Single family House - Bern, Switzerland

Luisenstrasse 30

3005

Bern, Schweiz

Architekt

Beat Wermuth und Partner Architekten GmbH
Bonstettenstrasse 6b, 3012 Bern
office@wup-architekten.ch
+41 31 305 02 01

Besitzer

Familie Hutterli Röthlisberger
Luisenstrasse 30, 3005 Bern
mhutterli@gmail.com
+41 31 352 82 12

Ansprechpartner

Dr Arch. Cristina S. Polo López
SUPSI - University of applied sciences and arts of southern Switzerland
cristina.polo@supsi.ch
+41 58 666 63 14

Other Information

Related publications
Swiss Solar Price 2014 (German and French)
Top view © C. Martig
The neo-baroque style house of the Hutterli Röthlisberger family from Bern/BE, dated 1898, has been extensively renovated and thermally refurbished between 2011 and 2015. The intervention concerns the thermal improvement of the envelope, intervening on walls, roof and windows. It also concerns the installation of a photovoltaic system and a solar thermal system, as well as the replacement of the gas heating system with a heat pump, geothermal probes and a stove. The intervention also involved the installation of a comfort ventilation system with heat recovery. This renovation deserved the Swiss Solar Prize 2014.
Energieeffizienz
35,22 kWh/m2.y

Klimazone Cfb

Höhe über dem Meer 542 m ü.d.M.

Heizgradtage 198

Kühlgradtage 0

Unterschutzstellung denkmalgeschützt

Ensembleschutz:
Ja

Stufe der Unterschutzstellung:
High

Baualter 1850-1899

Letzte Sanierung:
2015

Gebäudenutzung Residential (urban)

zusätzliche Nutzung:
NA

Gebäudebelegung:
Permanently occupied

Anzahl der Bewohner/Nutzer:
5

Gebäudefläche Nettogeschossfläche [m²]: 215,0

Gebäudetyp:
Detached house

Anzahl der Stockwerke:
2

Keller ja/nein:
Ja

Anzahl der beheizten Stockwerke:
3

Bruttogeschossfläche [m²]:
258,0

Thermische Gebäudehülle [m²]:
570,0

Volumen [m³]:
1250,0

NGF Berechnungsmethode:
SIA 416

Bauart
Stone masonry wall

Außen:
Rendered

Innen:
Plastered (on hard)

Dach:
Pitched roof

+ MEHR - WENIGER
Top view © C. Martig
Top view © C. Martig
View of the corner house, road fork © M. Hutterli
View of the corner house, road fork © M. Hutterli
View of the corner house © M. Hutterli
View of the corner house © M. Hutterli
South front © M. Hutterli
South front © M. Hutterli
Top view © C. Martig
Top view © C. Martig
Top view © C. Martig
MEHR SEHEN +
Top view © C. Martig
View of the corner house, road fork © M. Hutterli
View of the corner house, road fork © M. Hutterli
West view before interventions © M. Hutterli
West view before interventions © M. Hutterli
South-east view before interventions © M. Hutterli
South-east view before interventions © M. Hutterli
East view before interventions © M. Hutterli
East view before interventions © M. Hutterli
High aesthetic preservation © M. Hutterli
High aesthetic preservation © M. Hutterli
South view before interventions © M. Hutterli
South view before interventions © M. Hutterli

RENOVIERUNGS-PROZESS

Architektur

BESCHREIBUNG

The building is a detached single-family house, a two-floors neo-baroque construction with a mansard rooftop and is dated 1898. The general situation of degradation and the need to minimize energy demand collide with the important aspect of historic buildings preservation. The challenge is to achieve maximum results in both fields, opting for several high efficiency interventions, but at the same time with minimum aesthetic impact.
Städtebaulicher Kontext
As usual at road forks and corner houses in the Kirchenfeld district, according to the Kirchenfeld-Brunnadern building inventory, the house was designed with special care: the south-east corner of the house is characterized by a corner risalite, which is covered with the mansard roof. The house is listed in the cantonal building inventory and classified as worthy of protection (highest protection level). For this reason, any changes must obtain the approval of the Department of Historic Monuments.

Erhaltungszustand

Erhaltungszustand der Gebäudehülle
The existing building presents a general poor condition of the envelope and needs an energy upgrade. It also needs a replacement of the existing gas heating system. A total renovation was indicated.
Haustechnische Anlagen vor Sanierung
The single family house was equipped with a gas heating system and no precautions has been taken for heat losses.

DENKMALWERT

ERHALTENSWERTE ELEMENTE
Due to the high protection level of the building, the goal is to achieve the highest aesthetic demand. Because of this, it was initially difficult to receive approval from the authorities. This led to the search for the best possible solution.
Denkmalwert und wie er bestimmt wurde
The building is part of a protected area where the two street-side facade are well cared for and are part of the historical context of the district.

Ziel der Sanierung

Renovation
The energy renovation has a special focus on aesthetic preservation and in maintaining the character of the house. The goals for the renovation of this building are manifold: minimize energy demand (reach a Minergie level), use environmentally friendly building materials, maintaining the character of the house (preservation of historical monuments), consider urban environment, adhere to the cost framework (subsidies as Minergie and Bern renovated) and, where necessary, seek and implement new solutions.
Was the intervention planned following a step-by-step approach?
First step was a preliminary study some years before renovation. Second step was to define exactly the goals to achieve and at last every single intervention has been studied to fit with the overall renovation.
Gewonnen Erkenntnisse / besondere Erfahrungen
The integrated solar system is the main element of this renovation. At the beginning it was difficult to obtain a licence to operate the building, but this solution demonstrate that it is possible not to affect the aesthetics of the element. This is a great example for the future renovations and for the building industry in general. In addition, it shows many different interventions that can well improve the whole.
Beteiligte Akteure
Öffentliche Hand
Bauinspektorat der Stadt Bern
Bundesgasse 38, 3001 Bern
bauinspektorat@bern.ch
Tel.+41 31 321 65 45
Architekt
Beat Wermuth und Partner Architekten GmbH
Bonstettenstrasse 6b, 3012 Bern
office@wup-architekten.ch
Tel.+41 31 305 02 01
Berater Denkmalpflege
Manuel Hutterli
Luisenstrasse 30, 3005 Bern
mhutterli@gmail.com
Tel.+41 31 352 82 12
Energieberater
Manuel Hutterli
Luisenstrasse 30, 3005 Bern
mhutterli@gmail.com
Tel.+41 31 352 82 12
Andere
Hans Dürig AG, Markus Dürig, Ing. HTL
Hintere Gasse 11, 3132 Riggisberg
info@hans-duerig.ch
Tel. 41 31 809 02 50
Andere
Meyer Burger AG, PV Systems
Schorenstrasse 39, 3645 Gwatt
mbtinfo@meyerburger.com
Tel.+41 33 221 24 07
Andere
INNOVAR, Christian Käsermann
Route des Genevrés 35, 1784 Courtepin
Tel.+41 26 684 10 87
Eingesetzte Software/Berechnungstools
Folgte die Sanierung einer spezifischen Methode? Minergie. This label corresponds
Energiebilanz SIA 380/1
Hygrothermische Bewertung No
Life Cycle Analysis (LCA) No
Anderes No

SANIERUNGS-LÖSUNGEN

Außenwände

Double-shell masonry wall

Double-shell masonry wall

The external wall was insulated with a double-shell blowing system with Isofloc H2Wall. This is the best possible insulation for an external wall, as reported in the cantonal buildings inventory. This was a premiere in Bern. In addition, it has been included on the inside a wall heating with 1cm aerogel insulation (corresponds to 3cm of conventional isolation).

The intervention maintains the original aesthetics of the wall and the the increase in wall thickness is minimal. This way, the interior space of the building remains practically unchanged.

U-Wert (vor Sanierung) [W/m2K]: 0,68 W/m²K U-Wert (nach Sanierung) [W/m2K]: 0,44 W/m²K
Mehr Details
Aufbau Bestandswand
Plaster - The external wall has a yellow finish:
20 mm
Stone - Double-shell masonry wall, external:
180 mm
Air gap - Double-shell masonry wall, air gap:
60 mm
Stone - Double-shell masonry wall, internal:
180 mm
Plaster - White:
15 mm
Aufbau sanierte Wand
Plaster - The external wall has a yellow finish, reproducing the original one:
20mm
Stone - Original double-shell masonry wall, external:
180 mm
Insulation - Double-shell blowing system with Isofloc H2Wall (in existing air gap):
40 mm
Stone - Original double-shell masonry wall, internal:
180 mm
Other - Wall radiator behind plasterboard (insulation and wood beams):
50 mm
Plaster - Plasterboard with white finish:
25 mm


Fenster

Wood windows

Wood windows

Most of the existing windows have been renovated and only a few have been replaced with a copy, due to the bad state of conservation.

The existing windows have been improved. The original single glazing was replaced with the thin, krypton filled double glazing and seals for airtightness. Where improvement was not possible, the windows have been replaced with a reproduction (west facade). The historical front windows have also been renovated.

Bestandsfenster U-Wert Glas [W/m2K]: 3,0 Neues Fenster U-Wert Glas [W/m2K]: 0,7 Bestandsfenster U-Wert Rahmen [W/m2K]: 3,0 Neues Fenster U-Wert Rahmen [W/m2K]: 1,3
Mehr Details
Fenstertyp Bestand Casement window
Verglasungsart Bestand Single
Verschattung Bestand Outer shutter
Ungefähres Einbaujahr 1898
Neuer Fenstertyp Casement window
Verglasungsart des neuen Fensters Double
Verschattung des neuen Fensters NA
Neuer Energiedurchlassgrad g [-] 45,0

Weitere Maßnahmen

DACH

ERDGESCHOSS

DACH

The roof has been improved with cellulose insulation and also used to place a PVT and an hybrid system. The roof structure has been improved both statically and thermally. Originally the building had a U-value of 1.36 W/m2K for the roof, which was very high (as expected). The intervention made possible to reach a U-value of 0.19 W/m2K.

Thanks to the aesthetic integration of the PVT hybrid system, the compatibility is assured. The natural slate hides the collectors in the steeply sloping roof, making them invisible from the outside. The production of heat is therefore less efficient and more third-party energy is required, but it is a good compromise to maintain the original appearance of the building.

U-Wert (vor Sanierung) [W/m2K] 1.36 U-Wert (nach Sanierung) [W/m2K] 0.19
Mehr Details
Aufbau Bestandsdach
Slate - Original black slate cover has been replaced by elements that maintain its original appearance:
10 mm
Other - Wood board (spruce):
22 mm
Other - Wooden carpentry:
160 mm
Other - Plasterboard:
60 mm
Aufbau saniertes Dach
Slate - Integrated PVT system:
10 mm
Other - Pavatex-plus: roof layer with additional high thermic performance:
22 mm
Other - Insulation isofloc (in wooden carpentry 160+80mm):
240 mm
Other - Plasterboard (Fermacell):
12 mm
ERDGESCHOSS

The intervention consists in the installation of thermal insulation under the ceiling of the cellar to keep the floor covering intact.

The intervention was carried out in the cellar where it was not necessary to pay particular attention to conservation.

U-Wert (vor Sanierung) [W/m2K] 1 U-Wert (nach Sanierung) [W/m2K] 0.19
Mehr Details
Aufbau Boden/Kellerdecke im Bestand
Finish - Oak floor:
40 mm
Concrete slab - Concrete:
120 mm
Aufbau Boden/Kellerdecke nach Sanierung
Finish - Oak floor:
40 mm
Concrete slab - Concrete:
120 mm
Insulation - Mineral wool:
140 mm

HVAC

HEIZUNG

LÜFTUNG

BRAUCHWARMWASSER

HEIZUNG

The original gas heating system has been replaced with a heat pump, a solar thermal system and a geothermal system. The main source is the water heat pump, which is supplied partly by geothermal probes and partly by the PVT and the natural slate collector systems. Both systems are used to support the heat pump by increasing the water temperature into the heat pump whenever possible and thus to improving the COP. The heat is distributed through radiators and through a stove. Historical radiators were not changed during the renovation (except newly painted). The solar thermal system is well implemented in the building.

The system has been designed to perfectly integrate with the construction. Wall radiators have been fitted to the wall with a minimal intervention in terms of space, while the PVT system (as well as the hybrid) has been built to adapt perfectly to the shape, colour and materials of the roof.

Mehr Details
Heizungssystem nach Sanierung zusätzliches Heizungssystem nach Sanierung
Art der Heizung Heat pump Stove
Brennstoff Electricity Biomass
Wärmeverteilung Radiators and radiators wall Air
Nennleistung 8 kW 10 kW
LÜFTUNG

A Zehnder comfort ventilation system with heat recovery has been introduced.

On the top floor, the supply air is routed via the screed into the built-in cupboards: apart from the inconspicuous supply air grilles in the cupboard walls (usually behind furniture), no architectural intervention in the rooms (pipes) is necessary. No audible ventilation noises.

Mehr Details
Aufbau Bestandsdach Neues Lüftungssystem
Lüftungstyp Centralized
Type flow regime Overflow
Wärmerückgewinnung Ja
Feuchterückgewinnung Nein
Nennleistung NA kW
Elektrische Leistung 0,0 kW
Regelung Customized
BRAUCHWARMWASSER

The hot water preparation is carried out by the 2’840l tank, which is mainly supplied by the heat pump and the PVT system.

The system doesn't need conservation compatibility.

Mehr Details
Brauchwarmwasserbereitung nach Sanierung
Typ with heating system
Brauchwasserspeicher Ja
Wärmerückgewinnung aus Brauchwasser Ja

ERNEUERBARE ENERGIE

Solarthermie

Photovoltaik

Biomasse

Geothermie

Solarthermie

Two different types of STh have been used: special system on the lower part, PVT on the top of the roof (cfr. section PV)

Due to preservation orders, no conventional collectors were allowed. The collectors of the special system (lower part of the roof) are integrated in the underroof (layer battens and counter battens). External layer of the roof is natural stone plates, and the system is not visible at all.

Since originally no conventional solar system was possible due to monument preservation regulations, a collector that is not visible from the outside has been developed, with which the heat can be efficiently extracted from the natural slate roofing. 13m2 of natural slate collectors were installed, which corresponds to an output of about ~5kWp. The collector consists of copper lamellas, which are clamped between the slate plates. The heat is conducted via the fins into a soldered copper tube, through which it is dissipated via a glycol solution, as in conventional collectors. Due to possible condensation moisture and to increase efficiency, a 1 cm aerogel insulation, covered by a sub-roof foil, was placed between the roof battens and the slate. PVT and the natural slate collector systems are used to support the heat pump by increasing the water temperature into the heat pump improving the COP. The PVT and natural slate collector systems are also used to regenerate the geothermal probes/ground temperatures with excess heat available from the PVT and the slate collectors on multi-day to seasonal time scale (on diurnal time scale the solar tank is the heat storage). The regeneration thus increases the net solar electricity production and at the same time prevents the ground to cool down over time, assuring a constantly high COP over the lifetime of the geothermal probes. In addition, the cooled roof helps the rooms of the top floor to remain cooler in summer. This renovation deserved the Swiss Solar Prize 2014.

Mehr Details
SolarThermal System
Type Natural slate collectors
Collector area 13,0 m²
Elevation angle 80,0
Azimuth 5,0
Overall yearly production 10000,0 kWh
Heating_contribuition 6242,0 kWh
DHW contribuition 1330,0 kWh
Cooling contribuition 0,0 kWh
Photovoltaik

Roof-integrated PVT (13 m2) + roof integrated PV (5.5 m2) + STh natural slate collectors (13 m2)

Due to the high level of protection, solar panels are slightly visible from the street, leaving part of the original slate roof intact. During the refurbishment, the requirements of the preservation of historic monuments were somewhat softened, so that both PV+PVT system was possible on the flat (upper) part of the roof.

The arrangement of solar panels on triangular pitched roofs approaches solves the critical points with tailored solar modules with attention to detail and fixing systems. First 'optical' roof-integrated system with 3S Hybrid 900/240 modules. Optically' integrated into the roof, because the installation is integrated into the roof and flush with the eaves, but the solar system is not a completely tight roof skin. The actual dense and back-ventilated roof skin lies underneath, i.e. the installation is hybrid roof-integrated and 'on roof'. - Eight hybrid collector modules (13 m2) and 12 purely photovoltaic special modules (5.5 m2) on the southern, 25° inclined roof surface. - Electrical output: 2,728 kWp. Active cooling of the modules increases the annual electrical yield by up to 10%. - The thermal output of the hybrid collectors is at least 7.2 kWp (manufacturer's specifications).

Mehr Details
Photovoltaic System
Type Monocrystaline
Collector area 18,5 m²
Total nominal power 2,7 kW
Elevation angle 28,0
Azimuth 170,0
Overall yearly production 3207,0 kWh
Heating contribuition 0,0 kW
DHW contribuition 0,0 kW
Cooling contribuition 0,0 kW
Lighting contribuition 3537,0 kW
Biomasse

Stove

In the building there was already a fireplace/stove whose only element visible from the outside was a chimney that came out in the north-west part of the roof. This chimneypot remained intact, while the gas boiler chimneypot was removed. The new stove is located in the living room and is connected to the central heating system.

The new heating system includes several interventions. The main source is the water heat pump, which is supplied partly by geothermal probes and partly by the PVT and the natural slate collector systems. Both systems are used to support the heat pump by increasing the water temperature into the heat pump whenever possible and thus to improving the COP. The water is stored in a 2840 L tank. It also works thanks to the stove. In addition, a 'Frischwasserstation' which contains a small heat exchanger to provide warm water (Brauchwasser) on demand have been installed which prevents the formation of legionella. The hot water of the solar tank is used to heat up the 'Brauchwasser' in the Frischwasserstation when required. From the tank the water is then distributed to the radiators and wall radiators.

Mehr Details
Biomass System
Type Logs
Storage size Normal cellar in the basement
Origin of biomass Kanton Bern
Overall yearly production 2798,0 kWh
Geothermie

Heat pump with bore holes

The execution in a geothermal heat pump is not very invasive for any building, in fact all the pipes coming out of the building are underground, while inside the building there will be a presence of greater pipes due, in this case, to the complexity of the system that combines several energy carriers. The use of more vectors allows a better management because it gives priority to the vector that has production potential at any specific moment.

The new heating system includes several interventions. The main source is the water heat pump, which is supplied partly by geothermal probes and partly by the PVT and the natural slate collector systems. Both systems are used to support the heat pump by increasing the water temperature into the heat pump whenever possible and thus to improving the COP. The PVT and natural slate collector systems are also used to regenerate the geothermal probes/ground temperatures with excess heat available from the PVT and the slate collectors on multi-day to seasonal time scale (on diurnal time scale the solar tank is the heat storage). This regeneration is a win-win situation: By cooling the PVT panels and transferring the excess heat (up to 12 kW) into the ground e.g. in summer, the PVT panels produce significantly more electricity (up to 500 W) than the pump required to transfer the heat into the ground (~50W). The regeneration thus increases the net solar electricity production and at the same time prevents the ground to cool down over time, assuring a constantly high COP over the lifetime of the geothermal probes. In addition, the cooled roof helps the rooms of the top floor to remain cooler in summer. The water is stored in a 2840 L tank. It also works thanks to the stove. In addition, a 'Frischwasserstation' which contains a small heat exchanger to provide warm water (Brauchwasser) on demand have been installed which prevents the formation of legionella. The hot water of the solar tank is used to heat up the 'Brauchwasser' in the Frischwasserstation when required. From the tank the water is then distributed to the radiators and wall radiators. The geothermal system includes two probes of 150 m each.

Mehr Details
Geothermal System
Type Vertical loop
Exchange area 33,6 m²

Energieeffizienz

Energieeffizienz
Energieausweis Before renovation: envelope G global G After renovation: envelope B global A
Freiwillige Zertifikate In this case Minergie it corresponds to the EPC cathegory B
Energievrabrauch
Heizung
Berechnungsmethode Steady state simulation (e.g. EPC, PHPP)
Documents:
Technische daten.JPG
Swiss solar price

Energieverbrauch vor Sanierung 43312 kWh/y
Energieverbrauch nach Sanierung 35,22 kWh/m2.y

Primärenergie
Berechnungsmethode Steady state simulation (e.g. EPC, PHPP)
Energieverbrauch incl Brauchwarmwasser Ja
Energieverbrauch vor Sanierung 46867 kWh/y
Energieverbrauch nach Sanierung 11109 kWh/y
Gemessene Parameter
Raumklima
Type_of_monitoring: Punctual
Description: Complexity of the plant requires performance and flexibility, which is not available in typical control systems of individual components. Temperature and flow rate data should not only be used for monitoring and control, but also be recorded as a basis for optimisation. The control system was put together and programmed from inexpensive components.

Außenklima
Type_of_monitoring: Continuous
Description: The strategy of monitoring ist to follow the temperature of the solar systems (sloping, PV, PVT) according to the external air temperature. This is the link: https://grovestreams.com/singleDash.html?org=2776f02c-f718-3407-83e0-78bc4c61ecda&itemUid=10f024e4-0cf4-37df-a184-79853932b9d6&api_key=f66a4104-ad33-3159-90e6-10bd46a26c29
Documents:
Monitoring temperature esterne_1.JPG

Bauteile
Type_of_monitoring: Continuous
Description: The strategy of monitoring is to follow the temperature of the solar systems (sloping, PV, PVT) according to the external air temperature. Information available: https://grovestreams.com/singleDash.html?org=2776f02c-f718-3407-83e0-78bc4c61ecda&itemUid=10f024e4-0cf4-37df-a184-79853932b9d6&api_key=f66a4104-ad33-3159-90e6-10bd46a26c29
Documents:
Monitoring temperature esterne.JPG
Print screen of the overview of solar elements temperature


Nurzerverhalten
Type_of_monitoring: Punctual
Description: Thanks to the ventilation control, the temparture is monitored, and the ownership wishes to have light reduced temperature. The automatically change of air doesn't require other minotoring.

Raumklima

Temperatur

The thermal comfort of the occupants improved thanks to the new walls and roof insulation and the new heating system.

Indoor Air Quality

Indoor air quality improved thanks to the new ventilation system. The automatically change of air guarantees the necessary hygienic exchange.

Daylight

Daylight does not change compared to pre-intervention due to the original size of the openings which was determined by the existing structure. In some rooms where the size of the windows are large in comparison to the surface of the room itself, the deepening has been done to avoid overheating in summer.

akustischer Komfort

The change of glazing windows improved the acoustic comfort of the house. The introduction of a ventilation system has been well elaborated, in fact there are no audible noises.

Erhaltung von Ausstellungsstücken

NA

Kosten

Finanzielle Aspekte

The roof intervention cost is around CHF 45,000. The estimation costs were made on the basis of the annual CHF savings due to the renovation. An interesting aspect is that many of the interventions were carried out with the help of the owners. As well as being very involved and enthusiastic about the renovation, the owners were able to keep some costs down.

Investitionskosten

Cost of energy related interventions:
about 200'000.- CHF (total)
Amount includes: Roof, walls, doors and windows, insulation cellar,
Betriebskosten
Lifecycle cost
Nein

Umwelt

Water Management

Inside the building there are water-saving taps/mixers.

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