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
Neste – EUR 500 million refinancing arrangement
We advised Neste Corporation on the refinancing of its EUR 500 million term facility by way of two EUR 250 million bilateral term facilities provided by OP Corporate Bank plc and Danske Bank A/S, Finland Branch.  Each term facility has a maturity of three years with extension options.
Case published 25.11.2025
Prisma Properties – Sale and leaseback of ten grocery retail properties
We are assisting Prisma Properties AB in a sale and leaseback arrangement with Kesko Oyj comprising ten grocery retail properties. The transaction value is approximately EUR 59 million, and the properties are located in Sastamala, Jyväskylä, Lappeenranta, Vihti, Oulu, Saarijärvi, Liminka, Imatra, Loviisa, and Eurajoki.  As part of the arrangement, the properties are leased back to Kesko Oyj under lease agreements with a weighted average lease term of 11.6 years. The portfolio includes well-known store concepts such as K-Citymarket, K-Supermarket, and K-Market.
Case published 20.11.2025
YIT – Data centre construction agreements with XTX Markets
We advised the urban developer and construction company YIT on the drafting and negotiation of two construction agreements with the leading algorithmic trading firm XTX Markets for the development of two data centres in Kajaani, Finland, which are part of XTX Markets’ data centre complex. The first agreement, valued at approximately EUR 100 million and signed in December 2024, marked the commencement of the construction of the first data centre facility in Kajaani, establishing Kajaani as a strategic hub for high-performance computing infrastructure.  Building on the success of this collaboration, YIT and XTX Markets entered into a second agreement in August 2025 to commence construction of a second data centre facility. This phase includes the delivery of the shell and core of the new building.
Case published 20.11.2025
Rabobank – Financing arrangement for Olana Energy
Castrén & Snellman acted as legal advisor to Coöperatieve Rabobank U.A. in its capacity as sole lender and hedging bank providing senior financing to Olana Energy for a Battery Energy Storage Systems (BESS) portfolio in Finland. Our advice included preparing a legal due diligence report on the projects as well as advising on the negotiation of the various finance and project agreements. Olana Energy is a management-owned fast-growing independent power producer with an international pipeline of over 1 GW. The diversified portfolio of assets ranging from 5 to 30 MW reinforces the Finnish grid at a granular level.
Case published 18.11.2025

Get to know our other experts in the field

Marius af Schultén
Position: Partner
Primary service Environment, Energy & Green Transition
 +358 40 565 7034
Tarja Pirinen
Position: Partner
Primary service Environment, Energy & Green Transition
 +358 40 350 7797
Samuli Tarkiainen
Position: Partner
Primary service Environment, Energy & Green Transition
 +358 41 436 0953
Kanerva Sunila
Position: Counsel
Primary service Environment, Energy & Green Transition
 +358 20 776 5060
Sanna Aalto-Setälä
Position: Senior Associate
Primary service Environment, Energy & Green Transition
 +358 50 331 5889
Fiiu Linninen
Position: Senior Associate
Primary service Environment, Energy & Green Transition
 +358 44 032 6866
Jonas Holm
Position: Associate
Primary service Environment, Energy & Green Transition
 +358 50 431 9189
Sonja Leinonen
Position: Associate
Primary service Environment, Energy & Green Transition
 +358 50 534 8412
Minttu-Maria Miettinen
Position: Associate
Primary service Environment, Energy & Green Transition
 +358 40 071 0263
Konsta Peussa
Position: Associate
Primary service Environment, Energy & Green Transition
 +358 45 788 18016