Joel Aartolahti

Associate, Master of Laws

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

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
Fingrid – Ilmarinen’s sale of shares to the Finnish State and OP Pohjola Kantaverkko
We advise Fingrid Oyj in a transaction in which Ilmarinen Mutual Pension Insurance Company is selling its holding of approximately 20 per cent of the shares in Fingrid to the Finnish State and OP Pohjola Kantaverkko Holding Ky. Fingrid owns Finland’s main electricity transmission grid and all significant cross-border transmission connections. The main grid is the backbone of the electricity transmission network, to which major power plants, industrial plants and regional electricity distribution networks are connected. 
Case published 11.2.2026
Metsäkonepalvelu – Acquisition of PJP Metsäexpertit
We advised Metsäkonepalvelu Oy in its acquisition of the entire share capital of PJP Metsäexpertit Oy. PJP Metsäexpertit is a Pirkanmaa-based company specialising in forest management and logging. The acquisition will strengthen Metsäkonepalvelu’s operations, particularly in the Pirkanmaa region, and expand its operations. Metsäkonepalvelu is a portfolio company of A. Ahlström Oy, a Finnish family-owned industrial owner. Metsäkonepalvelu provides mechanical timber harvesting services to forest companies, large private forest owners, and the public sector in Finland and Sweden. Metsäkonepalvelu Group employs nearly two hundred forestry professionals.
Case published 6.2.2026
EcoUp – Directed share issue
We acted as legal adviser to EcoUp Oyj in a directed share issue, through which EcoUp raised a total of approximately EUR 3 million in gross proceeds to strengthen the company’s capital structure and finance its growth. The share issue was directed to a limited group of domestic investors, deviating from the shareholders’ pre-emptive subscription right. EcoUp’s shares are traded on the First North Growth Market Finland marketplace maintained by Nasdaq Helsinki.  EcoUp promotes the green transition of the construction industry by producing carbon-neutral, energy-efficient and circular economy-based materials, services and technologies that help construction industry players reduce their environmental impact. The company has over 40 years of experience in developing and delivering circular economy solutions to customers.
Case published 29.1.2026
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

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Marius af Schultén
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 +358 40 565 7034
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 +358 50 431 9189
Minttu-Maria Miettinen
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Primary service Environment, Energy & Green Transition
 +358 40 071 0263
Sonja Pätäri
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Primary service Environment, Energy & Green Transition
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