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House Moroder - Bolzano (Italy)

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The historic residential building is located in the city center of Bolzano. It was built in 1926, near the old town, and it has hardly been changed on the outside, thanks to well thought-out renovation measures from the inside which ensure a new level of comfort and a minimization of the energy demand of the building.


The "Haus Moroder" shows the typical style of the urban villas of Bolzano from the 1920s and 1930s: the solid brick building situated in the middle of a large garden, the façade designed with textured plaster with a few decorative elements, and the filigree box-type windows. The internal staircase gives access to the three flats, one for each floor, as well as to the cellar and the previously unused attic.


The original aspect of the façade had to be preserved. In order to maintain the original plaster as well as the historic appearance of the windows and the floor frames, the building was insulated exclusively from the inside. The design of the new windows was modelled on the original one, so that no clear difference is visible from the outside. The interior staircase and the entrance door have not been changed.




The aim of the retrofit was to improve the indoor comfort while preserving the architectural character of the building. The main purpose of the process was to maximize the possibility of preserving the building and reaching high energy efficiency levels. To achieve this, the energy retrofit measures were taken exclusively from the inside the building. The concept of the retrofit was to reduce the thermal losses via walls, windows, and thermal bridges, and to use high-performance systems to guarantee high level of indoor comfort with minimum energy consumption. A ventilation system with heat recovery is installed to guarantee fresh air in the building, while space heating and cooling are provided by a heat pump system.




External walls: In order to leave the facade untouched, a 10-cm insulation was placed on the inside of all the external walls. A perlite insulation - TecTem from Knauf - was chosen because of its natural composition, which makes it suitable for indoor use. To install the insulation, the internal plaster was removed from the inner surface of the walls. Moreover, a few centimeters of flooring were removed along the wall joints, in order to place a layer of insulation underneath, to avoid thermal bridges. In this way, there won´t be cold spots that cause heat losses.


  • U-value (pre-intervention) [W/m2K]: 2,5 W/m²K
  • U-value (post-intervention) [W/m2K]: 0,38 W/m²K

Windows: The new wooden window with triple glazing and energetically optimised frame has two sashes again, the division into 3 fields each takes up the look of the original two sashes under the transom and the bottom-hung sash above. It is positioned in the place of the inner plane of the old box window in the existing window frame, so that (I) the window area remains the same size even with the new frame and (II) the frame perceived on the outside is very filigree, (III) installation is very simple and (IV) the installation thermal bridge is very easily avoided - by insulating the indentation in the "old" box cavity and on the inside the adjoining reveal.


  • Existing window U-value Glass [W/m2K]: 1,4
  • New window U-value Glass[W/m2K]: 0,7
  • Existing window U-value Frame [W/m2K]: 2,7
  • New window U-value Frame [W/m2K]: 1,1



Heating: Since there was no heating system in the entire house before the renovation, the single gas-heater was replaced by a central heat pump heating system. To make the installation as easy as possible, the heating system was installed in the ceiling. With a room height of 2.85m, it was possible to install the clay panels with embedded heating pipes in a suspended ceiling. In addition to the insulation made of natural material, a user-friendly design was also chosen for the heating system by using clay. In addition, clay has humidity-regulating properties, which allow the material to absorb the humidity and to gradually release it.


Ventilation: In order to guarantee a constant good air quality and to avoid the heat waste related to ventilation, each flat was equipped with a dedicated ventilation system with heat recovery. The ventilation unit themselves were places in the bathroom and the air ducts were led through the suspended ceiling.


Read more about the case here.

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