IVL Swedish Environmental Research Institute

1970s Office Block Turned into Energy-Efficient Building

The Pennfäktaren office block, originally built in the 1970s, was ambitiously refurbished to make it one of Stockholm’s most modern and sustainable office buildings, achieving Sweden’s first LEED certificate.

The building is centrally located in Stockholm, with 10 floors and a total area of 12,000 sqm. In 2005, the building was taken over by Vasakronan, Sweden’s largest property company, which started an ambitious refurbishment programme to modernise the building to create light, attractive office spaces and achieve environmental certification.

The transformation has resulted in a modern, environmentally friendly office building, with several smart cleantech solutions, primarily in energy efficiency and energy supply.

Sweden’s first LEED-certified building

Work was completed in 2010, following extensive renovation of both the interior and exterior, including a completely new facade. As a result, the house became Sweden’s first building certified under LEED (Leadership in Energy and Environmental Design). This is an internationally recognised green building certification system focusing on high sustainability performance within areas such as energy savings, water efficiency, low CO2 emissions, improved indoor environmental quality, and stewardship of resources.

Energy consumption halved

During the renovation, the building was fitted with energy-efficient windows and glass facades with low heat transmission qualities. Solar panels and collectors have been installed on the roof, with a capacity of 5,000 kWh of electricity and 50,000 kWh of heat. These measures have helped the building cut its energy consumption by more than 50%, from 260 kWh/sqm to about 125 kWh/sqm.

Sedum roof with low-carbon features

The roof is partly covered with sedum, a type of green roof system, which absorbs air pollution. Another benefit of the sedum roof is its capacity to manage stormwater, helping reduce the load on the city’s stormwater system. The project sets an inspiring example, showing that even old, outdated constructions can be transformed into sustainable buildings using smart technology.

Facts and figures

Built/refurbished: 1977/2009
Environmental certification: LEED Gold (2009)
Offices: 10,426 sqm
Other areas: 1,584 sqm


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