Energy-efficient construction at a height of over 2,000 m

At an altitude of 2,315 m, accessible by gondola only, Berghotel Rudolfshütte on the bank of Weißsee lake offers guests an extraordinary holiday experience. The traditional hotel located within Hohe Tauern National Park, Austria, is a magnet for mountaineers, skiers and nature lovers. Its owners have responded to increasing demand by constructing a new extension that is integrated into the landscape with architectural flair. There, heroal window and door systems provide a generous view of the Alpine peaks and, with their optimum tightness, ensure energy efficiency and comfort, even with strong gusts of wind.

As one of the first alpine huts in Austria’s Hohe Tauern mountain range, today’s Berghotel Rudolfshütte in the State of Salzburg can look back on an eventful history. Beginning in 1874, it has seen various expansions as well as the construction of a building to serve as a hotel in 1959. Since then, numerous illustrious personalities have stayed here, from the Dutch Princess Irene to Austrian skiing legend Toni Sailer. The hotel owes its current size and popularity to Dr Wilfried Holleis, who took over the hotel together with his family in 2004, readopting its original name after Rudolf, Crown Prince of Austria, son of then Emperor Franz Joseph I. In the years that followed, the owner family made multiple investments to enhance the attractiveness of this extraordinary hotel, which is one of the ten highest hotels in Austria and boasts its own ski area.

One of these investments is the new extension, which was built with a view to nature conservation and serves to increase the number of rooms while creating additional lounge areas. Aesthetically pleasing, its architecture harmonises with the design concept of the main building, together with which it blends gracefully into the surrounding mountain landscape. The exposed location of the property complicated the planning and implementation of the construction project, with the high wind velocities placing the highest demands on tightness and heat insulation. Due to the extreme altitude of the building, the hotel was to be heated exclusively with electricity – a factor that lent additional weight to the issue of energy efficiency.

In order to ensure that no cold mountain air could enter the interior through the building shell, great care was invested in the planning of the windows and doors. The owner family entrusted the job to Alois Mayr Bauwaren GmbH, a nationally active building materials retailer that has been supplying the family with heroal window and door systems to their complete satisfaction for many years. heroal specialist partner alu-one Metallbaupartner GmbH, which has extensive experience in the construction of aluminium windows, doors and glass façades, was commissioned to manufacture the elements. The two companies worked together closely at an early stage to coordinate the technical details for selecting the heroal window and door systems that best meet the high requirements for energy efficiency and tightness, even at wind speeds of over 180 km/h.

heroal Project Services gave them added planning security. In consideration of property-specific requirements, the focus of heroal Project Services is on finding a technically flawless solution that offers the greatest sustainability and economic feasibility for a construction project. With the help of a structural analysis, they ensured the required tightness of the window and door systems at Berghotel Rudolfshütte. For engineer Ferdinand Reisenberger, authorised representative of alu-one Metallbaupartner GmbH, these efforts proved effective: “We were completely satisfied with the technical support provided by heroal Project Services. That also applies to the later project management, which went extremely well.”

For the implementation of the project, Alois Mayr Bauwaren GmbH opted for the heroal W 72 window system and the heroal D 72 door system. A number of the 80 elements have multiple glass panels, combining maximum wind resistance with transparency for bright interiors. In terms of colour, the design picks up on the aesthetic concept of the main building, which cleverly combines colour accents with natural tones harmoniously adapted to the mountain landscape. The choice for the extruded aluminium systems was RAL 9016 M Traffic White on the interior of the building and RAL 6005 M Moss Green on the exterior. With its in-house powder coating plant, heroal can ensure high surface quality. Furthermore, thanks to its highly weather-resistant hwr powder coating, heroal guarantees excellent long-term colour stability, gloss retention and resistance to weathering, as well as a perfect colour match between the different heroal systems.

With profiles composed of aluminium half shells, polyamide insulating bars and a completely foam-filled insulation zone, the windows of the heroal W 72 system offer Berghotel Rudolfshütte top quality along with maximum energy and cost efficiency. Thanks to their unique bar geometry, they achieve U_w values that meet current thermal insulation requirements for windows at a design depth of 72 mm. Implemented in the upper floor of the three-storey extension, the chamfered profiles imitate the surrounding Alpine peaks and blend stylishly into the mountain landscape. Their high level of heat insulation is further enhanced by the heroal WF 100 fitting, which meets the highest standards of tightness, ease of use and design. Thanks to its pre-assembled, clamp-on building components, the surface-mounted fitting is quick and easy to install and is impressively smooth-running thanks to its convenient mushroom head locks mounted on roller bearings.

The heroal D 72 commercial door system provides an aesthetic and functional solution for Berghotel Rudolfshütte. The 72 mm profile installation depth of the frame profiles is identical to that of the heroal W 72 window system, thereby ensuring optimum combination options with a consistently appealing look. The tested and certified system has been approved based on the applicable requirements for public buildings for use in escape and rescue routes in accordance with DIN EN 179/1125. Thanks to its sealing technology with a modular construction and the innovative insulating bar geometry with reduced heat conduction from the interior to the exterior, the heroal D 72 door system also achieves optimum insulation values, contributing to the energy efficiency and overall value of the mountain resort. According to Josef Steiner, project manager at Alois Mayr Bauwaren GmbH, cooperation with heroal throughout the project proved to be very successful: “The heroal window and door systems helped us meet the client’s high demands. The involvement of heroal Project Services in the planning phase also turned out to be a great advantage and contributed to the smooth implementation of the project.”