Pioneering zero-emission off-road machinery: Inside Oslo’s Sophies Minde project

Following my recent piece on Oslo’s Fornebu Line project—a pioneering effort in zero-emission metro construction that features a more than 75% machinery electrification rate—I’d like to turn to another groundbreaking construction project in Oslo, Sophies Minde. This project represents Oslo’s next frontier: achieving 100% zero-emission operations for heritage renovation.

Oslo’s public procurement policies for construction have propelled an industry-wide transition. By 2023, 77% of the machinery deployed in municipal construction sites was zero-emission, and starting in 2025, “emission-free” construction equipment becomes mandatory for all public projects. In September 2024, I visited Sophies Minde, where a former hospital is being revitalized into a community center with district offices, a kindergarten, health services, and public spaces. Spanning 13,000 square meters of indoor space and 7,100 square meters of outdoor upgrades, the initiative exemplifies Oslo’s commitment to embedding sustainability in urban redevelopment. It’s scheduled to be completed next year.

Fully zero-emission

As Oslo’s flagship initiative realizing its 2025 mandate for 100% zero-emission municipal construction, Sophies Minde operates an all-electric machinery fleet that includes excavators, wheel loaders, lifting platforms, cranes, drills, and pavers. These machines handle tasks ranging from delicate renovations in indoor spaces to extensive outdoor earthwork like excavation, grading, and site preparation.

The project has comprehensive charging infrastructure on-site. There are two permanent power stations and one temporary one, and each is equipped with high-capacity chargers. Additionally, 24 geothermal heat pumps handle the building’s heating and cooling needs.

An electric excavator working on earthmoving at Sophies Minde. Photo by Jinjian Li

Beyond electrification, the project emphasizes material reuse to minimize its carbon footprint. The original brickwork, a key element of the building’s history, has been carefully preserved, rigorously tested for compressive strength, and reintegrated into the renovation. This approach achieves a 62% reduction in carbon dioxide (CO₂) equivalent emissions compared with new construction with conventional cement.

The Bobcat E10e electric mini excavator works well in relatively small indoor spaces. Photo by Hongyang Cui

Environmental, social, and cost benefits

As of June 2024, Sophies Minde had reduced emissions by over 200 tons of CO₂ equivalent by replacing diesel-powered equipment with electric alternatives. According to Mathias Kolsaker, the project manager, the team encountered no operational challenges. Drawing on their past experiences with diesel machinery and around a year’s worth of operations using 100% zero-emission machines, Kolsaker estimated that electric machines typically require approximately 10%–15% more units on-site to match diesel capacity, due to downtime during charging. However, this is expected to drop closer to zero as battery technology advances in terms of both the time spent charging and how long the charge lasts. Additionally, tethered electric charging has further optimized the efficiency of equipment that operates with limited movement.

In Norway, electric construction machinery is predominantly leased, and at Sophies Minde, we were told that costs for most electric models are around 10% higher than diesel equivalents. For certain specialized equipment, such as drills, the lease costs tend to be higher than that. However, project experience shows that for most mainstream machinery, lower electricity expenses offset the up-front price difference, making the overall costs of electric machines similar to diesel ones. Additionally, reduced greenhouse gas and air pollutant emissions, along with the quieter and vibration-free operations of electric machinery, improve operator comfort and minimize disruption to the surrounding neighborhood.

Lessons for others

Oslo’s procurement policies, which prioritize sustainability alongside cost and quality, have been instrumental in advancing zero-emission construction. These policies have enabled the use of electric models like mobile cranes and pilling machines for the first time in Oslo. At the same time, challenges remain. Securing adequate grid capacity and charging infrastructure is critical, as electric machinery currently requires more units on-site to compensate for charging downtime. For Sophies Minde, batteries typically allow for 6–8 hours of operation and lunchtime charging is used, but performance can be highly dependent on temperature. During one of Oslo’s coldest winters, when temperatures dropped to -25 °C, battery capacity decreased by 40%. Despite some delays to the project schedule under such extreme weather, electric machinery effectively met the demanding performance requirements across most operating conditions.

Market availability could also pose a hurdle. While commonly deployed electric machines are readily accessible through mainstream suppliers, sourcing electric versions of specialized equipment still proves more complex. This is particularly true for two categories: medium- and large-scale electric equipment such as large excavators and cranes and equipment with niche applications including road pavers and rollers. Increased demand from major buyers and large municipal projects could incentivize producers to scale up production of their electric models. Nonetheless, by integrating green technologies and reusing materials, Sophies Minde proves the feasibility of zero-emission construction machinery and charts a clear path for sustainable urban development.

Acknowledgement: The author extends sincere gratitude to the City of Oslo for coordinating the visit to Sophies Minde and for sharing valuable insights on the applications of zero-emission machinery.