Senior Modeling Engineer

Johnson Controls; Milwaukee (PA); On-site; USD 120,000 - 170,000; Full time

Job summary

Johnson Controls is seeking a Research and Advanced Development Engineer for the Data Center Thermal Technology Solutions group.

You will develop numerical models to simulate end-to-end performance of data center cooling systems and guide design and application decisions based on model results.

Qualifications

• Master’s or PhD in Mechanical Engineering or a related field.
• 10+ years of industry experience with thermal products or systems.
• Strong theoretical foundation in thermodynamics, heat transfer, and fluid mechanics.
• Experience with HVAC system design, refrigerant cycles, and component selection.
• Proficiency with numerical simulation tools for building and thermal applications (Modelica, MATLAB/Simulink, EES, EnergyPlus).
• Demonstrated ability to execute cross-functional projects.

Responsibilities

• Develop numerical simulations of thermal components used in data center applications.
• Integrate subsystems into complete thermal solutions across cooling loops, controls, and heat-rejection equipment.
• Predict chip-to-ambient performance of data center cooling systems.
• Provide technical guidance to customers from model results.
• Present findings and recommendations across departments; write white papers communicating JCI's technical perspective.
• Engage with industry groups such as ASHRAE and the Open Compute Project.

Skills

Thermodynamics

Heat transfer

Fluid mechanics

Cross-functional projects

Python scripting

HVAC system design

Refrigerant cycles

Education

Master's or PhD in Mechanical Engineering

Tools

Modelica

MATLAB/Simulink

EES

EnergyPlus

Job description

About Johnson Controls

Johnson Controls, a global leader in thermal management, mission-critical building systems, energy efficiency, and decarbonization, helps customers use energy more productively, reduce carbon emissions, and operate with the precision and resilience required in rapidly expanding industries such as data centers, healthcare, pharmaceuticals, advanced manufacturing, and higher education.

About Johnson Controls

Johnson Controls, a global leader in thermal management, mission-critical building systems, energy efficiency, and decarbonization, helps customers use energy more productively, reduce carbon emissions, and operate with the precision and resilience required in rapidly expanding industries such as data centers, healthcare, pharmaceuticals, advanced manufacturing, and higher education.

For more than 140 years, Johnson Controls has delivered performance where it really matters. Backed by advanced technology, lifecycle services and an industry-leading field organization, we elevate customer performance, turn goals into real-world results and help move society forward.

Visit johnsoncontrols.com for more information and follow @Johnsoncontrols on socialplatforms.

What You Will Do

Johnson Controls’ Data Center Thermal Technology Solutions group is seeking a Research and Advanced Development Engineer. As a member of the modeling team, you will develop and apply numerical models to simulate the end-to-end performance of data center cooling systems. You will play a key role on cross-functional teams responsible for creating comprehensive thermal solutions for data center applications.

Your primary focus will be simulating system performance and providing design and application guidance based on model results. As part of the advanced development team, you will also stay current on emerging technologies in the data center cooling space and evaluate innovations that may influence future product offerings.

This position is based on-site at the Warren Johnson Engineering Lab in Glendale, WI, with a minimum requirement of three days per week on-site. Other locations that will be considered are New Freedom, PA, Boston, MA, or remote for the right person. Various relocation packages are available.

How You Will Do It

• Develop numerical simulations of thermal components commonly used in data center applications.
• Integrate subsystems into complete thermal solutions, coordinating across cooling loops, controls, and heat-rejection equipment.
• Use simulation tools to predict chip-to-ambient performance of data center cooling systems.
• Apply system-level performance models to provide technical guidance to customers.
• Present project status, technical findings, and strategic recommendations across departments.
• Deliver presentations and/or write white papers communicating JCI’s technical perspective on emerging technologies and system architectures.
• Actively participate in industry groups such as ASHRAE and the Open Compute Project.

What You Will Need

• Master’s or PhD in Mechanical Engineering or a related field.
• 10+ years of industry experience with thermal products or systems.
• Strong theoretical foundation in thermodynamics, heat transfer, and fluid mechanics.
• Experience with HVAC system design, refrigerant cycles, and component selection.
• Proficiency with numerical simulation tools for building and thermal applications (e.g., Modelica, MATLAB/Simulink, EES, EnergyPlus).
• Demonstrated ability to execute cross-functional projects.

Preferred

• Python scripting and environment management (package installation, virtual environments, basic automation).
• Fundamentals of controls engineering (feedback loops, PID tuning, system response).
• Basic understanding of electrical systems (motor sizing, VFDs, power distribution).
• Experience with refrigeration system design and refrigerant properties.
• Familiarity with data center cooling architectures (direct liquid cooling, rear-door heat exchangers, CDUs).
• Expertise in one or more thermal domains (CDUs, chillers, dry coolers, cold-plate systems).
• Broad cross-domain knowledge spanning thermal, controls, and electrical systems—generalists with strong multidomain capability.

SALARY RANGE: $120,000 - $170,000 (Salary to be determined by the education, experience, knowledge, skills, and abilities of the applicant, internal equity, and alignment with market data.) This role offers a competitive Bonus plan that will take into account individual, group, and corporate performance. This position includes a competitive benefits package. The posted salary range reflects the target compensation for this role. However, we recognize that exceptional candidates may bring unique skills and experiences that exceed the typical profile. If you believe your background warrants consideration beyond the stated range, we encourage you to apply. To support an efficient and fair hiring process, we may use technology assisted tools, including artificial intelligence (AI), to help identify and evaluate candidates. All hiring decisions are ultimately made by human reviewers. For details, please visit the About Us tab on the Johnson Controls Careers site at https://jobs.johnsoncontrols.com/about-us