Freihof Sulz

The Building

Building pre-intervention

Building post-intervention

Renovation of ecological Freihof Sulz: Holistic redevelopment of the cultural heritage "Freihof Sulz", which is worthy of preservation, into a lively meeting place. The older part of the country inn, preserved in rare originality, dates from 1796, with vaulted cellars of various sizes and room heights in the basement. On the ground floor there are the guest rooms of different character, a bakery, the kitchen and storerooms, still preserved in their original state. The upper floors accommodated the guest rooms as well as the event hall. This solid part of the building was built of quarry stones and was extended in 1899 to include a further hall and a storage room. According to the time, the construction method with fired bricks was simpler and cheaper. In 1914 the oven, which is still in good working order today, was installed. The increasing need for space resulted in a further reconstruction in 1927. From the 1950s onwards, the house lost its importance as a centre of local supply and one room after the other fell into a deep sleep.

More Details

The Solution

Solution pre-intervention

Solution post-intervention

What is the Solution?

On the ground floor, where possible, the well preserved cambered windows have been retained. The decision was made to retain the box-type windows due to the protection of historical monuments. The glass was coated with a low-E coating. Low-E glass is the abbreviation for low-emissivity glass (= low heat radiation) and refers to an insulating glass to which a wafer-thin metal layer of about 100 nm is applied. This reduces the emissivity of the glazing and serves as a thermal and/or solar control layer. The structure of the coating as well as its technical and optical properties can vary depending on the type of coating.

Why Does it work?

The application of a foil is a compromise and a solution to conserve and maintain valuable historic glazing while still respecting the building regulations.

PROS

Low impact on historic glazing.
Can be the only solution if building regulations require safety glazing.

CONS

Very low effect on energy efficiency.
Windows remain the coldest part of the façade (even more if the walls are insulated) and condensation could occur on the glass.
Depending on the film, the appearance of the window may be altered (colouring, transparency etc.)
The solution might not be suitable for very thin historical glass with many irregularities.

Window Type before retrofit

Box Type Window

Window glass type

Two single glazing as box-type windows with low-e

Window frame material

Wood

Window position

In the middle

Shading

Type: shutters partly closed at the bottom and equipped with fixed slats or adjustable slats for display Position: exterior Material: wood

Health issue

information not available

Additional documentation

Freihof Sulz - addition of foils or coatings to the glass.pdf

Installation Method

The windows were repaired and replaced using old wood material parts that were rotten, fell off or were infested with pests. New wood was used for large damaged areas. Holes were filled in, irregularities were sandpapered or puttied. Old varnish was sanded off, the oil rubbed off with spirit. The windows were glazed out, the old putty was removed. With a special tool, only loose spots were sanded and then patched because otherwise, the paint would not have adhered. Afterwards, they puttied with linseed oil putty. The renewed glass was coated with a low-E coating. Partly the glass was re-glazed. In the listed rooms on the ground floor, the old cambered glass was used. The fittings were rubbed off and after a function check they were lubricated and set up. Windows were partly machined at the bottom with a planning machine to ensure tightness. Glazing was done without silicone, instead, oil glue putty was applied with a spatula. Weather shanks were removed and new ones made of larch wood were fitted. For sealing, sheep's wool was stuffed from the outside and grouted with acrylic. Inside, the carpenter sanded, puttied and patched the frames and checked and reattached the fittings. In some cases, holes had to be drilled on the sides and the frames screwed to the masonry.

Moisture Management and Technical Compatibility

information not available

Airtightness

Windproof connections of the masonry to the window frames were implemented. The joint between sandstone and window frame was sealed with acrylic, sheep's wool and lime plaster. The historic box-type window was repaired by carpentry work, thus increasing the airtightness.

Before retrofit

After retrofit

Before retrofit

Uw-Value

information not available

After retrofit

Uw-Value

information not available

Before retrofit

Ug-Value

2.2

After retrofit

Ug-Value

1.8

Before retrofit

g-Solar factor

information not available

After retrofit

g-Solar factor

0.7

Assessment

Window type

Double window

Frame material

Timber

Aesthetic impact

Low Impact (no impact or minor impact from both inside and outside)

Frame improvement

Glazing improvement

Yes

Additional glazing

Airtightness improvement

Yes

Window U-value

1 < U <= 2

Shading

Yes - reuse existing appurtenances

Circular approach

Yes

Circular approach (Additional info)

The box-type windows were repaired and replaced using old wood material parts that were rotten, fell off or were infested with pests. New wood was used for large damaged areas. Holes were filled in, irregularities were sandpapered or puttied. Old varnish was sanded off, the oil rubbed off with spirit.

Investment cost

Medium High