The Urban Environment House is a new office building in Helsinki, Finland. The office collects all the Helsinki City Urban Environment Division’s services in one place and around 1500 people work in the building. High goals were set for the environmental and energy efficiency of the building, and it has received a BREEAM (Building Research Establishment Environmental Assessment Method) rating of Excellent. The roof of the building is mostly covered by vegetation and there are four green roof terraces around the building. A total of around 60 000 plants have been planted on the green roofs and terraces (including just under 100 trees). The plantings are partly or entirely dynamic and have been designed with the help of an ecologist. The roof covers an area of 4500 m², of which about 3500 m² is planted green roof.
Early stages of the project included the general plan for the area around the building. This included an experimental exhibition square. The character of the square was designed to be green, inviting and provide a public outdoor showroom for the city. The design put an emphasis on the stormwater management. The square was later constructed and designed further as a separate project.
The four roof terraces are located on different sides of the building. Each terrace has its theme based on the intended use and the location. The vegetation of each terrace is chosen according to the light conditions and to support the theme of the terrace. The useful or ornamental plants are native species to Finland.
The Shadow Terrace (theme: forest) has most of the time full shadow condition. The vegetation creates a miniature forest, and the chosen plants are typical to a forest in Southern Finland. The Gala Terrace (theme: sea) is designed for different events and gatherings and therefore the vegetation is impressive and colourful, consisting of different grasses and blooming plants. The plantings are dynamic. The Work Terrace (theme: cultural landscape, fields) opens to the east and towards the rural landscape and the fields of the University of Helsinki. The terrace is a place to eat lunch or work. Most of the plants are typical Finnish herbs or useful plants. The Active Terrace (theme: urban) offers a place to relax, play or spend time with colleagues. The vegetation is inspired by urban ruderals, and it reflects the appearance of rough and rugged wastelands. The significant part of the vegetation is the different species of roses. A few of the species originate in Helsinki.
The extensive green roof consists of four different areas: three different habitats and a testing area of sedum carpet products. The three habitats resemble habitats typical to Helsinki and Finland: sand and gravel shores of the Baltic Sea, a dry meadow of an old fortress and heath with grass and subshrub. All the plant species are native species in Finland and the substrate has been made according to the needs of each plant selection. The plants together with stones and tree trunks attract insects, butterflies, and birds. Drainage and rainwater storing elements are mounted under the green structures.
Readymade sedum carpets from four different manufacturers are tested in local climate conditions and different thicknesses of the substrate layer in the Eastern corner of the roof. Every type of carpet is mounted in three different substrate layers: thin according to the manufacturer’s manual, semi-thin 50-70mm and thick 80-150mm. The experimental plot will be used to determine which substrate solutions are the most favourable in terms of vegetation, water retention and biodiversity of liverwort covers.
Architecture offices involved in the design: Lahdelma & Mahlamäki Architects Ltd
Biologist: Jere Salminen
Client: City of Helsinki
Plant Nursery: Terola Plant Nursery
Landscape contractor (green roof): Viher-Pirkka Ltd
Building contractor: Skanska Talonrakennus Ltd
Location: Työpajankatu 8, 00580 Helsinki, Finland
Design year: 2018-2020
Year Completed: 2020
Main photo: Maite Gonzalez Laurens
