Across the country, utilities are turning to inverter-driven heat pumps as a cornerstone of their decarbonization and energy efficiency strategies. These systems promise cleaner heating, better comfort, and smarter grid performance. But translating that promise into real-world impact depends on more than just equipment—it depends on how it’s installed, configured, and experienced in people’s homes.
In this case study, ILLUME and Georgia Power explore what happens when advanced heat pump technology meets everyday installation practices. Through field data and customer feedback collected over two heating seasons, this research reveals the hidden levers that drive or derail performance and offers insights to help energy programs deliver on their full potential.
The Challenge
As Georgia Power looks to the future of home heating and cooling, inverter-driven heat pumps emerged as a promising solution for meeting energy efficiency and decarbonization goals. Yet the utility recognized that getting the technology into homes was only part of the equation. How these systems were installed, and how well they were configured, would ultimately determine their success. Georgia Power partnered with ILLUME to evaluate not just performance metrics, but the real-world interplay between advanced system controls, energy savings, and customer comfort. The opportunity: to use robust field data captured over two heating seasons to uncover the story behind the settings and help shape smarter program planning.
The Approach
Georgia Power had big questions: How do inverter-driven heat pumps perform in real-world homes? How do installation settings affect savings, demand, and comfort, and how do those outcomes vary for dual fuel and all electric heat pumps? And how can these insights shape smarter program planning? Answering these questions meant navigating complexity across systems, seasons, and data types.
ILLUME brought that complexity into focus and led a comprehensive evaluation spanning two heating seasons. We wove together three core datasets to tell a complete performance story:
AMI usage data provided whole-home electric usage and trends across time.
HVAC submetering, captured at one-minute intervals, revealed the inner workings of each system—modes, runtime, and efficiency.
Customer surveys and interviews grounded our findings in lived experiences of comfort, system performance, and satisfaction.
The evaluation unfolded in two phases. In the first heating season, systems operated with default manufacturer settings. Before the second season, Georgia Power updated systems with optimized, efficiency-focused settings, creating a rare opportunity to isolate the effects of control settings alone. ILLUME examined detailed, real-time data from newly installed systems to evaluate their performance relative to each participant’s original equipment. This analysis quantified energy and bill impacts, carbon savings, and comfort outcomes, all within the context of seasonal weather conditions.
By stitching together granular technical data with human insights, ILLUME delivered a field-validated, multidimensional view of this emerging technology and a clear path for making it work better for customers, their utilities, and their air quality.
The Results
Working with ILLUME, Georgia Power gained far more than performance metrics—they gained a clearer understanding of what makes inverter-driven heat pumps succeed or stumble in the field. The results revealed that installation settings, not just the equipment, ultimately drive energy savings, customer comfort, and peak demand impacts.
Key Findings
- Installation settings matter—immensely. Optimized controls reduced reliance on inefficient backup heating, improved comfort, and delivered measurable energy savings. In all-electric systems, efficient settings led to higher heating season savings and lower bills, while dual-fuel systems showed greater fossil fuel displacement and reduced GHG emissions.
- Default settings undercut performance. During the first winter, heat pumps frequently relied on backup heat, resulting in higher energy use and comfort complaints. After settings were optimized for the second winter, both performance and satisfaction improved as customers reported warmer homes, fewer issues, and more stable bills.
- Electric demand peaks dropped. With optimized settings, all-electric systems showed signs of reduced winter peak demand—a critical insight for planning around grid flexibility and load management.
- Customer experience told the same story. Surveyed and interviewed participants consistently cited more stable temperatures, quieter operation, and improved comfort in the second season. Issues like cold rooms or high bills faded once systems were configured appropriately.
Putting Insights into Action
ILLUME’s evaluation provided Georgia Power with field-tested evidence that installation quality must be central to any future program featuring advanced HVAC systems. As a result:
- Georgia Power will consider installation protocols for any future program designs, potentially including contractor training and quality assurance measures.
- Evaluation findings can inform updates to the utility’s Technical Reference Manual (TRM), particularly around load profiles, heating hours, and distinctions between all-electric and dual-fuel systems.
- Results can guide and support cross-team discussions around energy efficiency, demand response, load management, and decarbonization planning.
By connecting the dots between hardware, human behavior, and complex data, ILLUME helped Georgia Power unlock the real story behind a promising technology and inform internal cross-team collaboration that is shaping smarter paths forward.
The Takeaway
As utilities chart a course toward electrification and decarbonization, variable-speed heat pumps are often seen as a clear win with big potential for efficiency, emissions reduction, and grid flexibility. But this evaluation shows that potential isn’t performance. Realizing the benefits of emerging technologies requires more than installing new equipment—it requires paying attention to how it’s installed, configured, and experienced.
Georgia Power’s work with ILLUME demonstrates that thoughtful field evaluations, those that integrate advanced metering, submetering, and customer feedback, can uncover the subtle but critical levers that drive outcomes. This approach doesn’t just answer what happened, but explains why, and provides the evidence needed to make programs better, smarter, and more equitable.
For utilities, regulators, and implementers, this is a blueprint: design programs that treat installation as a strategy, not a box to check. Build in training, guidance, and accountability. And when piloting new technologies, evaluate them holistically through the lens of data, engineering, and lived experience. That’s how we ensure the technologies we invest in actually deliver for the people we serve and for the future we’re working toward.
Want to explore how field data, customer insights, and emerging technologies can shape your program strategy? Reach out to ILLUME to learn how we can help.
