Why we do what we do: Our investment into Kelvin

4 min readMay 18, 2023



NY Radiators courtesy of Midjourney

New York City buildings have a problem… over 3.5 million apartments are heated by central boiler-powered steam radiators. Most of them date to the WWII period or before. And their owners are now facing the highest operational carbon tax in the world (LL97) at $268 per tonne of CO2. Upgrading the heating infrastructure is CAPEX prohibitive and these old radiators are notoriously inefficient.

What is a Landlord to do? What if a very low cost solution existed that could lower the heat energy consumption by 25–40% and did not require a specialist installer? (“the Super could do it!”). That is what Kelvin, our newest investment, started with.

They call it the “Cozy”. A radiator cover that looks simple but actually integrates years of IP, testing and approvals to make analog, old, overheated radiators into modern, digitally connected hyper-efficient heat releasing beauties. No more need to open the window 😱 to cool down the apartment.

The original Cozy

Alex and Christian fell in love with this company. It is the most elegant solution we have seen to the challenge of decarbonizing an existing building… and the roadmap is even more exciting.

Kelvin has now launched a “hybrid electrification” offering which pairs the Cozy with a custom heat pump and a thermal battery so that not only can the boiler still warm the tenant on the coldest of days, but also so that hundreds of thousands of apartments can provide demand response to the grid.

Cozy’s are already installed in thousands of apartments in New York and soon to be installed in Boston, Chicago and Washington, DC. Utility incentives, the IRA and LL97 have simply supercharged demand for the offering (while lowering the cost to the landlord to nil).


That is the sexy part of the story… The gritty part of the story is all about Marshall Cox, the founder, who first invented the solution as a Columbia student as his professional ballet dancer twin brother, Jeremy, slept on his floor and complained of being cold.

Marshall, the scientist, started tinkering in 2011, while still a PhD student and raised his first round of funding in 2012. It chugged along joining a number of accelerators and receiving grants until it raised a Seed round from our friends at Third Sphere (fka Urban.us) in 2016.

And then came LL97 and things took off… without disclosing too much, the last two years have been exponential for Kelvin (fka


We first heard about them from

before 2150 was even a fund and we tracked them over time. Ironically (or not) we met Marshall face to face in September, 2022 during NY Climate Week and proceeded to dig deeper.

As Christian (overly?) passionately stated during one of our Investment Committee meetings: “THIS is the reason why we exist! THIS is the deal only 2150 would know enough about to understand! THIS is why we do what we do!”

And it is. We have come across few other technologies whose cost to deploy is so low yet impact is so high. It started by working for New York but could easily be applied to Paris or Amsterdam. Kelvin’s technology is a critical tool to help cities, landlords (and their tenants!) to have a quick and massive impact on their carbon emissions.

This is why we exist. This is why we do what we do. Welcome to the family Kelvin!

PS Trivia: Lord Kelvin of the UK was the inventor of the “heat pump” in 1852 (!). The irony that this magical machine has yet to be deployed widely as it could in 2023 is not lost on us.


2150 is a venture capital firm investing in technology companies that seek to sustainably reimagine and reshape the urban environment. 2150’s investment thesis focuses on major unsolved problems across what it calls the ‘Urban Stack’, which comprises every element of the built environment, from the way our cities are designed, constructed and powered, to the way people live, work and are cared for. Find out more at www.2150.vc. 2150 is a part of Urban Partners.




2150 is a venture capital firm investing in technology companies that seek to sustainably reimagine and reshape the urban environment.