location: Grič, Ljubljana
client: DARS d.d, studio abiro
area: 1 ha

competition: 2019
design period: 2020
implementation: 2024

project team:
Ana Kučan, Luka Javornik, Lara Gligić, Danijel Mohorič, Tomislav Krnač
architecture: studio abiro, leading architect Matej Blenkuš

consultants: prof. dr. Mihael Jožef Toman, BF UL, izr. prof. dr. Simon Rusjan, FGG UL
technical support during construction: Axis, Proctor
contractor: CGP d.d.

model: Klára Bohuslavová

photographs:

Handling the rainwater run-off at the Seat of DARS Company Grič

At the beginning of 2019, DARS launched a public competition for its new office building at Grič near Ljubljana. In addition to ensuring functionality, the competition criteria also highlighted the importance of sustainable and humane design, which the complex – the office building and its landscape – demonstrates in all its elements and criteria.

One of the elements of sustainable design is the management of rainwater – collection, retention, ventilation – which, in addition to collecting rainwater and regulating its discharge into the stormwater sewer system, also means less conventional storm sewerage and lower long-term maintenance costs. Based on this starting point, the architects at studio abiro invited us to participate in the competition.

Stormwater from the green roof and external paved areas is collected via underground pipes in a pond to the south of the building and in an underground storage tank. The grassed area in front of the building is sloping towards the pond so that rainwater from the grass simply flows into it. The rainwater collection flows through two ain gardens – vegetated retention basins – which significantly reduces the load on the public municipal storm water system. In addition, the pond also receives the underground drainage water. Both maintain the water level of the pond, which also influences the microclimate through evaporation and lowers the air temperature in the southern part of the building in summer.

Although the lake functions like a natural one, its form clearly highlights its anthropogenic origin and technical role. Therefore, the pond is shaped as a rectangle, whose geometric design language reflects on the architectural language of the office building, to which it is technically and functionally linked. The technical nature of a vegetated rainwater retention was guided toward a creation of a garden-park element; technical measures such as storage, ventilation, purification with plants etc. served as a strating point to create a space that will offer shelter and contact with nature for employees and those who come on business. Plant species from Barje (the Ljubljana Marsh) have been planted along the lake, as the DARS office building is located on the border between the Polhograjci Hills and the Ljubljana Marsh.

The completely flat lawn, covered with spring and autumn croccuses, is sloping towards the lake, with rainwater purified between layers of perennial and aquatic vegetation planted in straight lines around it: carex, typha, ločje and water iris. A long bench built above the storage tank, reached by a bridge over the water, completes the south side of the pond. Behind the bench, the terrain, planted with pine trees, is formed in undulating polygons, which additionally retain rainwater in the convex parts. This creates a pleasant ambience for a break outdoors, especially in summer when the pine trees cast a deep shade on the bench.

Despite a highly systematic and rational approach to planning, which, due to the nature of the public investment, was necessary to justify those elements of the project that exceed the usual practice in terms of quality and/or complexity, we have aspired to express the emotional, symbolic and, at times, even intimate side of the image and the experience of the place.

In order to achieve the harmony of the two spatial entities, the buildign and the garden, the design was developed in an ongoing dialogue with the architects of studio abiro during the competition, the design and the execution. The deliberately created ambiguous relationships between rigor and spontaneity, between the reflective and the porous, between the natural and the anthropogenic, between the precise and the indeterminate, between the suburban and the transcendental, stem from our deep understanding of the power and ability of architecture to foster environmental, spatial and interpersonal relationships.

We would like to thank Prof. Dr. Mihael Jožef Toman from the Biotechnical Faculty and a group of hydraulic engineers led by Prof. Dr. Simon Rusjan from the Faculty of Civil Engineering and Geodesy, both University of Ljubljana, for their help in finding innovative solutions. Due to the many unknowns, the decision was made to take a design-build approach to the planning of the technical support for the operation of the lake, and the advice and expertise of engineers from AXIS (Ivan Rus, Gregor Bajželj) and Proctor (Stane Hribar, Tomaž Hribar) as well as the experience and responsivenes of the contractors were indispensable in the implementation.