Joel Aartolahti

Associate, Member of the Finnish Bar

Services

  1. Environment, Energy & Green Transition

Contact details

I advise our clients in matters related to the environment, infrastructure and natural resources.

Before joining Castrén & Snellman I worked as a lawyer at another law firm and concentrated on real estate and construction related matters. Before my graduation I worked as a trainee in the real estate and environment team of another major law firm.

I graduated from the University of Helsinki in 2021. In addition, I studied energy and environmental law at the University of Aberdeen in Scotland for one semester.

Latest references

Downing – Acquisition of the entire share capital of Tornionlaakson Voima
We advised UK-based investment company Downing in its acquisition of the entire share capital of Tornionlaakson Voima Oy. Tornionlaakson Voima owns three hydropower plants in the Tengeliönjoki river system – the Portimokoski power plants in Ylitornio, the Jolmankoski power plants in Raanujärvi and the Kaaranneskoski power plants in Sirkkakoski. The power plants produce a total of approx. 45 gigawatt-hours of electricity per year. Tornionlaakson Voima’s daily operations will continue normally, and the transaction will not affect customers. The consummation of the transaction is subject to the approval of the Ministry of Economic Affairs and Employment. Downing has over 35 years’ experience in providing a wide range of investment solutions to the needs of institutional investors, advisers and retail investors. The company manages over £2 billion in assets in both the private and public markets and its current hydro power portfolio includes approx. 50 hydro power plants in the Nordics. 
Case published 27.3.2026
Merger of Oomi and Lumme Energia
We are acting as the joint legal advisor to Oomi Oy and Lumme Energia Oy in a transaction whereby Lumme Energia will merge with Oomi. As from the completion of the merger, the combined entity will be the largest electricity retail and service company in the Finnish market. In 2024, Oomi reported a turnover of EUR 373.9 million and had approximately 110 employees. Lumme Energia’s turnover for the same year was approximately EUR 314.6 million and it had approximately 50 employees. The transaction is primarily driven by the recent developments in the electricity market and the strategic goal to develop competitive products and services. Another key objective is to further enhance the customer experience, which is a shared value between the two companies. As a result of the merger, Lumme Energia’s customers will transfer to Oomi, and Lumme Energia will become one of Oomi’s shareholders. The completion of the transaction is subject to an approval by the Finnish Competition and Consumer Authority.
Case published 29.8.2025
Fortum – Acquisition of a project development portfolio for renewable power from Enersense
We are acting as a counsel to Fortum in a transaction in which Fortum is strengthening its renewable power project pipeline through the acquisition of a project development portfolio from Enersense. The debt-and-cash free purchase price is approximately EUR 9 million, with the potential for project-specific earn-outs subject to projects successfully reaching a final investment decision in the future. The transaction is subject to customary closing conditions and is expected to be completed during the first quarter of 2025. Fortum is a leading Nordic energy company with the purpose to power a world where people, businesses and nature thrive together. Fortum’s core operations comprise of efficient, CO2-free power generation as well as reliable supply of electricity and district heat to private and business customers. The company is listed on Nasdaq Helsinki. One of Fortum’s strategic targets is to develop at least 800 MW of ready-to-build onshore wind and solar projects by the end of 2026.
Case published 19.12.2024
Hanza AB – Acquisition of Leden Group
We acted as Finnish advisor to Hanza AB relating to its acquisition of all the shares in Leden Group Oy. Hanza AB is a Swedish mechanical engineering and electronics contract manufacturing company listed on the Stockholm Stock Exchange. Founded in 2008, the company has six manufacturing clusters in Sweden, Finland, Germany, Baltics, Central Europe and China and an annual turnover of approximately SEK 4.6 billion. Leden Group is a leading Finnish contract manufacturer specialising in sheet metal, machining and complex assembly. Leden Group has four production sites in Finland and one in Estonia and an annual turnover of approximately SEK 1.1 billion. 
Case published 13.12.2024
Fortum – Sale of recycling and waste business
We acted as the lead counsel to Fortum in a cross-border transaction in which Fortum sold its recycling and waste business. The business was sold to thematic impact investing firm Summa Equity through its portfolio company NG Group. The debt-free purchase price is approximately EUR 800 million.  Fortum’s recycling and waste business to be sold comprises municipal and industrial waste management and end-to-end plastics, metals, ash, slag and hazardous waste treatment and recycling services. These businesses are located in Finland, Sweden, Denmark and Norway and currently employ approximately 900 employees.
Case published 18.7.2024
castren snellman general atlantic iceye
General Atlantic – ICEYE’s EUR 1 Billion Series F Funding Round
We advised General Atlantic as the lead investor on ICEYE’s EUR 1 billion series F funding round, valuing the company at over EUR 10 billion. ICEYE raised EUR 450 million (USD 520 million) in a primary Series F funding round led by General Atlantic. Additional investors included Solidium, Tesi, Varma, Ilmarinen, Lifeline Ventures, Nokia, Qatar Investment Authority (QIA) and TCV. Together with a secondary placement, the total fundraising exceeds EUR 1 billion. ICEYE is the world leader in sovereign intelligence from space, providing continuous monitoring capabilities to detect and respond to changes in any location on Earth. The company operates the world’s largest and most advanced Synthetic Aperture Radar satellite constellation. General Atlantic is a leading global investor with more than four and a half decades of experience providing capital and strategic support for over 885 companies throughout its history. As of March 31, 2026, General Atlantic manages approximately USD 126 billion in assets across its investment strategies. We advised General Atlantic on this transaction in collaboration with the international law firm Paul, Weiss, Rifkind, Wharton & Garrison.
Case published 9.6.2026
Oomi Solar – Sale of a Solar Power Plant and Battery Energy Storage Project
We advised Oomi Solar Oy on the sale of a solar power park and battery energy storage project to Tuulipolar Oy. The transaction concerned a 24 MWp solar power plant and a 36 MW / 70 MWh battery energy storage system (BESS) to be constructed in Tornio. Tuulipolar Oy will act as the owner and operator of the plant, while Oomi Solar Oy will be responsible for its design and construction. The project will form the world’s northernmost industrial hybrid power plant, contributing to Finland’s green energy transition by increasing renewable energy production and electricity storage capacity in Northern Finland. The hybrid solution enables optimization of production as well as active participation in electricity markets and reserve services, improving the project’s profitability and supporting the balance of the electricity system year-round. Electricity production from the hybrid plant is expected to begin in 2028. Oomi Solar Oy is a Finnish renewable energy expert with experience from nearly 200 MW of installed solar capacity. The company helps businesses and communities accelerate the green transition by offering comprehensive solutions, including solar power plants, energy storage systems, and related lifecycle services from project development to maintenance. Oomi Solar Oy employs more than 20 energy professionals and delivers solar power projects across Finland. The company’s vision is to be Finland’s most desired partner for solar energy and energy solutions.
Case published 5.6.2026
United Bankers – Sale of three care properties
United Bankers – Sale of three care properties
We advised United Bankers on the sale of three care properties to Kinland AS. The buildings were completed between 2021 and 2022 and meet high technical and environmental standards. All three properties are fully leased. The portfolio has a weighted average unexpired lease term of 13 years.
Case published 1.6.2026

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