Fiiu Linninen

Senior Associate, Member of the Finnish Bar, Bachelor of Business Administration

Services

  1. Environment, Energy & Green Transition

Contact details

I advise clients on a wide range of legal issues related to the environment, natural resources and infrastructure in matters such as project planning and development, authority negotiations and procedures, administrative proceedings, business transactions and financial arrangements. My core expertise includes matters related to environmental and other permits, EIA processes, land use, environmental liability and nature conservation.

Prior to joining Castrén & Snellman, I worked at another business law firm, advising clients operating in sectors such as mining, forestry and energy. My clients include, for example, companies engaged in exploration and mining, ports and terminal operators, bioproduct plants, wind and solar power plants, and waste treatment and incineration plants.

I graduated from the University of Helsinki in 2020 with a Master of Laws degree. I also hold degree in business administration from a university of applied sciences, which has equipped me with an even better understanding of our clients’ business and needs.

Latest references

Nscale – Data centre project
Castrén & Snellman advised Nscale, a European AI infrastructure company, in connection with its planned data centre project in Harjavalta, Finland. The facility will be located in the Sievari industrial area. Castrén & Snellman’s advisory role encompassed the negotiation and execution of a site securing and development agreement (SSDA) with Fortum, as well as the preliminary land sale process for the Sievari site with the Town of Harjavalta. Under the SSDA, Fortum supports the advancement of Nscale’s project development, including grid connection design and permitting.
Case published 15.4.2026
Terrafame – Environmental and water management permit processes concerning the company’s entire operations and the KL1 side rock area
Castrén & Snellman successfully assisted Terrafame Ltd in environmental and water management permit processes concerning the company’s entire operations and the KL1 side rock area, on which the Supreme Administrative Court issued its decision on 12 February 2026 (KHO 366/2026 and 367/2026). The changes made to the decisions of the Vaasa Administrative Court as a result of Terrafame’s appeals, enable the company to implement its new strategy and develop its operations as planned. The decisions of the Supreme Administrative Court brought the nearly ten-year-long permit process to a close.
Case published 20.2.2026
Brookfield – EUR 1 billion holdco financing for DayOne Data Centers
We advised a leading global investment firm Brookfield, alongside a global sovereign wealth investor, on the Finnish law aspects of a EUR 1 billion holdco financing for DayOne Data Centers, a Singapore-headquartered developer and operator of hyperscale data centres. Structured as a seven-year secured holdco financing facility of €500 million, expandable to €1 billion – and secured by DayOne’s Finland platform – the financing will support the rollout of hyperscale developments in Lahti and Kouvola, providing nearly 300MW of planned capacity across Finland. The proceeds will also support DayOne’s global expansion across the EU and APAC, with flexibility to allocate to other key growth markets as required.
Case published 29.1.2026
NATO Innovation Fund – Kelluu’s EUR 15 million Series A funding round
We advised the NATO Innovation Fund as lead investor on Kelluu’s EUR 15 million Series A funding round, with participation from Keen Venture Partners, Gungnir Capital, and Tesi. Kelluu is a Finnish deep tech company operating the world’s largest autonomous airship fleet. We advised NIF on this transaction alongside global law firm Latham & Watkins.
Case published 17.4.2026
Taaleri – Acquisition of a majority stake in Nordic Science Investments
We are acting as legal adviser to Taaleri Plc on its acquisition of a 51 per cent ownership stake in Nordic Science Investments Oy (NSI), marking Taaleri’s expansion into deeptech-driven venture capital. Through the transaction, Taaleri broadens its private equity offering into early-stage venture capital funds as well as the commercialisation and scaling of research-driven innovations. NSI is a Finnish venture capital fund manager operating across the Nordic and Baltic regions, focusing on early-stage investments in research- and science-based technologies. Its portfolio companies develop, among other things, health technologies, life sciences, advanced materials and AI-driven solutions. In addition to providing growth capital, NSI supports spin-out companies with strategic guidance, access to networks and assistance in building teams during the early phases of business development. NSI’s first fund, the EUR 45 million NSI Nordic Science I Ky, was established in 2024 and has to date invested in 22 early-stage companies in Finland, Sweden and the Baltic countries. Taaleri is a specialist in investments, private asset management and non-life insurance, with a strong position in renewable energy, bioindustry and housing investments as well as credit risk insurance. Taaleri has EUR 2.7 billion of assets under management in its private equity funds, co-investments and single-asset vehicles, employs approximately 130 people and is listed on Nasdaq Helsinki. The founders of NSI will continue in their operational roles following the transaction. The completion of the transaction is subject to approval by the FIN-FSA.
Case published 13.4.2026
Finnish Centre for Pensions – Information design workshop
We delivered two information design workshops for the legal department of the Finnish Centre for Pensions, with participants from both legal and other professional backgrounds. In the sessions, we applied the principles of legal design thinking to the Finnish Centre for Pensions’ field of operation and background materials, also utilising AI as a design tool. The participants found the tailored training highly useful and commended the trainers for their in-depth familiarisation with the Centre’s opinion drafting process and operating environment. As a result of the workshops, our experts proposed a new structural and linguistic model for the legal department of the Finnish Centre for Pensions for drafting opinions and guidelines. The proposal was well received as clear and applicable to the participants’ everyday work. In addition, we presented tailored AI use cases to support experts, allowing for a more efficient AI-assisted way of working. Our experts who delivered the workshops combined their legal expertise with their leading experience in legal design. The participants appreciated this versatile expertise, which enabled a knowledgeable, creative and applied approach to legal writing. ‘C&S created a well-structured training tailored to our needs, providing clear direction for our organisation and concrete takeaways for our experts in their day-to-day work,’ says Mari Kuunvalo, Head Of the Legal Department at the Finnish Centre for Pensions.
Case published 10.4.2026
Aktia Bank – EUR 80 million AT1 bond
We advised Aktia Bank Plc on the issuance of an EUR 80 million Additional Tier 1 (AT1) bond. The bond pays a fixed interest rate of 6.75 per cent semi-annually. The bond is perpetual, and Aktia has the right to redeem or repurchase it in accordance with the terms of the bond, subject to certain conditions. The bond was issued on 1 April 2026. In addition, we assisted Aktia in listing the bond on the Nasdaq Helsinki Ltd stock exchange. For the listing, we prepared Finland’s first EU Follow-on prospectus for a bond. The EU Follow-on prospectus was introduced on 5 March 2026 with an update to the Prospectus Regulation (EU) No. 2017/1129. The EU Follow-on prospectus is a new type of prospectus that can be used, among others, by issuers whose securities have been admitted to trading on a regulated market continuously for at least the 18 months preceding the offer to the public or the admission to trading on a regulated market of the new securities. A follow-on prospectus is simpler than a so-called traditional prospectus, and it is intended to avoid repeating information that the issuer has already disclosed. Nordea Bank Abp acts as the sole structuring advisor for the issue of the Notes. Nordea Bank Abp, Danske Bank A/S and ABN Amro Bank N.V. act as the lead managers for the issue of the Notes. 
Case published 7.4.2026
Aurevia and Labquality – Strategic reorganisation
We advised Aurevia Oy, a portfolio company of French private equity sponsor Mérieux Equity Partners, in a strategic reorganisation that involved splitting Aurevia and its parent companies into two independent groups of companies and reorganisation of its existing debt-financing arrangements. Following the reorganisation, the newly formed Aurevia continues as a leading provider of Contract Research Organization (CRO) and Quality Assurance and Regulatory Affairs (QARA) services, while the newly formed Labquality focuses on delivering External Quality Assessment (EQA) services. Aurevia serves operators in the medical devices, in vitro diagnostics and pharmaceutical sectors. Labquality’s customers include clinical laboratories and social and healthcare organisations. The reorganisation positions Aurevia and Labquality to allocate investments more effectively, accelerate growth within their respective customer segments, and respond to evolving market and client needs. The transaction was implemented through multiple parallel demergers and required comprehensive legal and tax structuring across several jurisdictions. Our team supported Aurevia throughout the planning and implementation phases, covering corporate, tax, employment law, and regulatory matters, as well as the optimisation of each group’s financing structure.
Case published 7.4.2026

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