Atwater Apartments

At a Glance
• System Configuration: 2 × C65 ICHP Grid Connect Capstone Microturbines (130 kW) with integral gas boosters & BAS controls
• Annual Generation: >1.1 Million kWh/year
• Energy Savings: ~$150,000 / year in reduced operating expenditures ($100,000 ComEd incentive secured)
• Thermal Integration: 860,000 BTU/hr of hot water for hydronic space heating and domestic hot water


The Challenge
At Atwater Apartments—a 55-story, 480-unit luxury residential tower in downtown Chicago—residents faced extreme winter electricity bill spikes driven by inefficient electric space heating. To improve tenant retention and satisfaction, building ownership planned a complex conversion of the 760,000-square-foot facility from electric heat to a centralized hydronic (hot water) heating system. However, shifting heating loads from tenant electric bills onto the landlord’s natural gas account threatened to dramatically increase building operating costs. Ownership needed a high-efficiency power plant that could absorb this new thermal load, generate low-cost electricity for common areas, and fit into a tight 54th-floor mechanical layout without disruptive building-wide infrastructure overhauls.


The Solution
Veristar Energy collaborated with project engineers to design and deliver a rooftop 130 kW Combined Heat & Power system, featuring two dual-mode microturbines integrated directly with new high-efficiency condensing boilers and the building automation system (BAS).
• Onsite Baseload Power: Generates over 1.1 GWh of continuous electricity annually, taking direct control of energy supply to offset high grid power tariffs and eliminate transmission line losses.
• Dual Thermal Energy Recovery: Recovers 860,000 BTU/hr of high-grade exhaust thermal energy to feed the building’s new hydronic heating loop in winter and maintain domestic hot water supply year-round, displacing 80%-efficient legacy gas water heaters.
• Engineered Gas Pressure Solution: Utilized microturbines with internal fuel gas boosters to operate on standard low-pressure gas, saving $30,000 on basement booster equipment and avoiding invasive, high-cost gas riser construction through tenant suites.
• Long-Term Operational Protection: Covered by a 10-year Factory Protection Plan (FPP) to provide predictable, low-maintenance operations and eliminate technical overhead for building staff.


The Results
• $150,000 Annual Savings + $100,000 Utility Incentive: Mitigated the financial impact of the hydronic heating conversion while capturing a major ComEd utility rebate to boost upfront project ROI.
• 99% Operating Uptime: Both microturbines achieved over 16,000 continuous operating hours with 99% availability, ensuring reliable energy delivery in Chicago’s harsh winter climate.
• ASHRAE Award-Winning Innovation: Recognized with a prestigious 2020 ASHRAE Technology Award for engineering excellence in hydronic system conversion and thermal mass storage optimization.
• Tenant Satisfaction & Retention: Successfully eliminated tenant winter electric bill spikes while significantly reducing site-wide carbon emissions and thermal energy waste.