Sero wins growth funding to retrofit social housing and monitor energy performance
This article covers Sero, a Cardiff-based energy startup, which has closed a growth funding round with an investment from Innovation Investment Capital (IIC), a Cardiff Capital Region-backed fund. The investment supports Sero’s work retrofitting homes and managing energy performance for social housing landlords, aiming to help reduce household energy bills and advance the UK’s net-zero objectives.
Sero, a Cardiff-based energy startup, has closed a growth funding round with an investment from Innovation Investment Capital (IIC), the Cardiff Capital Region-backed fund. The deal matters because it backs a firm that works directly with social housing landlords to retrofit homes and manage energy performance, addressing UK net-zero and household bill pressures at scale.
Why it matters
Retrofit of existing housing stock is a central challenge for the UK’s net-zero goals and for reducing household energy bills. Sero says it currently provides retrofit and energy services in up to 2,500 homes, with a contracted pipeline covering as many as 10,000 more. Those numbers indicate the company is moving beyond pilots into larger operational programmes with local authorities and housing providers — a necessary shift if national decarbonisation targets are to be met.
The investment from a regionally focused fund also signals continued public-private collaboration on climate and social outcomes in Wales and neighbouring regions.
Inside the product
Sero combines retrofit delivery, energy management and a proprietary technology layer that it describes as spanning strategy support through to ongoing energy management services. In practical terms the company works with local councils and social housing providers to identify retrofit opportunities, implement measures and then monitor performance to ensure savings and lower emissions are realised over time.
Its geographic footprint is UK-wide with particular concentration in South Wales, the South West, Southern England and London. The company’s model is aimed at landlords that need both capital-light deployment and data-backed performance monitoring to meet regulatory and tenant expectations.
Who are the investors?
The lead investor is Innovation Investment Capital Limited Partnership, a fund backed by Cardiff Capital Region (CCR) with initial capital of £50 million provided by UK Government funds and CCR when it launched in November 2022. Capricorn Fund Managers (CFM) acts as the alternative investment fund manager and PwC provides investment research and sourcing on behalf of CFM. Legal advice for the transaction was provided by Hugh James.
Kellie Beirne, Chief Executive Officer, Cardiff Capital Region, said:
Supporting Sero reflects strategic backing of our local companies that leverage innovation to deliver strong commercial and societal outcomes. Sero’s growth trajectory, rooted in technology and its contribution to improving the energy efficiency of housing stock, makes it a compelling story. We are proud to back a business that not only drives economic value but also supports meaningful climate action and community benefit in our region.
Lynda Stoelker, Capricorn Fund Managers’ COO and Chair of the IIC Investment Committee, added:
Sero fits well within the IIC’s investment philosophy, combining sustainable technology, scalable growth potential and a mission-centric business model. We see this investment as a strong strategic and financial fit that contributes to regional development and decarbonisation objectives.
Rob Asplin, PwC Partner, concluded:
Sero was recognised as an investment opportunity for the fund due to its blend of technology-enabled solutions, strong leadership and robust market opportunity within the energy efficiency and retrofit sector. These qualities align with the fund’s investment criteria and its mandate to help scale regional innovators with the potential to deliver measurable impact.
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Founder perspective
James Williams, Sero CEO, said:
IIC’s investment is a vote of confidence in Sero’s vision and technology and was driven by a clear alignment between CCR and Sero, which both share the aim of using innovative solutions to drive down bills, cut carbon emissions and deliver better, more comfortable homes for residents. With this support, we will accelerate deployment of our energy-efficiency solutions, deepen partnerships with housing providers and unlock new pathways for sustainable growth.
The bigger picture
This transaction sits at the intersection of regional economic development and the national push to decarbonise housing. Publicly backed regional funds such as IIC are increasingly targeting companies that can deliver measurable social and environmental impact alongside commercial returns. The deal also reflects growing interest from energy investors in business models that link retrofit delivery to ongoing energy management and performance verification.
If Sero can translate its contracted pipeline into long-term managed portfolios of energy-improved homes, it would offer a repeatable template for other regions seeking to combine public funding, housing providers and private capital to meet net-zero and tenant affordability goals across the UK and Europe.
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