Kelchalm - Bochumer alpine hut

Kelchalmweg 1

6371

Aurach bei Kitzbühel, Austria

architetto

DI Christina Krimbacher
Mentlgasse 10/29 | A-6020 Innsbruck
info@christina-krimbacher.at
Tel. u. Fax 05 12 / 57 32 55

Owner

German Alpine Club, Bochum Section
alpenverein.de

User

Hut-landlords Gerhard Pirker, Ilona Hultsch hired by German Alpine Club, Bochum Section
Kelchalmweg 1, A - 6371 Aurach
info@kelchalm.at
+43 5356 202 99

Contact Details

Pavel Sevela
University of Innsbruck - Unit for Energy Efficient Buildings
pavel.sevela@uibk.ac.at

Other Information

Visits
https://bochumer-huette.jimdo.com/ The hut is a popular destination for hikers and also has overnight accommodation.

Related publications
Model renovation of Bochumer Hütte
Kelchalm - Bochumer alpine hut, ©DI Christina Krimbacher
Exemplary sustainable renovation of a historic mountain hut at 1,432 meters above sea level in Aurach near Kitzbühel. The renovation resulted in a significant increase in the levels of comfort in a mountain hut exposed to severe weather conditions. The building is used all year round after renovation.
Energy performance
38 kWh/m2.y

Climate Zone Dfb

Altitude 1432 s.l.m.

HDD 2375

CDD 0

Protection level Not listed

Conservation Area:
No

Level of Protection:

Building age 1800-1849

Year of last renovation:
2013

Year of previous renovation:
1831

Building use Hotel/Restaurant

Building occupancy:
Discontinuous occupancy (i.e. holiday home)

Number of occupants/users:
70

Building area Net floor area [m²]: 650,0

Building typology:
free-standing building

Number of floors:
4

Basement yes/no:
Si

Number of heated floors:
4

Gross floor area [m²]:
812,0

Thermal envelope area [m²]:
1087,0

Volume [m³]:
2380,0

NFA calculation method:
NGF (de)

Construction type
The 3 upper floors are made out of a timber frame constructio, the groundfloor and basement walls are heavy stones walls.

External finish:
Rendered

Internal finish:
Exposed woodwork

Roof type:
Pitched roof

+ MORE - LESS
Kelchalm - Bochumer alpine hut, ©DI Christina Krimbacher
Kelchalm - Bochumer alpine hut, ©DI Christina Krimbacher
Kelchalm - Bochumer alpine hut OLD, ©DI Christina Krimbacher
Kelchalm - Bochumer alpine hut OLD, ©DI Christina Krimbacher
South-historic, ©DAV, DI Christina Krimbacher
South-historic, ©DAV, DI Christina Krimbacher
West, ©DI Christina Krimbacher
West, ©DI Christina Krimbacher
West-Historical, ©DAV, ©DI Christina Krimbacher
West-Historical, ©DAV, ©DI Christina Krimbacher
Window, ©DI Christina Krimbacher
Window, ©DI Christina Krimbacher
Perspective, ©DI Christina Krimbacher
Perspective, ©DI Christina Krimbacher
Historical picture - west facade, ©DAV ©DI Christina Krimbacher
Historical picture - west facade, ©DAV ©DI Christina Krimbacher
South facade before renovation ©DI Christina Krimbacher
South facade before renovation ©DI Christina Krimbacher
South facade - historical picture, ©DAV ©DI Christina Krimbacher
South facade - historical picture, ©DAV ©DI Christina Krimbacher
https://mapio.net, ©DI Christina Krimbacher
https://mapio.net, ©DI Christina Krimbacher
©DI Christina Krimbacher © DAV Sektion Bochum
©DI Christina Krimbacher © DAV Sektion Bochum
Damage to facade, © DI Christina Krimbacher
Damage to facade, © DI Christina Krimbacher

RENOVATION PROCESS

Architecture

BUILDING DESCRIPTION

The Bochumer Hütte (alias Kelchalm) is one of the most popular local recreation destinations for the population of the Kitzbühel district, for numerous winter and summer sports enthusiasts from southern Germany. The Bochumer Hütte offers attractive leisure and recreational opportunities all year round: hiking and mountain biking in summer, tobogganing, ski touring and snowshoe tours in winter. With 60 beds and 60 seats in the guest room, larger groups can also be looked after for seminars, parties, etc. The hut is also one of the rare historical buildings from the Kitzbühel copper mining era. During this time the building served as accommodation for the miners. The first documented mention of copper mining in this area dates back to 3,000 BC. The largest part of the smelter, which served the miners as accommodation in what appears to be the richest tunnel in the district, is about 200 years old. A smaller part is much older, probably up to 500 years old. In 1842 the present condition was restored.
Urban context
The building is located in the Kitzbühler Alps, in the middle of nature, surrounded by forests.

HERITAGE SIGNIFICANCE

ELEMENTS WORTHY OF PRESERVATION
The ground floor consists of meter-thick natural stone masonry, the three upper floors are built in the local wood block construction. Unusual for the Tyrolean lowlands is the roof shape, which forms a hipped roof, which is rather untypical in the whole of Tyrol. Very beautiful vaults adorn the small dining room and the bathrooms on the ground floor.
Heritage Value Assesment
The hut is one of the rare historical buildings from the time of Kitzbühel copper mining. During this time the building served as accommodation for the miners. Copper mining in this area was first mentioned in documents as early as 3,000 BC. The largest part of the hut, which served as accommodation for the miners in what is apparently the richest gallery in the district, is about 200 years old. A smaller part is much older, probably up to 500 years old. The current state was established in 1842.

State of repair

Conditions of the envelope
The last renovation cycle of the building took place in the 1960s. At that time, a small extension with toilets and washrooms was added to the east side and the facade was renewed. Unfortunately, at that time, there were incorrect structures in terms of building physics (from today's point of view), which already caused damage to the building. These facade parts had to be removed and rebuilt urgently.

Aim of retrofit

Renovation
A major theme of the refurbishment was energy saving and the associated increase of comfort. In recent years, for example, it has not been possible to sleep with children in the beds under the uninsulated roof in winter, the temperatures dropped so much that the water in the rooms could freeze. The planned renovation measures were: Mains electricity supply, construction of a small biological sewage treatment plant, renovation of the kitchen, improvement of the fire protection system and a comprehensive thermal renovation of the façade, the roof and the windows. In order to realize all this, according to the guidelines of the DAV, a lot of personal contribution of DAV has to be made: here, the ladies of the Bochum section, especially Mrs. Gisela Schöngraf, have to be mentioned, who made a lot possible with their commitment!
Was there any change of use?
The hut is used all year round after renovation.
Lessons learned
As architect DI Christina Krimbacher said, ecological renovation was not more complicated and extensive than renovation with "conventional" materials such as EPS insulation. Building so high up on the mountain is very specific because of the short summer, unexpected weather and limited and expensive transport possibilities.
Stakeholders Involvement
Private Sector
Capatect Baustoffindustrie GmbH
Bahnhofstraße 32; 4320 Perg
info@capatect.at
Tel.+43/7262/560-0
Architect
DI Christina Krimbacher
Mentlgasse 10/29 | A-6020 Innsbruck
info@christina-krimbacher.at
Tel.Tel. u. Fax 05 12 / 57 32 55
Other
Isocell GmbH
Gewerbestraße 9, 5202 Neumarkt am Wallersee
office@isocell.at
Tel.+43 (0)6216 / 41 082 5
Other
Ingenieurbüro Tassenbacher GmbH, umwelt : energie : mikrobiologie
Mühltal 13, 6363 Westendorf
office@tassenbacher.at
Tel.+43 664 34 201 38
Tools used
Was the renovation process done following a specific methodology? No
Energy calculation Energieausweis

RETROFIT SOLUTIONS

External Walls

External wall ground floor

External wall first floor

External wall ground floor

The natural stone masonry was insulated with 18 cm thick hemp insulation panels. The only "plastic insulation" Swisspor PSN (awarded the Austrian eco-label) was used in the ground area, as it was the only alternative. Perimeter below ground insulated with foam glass gravel.

U-value (pre-intervention) [W/m2K]: 1,56 W/m²K U-value (post-intervention) [W/m2K]: 0,2 W/m²K
More Details
Original wall build-up
Render - Lime plaster:
15 mm
Stone - Natural stone masonry:
1000 mm
Render - Cement plaster:
30 mm
Retrofitted wall build-up
Render - Texture plaster:
10mm
Insulation - Capatect hemp insulation board:
180 mm
Render - Lime plaster:
15 mm
Stone - Natural stone masonry:
1000 mm
Render - Cement plaster:
30 mm
External wall first floor

On the facade 16 mm wood fibre board filled and insulated with 18 cm cellulose was used. Then came battens and local untreated larch. From the inside, dormer cladding, window shades and some bathrooms were left in natural spruce.

The wall was renovated from the outside, where the layers were removed up to the load-bearing wooden log construction. The combination of a closed air cavity and mineral wool insulation without a vapour barrier trapped the heat and moisture coming from inside the hut in the insulation, causing condensation in the mineral wool and local damage to the wood block structure, which had to be repaired. The new difuse oppened structure consists of Eco-natur vapour barrier on the wooden structure, which prevents heat and moisture from penetrating the insulation, so that no condensation is created in the insulation and the wooden structure is protected.

U-value (pre-intervention) [W/m2K]: 0,34 W/m²K U-value (post-intervention) [W/m2K]: 0,19 W/m²K
More Details
Original wall build-up
Cladding - Wood panelling:
24 mm
Other - Bituminous cardboard:
2 mm
Air gap - Closed air gap:
70 mm
Insulation - Mineral wool:
40 mm
Wood - Timber log construction:
140 mm
Wood panelling - Wooden panneling:
25 mm
Retrofitted wall build-up
Cladding - Wooden cladding:
25mm
Air gap - Ventilated air gap:
50 mm
Other - Windbrake AGEPAN DWD:
16 mm
Insulation - Cellulose ISOCELL B-s2-d0 (blown in) + Lathing with wood I-beam:
180 mm
Other - Vapour barrier and airtight layer ÖKO NATUR DSP ISOCELL (Sd:6,45m):
1 mm
Wood - Timber log construction:
140 mm
Wood panelling - Wooden panneling:
24 mm


Windows

Window external wall, first floor

Window external wall, first floor

A paper vapour barrier is applied over the wooden block construction (upper floors), window blind sticks are set into the insulation level and glued to the vapour barrier. Larch windows oiled with glazing 0.60 W/m²K. Glued vapour-tight on the inside and diffusion-open on the outside. The window joints are manually stuffed with cellulose fibre strips by the ladies of the Bochum section!

The design and materials of the windows imitate the original windows. The proportions of the building and the installation depth of the windows have been maintained even after the increase in the wall depth by inserting the new windows into the insulation layer, which also reduces the thermal bridges of the window installation.

Existing window U-value Glass [W/m2K]: 2,2 New window U-value Glass[W/m2K]: 0,6 Existing window U-value Frame [W/m2K]: 2,2 New window U-value Frame [W/m2K]: 1,02
More Details
Existing window type Box-type window
Existing glazing type Single
Existing shading type NA
Approximate installation year 1900
New window type Coupled window
New glazing type Triple
New shading type NA
New window solar factor g [-] 0,4

Other interventions

ROOF

MEASURES TO INCREASE AIRTIGHTNESS

ROOF

The roof was opened, the dormers were demolished and replaced. The vapour barrier was newly applied to the roof boarding and later glued with a wall vapour barrier. The new dormers (wooden beam construction with cellulose ged.) were built. The roof was then provided with 24 cm thick insulation of single-layer wood fibre boards with a U-value of 0.15 W/m²K.

The new roof was built for financial reasons and also because of a practical use of the folding roof as an appearance from the 1960s.

U-value (pre-intervention) [W/m2K] 1,65 U-value (post-intervention) [W/m2K] 0,15
More Details
Original roof build-up
Metal sheets - Seam metal roof:
2 mm
Other - Wooden formwork:
25 mm
Other - Roof truss with rafters:
118 mm
Other - Wooden panneling:
25 mm
Retrofitted roof build-up
Metal sheets - Seam metal roof on wooden formwork (24mm):
25 mm
Other - Ventilation lathing on nail sealing tape:
120 mm
Other - Wood fibre insulation HOLZFLEX HDP Q11-PROTECT single layer + diffusion-open, waterproof subroof membrane Sarnafil® TU 222 :
240 mm
Other - vapour barrier: AMPATEX SB 130, sd-value 40m:
1 mm
Other - Wooden formwork:
30 mm
Other - Roof truss with rafters:
120 mm
Other - Wooden panneling:
25 mm
MEASURES TO INCREASE AIRTIGHTNESS

Blower Door Test with comprehensive leakage detection. Facade and roof tested from the outside with overpressure. Unfortunately no result, because of too high pressure losses via the foundations (not sanitable).

Airtightness (pre-intervention) [ach@50Pa] 8 Airtightness (post-intervention) [ach@50Pa] 3

HVAC

HEATING

VENTILATION

DOMESTIC HOT WATER

HEATING

Until 2014, the primary heating system of the hut was a biodiesel cogeneration plant that produced both heat and electricity. Since the hut now has its own electricity connection, it was possible to retrofit the heating system. Currently, the main heating system consists of a pellet boiler that heats the two thousand liter tanks connected in series. In addition, the heat generation is supported by a solar system installed on the south-east facade of the hut. The secondary heating system is the wood tiled stove in the stube.

The original heating system with a wood-tiled stove was retained, as it is a very traditional aspect of the mountain huts, but also provides tangible warmth, which is part of the well-being of the Tyrolean mountain hut experience and is expected by visitors.

More Details
New primary heating system New secondary heating system
New system type Stove NA
Fuel Biomass Hot water
Distribuition system Radiators
Nominal power 22 kW kW
VENTILATION

A group of two ventilation units (INVENTERIV25) mounted in the wall provides ventilation of the laundry rooms with heat recovery.

The openings for the supply air and exhaust air are hidden behind the solar thermal collectors on the façade so that they are not visible.

More Details
Original roof build-up New ventilation system
Type ventilation system Decentralized
Type flow regime Single room ventilation
Heat recovery Si
Humitidy recovery No
Nominal power 0,010 kW
Electric power 0,01 kW
Control system CO2 sensor CS1, humidity sensor Controller / CO2-Sensor CS1, Feuchtesensor Regler
DOMESTIC HOT WATER

The hot water is produced by flowing through a heat exchanger in a 1000-litre storage tank with heat supplied primarily by the solar thermal system and additionally by the pellet heating system.

This solution is a sustainable way to produce hot water. Having hot water for cooking and showering is a relatively new requirement of the visitors of the mountain hut, so there are not many historical aspects to follow.

More Details
New DHW system
Type with heating system
Hot_water_tank Si
With heat recovery No

RENEWABLE ENERGY SYSTEMS

SolarThermal

Biomass

SolarThermal

The solar thermal system consists of 7 flat collectors of 2.3m2 each, which are mounted in the south-east facade of the hut. The heat is stored in a 1000-litre tank, which is primarily used to heat water and also supports the heating system.

The solar thermal system is mounted on the south-east facade of the hut, which is basically hardly visible to tourists and visitors due to the orientation of the hut towards the hiking routes. Therefore the system is gentle on the historical appearance and does not look conspicuous.

More Details
SolarThermal System
Type Flat collector
Collector area 16,1 m²
Elevation angle 59,0
Azimuth 165,0
Cooling contribuition 0,0 kWh
Biomass

Until 2014, the primary heating system of the hut was a biodiesel cogeneration plant that produced both heat and electricity. Since the hut now has its own electricity connection, it was possible to retrofit the heating system. Currently, the main heating system consists of a pellet boiler that heats the two thousand liter tanks connected in series. In addition, the heat generation is supported by a solar system installed on the south-east facade of the hut. The secondary heating system is the wood tiled stove in the stube.

The original heating system with a wood-tiled stove was retained, as it is a very traditional aspect of the mountain huts, but also provides tangible warmth, which is part of the well-being of the Tyrolean mountain hut experience and is expected by visitors.

More Details
Biomass System
Type Pellet
Storage size 8 m3
Origin of biomass
Overall yearly production 66750,0 kWh

Energy Efficiency

Energy Performance
Energy performance certificate: The refurbishment has reduced the heating demand by 74% from 145 kWh/m²a prior refurbishment to 38 kWh/m²a after refurbishment.
Voluntary certificates: The building fulfilled all mandatory criteria and achieved more than 750 points, so that it was awarded the "climate-active silver" level. All klimaaktiv criteria catalogues are based on a 1,000-point system, which is used by a neutral party to assess and evaluate the quality of planning and execution, energy and supply, the quality of building materials and construction, as well as central aspects of comfort and indoor air quality.
Energy Use
Heating
Primary Energy 157156 kWh/y
Documents:
2015_06_12_EA SANIERUNG_nach OIB2011_MIT PELLETS.pdf
© DI Christina Krimbacher

Consumption_estimation_Before: 145 kWh/m2.y
Consumption_estimation_After: 38 kWh/m2.y

Primary Energy
Consumption_estimation_Calculation_method: Steady state simulation (e.g. EPC, PHPP)
Consumption_estimation_Including_DHW: Si
Consumption_estimation_After: 157156 kWh/y

Internal Climate

Indoor Air Quality

Chemical analysis of dust performed! No alarming values, no asbestos, but all the building flaws of the last decades are found. - Residues from PVC floors - Wood polish - Flame retardants from EPS - upholstered furniture - Cleaning agents

Costs

Financial Aspects

The price is not known.

Running Costs
Lifecycle cost
No

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