The building sector has a large carbon footprint. In the EU for example, the building sector is the single largest consumer of energy – amounting to 40 per cent of the region’s total consumption. In addition, 36 per cent of the EU’s total greenhouse gas emissions stem from buildings. On a global scale, these figures are 35 and 38 per cent respectively. Reducing these figures will contribute to limiting the global rise in temperatures to less than 2 degrees Celsius.

Additionally, very few buildings are designed to withstand the effects of climate change in the form of heat waves or floods.

With this in mind, the challenge for the Danish government when deciding to gather the UN’s regional agencies and functions into a single complex was to come up with a building that was not only designed and constructed to have a minimal environmental impact, including during the operational phase, and be able to withstand climate change. How would this work in practice?

Prior to UN City’s construction, employees in 11 different UN agencies worked in locations dotted across Copenhagen. To deepen inter-agency cooperation, sharing of experts and knowledge exchange, the Government of Denmark took the decision to group them into one complex. Known as UN City, the Nordic headquarters of the UN are located in one of Copenhagen’s newer suburbs, that of Nordhavn (the North Harbour), which previously was an industrial port area, and occupy an area of 45,000m².

Home to approximately 1,600 employees, the UN City’s office building was designed by the Danish architectural firm, 3XN. Based on the UN’s objective that the new UN City should reflect the UN’s guiding value as an organisation, ‘Together as one’, the UN City’s office building is designed as an eight-pointed star, with open and flexible working spaces that help maximise efficiency and enjoy large amounts of natural light.

A number of measures minimise the amount of energy used for heating, cooling, lighting and ventilation, which results in lower CO2 emissions. For example, 1,400 square metres of solar panels situated on the roof generate electricity for the building. In addition, the roof which the solar panels are located on is painted white and constructed of recyclable, plant-based materials. This allows the roof to absorb the sun’s heat, thus keeping the building’s temperature at comfortable levels, and lessening the need for air conditioning. White perforated aluminium shutters have been utilised to make up the building’s façade cladding. The shutters ensure shade from the sun without impeding views or natural light, and employees can control the shutters from their computers. When needed, seawater is used to provide cooling, which ensures a minimum of electricity is used.

UN City also aims to use water efficiently. The building captures rainwater via the roof and reuses it to flush the building’s toilets.

To reduce the campus’ overall CO2 footprint and encourage employees to cycle to work, more than 680 bicycle racks are available on-site. Furthermore, UN City is located close to both a train station and an underground metro station, making it easier to access via public transport.

The resulting UN City building is of a high environmental and energy standard. This means that:

1. The use of rainwater to flush toilets and taps with in-built sensors has reduced the building’s annual water consumption by 60 per cent.
2. UN City is one of the most energy-efficient buildings in Denmark, with an annual energy consumption of less than 50 kWh per m².
3. Ensuring that all elements and materials used to construct UN City were sourced within an 800km distance from the complex has contributed to a reduced CO2 footprint.
4. Locating UN City close to public transport links makes it attractive for employees and visitors to leave their cars at home when travelling there, thus further minimising UN City’s CO2 footprint.
5. UN City consumes 55 per cent less energy than office buildings that are the same size.
6. UN City was the first UN building to be awarded the LEED Platinum certification – the world’s most widely used green building rating system, and the highest certification available.

In 2012, UN City was awarded the EU’s Green Energy Building award for new buildings in recognition of its impressive level of energy efficiency.

Read more about the case: https://3xn.com/project/un-city

Read more about 3XN: https://stateofgreen.com/en/solution-providers/3xn/