“KOKON” Rietstrasse, Erlenbach

Competition for residential building, 1st  Prize

Energy standard


Contract type / Realisation

Competition 2017 / 2018-19

Building typology




Project description

The different project guidelines together with the construction field defined by the Building Act and the Servituten initially required a weighting and ranking.

Primarily, the goal of the lake view was pursued, which has a direct influence on the quality of housing. This increases vertically in the building.

On the first floor there is the possibility to look across the neighboring building to the south, which is why duplex apartments were given preference.

Secondarily, the escape route from the attic was design-critical. This is to be guided by a stairwell that complies with the valid VKF regulations. The smallest possible platforms along this vertical escape route are at least two 1.2m x 1.2m areas. The building dimension allows only an internally located staircase, in which the stairs of the maisonette apartments can be integrated meaningfully. In-house stairs simply create the separation between the public spaces of an apartment (living and dining room) and the private rooms (family bathroom, children’s bedroom and bedroom) and are also among the rentable space. The location of the development core is in the middle of the building, enabling two equally attractive apartments.

Tertiary, the construction costs were taken into account. Efficient double parkings along the eastern facade and the deepening of the basement level to the property boundary in the north to make room for the necessary basement storage rooms and the technical room made it possible to dispense with an additional basement floor and thereby save costs.

Volumetry and building envelope

Volumetrically, the design pursues a clear and compact line. Overhanging parts of the building and offsets of the storeys have been dispensed with in favor of energy and construction cost efficiency. The generous terraces are integrated in the volume. A physicality of the entire design is in the foreground. Concrete ceilings are visible as headbands, thermally separated, on the facade. A horizontal sliding wooden battens between these headbands gives the building a different expression depending on the current use. Dimension of the slats and their distance from each other, are chosen so that an optimal balance between exposure and shading is guaranteed. A darkening can be done inside by the tenants. The window widths are wooden sliding elements on two rails in front of the window wall level of the apartments. Terraces are secured with glass balustrades to ensure maximum lake view.

Building envelope

Wooden stand 30 cm with 18 cm mineral insulation.

Guideline Minergie: mineral plaster. Flat roof with PV units, extensively landscaped. Terraces and roof terraces in wood.

Doors / windows

House entrance doors in wood / metal with glass filling and multi-point locking. Interior doors in wood, coated. Windows in wood-metal with triple glazing. Apartment doors to the stairwell eg Franke sliding door EI 30, 1-winged, full door leaf

Sun protection

External two-layer wooden sliding elements with vertical lathing. Curtain rails fitted, recessed inside.

Patio: Parasol Tenant side. Terrace attic with cantilever awning.


Electrical installations with sufficient switches, ceiling connections for luminaires and sockets. Multimedia installation for data, TV, radio and telephony.

Heating / hot water

Floor heating powered by water heat pump with geothermal probes and individual heat measurement. Hot water with central heat pump boiler.


Wet exhaust


Modern kitchen equipment with energy-saving appliances.


All plumbing appliances white, chrome fittings, mirror cabinet with integrated lighting, bathtub, low shower tray with glass partition.


In the residential floors white plaster, painted. In the stairwell in exposed concrete raw. In the basement concrete raw.


In the residential floors abrasion, painted.

Walls of the staircase inside and outside the apartments exposed concrete raw In the basement concrete raw.

In the wet rooms, ceramic plates.


Living / sleeping areas incl. Kitchen and in-house stairs with parquet in oak, matt sealed. Wet rooms with ceramic plates in the color lime.


Wardrobe, cleaning cabinet and other built-in wardrobes.


GSA with video


House access with concrete paving stones, access roads between the houses with solidified pebbled areas, seating of ground floor apartments with garden plates, landscaping with perimeter band, flower lawns, hedges and various trees, lighting.

Underground car park

Automatic garage door with remote controlled radio remote control.