Klostergebäude Kaiserstrasse

Kaiserstrasse 7

1020

Wien/Vienna, Austria

Architect

Trimmel Wall Architekten ZTGmbH
Johann-Hörbiger-Gasse 30, 1230 Wien - Mauer
info@architekten.or.at
+43 1 8893079

Owner

Kongregation der Mission vom hl. Vinzenz von Paul (Lazaristen)
1070 Wien, Kaiserstrasse 7

Contact Details

Walter Hüttler
e7 energy innovation & engineering
office@e-sieben.at
+43-1-907 80 26

Other Information

NA

Visits
Parts of the building can be visited.

Related publications
Rammerstorfer J. et al., Gründerzeit mit Zukunft - Demonstrationsprojekt Kaiserstraße - Dokumentation und Monitoring, e7 Energie Markt Analyse GmbH, März 2017
A multi-purpose used convent building in the heart of Vienna has been refurbished with particular attention to monument preservation and to a new solution for renovating Viennese-type box windows.
Energy performance
75,75 kWh/m2.y

Climate Zone Cfb

Altitude 171 m a.s.l.

HDD 3460

CDD 76

Protection level Listed

Conservation Area:
No

Level of Protection:
Building is under monument protection

Building age 1850-1899

Year of last renovation:
2013

Year of previous renovation:
2013

Building use Residential (urban)

Secondary use:
Offices

Building occupancy:
Permanently occupied

Building area Net floor area [m²]: 2750,0

Building typology:
Semidetached house

Number of floors:
4

Basement yes/no:
Yes

Number of heated floors:
4

Gross floor area [m²]:
3098,0

Thermal envelope area [m²]:
2559,51

Volume [m³]:
8732,37

NFA calculation method:
Gross floor area (BGF) according to Austrian "Energieausweis"

Construction type
Brick masonry wall

External finish:
Exposed brickwork

Internal finish:
Plastered (on hard)

Roof type:
Pitched roof

+ MORE - LESS
Photo credit: courtesy of Trimmel Wall Architekten ZTGmbH
Photo credit: courtesy of Trimmel Wall Architekten ZTGmbH
Photo credit: courtesy of Trimmel Wall Architekten ZTGmbH
Photo credit: courtesy of Trimmel Wall Architekten ZTGmbH
Photo credit: courtesy of Trimmel Wall Architekten ZTGmbH
Photo credit: courtesy of Trimmel Wall Architekten ZTGmbH
Photo credit: courtesy of Trimmel Wall Architekten ZTGmbH
Photo credit: courtesy of Trimmel Wall Architekten ZTGmbH
Photo credit: courtesy of Trimmel Wall Architekten ZTGmbH
Photo credit: courtesy of Trimmel Wall Architekten ZTGmbH
Photo credit: courtesy of Trimmel Wall Architekten ZTGmbH
Photo credit: courtesy of Trimmel Wall Architekten ZTGmbH
Photo credit: courtesy of Trimmel Wall Architekten ZTGmbH
Photo credit: courtesy of Trimmel Wall Architekten ZTGmbH
Photo credit: courtesy of Trimmel Wall Architekten ZTGmbH
Photo credit: courtesy of Trimmel Wall Architekten ZTGmbH
Photo credit: courtesy of Trimmel Wall Architekten ZTGmbH
Photo credit: courtesy of Trimmel Wall Architekten ZTGmbH
Photo credit: courtesy of Trimmel Wall Architekten ZTGmbH
Photo credit: courtesy of Trimmel Wall Architekten ZTGmbH
Photo credit: courtesy of Trimmel Wall Architekten ZTGmbH
Photo credit: courtesy of Trimmel Wall Architekten ZTGmbH
Photo credit: courtesy of Trimmel Wall Architekten ZTGmbH
Photo credit: courtesy of Trimmel Wall Architekten ZTGmbH
Photo credit: courtesy of Trimmel Wall Architekten ZTGmbH
Photo credit: courtesy of Trimmel Wall Architekten ZTGmbH
Photo credit: courtesy of Trimmel Wall Architekten ZTGmbH
Photo credit: courtesy of Trimmel Wall Architekten ZTGmbH

RENOVATION PROCESS

Architecture

BUILDING DESCRIPTION

The building is a symmetrical structure with two wings, which frame the forecourt of the Lazaristenkirche. The north wing was the subject of renovation. It dates from the late "Gründerzeit" period of 1884-1918, was built in 1904 and designed by architect Cajetan Miserowsky. The renovated building is located on the north side and has a predominantly south-facing orientation of the habitable rooms. The north side to the adjacent Sophienspital is a closed firewall. The narrow side to the west faces the private garden.
Urban context
The property is located in the 7th district of Vienna, which is heavily influenced by Gründerzeit buildings. The refurbished building is part of a larger ensemble between Kaiserstrasse 5-7 in the east and the busy Gürtelstrasse in the west. The ensemble is located completely in a protection zone and is a listed building.

HERITAGE SIGNIFICANCE

ELEMENTS WORTHY OF PRESERVATION
The architectural quality in particular the appearance of the main façades with clinker surfaces, the historic windows & dormers, the house chapel and the shape of the roof were worth preserving. An innovative package of measures for the preserved Gründerzeit house was conceived as follows: The Viennese box windows in the articulated facades covered with ceramic tiles were preserved and supplemented with passive-house-fit internal wooden windows and energetically optimized. The thermal quality of the building envelope was enhanced by an interior insulation with calcium silicate panels. A comfort cover with a central ventilation unit and heat recovery for the living and recreation rooms was integrated into the historic building fabric. The Gründerzeit roof truss was statically reinforced and thermally renovated while retaining the existing roof contour, the ornamental gable and the historic old slate cover. Light strips were integrated into the space-side roof areas, with the built-in residential units close to the passive house receiving roof terraces on the courtyard side. An external insulation was designed on the inner court facades and fire walls. Through a monitoring of the Vienna University of Technology, the demonstration project was scientifically monitored over a period of 2 years. By applying this innovative package of measures, it was demonstrated how a listed building can be adapted to a highly efficient and up-to-date standard of comfort and energy consumption.
Heritage Value Assesment
The building and it´s court were already under monument protection by the Federal Monuments Authority Austria when the project started. After completion, the project received first place in the 29th Vienna Urban Renewal Award 2014 (Wiener Stadterneuerungspreis)

State of repair

Conditions of the envelope
The property had significant static, fire safety and thermal deficiencies that had be addressed.
Description of pre-intervention building services
The building is located in the supply area of the district heating, which was used for the heat supply already before the renovation. The heat supply in the building took place via radiators. The transformer substation and the hot water supply were to be modernized.

Aim of retrofit

Renovation + Extension
The goal was to present a sustainable system solution with the energetic refurbishment of the existing building and the highly efficient loft conversion according to the requirements of the monument protection. This solution should have a high multiplicativity for a large number of Gründerzeit buildings. The property had significant static, fire safety and thermal deficiencies that had be addressed. Futhermore the measures should increase the user comfort by adding an elevator and a small building extension. Both the investment costs of the implemented innovative measures and the running costs in the operation were to be documented in order to be able to perform life cycle cost calculations. The goal was a certification, which documents a holistic representation of the building according to defined sustainability criteria.
Was there any change of use?
Rental appartments were added whereas social facilities and owner-occupation were reduced by half.
Lessons learned
The most relevant finding from the Kaiserstraße project is that complex refurbishment projects can only be realized with a consistently ambitious planning team and an open-minded client. A continuous process of coordination between an experienced planner and the building preservation authority is necessary. Especially the complication of the strict monument protection for facade and roof landscape shows that an ambitious architect can develop innovative solutions with general applicability from the alleged impediments. One of the keys to cost-effectiveness is the expansion of floor space by 30% and the adaptation of usable space to well-rentable standard, again of particular value the newly created attic floor space. The main contribution of the Kaiserstraße project seems to be that even under the complex conditions of monument protection, high-quality renovations enable innovative, contemporary solutions.
Stakeholders Involvement
Public sector
Wohnfonds Wien
Lenaugasse 10, 1080 Wien
office@wohnfonds.wien.at
Tel.+43 1 4035919-0
Private Sector
Neighbour/abutter
NA
Research Development
e7 energy innovation & engineering
Walcherstraße 11/43, 1020 Wien
office@e-sieben.at
Tel.+43 1 90782810
Architect
Trimmel Wall Architekten ZTGmbH
Johann-Hörbiger-Gasse 30, 1230 Wien - Mauer
info@architekten.or.at
Tel.+43 1 8893079
Conservation Consultant
Bundesdenkmalamt (Federal Monuments Authority Austria)
Hofburg, Säulenstiege, 1010 Wien
service@bda.gv.at
Tel.+43 1 534150
Energy Consultant
kppk Ziviltechniker GmbH
Schottenfeldgasse 65/10, 1070 Wien
office@kppk.at
Tel.+43 1 5352123
Structural Engineer
kppk Ziviltechniker GmbH
Schottenfeldgasse 65/10, 1070 Wien
office@kppk.at
Tel.+43 1 5352123
Services Engineer
Schöberl & Pöll GmbH
Lassallestraße 2/6-8, A-1020 Wien
office@schoeberlpoell.at
Tel.+43 1 7264566
Other
Paul Wegerer, TU Wien, Institut für Hochbau und Technologie
Karlsplatz 13, 1040 Wien
Other
Margarete Havel, Havel und Havel
Rekawinkler Hauptstraße 18, 3031 Pressbaum
Tools used
Energy calculation standard calculation tool according to Austrian building code
Life Cycle Analysis (LCA) econ calc, version 2.0.1, by Energieinstitut Vorarlberg
Other Software Ham4D_VIE for building physics rsp. inside insulation

RETROFIT SOLUTIONS

External Walls

Plastered facade with facing bricks

Exterior wall of extension

Plastered facade with facing bricks

The existing facade was made of ceramic clinker tiles. Conservative measures such as substance-saving cleaning and repair of the facing brick surfaces, supplementing the historical clinker tiles and hydrophobing were made. The ceramic statue in the wall niche of the southern ornamental gable has been restored. The circular sandstone slabs, sandstone cross ornaments and sandstone coverings on the eastern and southern ornamental gables were cleaned, repaired and color-matched. Articulated facades and profiled plaster surfaces, such as cornices, window casings, window roofs and ornamented roof gable incl. figural representations were repaired and restorated as follows: - Manual removal of various later lime-cement coating - Surface cleaning, mechanical manual exposure of various decorative elements - Stabilisation of the sanding surface, closing of cracks - Plaster additions with cement-free natural hydraulic finished products

Paint systems were used in consultation with the Federal Monuments Authority Austria according to the following procedure: - Etching the facade - Pore-filling lime mud for closing cracks and small bumps - Double silicate glass topcoat

U-value (pre-intervention) [W/m2K]: 0,917 W/m²K U-value (post-intervention) [W/m2K]: 0,444 W/m²K
More Details
Original wall build-up
Render - Exterior rendering:
30 mm
Brick - Solid brick:
600 mm
Plaster - Lime-cement plaster:
30 mm
Retrofitted wall build-up
Render - Lime Plaster:
30mm
Brick - Solid brick:
600 mm
Plaster - Lime-cement plaster:
30 mm
Insulation - Mineral insulating board:
50 mm
Plaster - Coat:
3 mm
Exterior wall of extension

The extension was designed with a contemporary ceramic facade.

The outer material was adapted to the historic ceramic facade.

U-value (post-intervention) [W/m2K]: 0,13 W/m²K
More Details
Original wall build-up
:
:
Retrofitted wall build-up
Render - Silicate plaster:
5mm
Insulation - High insulating board:
120 mm
Brick - Brick with integrated mineral wool insulation:
250 mm
Plaster - Interior gypsum plaster:
15 mm


Windows

Viennese box window

Slanted glazing in monument protection

Viennese box window

The outer wings of the box windows in listed facades were renovated and on the inside a new wooden window with special interior insulation was added. The solution sets the new inner wing completely flush with the inner wall and improves the thermal situation through internal insulation and reveal insulation. The sunshades are positioned between the wings in the lintel in existing roller blind niches. This layout represents a novel solution for old buildings.

Some parts of the window were maintained (e.g. frame)

More Details
Existing window type Box-type window
Existing glazing type Single
Existing shading type Roller blinds
New window type Box-type window
New glazing type Double
New shading type Roller blinds
New window solar factor g [-] 0,6
Slanted glazing in monument protection

The sufficient exposure of the two-storey loft extension was a particular challenge because of the huge closed listed roof area to the south. In cooperation between the monuments office and the planner, an exemplary solution was developed and implemented with this project. Thus, large-scale two-storey vertical light bands are integrated into the roof landscape due to the special shape of the outer sunblinds. The sunblinds lie flush with the outside of the roof and are fixed so that the horizontal view and sufficient sun protection are in balance. The exterior cleaning of the glass surfaces takes place annually with a special cleaning device.

New wlight bands were integrated into the roof landscape

Existing window U-value Glass [W/m2K]: 0,0 New window U-value Glass[W/m2K]: 0,0
More Details
Existing window type
Existing glazing type
Existing shading type NA
New window type Fixed window
New glazing type Double
New shading type Fixed shading
New window solar factor g [-] 0,6

Other interventions

ROOF

ROOF

The roofing to the street was made of the original slate, the one to the courtyard-side was done with Eternit lace stencils and the dormers in zink. The roof was equiped with a high quality intermediate rafter insulation and an inside, mineral rafter insulation. The roof gaiters were insulated with highly efficient insulating material. The gallery floor is illuminated on the court side via generous glass fronts of the dormers. In order to ensure an appropriate illumination of the attic apartments, 4 vertical light bands with 4 roof windows each were installed symmetrically to the south gable-end in the roof area. The fixed sunblinds avoid the summer overheating, but allow solar heat gains to be used in the winter. On the one hand, they guarantee a view into the open and on the other hand they create a homogeneous roof surface. In order to be able to mount the lamellas flush with the roof surface, an installation detail has been developed in which the level of the roof windows is located on the inside. The lowest window of each lightband is openable and manufactured with a ladder, so that the second escape and rescue route is given from each unit in the attic.

The roof surfaces were covered with historic slate cover and all zinc plating was redone.

U-value (pre-intervention) [W/m2K] 0,896 U-value (post-intervention) [W/m2K] 0,157
More Details
Original roof build-up
Tiles :
13 mm
Other - Battens:
30 mm
Other - conter battens:
80 mm
Retrofitted roof build-up
Tiles :
13 mm
Other - Battens and Counterbattens:
110 mm
Other - Windy (0,2 mm):
1 mm
Other - Shuttering, battens and insulation (glass wool):
340 mm
Other - OSB-board:
15 mm
Other - Vapour barrier (0,4 mm):
1 mm
Other - Double gypsum firecheck wallboard:
25 mm

HVAC

HEATING

VENTILATION

DOMESTIC HOT WATER

HEATING

The existing converter station which connects the district heating system with the heating system of the building was renewed. The attic floor is heated by a floor heating. On the third floor a floor heating could be realized on a footfall sound insulation due to a completely new floor structure with screed. On the second floor, there is a mixed system: in the rooms with interior insulation, floor heating was carried out due to the limited possibility of fixing the radiator consoles to the walls. On the second floor the remaining rooms are supplied by radiators. The first floor and the ground floor are heated by radiators. On the first floor some of these radiators were partially renewed. On the ground floor, the existing heat supply was not renewed. The chapel was equipped with wall heating on three sides.

This wall heating in the chapel was installed with the aim to prevent contamination of the wall painting. Since the heat dissipation now mainly works through radiation, in contrast to former convection-induced air movements, the transport of impurities are largely reduced.

More Details
New primary heating system
New system type Existing district heating / heat exchanger
Fuel Waste (approx. 33 %) and CHP
Distribuition system Floor heating, radiators or wall heating
Nominal power 160 kW
VENTILATION

The existing basement rooms could be used for the location of the ventilation station. The external air intake takes place via the outer wall of the parish garden. Existing shafts were used for the exhaust air and the supply and exhaust air ducts . The semi-central system was chosen for comfort ventilation. The heat recovery rate of the heat exchanger (plate countercurrent exchanger) is at least 82.5%. The filtering of the outside air is done with a high quality F7 pocket filter. The individual regulation of the air volume flow for each residential unit is ensured by a V-Box.

In order to keep the renovation work in the building minimally invasive, the former coal lift shaft was used for the exhaust air duct and part of the existing toilet tower was used for the routing of the supply and exhaust air. The ventilation distribution in the floors is located in the suspended false ceilings in the easily revisable corridor and staircase area.

More Details
Original roof build-up New ventilation system
Type ventilation system Semi-centralized
Type flow regime
Heat recovery Yes
Humitidy recovery No
Nominal power 1,051 kW
Electric power 0,8
Control system individual control in each dwelling
DOMESTIC HOT WATER

The hot water supply for the attic floor, as well as for the second and third floor is made via decentralized home stations. The home station is a prefabricated unit for supplying heating surfaces (floor heating or radiators) and for heating water in a 2-wire system. The station is fed from the heating flow and from the cold water network from the central installation shaft. This requires a year-round operation of the network; Decentralized heating saves a separate hot water and a circulation line as well as the resulting storage and circulation losses. In the refurbished apartments, attention was paid to the use of water-saving fittings. The ground floor and the first floor are supplied centrally from the technical room. The distribution is made from a 1,000 l water heater in the basement. The storage tank is charged with district heating via its own heat exchanger.

No measures had to be taken on count of conservation.

More Details
New DHW system
Type decentral boiler
Hot_water_tank Yes
With heat recovery No

Energy Efficiency

Energy Performance
Energy performance certificate: The energy certificates "Energieausweis für Wohngeböude Bestand" and "Energieausweis für Wohngebäude nach Sanierung" for a residential floor were compiled.
Voluntary certificates: In the context of "Gründerzeit mit Zukunft" and in cooperation with the House of the Future plus project "Monitor +", a building certification with Total Quality Building (TQB) was carried out according to the quality criteria of ÖGNB (Austrian Sustainable Building Council). The aim of the certification was a holistic representation of the building according to defined sustainability criteria. In addition, the building was certified according to the criteria of klima:aktiv. In total, 708 out of 1,000 possible points were achieved for the project.
Energy Use
Heating
Primary Energy 125 kWh/m2.y
Consumption_estimation_After: 75,75 kWh/m2.y

Primary Energy
Consumption_estimation_After: 125 kWh/m2.y
Measured Parameters
Internal Climate
Type_of_monitoring: Continuous
Description: Detailed moniroting of thermal comfort, comfort in terms of humidity and air purity (CO2 content)

Construction
Type_of_monitoring: Continuous

Internal Climate

Temperature

The regulation of underfloor heating may not be optimally adjusted, because the thermostat is mounted in an apartment in the bedroom, but where cooler temperatures are desired, so that the living room is then too cool. The bathroom is described as too warm. With the warming and ventilation of the apartments in the cooler season, there is high satisfaction. There are no disturbances and noises. The overheating of the apartments in the summer is described as unpleasant. Despite the installation of a sun blinds, a tenant built an air conditioner.

Costs

Investment Costs
Total investment costs
5,160,000 € (total)
Amount includes: Structural work: approx. 1,100,000 €, Building services: approx. 900,000 €, Fillout: approx. 2,400,000 €, Fees and building site facilities: approx. 760,000 €

Cost of energy related interventions:
912,000 € (total)
Amount includes: Exterior insulation, interior insulation, renovation of the windows, roof renovation, heating installation and installation of the ventilation system including air distribution
Running Costs
Total annual energy cost
11.48 € (per m2)

Annual heating cost
7.60 € (per m2)
(includes DHW) Yes

Annual electricity cost
0.78 € (electricity costs for building services), 3.10 € (electricity costs for use of building) (per m2)

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