitted jobs, where the city also requires an energy and water efficiency compliance form with the application.

The recommendation, in one line. Treat 0.30 and 0.40 as the floor of the conversation rather than the goal, get them written down, and check them twice: once on the quote and once on the glass.

What a code-compliant window costs

No figure appears here, and that is on purpose. We have read no attributable source for what a window meeting Chicago's 0.30 and 0.40 costs installed, and this site publishes a price with its source and its date or does not publish it. A cost range copied from a national article is not a Chicago figure and a manufacturer page is not an independent one.

What you can do instead is make the comparison structural. Ask each quote for the rated U-factor and SHGC of the exact unit priced, then compare quotes only where those match. Two prices for two different performance levels are not a price comparison at all, which is the single most common way a window bid gets misread. How we source anything we do publish, and what we refuse to publish, is set out on our methodology page.

What we could not confirm, and will not guess

• The commercial values in Table C402.4. The ordinance revises the table but it did not survive text extraction from the PDF. No U-factor or SHGC for buildings over four stories is published on this site as a result.
• The base IECC text Chicago adopts by reference. Chicago reprints only its modifications to Section R503. The underlying model-code text is copyrighted and is not on chicago.gov, so we did not read it and we quote only Chicago's own published text.
• Whether a residential historic exemption exists. The commercial one is quoted above. No residential equivalent appears in Chicago's published modifications, and absence from a modification list is not proof of absence from the code.
• Whether the 2022 code has been superseded. The chicago.gov page for the Chicago Energy Conservation Code presents the 2022 code as current, read 2026-08-11, and lists no successor. The Department of Buildings alerts index is JavaScript driven and rendered empty for us, so we could not sweep it. Treat this as confirmed from the landing page, not from an exhaustive check of every alert.
• How compliance is documented on a permit-exempt job. We found no Chicago provision describing it. That is precisely why the contract language above matters.

Where to go next

• Do I need a permit to replace windows in Chicago, which walks the exemption lists, the in-kind definition and the landmark question in order.
• The Express Permit Program, the route for jobs that do need a permit, including the energy and water efficiency compliance form and the terms that bind glazing and openable area.
• The permits and rules hub, which links every page in this pillar.

Sources

All read 2026-08-11: the Chicago Energy Conservation Code page; the Department of Buildings energy code alert of October 18, 2022, updated October 31, 2022; the adopting ordinance SO2022-2008, for Tables R402.1.2 and R402.1.3, the residential scope sentence, Section C301.1, 14N-R5-R503, 14N-R5-R501 and 14N-C5-C501.5; the Express Permit Program terms for window and door replacement; work not requiring a building permit, exterior; and 20 ILCS 3125/45 at the Illinois General Assembly. No competitor page, contractor blog, manufacturer brochure or search summary informed any statement above.

If you want quotes you can hold against these two numbers, the form below passes your details to an independent licensed window contractor working in your part of the city. What that relationship is, and is not, is set out on the about page.

Straight answers

Questions Chicago homeowners ask

Do replacement windows in an existing Chicago home have to meet the energy code?

Yes. Chicago's revised alterations rule states that "Alterations to an existing building or building system shall comply with the requirements of the code for new construction, without requiring the unaltered portions of the existing building or building system to comply with this code." The code's own exception list then names storm windows and surface-applied window film as alterations that do not have to meet new-construction requirements. Replacing a window is not on that list. The city says it a second way in the Express Permit Program terms: "Replacement windows and doors installed under this permit must meet the U-value and solar heat gain requirements of the Chicago Energy Transformation Code." Read at chicago.gov and in the adopting ordinance, 2026-08-11.

What U-factor does a Chicago replacement window have to meet?

For a residential building up to four stories, the maximum window U-factor is 0.30 and the maximum solar heat gain coefficient is 0.40. Skylights are allowed a maximum U-factor of 0.55. Those three values are read from Table R402.1.2 of the ordinance that adopted the 2022 Chicago Energy Transformation Code, and the same three repeat in Table R402.1.3, which is a useful cross-check. Footnote b to that second table states: "The fenestration U-factor column excludes skylights. The SHGC column applies to all glazed fenestration." Read in SO2022-2008.pdf on chicago.gov, 2026-08-11.

If no permit is required, who actually checks the energy code?

Nobody from the city, on an exempt job, and that is the honest answer. Chicago publishes that a building permit is not required for in-kind window replacement in the existing opening of a residential building up to four stories, and on the same page it publishes that work done without a permit "must still comply with all applicable requirements of the Chicago Construction Codes". The energy code is one of those codes. So the requirement is real and no inspector arrives to test it. Our reading, said plainly: on an exempt job the contract and the rated numbers on the units you buy are where compliance is actually settled.

Are storm windows or window film held to the same numbers?

No, and the code says so by name. The exception list covers "Storm windows installed over existing fenestration" and "Surface-applied window film installed on existing fenestration assemblies to reduce solar heat gain provided that the code does not require the glazing or fenestration assembly to be replaced", in both cases "provided that the energy use of the building is not increased". This matters more than it sounds. Chicago also lists installing or removing a storm window as work needing no building permit in any building, at any height, so a storm window is the one improvement here that is outside both the permit requirement and the new-construction performance numbers.

My condo is on the 14th floor. Do the same numbers apply?

No, and we cannot give you your numbers. The ordinance states that "The residential provisions of the Chicago Energy Transformation Code apply to Group R-2, R-3, R-4, and R-5 occupancies with no more than four stories above grade plane." Above four stories the commercial provisions and Table C402.4 govern instead. We could not extract that table from the ordinance PDF, so no value for it appears anywhere on this site rather than a number we cannot stand behind. Ask the Department of Buildings, or read Table C402.4 in SO2022-2008.pdf yourself. A high-rise unit also has an association declaration sitting over the whole question.

Does the code force me to replace windows I have not touched?

No. Chicago's revised R501.1.1 is explicit: "Except as specified in this chapter, this code shall not be used to require the removal, alteration or abandonment of, nor prevent the continued use and maintenance of, an existing building or building system lawfully in existence at the time of adoption of this code. Unaltered portions of the existing building or building system shall not be required to comply with this code." A single-glazed 1920s sash you leave alone is lawful. The code engages when you alter something. Nothing in it obliges a homeowner to start.

Do these same numbers apply in Oak Park, Evanston or Berwyn?

Do not assume so. Illinois preempts local energy standards for residential buildings, at 20 ILCS 3125/45(b): no unit of local government, "including any home rule unit", may regulate them more or less stringently than the state Act, with a short list of exceptions. One of those exceptions is "a municipality with a population of 1,000,000 or more". We could not read a population figure for any Illinois municipality at a primary source, so this site does not tell you which municipalities meet that test. Ask your own village or city building department whether it meets it, and which residential energy standard it enforces. The numbers on this page come from the ordinance Chicago adopted, and this site does not publish the state numbers because we have not read them at source. Read at ilga.gov, 2026-08-11.