City Hotel "Kleiner Löwe", Bregenz, Austria

A building on an eight-meter narrow but 23-meter-deep (26¼ by 75½ ft) plot stood empty for several years after a fire in the attic. Only the neo-baroque façade facing the square could be salvaged- it dates to the early 20th century when the building was used as a bank.
The top two floors of the new structure, which rise behind the old façade, now house the owners' apartment, topped with a white metal roof that is shaped like a barrel vault. The two floors below are the hotel rooms, each with four rooms measuring between 22 to 29 m² (237 to 312 ft²). The generous window front allows views of Lake Constance and the mountains over the rooftops. The preserved façade has horizontal slits at the upper section, providing views from the loggia behind onto the marketplace.
On the ground floor, there is a lounge with bar overlooking the marketplace, and a breakfast and restaurant area facing the garden. There is no kitchen; a restaurant at the other end of the garden handles the catering. A flexible partition allows for the separation of the ground floor into two rooms.
A heat pump with a heating capacity of 40 kW is located in the basement and combined with five double U geothermal probes under the building, covers the heating and cooling needs for the building. The cooling of the building as well as the air handling system is achieved through free cooling directly via the ground probes. In summer, the system maintains the indoor temperature about 5°K below the outdoor temperature. The room conditioning in winter keeps the indoor temperature statically at 22°C / 71,6 °F (at an outdoor temperature of -11°C / 12,2 °F).
To ensure that the „kleine Löwe“ achieves the hygienically required air exchange rates in the areas of gastronomy/hotel and residential space, a ventilation system with heat recovery has been installed. The central ventilation unit is also located in the technical room in the basement. Outside air is drawn from the east side through a supply tower in the courtyard; exhaust air is expelled centrally above the roof.
Transsolar has developed a climate concept in the preliminary design through variation studies of the building envelope and building services technology. Through thermal simulations, thermal comfort and heating and cooling loads were determined. Based on the simulation results, a building services concept was developed in the preliminary design, which served as a template for the HVAC planning. For the conditioning of the rooms, underfloor heating and cooling were proposed. Daylight simulations helped to evaluate and optimize the daylight supply. The proposed photovoltaic system was not implemented due to budgetary constraints.