Single Family House - Gstaad, Switzerland

Moosfangstrasse 23

3780

Gstaad, Suisse

Architect

Gehret Design GmbH
Gewerbestrasse 19, 3784 Feutersoey
michi@gehret.ch
41 78 737 38 85

Owner

Gabriela, Arani and Nick Matti
Moosfangstrasse 23, 3780 Gstaad
tuttimatti@gmail.com
+41 79 656 06 00

User


Contact Details

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

Visits
For individuals with an appointment.

Related publications
Swiss Solar Price 2019
Credits: Solaragentur Swiss Solar Prize 2019
Every year in Switzerland more than 2,000 agricultural holdings are abandoned. The buildings often remain unused (CVP-Mo 11.3285). A redevelopment or conversion of older buildings into residential buildings is not always possible due to the federal legal restrictions on the preservation of cultural landscapes. It is questionable what a half- decayed building can do on a planet rendered uninhabitable by global warming due to development. Gabriela Matti proves that traditional buildings can easily be combined with the latest technology with the conversion of the unused Maiensäss in Gstaad. A comprehensive renovation transformed the unused and unheated wooden house into a modern PlusEnergyBuilding, that hasn't lost its "old charm."
Energy performance
4984 kWh/y

Climate Zone Cfb

Altitude 1050

HDD 3009

CDD 22

Protection level Listed

Conservation Area:
Oui

Level of Protection:
Federal legal restrictions on the preservation of cultural landscapes

Building age 1700-1800

Year of last renovation:
2018

Year of previous renovation:
0

Building use Residential (rural)

Secondary use:
NA

Building occupancy:
Permanently occupied

Number of occupants/users:
3

Building area Net floor area [m²]: 160,0

Building typology:
Detached house

Number of floors:
2

Basement yes/no:
Oui

Number of heated floors:
2

Gross floor area [m²]:
209,0

Thermal envelope area [m²]:
0,0

Volume [m³]:
1122,0

NFA calculation method:
SIA 416

Construction type
Solid timber wall

External finish:
Partly exposed woodwork and partly plastered.

Internal finish:
Partly exposed woodwork and partly plastered.

Roof type:
Pitched roof

+ MORE - LESS
Credits: Solaragentur Swiss Solar Prize 2019
Credits: Solaragentur Swiss Solar Prize 2019
© Daniel Baggenstos
© Daniel Baggenstos
© Daniel Baggenstos
© Daniel Baggenstos
© Daniel Baggenstos
© Daniel Baggenstos
© Michi Gehret, Gehret Design
© Michi Gehret, Gehret Design
© Michi Gehret, Gehret Design
© Michi Gehret, Gehret Design
© Michi Gehret, Gehret Design
© Michi Gehret, Gehret Design
© Michi Gehret, Gehret Design
SEE MORE +
© Michi Gehret, Gehret Design
© Solaragentur Swiss Solar Prize 2019
© Solaragentur Swiss Solar Prize 2019
General view before interventions © Gehret Design
General view before interventions © Gehret Design
Old wall © Gehret Design
Old wall © Gehret Design

RENOVATION PROCESS

Architecture

BUILDING DESCRIPTION

The building is located in Gstaad and was originally used for agricultural purposes, but later abandoned. It was completely renovated in 2018 to become a single-family house. The project includes an extension of the basement floor (that doesn't change the external volume) for a total energy requirement of 17,600 kWh/y. The photovoltaic roof is aesthetically perfectly integrated in terms of shape and provides 154% of the energy required. The renovation of the building was largely managed by the family themselves, who took it step by step. For this reason some details are not available because they were carried out on site.
Urban context
The building is located in a rural area, surrounded by greenery and not in close contact with other buildings. In fact, it is placed in a typical alpine area.

HERITAGE SIGNIFICANCE

ELEMENTS WORTHY OF PRESERVATION
To preserve their original appearance, not all original walls have been covered with external thermal insulation. This leads to a fairly high energy index of 84 kWh/m2a (in comparison with other similar buildings). The original shape of the roof has been maintained thanks to an integrated photovoltaic system that works as a roof cover as well. In the demolition/new plan it is possible to see exactly which parts were maintained (black) and which are new (red).
Heritage Value Assesment
The building is located in an area with federal legal restrictions on the preservation of cultural landscapes, so it is important to keep its original appearance in the environment. The focal elements for the preservation of the building are mainly the external ones. In fact, due to the total change in function, it has not been possible to maintain the interior appearance of the building (it has been made livable and therefore requires certain technologies and spaces). The main facade, the shape of the roof and the windows are the elements that have been taken into consideration most for the preservation, as they are the most visible and characteristic elements of the building. The house is composed by two floors and a basement. The original function provided a double height between ground and 1st floor, which has been maintained. An extension of the basement floor was carried out during the renovation. The typical 4-pitch roof, with its peculiar shape, has been completely renewed but maintained in the original form.

State of repair

Conditions of the envelope
The building was in a state of abandonment. The exterior appearance has been preserved in the best possible way to maintain the original character of the building and not to spoil the appearance of the area. Regardless of the state of conservation, the interior structure has been extensively modified to make it liveable.
Description of pre-intervention building services
Before the intervention the building had no heating system. Its function was completely different from after the renovation, in fact it was an agricutural building.

Aim of retrofit

Renovation + Extension
It has been decided to give new life to the otherwise abandoned building. The total change in its function has led to compromises to combine energy efficiency with the preservation of its original appearance. Walls, floor slabs, roofing, heating and electricity systems have been affected.
Was there any change of use?
Transformation of an old unused and unheated agricultural building into a residential single family house.
Lessons learned
This renovation of PlusEnergieBau shows how tradition and integrated photovoltaics can complement each other. It teaches us how to bring old characteristic buildings back to life, increasing their efficiency but maintaining as much as possible their original charm.
Stakeholders Involvement
Architect
Gehret Design GmbH
Gewerbestrasse 19, 3784 Feutersoey
michi@gehret.ch
Tel. 41 78 737 38 85
Energy Consultant
SolarUp Energie, Christoph Ogi
Cheseryplatz 3, 3780 Gstaad
info@solarup.ch
Tel.+41 33 748 10 31
Structural Engineer
Egger Ingenieure AG
Mettlenstrasse 49, 3780 Gstaad, Schweiz
info@eggering.ch
Tel.+41 (0)33 748 84 22
Other
Benz Hauswirth AG
Gstaadstrasse 72, 3792 Saanen
info@benzhauswirth.ch
Tel. 41 33 748 04 44
Tools used
Was the renovation process done following a specific methodology? MuKEn-Standard Exemplary solar architecture + large passive use
Energy calculation SIA 380/1
Hygrothermal assessment No
Life Cycle Analysis (LCA) No
Other No

RETROFIT SOLUTIONS

External Walls

Solid timber wall - external insulation

Stone wall

Solid timber wall - internal insulation

Solid timber wall - external insulation

Three facades have been clad with external thermal insulation while front facade has been clad with a thinner inner layer to preserve its original external appearance. It was chosen to provide external insulation for most of the building to achieve better energy efficiency results, but to maintain at least the main façade. The U-value post intervention is 0.2 W/m2K. There are no evaluation of the U-value before intervention, due to the previous function of the building.

At 84 kWh/m2a, the energy index is relatively high compared with other similar buidings, indicating suboptimal insulation values. However, it was a balancing of interests that led to the original front wall not being covered with external thermal insulation. This made it possible to maintain the original character of the building.

U-value (post-intervention) [W/m2K]: 0,2 W/m²K
More Details
Original wall build-up
Wood - Original wood has been partially maintained.:
150 mm
- Originally it was a one layer wall.:
0 mm
Retrofitted wall build-up
Wood panelling - External finish simulates the original one.:
30mm
Air gap - Cold facade.:
30 mm
Other - Wind paper.:
0 mm
Insulation - Stone wool.:
160 mm
Other - Vapour barrier.:
0 mm
Wood - Original wall has been cladded. :
150 mm
Stone wall

External walls touching the ground are stone made. They are externally insulated as well as the solid timber ones. The transition between timber wall and stone wall is protectet from water infiltration thanks to a moisture barrier.

The original structure is maintained. The original wall was prepared prior to the addition of the insulation by levelling and reinforcing through the application of a layer of concrete. A moisture barrier has been applied. The wall on the back side of the house, where the basement is fully below ground, is part of the extension and is a simple concrete structure with XPS insulation and a waterproof barrier.

U-value (post-intervention) [W/m2K]: 0,2 W/m²K
More Details
Original wall build-up
Stone - Original stone structure.:
370 mm
- Original one layer wall.:
0 mm
Retrofitted wall build-up
Stone - Cladding:
40mm
Insulation - XPS:
160 mm
Concrete - Structure:
220 mm
Stone - Original structure:
150 mm
Solid timber wall - internal insulation

Three facades have been clad with external thermal insulation while front facade has been clad with a thinner inner layer to preserve its original external appearance. It was chosen to provide external insulation for most of the building to achieve better energy efficiency results, but to maintain at least the main façade. No problems were found with humidity.

At 84 kWh/m2a, the energy index is relatively high compared with other similar buildings, indicating sub-optimal insulation values. However, it was a balancing of interests that led to the original front wall not being covered with external thermal insulation. This made it possible to maintain the original character of the building.

U-value (post-intervention) [W/m2K]: 0,2 W/m²K
More Details
Original wall build-up
Wood - Original wood has been partially maintained.:
150 mm
Retrofitted wall build-up
Wood - Original wood structure is exposed:
150mm
Insulation :
80 mm
Air gap :
30 mm
Wood panelling :
30 mm


Windows

Triple glazing wood windows

Triple glazing wood windows

Windows have been renewed to optimise thermal comfort but the original position and shape have not been altered. Some windows contains outer shutter, while others contains roller blinds.

Triple glazing guarantees a high comfort level. Only one window has been added to reach the amount of light necessary in the kitchen space.

Existing window U-value Glass [W/m2K]: 3,0 New window U-value Glass[W/m2K]: 0,7 Existing window U-value Frame [W/m2K]: 3,0 New window U-value Frame [W/m2K]: 1,35
More Details
Existing window type Casement window
Existing glazing type Single
Existing shading type NA
Approximate installation year 1900
New window type Casement window
New glazing type Triple
New shading type Outer shutter and roller blinds.
New window solar factor g [-] 55,0

Other interventions

ROOF

GROUND FLOOR

OTHER

ROOF

The roof has been renovated with the addition of external thermal insulation and an integrated photovoltaic system that covers 154% of the building's energy requirements.

The intervention keeps the original shape of the roof intact, demonstrating that conservation and innovation can work together.

U-value (post-intervention) [W/m2K] 0.17
More Details
Original roof build-up
Shingles - One layer wood shingles roof.:
150 mm
- Exposed wooden work.:
0 mm
Retrofitted roof build-up
Other - Integrated PV system.:
6 mm
Other - Under-roof :
0 mm
Other - Insulation Flumroc PARA:
160 mm
Other - Ampatex DB 90 (vapour barrier and airtight layer):
0 mm
Other - Wood board:
24 mm
Other - Insulation and wooden battens.:
120 mm
Other - Wood surface.:
10 mm
GROUND FLOOR

Floors have been completely replaced with massive concrete slabs. This section describes the basement slab (touching the ground) to show the layering that involves the envelope of the building.

The massive intervention is necessary. In fact, the pre-existing slabs were in no way recoverable. The inclusion of a coils heating system allows a better heat distribution and therefore greater thermal comfort for the inhabitants.

U-value (post-intervention) [W/m2K] 0.17
More Details
Original groundfloor build-up
Floor joists - Wood:
150 mm
Finish - Wood:
20 mm
Retrofitted groundfloor build-up
Finish - Wood (oak):
25 mm
Concrete slab - Lean concrete:
80 mm
Insulation - SwissporLUXIT EPS-T:
20 mm
Concrete slab - Basement slab:
200 mm
Other - Separating layer:
0 mm
Insulation - XPS :
180 mm
Concrete slab - Lean concrete:
50 mm
OTHER

Ground floor and first floor slabs have also been replaced, as the original ones were not in a state of preservation (static and comfort requirements). The wood finish covers most of the floor, excluding the stairs area which has a stone finish.

The wood finish conforms to the final appearance of the house, but does not retain its original appearance. The inclusion of a coils heating system allows a better heat distribution and therefore greater thermal comfort for the inhabitants.

HVAC

HEATING

DOMESTIC HOT WATER

HEATING

The building was not heated. With the renovation an air/water heat pump was installed.

The intervention inside the building was massive due to the absence of comforts in the original construction (change of function). An air-water heating system has been chosen which, through the coils, allows better thermal comfort as the heat is evenly distributed inside the spaces.

More Details
New primary heating system
New system type Heat pump
Fuel Electricity
Distribuition system Radiating floor
Nominal power 6 kW
DOMESTIC HOT WATER

The building did not have domestic hot water previously. The heat pump also provides for this.

The intervention inside the building was massive due to the absence of comforts in the original construction (change of function). An air-water heating system has been chosen which, through the coils, allows better thermal comfort as the heat is evenly distributed inside the spaces.

More Details
New DHW system
Type with heating system
Hot_water_tank Oui
With heat recovery Oui

RENEWABLE ENERGY SYSTEMS

Photovoltaic

Photovoltaic

Roof-integrated solar system, so the PV-panels function as roof cover as well. This intervention is included in the Swiss Solar Prize 2019. It was decided to install the PV system on the roof to take advantage of its favourable position and avoid damaging the green landscape with a ground system. Placing it on the roof takes advantage of an existing element in the panorama.

The building in alpine Gstaad, which was originally used for agricultural purposes but later abandoned, was comprehensively renovated in 2018. The total energy requirement of the now spacious detached house (EFH) is 17,600 kWh/a. The exemplary integrated 32 kW PV system generates around 27,000 kWh of CO2-free solar electricity annually. The resulting homogeneous roof surface corresponds to the simple external appearance of the building. This PlusEnergieBau renovation shows how tradition and integrated photovoltaics can be combined aesthetically very well. Overall, the EFH has an energy supply of 154%. A 13 kWh battery storage increases the own consumption.

More Details
Photovoltaic System
Type Monocrystaline
Collector area 178,0 m²
Total nominal power 31,7 kW
Elevation angle 39,0
Azimuth 44,0
Overall yearly production 27000,0 kWh
Heating contribuition 4984,0 kW
DHW contribuition 2492,0 kW
Cooling contribuition 0,0 kW
Lighting contribuition 3916,0 kW

Energy Efficiency

Energy Performance
Energy performance certificate: MuKEn-Standard Exemplary solar architecture, large passive use
Voluntary certificates: No
Energy Use
Heating
Consumption_estimation_Calculation_method: Steady state simulation (e.g. EPC, PHPP)
Consumption_estimation_After: 4984 kWh/y

Primary Energy
Consumption_estimation_Calculation_method: Steady state simulation (e.g. EPC, PHPP)
Consumption_estimation_Including_DHW: Oui
Consumption_estimation_After: 17'576 kWh/y

Internal Climate

Temperature

The thermal comfort of the occupants is guaranteed thanks to the new walls, roof and floor insulation and the new heating system.

Indoor Air Quality

The building has excellent natural ventilation, so it does not require a mechanical ventilation system. Indoor air doesn't need any intervention due to the privileged position and the good natural air quality.

Daylight

Daylight does not change compared to pre-intervention due to the original size of the openings which was determined by the existing structure.

Acoustic Comfort

Triple glazing windows also improved the acoustic comfort of the house, but the location doesn't need particular expedients. The choice of triple glazing is due to thermal aspects.

Artifact Conservation

NA

Costs

Financial Aspects

There are no financial aspects available.

Running Costs
Lifecycle cost
No

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