Impact Analysis: A Snapshot
Karis Critical has made bold claims regarding projected benefits for the City of Naperville if their data center is built. Despite lofty promises regarding tax revenue and job creation, a closer look at the numbers paints a dark picture.
Not only are the tax revenue and job projections misleading, experts show that Naperville’s power grid is already under immense pressure. Additionally, data centers have historically caused utility prices to rise in other cities around the nation.
Lastly, residents are immensely concerned by the health impacts of living within the vicinity of a data center-and this one would be closer than all of them at only 1000 feet from the homes of Naper Commons.
Countless physicians, infrastructure and tech experts and environmental experts are sounding the alarm: data centers pose a risk to health, finances, wildlife and more. While data and data centers are a necessary element of society and progress, they have no place next to homes!
We’re calling for Naperville to prioritize its residents over development and plan responsibly!
Energy Usage: A Strain on an Already Struggling System
Capacity Concerns
The Illinois Municipal Electric Agency (IMEA) is the sole wholesale electric power supplier for the City of Naperville. As one of IMEA’s 32 member municipalities, Naperville purchases all of its electric power through IMEA. The Karis data center’s enormous demand must be accommodated by the supply IMEA provides.
Any major new load like a data center requires IMEA ensure it has the necessary generation and transmission capacity to serve the city, putting them at the center of the utility capacity discussion.
Data Centers are causing a strain on the energy grid in every location they have been developed. In Naperville, IL, the proposed data center is expected to draw 10% of the city’s already-strained capacity…using the energy equivalent to 16,000 homes!
Financial Risk
Approving a data center of this size with such a massive, long-term power requirement creates significant financial risk. It is difficult to determine the ultimate cost of providing such power to Karis Critical’s proposed development…but the impact will be felt most by Naperville residents.
Historically, data centers drawing from local electrical grids has caused electric rates to increase for other local residents and businesses, and Naperville’s residents and business will be no different. The US Energy Information Agency has shown that between May of 2024 and May of 2025, state energy consumption increased significantly as data enters boomed. (Find the map HERE).
More sources:
Data Centers Are Already Increasing Your Energy Bills. We Have the Receipts.
Environmental Impact
IMEA currently owns a share of thermal energy plants to cover the base load of energy requirements for its members. The volume of energy the data center would draw from IMEA’s current portfolio would effectively increase Naperville’s reliance on carbon-intensive sources like coal.
While IMEA has a Sustainability Plan with a goal of net-zero carbon emissions for its members by 2050, and Karis has pledged to purchase renewable energy certificates (RECs) to offset its load, the immediate impact will be felt by Naperville residents.
Data Centers Will Make You Sick
On November 5, 2025, 25 physicians across a variety of specialties signed on to a letter expressing concern about the adverse health impacts due to the proximity homes near the data center. As experts in their field, each physician attested to the hazardous conditions a data center would pose for children, pets and sensitive populations due to exposure to diesel fumes, constant noise and more in the 8-page letter, complete with sources like the American Academy of Pediatrics, the American Lung Association, the Environmental Protection Agency, and more.
“World Health Organization has classified diesel exhaust as a Group 1 human carcinogen way back in 2012 - this is the same category as tobacco and asbestos.”
Negative Health Outcomes from Diesel Emissions
Karis Critical’s Cancer-Causing Pollution
The proposed data center by Karis Critical will host 24 diesel backup generators. The emissions from these generators pose a major public health hazard, particularly to those that live in the adjacent communities.
Diesel exhaust is a Group 1 Carcinogen according to a World Health Organization finding from 2012-the same category as tobacco and asbestos. Diesel exhaust also carries over 40 toxic compounds including nitrogen oxides (NOx), fine particles (PM2.5) and ultrafine particles (<100nm). There is NO safe level of exposure to breathing diesel exhaust, according to a 2019 EPA finding.
Naperville’s Already-Poor Air Quality
According to the American Lung Association, Naperville is part of a metropolitan region that ranks amongst the 15 worst in the US for air quality, earning it an “F” grade for year-round particulate pollution. Diesel emissions from generators will only add to poor air quality in the air around the data center, making it even more hazardous for the families that live in the vicinity.
Risk to Children
Children’s lungs are still developing until about 18 years old. Children inhale more air than adults per kilogram of body weight and spend more time outdoors. Diesel exhaust exposure during these critical growth years can cause lifelong damage with established links to asthma, reducing lung capacity and cancer.
In Virginia, there was a documented increase in asthma cases in adults and children (about 14,000) linked to backup diesel generators since 2023 (UC Riverside & Caltech, 2024).
The long-term health and economic harms will likely far exceed any initial investment or recurring revenue benefits that may have been promised by the developer.
American Lung Association, 2025
Karis Critical’s Talking Points
Tier 4 Generators
Karis Critical provided misleading testimony that their proposed Tier 4 diesel generator emission control systems reduce PM2.5 and NOx emissions. But mitigation is NOT elimination.
Tier 4 emissions control systems can fail to control emissions during start up and low load testing with short runs-real world emissions would be far higher.
Furthermore, Tier 4 generators do NOT effectively filter ultrafine particles (<100nM…the cancer-causing kind!).
And to reiterate, WHO found that there is NO SAFE LEVEL OF EXPOSURE TO DIESEL EXHAUST. Therefore, any claimed mitigation would not alleviate the risk to the public as it would not eliminate the harm.
The I-88 Corridor
One of Karis Critical’s main talking points is that due to the proximity to I-88, diesel fumes and exhausts should not be a factor for resident opposition. Here’s why that’s wrong:
Proximity and Exposure
The I-88 highway corridor lies significantly farther from our neighborhoods, allowing meaningful dispersion of pollutants before they reach residential areas. In contrast, the proposed generators would be located immediately adjacent to homes and playgrounds (within a few hundred feet).
Even small increases in diesel exhaust exposure are associated with well-documented carcinogenic, cardiovascular, and respiratory risks. When layered on top of existing background pollution from the highway, this close-range exposure presents a substantially elevated health concern for the community.
Emission Intensity
The generators proposed for the site are exceptionally large, comparable in scale to locomotive engines, and would operate as a cluster of 24 units. Even brief testing cycles produce concentrated bursts of fine and ultrafine particulate matter at ground level, which Tier 4 controls do not fully eliminate, especially during cold starts and short runs. By comparison, emissions from I-88 originate from a broad mixture of vehicle types, contain lower concentrations of diesel particulates, and disperse across a moving roadway rather than accumulating in one stationary location.
Dispersion and Airflow Limitations
Diesel generator exhaust stacks at data centers are typically low in height, limiting vertical dispersion and causing pollutants to remain closer to ground level. This is especially concerning given the proximity of the proposed facility to residential properties and playgrounds. Highway environments, by contrast, benefit from greater air movement and mixing, which improves dilution of emitted pollutants.
Localized Hotspots Near Buildings-EPA modeling indicates that diesel plumes can recirculate around adjacent buildings,generating localized pollution “hotspots,” an effect intensified when generators operate in large clusters.
EPA Office of Air and Radiation. “Tier 4 Generator Plume Modeling.” EPA HERO Database, Ref. ID 3023194.
Tier 4 Standards Not Designed for This Scale-Tier 4 rules were developed for single, occasional-use generators—not dozens of 3 Megawatt engines concentrated at industrial campuses. Real-world validation at this scale is lacking.
Clean Air Task Force. “Diesel Pollution Health Impact Analysis.” 2019.
Ultrafine Particles Remain Uncontrolled- Ultrafine particles (<100 nm) remain abundant even with Tier 4 filtration and are not addressed by mass-based U.S. standards. Their health impacts are a driving factor behinD Europe’s adoption of Stage V standards.
U.S. EPA Clean Air Northeast. “Diesel Particulate Filters and Ultrafines.”
Emerging Health Data from Data-Center Regions- Recent analysis from Virginia links large data-center generator operations to an estimated 14,000 asthma cases, demonstrating the magnitude of community-level health impacts.
Han, Y., Wu, Z., Li, P., Wierman, A., & Ren, S. (2024). “The Unpaid Toll: Quantifying and Addressing the Public Health Impact of Data Centers.” arXiv:2412.06288v2
Nuisance of Noise
Data centers are noisy. They emit a low frequency hum, their generators sound like a lawnmower, the trucks servicing them are rumbling constantly. But noise is more than just a nuisance…the noise generated by data centers can have dire impacts on health and enjoyment of property.
Naperville Noise Ordinances
The proposed data center is located in an area zoned “Office Research and Light Industry” (ORI), which requires a conditional use permit and must comply with specific local and state noise regulations. The project MUST adhere to the noise level requirements detailed in Naperville City Code (Title 6, Chapter 14 (6-14-4) listed below.
Compliance is also measured against the Illinois Polution Control Board (IPCB) standards. The noise emitted by the facilities is assessed as transitioning from a Class C property (industrial) to a Class A property (residential) due to the proximity to Naper Commons.
Karis’ Noise Impact Analysis
The Model
Karis Critical commissioned a Noise Impact Assessment (NIA) by Jacob & Hefner Associates, Inc to demonstrate compliance with these regulations…but it was highly misleading.
The analysis used SoundPlan, a sound modeling program to predict operation noise levels at the site perimeters. The goal was to show that routine operation of the facility, including the constant hum from HVAC chillers, generators and more would comply with city ordinances.
Sound level meters were set up at four perimeter locations (N1-N4), bordering the proposed site to capture existing background noise levels. Readings were taken every second, averaged into 15-second intervals, and then combined into one hour averages for the analysis against Naperville’s noise ordinances (listed in the chart above). The final analysis modeled the predicted noise of the proposed facility.
The Sham Analysis
But Karis conducted their analysis between March 28, 2025 and April 1, 2025-a period of approximately 3 days. Additionally, the analysis itself states that exceptionally loud readings (lasting approx 18 hours) were excluded from the averages at one location. This raises concerns about the resulting baseline’s conservatism, transparency and accuracy.
At the Planning and Zoning Committee Meeting on November 19, 2025, Karis Critical’s representative had the opportunity to present an expert witness. The witness admitted under oath that their analysis did not encompass any independent research or outside expert testimony, but rather the data collected by Karis Critical and provided to All4, a consulting firm hired by data centers around the country to convince communities they are safe.
Best Practices and Industry Standards
Collecting data over a 3 day period is not industry standard, and is considered inadequate for a project with a 24/7, high-volume noise profile like a data center, especially when attempting to establish a base-line.
Best practices for large-scale industrial projects, noise experts recommend monitoring over a longer period-one to two full weeks or more-to capture the full range of typical environmental conditions and existing noise sources.
A longer duration helps capture variations due to weather changes, daily traffic cycles, weekly usage patterns (weekdays vs weekends), and the full range of ambient noise sources.
A three-day duration is insufficient to establish baseline data. A shorter study makes it easier to argue that the data center’s continuous noise -even at a lower dBA level-is insignificant when compared to existing, but potentially short-lived, peak noises already present.
(This is the basis for the absurd claim that residents should not find the noise of the data center bothersome due to their proximity to I-88…nearly a mile away. But more on that later!)
Naperville’s Ordinance is primarily based on A-weighted decibels (dBA) which which is designed for overall sound level but is poor at accounting for low-frequency, tonal or constant nature of data center humming.Industry standards and best practices for assessing annoyance are needed to properly evaluate this constant industrial drone near residential areas.
The study primarily focuses on routine operation, but does not adequately detail the noise impact from emergency diesel generators during required testing and maintenance, or due to power outages.
Health Concerns
While noise seems to be an issue of “annoyance,” continuous noise can lead to major health concerns, causing sleep deprivation, headaches, cardiovascular issues, TMJ and more. Read more about the impact on health under “Data Centers Will Make You Sick.”