Towering above Lake Zurich, the historic The Dolder Grand has been reinvented to form a luxury-class city resort. The scheme integrates a substantial new extension, more than doubling the hotel accommodation and reconnecting it to the surrounding forest and resort. Remarkably, although it provides double the floor space, the new building consumes half the energy of the old - or 75 per cent less energy per square metre. The Dolderbahn cog railway station has been reinstated, enabling the local community to enjoy the site while experiencing something of the building itself.
The scheme restores the logic of the original hotel, designed in 1899 by Jacques Gros, and the external fabric has been restored and rendered in the original red and ochre palette.
Internally, the planning has been transformed. The most significant moves have been to create a linked suite of grand public rooms, including a new ballroom, and to reinstate the grand southern entrance so that arriving guests now enjoy breathtaking views across Zurich and the Alps. Two new wings frame the historic Dolder, complementing the addition of a spa and a new ballroom.
The new wings are fully glazed; and stencil-cut aluminium screens line the facades to form balustrades and provide shading, their tree pattern resonating with the surrounding forest. While the geometry of the new elements is fluid and organic, the colour palette echoes that of the existing building to harmonise the overall composition.
A highlight of the hotel is the new 4,000-square-metre spa. The winding stone walls that begin in the landscape continue inside to frame a canyon-like space for the pool. In some areas the walls are perforated to allow sunlight to filter in, and provide a dynamic play of light and shadow while maintaining absolute privacy. Geothermal heat pumps beneath the spa contribute to the efficient energy strategy. This is further enhanced by a high-performance envelope comprising insulated triple-glazing and natural shading.
Large internal courtyards are used to help increase daylight penetration into the building.
The design sought to substantially improve the thermal efficiency of the building. Insulation was installed to the inside walls, and triple glazing replaced the traditional single glazed windows. Natural ventilation was encouraged throughout the building.
An intelligent BMS system controls the building from lighting controls, to sensors on the windows, to switch off mechanical ventilation.
A ground source heat pump (GSHP) system containing 70 boreholes each 150m long provides the majority of the cooling and heating requirements for the building.
The hotel is located at the final stop of a tram line that goes to Zurich. In addition there is a regular shuttle service to the city centre.
The existing site encompassed a number of listed and non-listed buildings, all of the non-listed buildings were removed. The listed building was carefully preserved and renovated in keeping with original design. Where possible local and responsibly sourced materials were used such as the stone and timber.
To help conserve energy the project had both rainwater harvesting tanks and a greywater treatment system. Both of these were used to provide non-potable water requirements. Where possible low flow fixtures and fittings were used.
The hotel is within a forest that is protected from development. This meant that the majority of expansion occurred below ground, helping to preserve the existing flora and fauna. In addition green roofs were added to all new buildings where possible.
The existing building was preserved and extended down, rather than out, to reduce visual impact to existing building.
Access to daylight and natural ventilation were essential to providing a healthy environment within each room. Detailed BMS controls carefully monitor the environment within each space, to ensure optimum comfort for the hotel guests.
In order to respond to a changing climate, the building can be both naturally and mechanically ventilated through the use of low-energy systems.
There is a 50% reduction in energy consumption in the new facility vs. old despite it being twice the size.
Construction start: 2004
Area: 42 000 m²
Height: 25 m
Client: Dolder Hotel AG, Zurich
Collaborating Architect: Itten + Brechbuehl AG Architekten
Structural Engineer: Werner Sobek Ingenieure GmbH & Co. KG, Ernst Basler + Partner AG, Dobler, Schällibaum und Partner AG
Quantity Surveyor: Hoehler und Partner
M+E Engineer: Schmidt Reuter & Partner, Ernst Basler + Partner AG
Additional Consultants: Speirs and Major Associates, PromaFox AG, Emmer Pfenninger Partner AG,
Aluminium façade screens stencilled with 14 different patterns to resonate with surrounding forest.
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