Civil Engineering Works

Forest Observation House

Celje, Slovenia

Among the Trees 1 | Among the Trees
Built with wood from the same forest where it is located, this forest observation house serves as a green classroom open space for workshops and events.
Design: A forest observation house was built on natural elevation along a forest path in the the Celje city forest. Six trees and several pillars bear the load of the platform, made accessible through a spiral staircase. The platform translates the geometry of the surrounding trees architecturally into six “fingers”, whose room volumes are grouped around an interior with natural exposure. Originally designed to serve as a green classroom in order to bring school children closer to the forest ecosystem, the tree house soon also turned into a popular space for exhibitions, workshops, and cultural events as a new landmark for the city.

Wood: Douglas fir timber was used for the tree house, cut in the same forest where the building was later built. The head of the local forestry office accompanied the timber from the logging to the processing and finally to the construction stage. The Celje city forest, honoured as the best-managed forest of 2016 in Slovenia, is subject to legal regulations for close-to-nature forestry which are even stricter than the FSC and PEFC standards.

Energy: Due to its function, the building has no thermal insulation. By using local wood as a carbon sink, it contributes to sustainable development.
Interior 2 | Interior
Platform Structure 3 | Platform Structure
Wendeltreppe 4 | Wendeltreppe
Basic information
Year of Completion |  2015
Investor |  City of Celje (SI); Slovenian Forestry – Regional Unit Celje (SI)
Architecture |  Atelje Ostan Pavlin d.o.o., Ljubljana (SI)
Structural Engineering |  CBD d.o.o., Celje (SI)
Construction Time |  6 months
Number of floors |  --
Plot size |  350 m²
Gross floor area |  59 m²
Construction Costs (netto) |  1 100 €/m² (KG 300 & KG 400)
Awards |  Plečnik Award 2016 (Nominated); International Piranesi Award 2016 (Nominated)

Technical aspects
Concept |  Supports, frame, walls from Douglas fir, structurally connected to six surrounding trees
Woodworking |  MBT HIŠA gradnja, projektiranje d.o.o., Podplat (SI)
Origin of Timber, Certification |  Celje city forest with stricter standards of sustainability than FSC and PEFC
Traceability of Timber |  Confirmed and accompanied by the city’s head forestry official
Forestry Value Chain |  Exclusively local companies

Circular Economy Energy Efficiency

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