Decarbonizing buildings. Designed to scale.
How three partners from three different worlds built a company that decarbonizes the worst-performing 43 % of Europe's residential stock — without renovation.
Intro
Buildings are responsible for 34 % of global CO₂ emissions (UNEP 2024/25). In Germany, 80 % of residential energy use goes into heating and hot water — and the average German housing stock sits at energy efficiency class D. Traditional renovation is expensive, slow and often ineffective. More than 14 million gas boilers are still in operation in Germany alone.
termios offers a new path: an AI-powered, cloud-based system for hydraulic balancing — installed in existing buildings with just a few components, delivering 30% energy savings.
But beyond the product lies a bigger story — one of shared vision and joint execution across industry boundaries.
Situation
Huge potential - but no scalable solution
LEG Immobilien, Germany’s second-largest residential real estate holder, was facing a massive challenge: how to optimize energy efficiency in hundreds of thousands of flats - without deep renovation?
Oventrop, a leading manufacturer of hydraulic systems, knew the limitations of conventional balancing solutions.
What was missing? A venture partner with a builder’s mindset - someone to turn the problem into a scalable company.
LEG owns more than 171,000 residential units. The EU now requires the 43 % worst-performing buildings to deliver the bulk of a 20–22 % primary-energy reduction by 2035. On top of that, the ECB climate factor enters its collateral framework in mid-2026 — making inefficient real estate measurably more expensive to refinance. Portfolio landlords don’t need another research pilot. They need a product that ships, scales, and pays back.
Our job
Three perspectives, one vision
The partners aligned around one clear goal: enabling decarbonization in residential housing - fast, affordable and reliable. LEG brought market knowledge. Oventrop contributed product expertise. mantro built the company.
From problem to product to company
In under two years, a shared idea became reality — a certified IoT device, an AI platform, a 25+ person team and a standalone company.
mantro acted as institutional co-founder - driving team setup, product architecture, software development, company structuring and go-to-market.
Collaboration as an engine of innovation
termios wasn’t built in isolation. It grew through true co-creation. Disagreements were resolved. Differences were respected. Shared focus drove execution. The result? A working solution that delivers real-world impact - not just tech buzzwords.
Our job
Three perspectives, one vision
The partners aligned around one clear goal: enabling decarbonization in residential housing - fast, affordable and reliable. LEG brought market knowledge. Oventrop contributed product expertise. mantro built the company.
From problem to product to company
In under two years, a shared idea became reality — a certified IoT device, an AI platform, a 25+ person team and a standalone company.
mantro acted as institutional co-founder - driving team setup, product architecture, software development, company structuring and go-to-market.
Collaboration as an engine of innovation
termios wasn’t built in isolation. It grew through true co-creation. Disagreements were resolved. Differences were respected. Shared focus drove execution. The result? A working solution that delivers real-world impact - not just tech buzzwords.
What termios delivers today
Our own device — not someone else's
termios designed and certified its own retrofit thermostat — from industrial design to firmware. No whitelabel, no compromise.
30 %+ heating cost reduction
AI-driven hydraulic balancing for existing buildings — installed in under an hour per flat. No renovation needed.
From pilot to portfolio
Anchor customer LEG is both investor and user — scaling termios across a 171,000-unit residential portfolio.
Learnings
Collaboration is king
Real results come when strong partners work as one team - not in silos.
Shared goals create resilience
Aligned purpose helps navigate complexity, setbacks and growth phases.
Technology must follow purpose
Innovation means solving problems - not just building tech for its own sake.
Get in touch
If you want to stress-test an idea, unblock an initiative, or simply see whether we're the right partner, let's talk. You can book a straight-to-the-point session with our CEO Manni, or leave us a message.
30-minute call. No strings attached.
