With the objective of becoming the world’s northernmost energy-positive building, Powerhouse Brattørkaia by Snøhetta, an Oslo-based architecture and interior design firm, requires about 220,000 kWh per year, which is 80 % less energy to cover the requirements for heating, cooling, ventilation and lighting compared to a typical new office building in Trondheim, Norway. Embodied energy for producing all the materials, transportation and construction corresponds to about 255,000 kWh per year. This reduced demand in terms of operational and embodied energy makes it possible to balance the entire demand through solar power by using photovoltaic panels and providing good daylighting conditions and views for users. Producing more than twice as much electricity as it consumes daily on average, Powerhouse Brattørkaia will supply renewable energy to itself, its neighboring buildings, electric buses, cars and boats through a local micro grid. I sit down with Rune Grasdal, Senior Architect and Project Manager at Snøhetta, to discuss the sustainable building.
How does this project take into account the immediate surroundings in terms of its architecture, layout and systems design?
The aim of the project is threefold: to maximize the amount of clean energy produced by the building, to minimize the energy required to run it and to serve as a pleasant space for its tenants and the general public. The building’s skewed, pentagonal roof and the upper part of the façade are clad with almost 3,000 sqm of solar panels, strategically placed to harvest as much solar energy as possible. Over a year, this amounts to a total of about 500,000 kWh with clean, renewable energy. In effect, the building dually functions as a small power plant in the middle of the city. The office building is situated by the harbor and connects to Trondheim Central Station via a pedestrian bridge at the rear end of the building. The waterfront façade is the slimmest face of the building, allowing the project to be read at a similar scale with its neighbors. Clad with black aluminum and solar panels, the façade is reflected in the adjacent Trondheim Fjord.
What were the challenges and how did the project team overcome them?
Building energy-positive buildings is an extremely challenging task. No architectural practice, entrepreneur or developer could handle this individually. One of the key aspects of the Powerhouse alliance is that we are able to compose such strong teams with exceptional knowledge and experience of how we can build more sustainable buildings. This is truly a team effort. To achieve the Powerhouse standard, we need to also have a very sustainable building process. There will be a need for a very detailed construction management process to have a sustainable building phase as well. One of the challenges was to create safe access to the roof and required access for firefighters. Another challenge was to secure the roof to avoid ice and snow fallout. Rainwater management was also a challenge. These challenges were overcome (like on any other project) by installing snow stoppers and safety wires that can be used when people need to access the roof. In addition, secure attachment of both the PVs in the frames and the frame system itself is essential due to extreme wind exposure at the northwest ridge along the top of the building. The standardized size of the solar panels made it challenging to optimize the amount of square meters of panels on the roof.
The building produces more than twice as much electricity as it consumes daily. How do you harvest and store solar energy under the challenging climate conditions of Trondheim, Norway?
Powerhouse Brattørkaia is located in Trondheim, 63 degrees north of the earth’s equator, where sunlight varies greatly between the seasons. The building’s site and geometry has been carefully chosen to ensure maximum exposure to the sun throughout the day and seasons. The building produces more electricity than it uses in a year thanks to the solar panels integrated on the roof of the building. The building geometry is optimized to harvest solar energy specific to the location, and excess electricity produced by the solar panels will be sold to the electricity grid.
What findings from your past projects did you use when developing the design intent and strategies of Powerhouse Brattørkaia that contributed to its outcomes?
Powerhouse Brattørkaia is the third Powerhouse by the Powerhouse alliance. Snøhetta has also an active partner within the ZEN Research Center for environmentally-friendly energy. It was established in 2017 by the Research Council of Norway. Together with ZEN, Snøhetta completed the ZEB Pilot House alongside Scandinavia’s largest independent research body SINTEF, ZEB partner Brødrene Dahl and Optimera back in 2014. The building is intended for use as a demonstration platform to facilitate learning on building methodology for plus houses with integrated sustainable solutions. Both the Powerhouse projects and the ZEB projects have provided valuable insight into designing Powerhouse Brattørkaia and what it means to design sustainably in general. Although every project is unique, the projects have given us experience with natural ventilation, optimized design for solar harvest, lighting and how sensors can be used to reduce the building’s energy consumption. Our project for Powerhouse Kjørbo taught us a lot about rehabilitating buildings to optimize their carbon footprint.
What is your definition of sustainability? Why is it important to leave a minimal ecological footprint?
At Snøhetta, we have a long tradition of designing socially-sustainable structures. From the very beginning, one of our biggest missions has been to push the physical and intellectual boundaries of architecture through our buildings, interiors, landscapes and designs so that more people can take part, listen, interact and learn, like offering citizens in Oslo an opera house on which they can walk or creating a new headquarters for the Le Monde Group with a generous public plaza in the heart of Paris only weeks after the Charlie Hebdo attacks. We need to make more space available for the larger public to make sure that we are not pulling ourselves into nationalism, borders, isolation and, possibly, loneliness. For the past 12 years, we have had a strong focus on environmentally-sustainable designs, particularly through our Powerhouse projects, which span from built schools and office spaces to retrofitting projects. For over a decade, we have researched and experimented with energy-positive structures that are net carbon neutral over their life cycles. A key focus area of ours has been to design buildings that pay back their CO2 footprint over their lifetimes by returning clean energy to society, offsetting fossil energy that otherwise exists in the energy grid. Our “form follows environment” philosophy means that the design thinking of today should focus on environmental considerations and reducing our footprint first, and have the design follow this premise.
Do you believe that Powerhouse Brattørkaia can serve as a model for sustainable practices for other offices around the world, impact policy and change industry standards?
Yes, and hopefully the project will inspire others to take on projects like these also outside of Norway. We have proven that these structures can be built with existing technology, and we aim to scale up this strategy to the rest of our portfolio and ultimately the rest of the building industry.