Our Story

From Panera Bread Meetings to Boston’s Most Trusted Heat Pump Company

The idea for SumZero was conceived in 2018, during an HVAC training seminar in Florida. One of the instructors described homes as interconnected systems — where insulation, air sealing, and mechanical design work in harmony to manage load, airflow, and comfort. It reframed HVAC not as a standalone product, but as the engine of the home.
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That concept stuck with us.
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And by the start of 2019, we decided to make it real. We refinanced our homes, emptied our savings, and launched SumZero Energy Systems with nothing but conviction and two laptops at Panera Bread, which doubled as our morning office.
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We didn’t have jobs lined up. But we had a vision: to build a company that wouldn’t just swap equipment — it would build systems that actually worked.

We saw that the story was bigger than HVAC. And we’ve been writing that story every day since.

Heat Pumps, Lower Loads, and the Future of Home Design

At the same time, inverter-driven mini split systems were hitting the market — systems that could go as low as 4,000 BTUs per room. We saw entire 3,000 sq ft homes being heated with a single 9k BTU unit.

We understood right then: the future wasn’t one-size-fits-all. It was load-based, plan-driven, and conversation-led.

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And today, after designing and installing over 1,800 heat pump systems across Massachusetts, many of which fully heat and cool the entire home, we can confidently say: it's not just possible — it works.

Why We Started SumZero

We didn’t start SumZero to push heat pumps onto customers.
We started it to have transparent, honest conversations about whether they were right for each home.

We wanted to build a company where:

• Electrification wasn't a gimmick — it was responsibly guided
  
• Technicians could take pride in their craftsmanship
  
• Customers felt seen, heard, and respected
  
• Every install was done with design, not just desire
  
  

We believe every home has the potential to run on a heat pump — but feasibility, investment, and preferences matter. That’s why we take the time to assess everything: insulation, layout, budget, usage, and long-term goals.
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Because it’s not about pushing a product — it’s about building the right plan.

From Zero to SumZero — The Growth of a Team

2019 – The Start

David and Ilija founded SumZero with a simple conviction: homeowners and technicians deserved better. They launched the business from scratch — no leads, no installs — just vision and grit. Every day began with a laptop at Panera Bread and ended with hands-on execution.

2020 – Weathering the Storm

SumZero entered the market just as the pandemic hit. We adapted fast, stabilized operations, and launched a spray foam insulation division to reduce building loads and make early heat pump adoption more viable — even when heat pump performance below 32°F was still limited.

2021 – Early Adopters of Whole-Home Heat Pumps

As we stabilized the business, we hired key staff and led the charge in whole-home heat pump installations — at a time when most were still installing ductless systems as add-ons. With a dual focus on load reduction and system design, we proved heat pumps could replace fossil fuel systems in cold climates.

2022 – The Pivot to Full Electrification

In March 2022, we shut down our spray foam division due to its indoor VOC limitations and entrusted weatherization to the Mass Save program. That shift allowed us to focus 100% on what we do best: heat pump electrification done right — with clear communication, clean installs, and systems that perform year-round.

2023 – Recognition and Expansion

We strengthened our install teams, refined internal systems, and were honored to join the Inc. 5000 list, recognized for growing more than 35% year-over-year three years in a row.

2024 – A Trusted Name with 1,800 Installs

As of the close of 2024, we’ve installed over 1,800 heat pump systems across Massachusetts and maintained an outstanding reputation for customer service, system design, and whole-home performance.

Today, This Isn’t Just a Company — It’s a Movement

SumZero exists to lead Boston’s transition to electrification in a way that’s transparent, responsible, and grounded in the science of building performance.
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We aim to:

Be Boston’s most trusted and respected heat pump company. Test new products, stay on the cutting edge, and help shape best practices. Make customers feel proud that choosing SumZero was one of the best decisions they made when building or remodeling their forever home. We believe every house can be a heat pump house — but that doesn’t mean every house should. That’s why we layer every variable — budget, layout, insulation, comfort preferences — into to plan before offering recommendations.Because we don’t just install. We think. We listen. And we build systems we’d install in our own homes.