Ansitz Kofler

The Building

Building post-intervention

The main building of "Ansitz Kofler" was built in 1749 and had in 1769 Wolfgang Amadeus Mozart as a guest. The Orangerie was added a bit later: as 30m long and 5 m wide structure with spacious and bright rooms, used for breeding tropical fruits - for which the climate in Bozen, even if south of the Alps, would otherwise have been too harsh. In 1925 the Orangery was converted to a dwelling: the windows were scaled down, and internal walls were added, forming a suite of rooms aligned with each other (so called enfilade). As typical for buildings of this age in Bozen, the bearing structure is a stone masonry, with stones of different size, taken from the rivers in the area.

More Details

The Solution

Solution post-intervention

Solution post-intervention: WallInt_InstLayer.jpg

Solution post-intervention: WallInt_PlasterBoard.jpg

Solution post-intervention: WallInt_VapourBarrier.jpeg

Solution post-intervention: WallInt_WoodFibre.jpeg

What is the Solution?

All walls except the western facade were internally insulated. XPS was used in the lower part and placed all around the perimeter in direct contact with the floor insulation. From about half a meter upwards 14 cm thick mineral wool panels (FLUMROC Compact) form the main insulation layer. The following OSB panel serves as support for the vapour barrier (sd>100 m), special attention was paid to seal all joints with tape. At the junction with the ceiling, the vapour barrier of the wall and the vapour retarder (sd=2.0) of the ceiling were overlapped and taped. All wet piping, electrical wiring and ductwork is placed in the 4 cm thick installation layer - resulting in a total of 14+4=18 cm of insulation and no installation breaking through the vapour barrier. The internal surface was finished with 2.5 cm plasterboard. In the bedroom (west façade), instead of mineral wool insulation, wood fibre boards were used.

Why Does it work?

The external proportions of the building had to be kept the same, thus the choice of internal insulation. The thick internal insulation layer brings to consistent energy savings. The system uses mineral wool with a vapour barrier. The vapour barrier reduces the vapour diffusion and the airtight layer make sure that no convective moisture transport can happen. Special attention has been given to preventing thermal bridges. Where partition walls abut outside walls, wherever possible, the internal wall was cut and insulation placed vertically against the wall. Where new partition walls were built up, interspaces to the external wall were left in order to place insulation, OSB-boarding and vapour barrier behind. However, in some situations the wall was a bearing one and thus could not be cut. Therefore, insulation on the border had to be applied.

PROS

Use of materials that are well established in the market.
The design foresees a service layer that prevents accidental damages and punctures of the vapour control layer.

CONS

The need of reliability on execution of the vapour control layer.
The thermal bridges are difficult to prevent and require a special attention in the design.
Use of non-natural/original materials

Insulation material

Mineral wool panels (FLUMROC compact)

Insulation thickness

180

Thermal conductivity

0.033

Health issue

Energy performance certificate: KimaHaus/CasaClima A+. CasaClima A+ certification includes criteria concerning employed materials, which have to be sustainable for environment and health.

Technical drawings

Additional documentation

Ansitz kofler - mineral wool.pdf

Installation Method

The insulation panels were glued directly on the original interior plaster.

Moisture Management and Technical Compatibility

Since at Ansitz Kofler owner and architect aimed at an insulation thickness which was considerably higher than the ~8cm capillary active insulation - at that time in practice usually assumed as safe - they opted for a solution with vapour barrier (sd>100). Accordingly high effort was put in avoiding any potential failure: any penetration of the vapour barrier was avoided (4cm installation layer, all electric and hydraulic ducts and cables were installed on the inner side of the vapor barrier in order to prevent punctures), sealing tapes were applied with care.

Airtightness

A blower door test after preliminary installation was done to attest airtightness in a phase were they still could have intervened.