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
DNB Bank ASA – Lease and development of premises
We advised DNB Bank ASA in its agreement with Fennia Mutual Insurance Company on the development and lease of the premises at Fabianinkatu 8, Helsinki. With the lease agreement, DNB Bank ASA will focus all its Finnish operations at the Fabian 8 office. The other tenants at the renewed premises will be DNB Carnegie Investment Bank AB’s Finnish operations and DNB Auto Finance Oy. In connection with the long-term lease agreement, the parties also agreed on a major renovation project to completely refurbish the premises. The object of lease will be completed in the second half of 2027.
Case published 10.10.2025
Yellow Film Studios – Merger of Yellow Film Studios and REinvent Studios
We advised Yellow Film Studios, the largest independent film and television production company in the Nordics, in its strategic merger with Danish film industry sales and financing studio REinvent Studios. Together they form Reinvent Yellow, a unified hub for television and film production, sales, financing and innovation, combining over three decades of production experience and a vast catalogue of titles.
Case published 8.10.2025
International reinsurance companies – Ad hoc arbitration proceedings
We successfully represented a panel of reinsurance companies in an international ad hoc arbitration. The dispute arose out of a reinsurance treaty under the terms of which the reinsurers had reinsured a portfolio of risks underwritten by the cedent. The parties disagreed as to whether the reinsurance provided coverage for a certain loss that had occurred because of the market turmoil caused by the Covid-19 pandemic. The case involved highly complex legal and contractual questions requiring special expertise on reinsurance law and practice. The arbitral tribunal rejected the counterparty’s claims for reinsurance compensation against our clients in full. The amount in dispute was approximately EUR 34 million.
Case published 16.9.2025
byFounders.vc – DataCrunch’s USD 64 million Series A funding round
We supported byFounders.vc as the Finnish counsel in their investment in DataCrunch Oy in a USD 64 million Series A funding round. DataCrunch provides scalable AI compute solutions from energy-efficient data centers in Iceland and Finland. byFounders.vc is the community-powered early-stage venture fund investing in globally ambitious teams connected to the Nordic and Baltic countries.
Case published 11.9.2025

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