Photo: Ivan Brodey

Accelerating passenger growth called for an extension of Norway's main international airport, OSL Gardermoen. The aim: to double its capacity while making it the world's most energy-efficient airport. 

Increased prosperity, new travel habits and cheaper airline tickets are contributing to accelerating passenger growth. 

Back in 1998, Norway's main international airport, OSL Gardermoen, was built to handle 17 million passengers a year. However, as early as 2001,  the number had already reached 21 million. 

The need for expansion was clear. The client, Avinor, would achieve this by adding one more pier and extending the central terminal with one clear aim: to double the airport's capacity while leaving a minimal climate footprint. Sustainable and energy-efficient solutions thus became cornerstones of the extension project. 

But would it be possible to halve the energy use in the extension? Could it be achievable to build an airport rated BREEAM Excellent? And how would it be possible to design the world's most energy-efficient airport?  

Our client, Avinor, had very high ambitions for minimising the climate footprint: They wanted to halve the energy use compared to the existing terminal.

Frode Fjeldstad Chief Project Manager, COWI

1. OVAL SHAPE OF THE PIER

Think of it as though the pier turns its back towards the sun in summer, while holding its warmth during the winter. Thereby you reduce the demand for cooling and heating. The oval tube shape is very effective in reducing the area, too.

2. INSULATION THICKNESS

 The oval shape of the pier enables the same thickness of insulation to be used across the roof and down each side. Thereby it achieves a high level of insulation almost throughout the entire building.

3. EXCEPTIONAL GLASS QUALITIES

Glass is the single element with the highest energy leakage in a building. We put a lot of effort into pushing glass manufacturers to produce a glass with exceptional energy isolation abilities. This was a major factor in achieving such a low level of energy use.

4. SNOW COOLING

Snow from the airside is ploughed into a 4.5-metre deep snow pool. In the summer, the melting water cools the airport terminal.

5. SEWAGE for DISTRICT HEATING 

The airport borders on a local water treatment plant that releases large amounts of cleansed sewage into a local river. We borrow this water and extract heat from it, which we are able to use to heat the airport terminal.

6. VENTILATION

The new ventilation system reclaims 85 percent of the building's energy. The standard has previously been 80 percent, but with the T2 project 85 percent is becoming the industry standard.

KEEPING IT COOL WITH SNOW

While ensuring that the construction of the building would consume as little energy as possible, the project team also put great effort into finding a sustainable solution for how the energy would be produced. For the cooling element of this, the cold Norwegian winters provided the solution in the most natural way.

Oslo Airport already had one of the world's most advanced snow clearing systems as it needs to regularly remove snow from the runways and taxiways in the winter. Through COWI's solution, the snow is ploughed into a 4.5-metre deep hole on the airside of the airport. The total storage volume is estimated at 90,000 m³ by filling up to 9 metres above ground.

When the temperature rises in spring, the snow is covered with wood chips. Finally, when summer arrives and the demand for cooling peaks, they distribute the meltwater to the terminal to keep it cool. 

STAYING WARM WITH LOCAL SEWAGE

While snow is used to cool the terminal, the solutions for heating are equally sustainable. The airport's neighbour is a municipal wastewater treatment plant that releases treated sewage into a local river.

For COWI's heating solution, the airport borrows this water and extracts energy from it by lowering the temperature down towards 1 degree celcius  before releasing it into the river.

They then refine the heat by using a two-step heat pump before supplying it into the district heating system operated at the new terminal.

"Being able to cool with snow in the summer and heat with treated sewage in the winter is quite impressive from a sustainability point of view, and has also given us engineers some exciting challenges," says Frode.

The architect behind the sustainability

The new T2 terminal is based on the same aesthetic principles as the original part of the airport, only this time with a different architectural approach based around the question: "How can we minimise the climate footprint?" 

"Every single material was closely examined to ensure environmentally optimal choices. Some of the answers can be found in the tube shaped pier, which allows you to maintain the thick level of isolation all the way around the building," says Gudmund Stokke, architect, principal partner and chairman at Nordic – Office of Architecture. 

Photos: Nordic - Office of Architecture

One of the biggest architectural challenges, Gudmund explains, was to preserve the aesthetic and atmospheric qualities of the existing terminal, while doubling the capacity. The building was protected by the Directorate for Cultural Herritage and loved by its users. Many were sceptical about the proposed changes. 

"The tube shaped pier widens and opens up where it meets the original building. The touch is so light that we have named it a butterfly connection. This was an important answer to a significant architectural challenge."

BIM - THE DIGITAL ANSWER TO COLLABORATION

The use of BIM was essential in designing T2. For a time during the design construction, the BIM model was said to be the world's biggest. Advanced use of BIM has become a key element to success in complex projects, explains Frode.

"The customer has full access to the model at all times, and is then able to give continuous feedback during the entire process – not only at given milestones."

PRIDE IN SUSTAINABILITY

The project has also been of great magnitude for the COWI engineers designing tomorrow's sustainable solutions. A total of 228 COWI employees have worked on the project since it began in 2009. 

Frode Fjeldstad is among the many for whom the airport has been their main office over the last few years. Good years indeed, he explains.

"Ultimately I'm very proud to have contributed with sustainable solutions that effectively are part of making OSL the most climate-friendly airport in the world – and the only one that's rated BREEAM Excellent. I truly think that's something to be proud of".