Residential and commercial building Feldbergstrasse - Basel

Feldbergstrasse 4+6

4057

Basel, Switzerland

Architect

Viridén + Partner AG
Zweierstrasse 35, 8004 Zürich
info@viriden-partner.ch
+41 43 456 80 80

Owner

EcoRenova AG
Zweierstrasse 35, 8004 Zürich
info@ecorenova.ch
+41 43 456 80 60

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
General rooms such as building services center can be made for groups a visit, the apartments can not be visited. Registration at EcoRenova AG

Street view ©V+P
During the refurbishment of the building on Feldbergstrasse 4 + 6 in the old part of Basel, several requirements of the cityscape commission for façade and roof design had to be met. The challenge was to operate a 6-storey residential building with 12 apartments as completely as possible with solar energy in the protected zone of Basel-Stadt. The entire heat energy requirement (hot water, heating, home ventilation and auxiliary energy) is covered exclusively by the solar energy on the roof of the building.
Energy performance
35 kWh/m2.y

Climate Zone Cfb

Altitude 255 m a.s.l.

HDD 179

CDD 0

Protection level Not listed

Conservation Area:
Yes

Level of Protection:
"Schonzone" of Basel-Stadt, with aesthetic requirements

Building age 1850-1899

Year of last renovation:
2009

Year of previous renovation:
1937

Building use Residential (urban)

Secondary use:
Offices

Building occupancy:
Permanently occupied

Number of occupants/users:
16

Building area Net floor area [m²]: 745,0

Building typology:
Tenement (apartments)

Number of floors:
7

Basement yes/no:
Yes

Number of heated floors:
6

Gross floor area [m²]:
1054,0

Thermal envelope area [m²]:
1065,0

Volume [m³]:
3160,0

NFA calculation method:
SIA 416

Construction type
Brick masonry wall

External finish:
Plaster (on insulation)

Internal finish:
Plastered (on hard)

Roof type:
Pitched roof

+ MORE - LESS
Street view ©V+P
Street view ©V+P
Court view ©V+P
Court view ©V+P
Roof view ©V+P
Roof view ©V+P
Balcony attic ©V+P
Balcony attic ©V+P
Panels ©V+P
Panels ©V+P
Attic ©Nina Mann
Attic ©Nina Mann
Attic ©Nina Mann
Attic ©Nina Mann
Urban environment ©V+P
Urban environment ©V+P
Court before intervention ©V+P
Court before intervention ©V+P

RENOVATION PROCESS

Architecture

BUILDING DESCRIPTION

Two more than 100-year-old apartment buildings on Feldbergstrasse are being renovated to produce more energy than they use for heating/hot water, ventilation and auxiliary energy.
Urban context
The traffic roars incessantly from the Johanniter bridge through the Feldbergstrasse. Cloudy rows of houses bear witness to the bad air and give an idea of how noise and stinking are putting a strain on the health of many residents in the Kleinbasler Quartier. Crossing the road proves to be no easy task.

HERITAGE SIGNIFICANCE

ELEMENTS WORTHY OF PRESERVATION
During the refurbishment of the building on Feldbergstrasse 4 + 6 in the old part of Basel, several requirements of the City Picture Commission for façade and roof design had to be met. After analysis of the front on the Feldbergstrasse, and due to the need to put a new coat of insulation, the project provides formal layout of the façade divided in three levels: the base, shaft and the roof. As store windows are used along the street, a new store window has been realized in one building. In the shaft the windows are inserted with simple new jambs to align to the street front, avoiding to different formal decoration. The blins store boxes have to be inserted in the insulation layer (not visible like neighbor houses). The commission discussed as well the alignments of the roof with the neighbor houses. The colors were decided directly on site.
Heritage Value Assesment
The assessment has been done directly from the Architect with the "City Picture Commission" It includes only the street facade and the roof: as attachment some correspondence with the commission with some points under discussion (official docs in German - the contents of this documents are visible in the various sections regarding historic value)
Heritage Assessment Files

State of repair

Conditions of the envelope
The 12 apartments did not meet today's comfort requirements. Accordingly, the apartments were poorly rented or stood empty. The need for maintenance was high.
Description of pre-intervention building services
The plant was usual for the time of construction, with an oil boiler and high temperature distribution. The ventilation took place with manual opening of the windows. The energy consumption of the two houses was very high.

Aim of retrofit

Renovation
The 12 apartments did not meet today's comfort requirements. Accordingly, the apartments were poorly rented or stood empty. The need for maintenance was great.
Lessons learned
The challenge of covering all the energy needs of the two buildings was very demanding, in particular for the few surfaces that could be used for solar technologies and for certain protection constraints on the street front. However, the great improvement in energy efficiency and the laying of a large storage volume made it possible to achieve the goal.
Stakeholders Involvement
Research Development
Flumroc AG
post office box, 8890 Flums
info@flumroc.com
Tel.+41 81 734 11 11
Architect
Viridén + Partner AG
Zweierstrasse 35, 8004 Zürich
info@viriden-partner.ch
Tel.+41 43 456 80 80
Energy Consultant
Zurfluh Lottenbach
Hertensteinstrasse 44, 6004 Luzern,
kontakt@zurfluhlottenbach.ch
Tel.+41 41 367 00 60
Structural Engineer
Viridén + Partner AG
Zweierstrasse 35, 8004 Zürich
buesser@viriden-partner.ch
Tel.+41 43 456 80 80
Services Engineer
Zurfluh Lottenbach
Hertensteinstrasse 44, 6004 Luzern,
kontakt@zurfluhlottenbach.ch
Tel.+41 41 367 00 60
Other
energiebüro AG
Hafnerstrasse 60, 8005 Zürich
info@energieburo.ch
Tel.+41 43 444 69 10
Other
Arena, Arbeitsgemeinschaft Energie-Alternativen,
Schaffhauserstrasse 34, 8006 Zürich
juergnipkow@arena-energie.ch
Tel.+41 44 362 91 83
Tools used
Was the renovation process done following a specific methodology? 2000 Watt Society
Energy calculation SIA 380/1
Hygrothermal assessment No
Life Cycle Analysis (LCA) Yes
Other Calculation of "2000 Watt" and CO2 balancing

RETROFIT SOLUTIONS

External Walls

Massive wall

Massive wall

Tha facade has been formally changed. Description in the lower section regarding historic value.

All the intervention has been discussed with the "City Picture Commission". Description in the sections regarding historic value. In the "Schonzone" of Basel-Stadt, with aesthetic requirements, the protection constraints are not particularly restrictive.

U-value (pre-intervention) [W/m2K]: 1,4 W/m²K U-value (post-intervention) [W/m2K]: 0,16 W/m²K
More Details
Original wall build-up
Brick - Brickwall :
400 mm
Plaster - Outer plaster:
25 mm
Retrofitted wall build-up
Brick - Brickwall existing:
400mm
Insulation - Mineral wool:
400 mm
Plaster - Outer plaster:
10 mm


Windows

Windows

Windows

The facade on the street has been formally changed (cfr. Wall). Although the windows have been substituted, the dimension of them hasn't been changed, due to the alignment to the neighbour houses. In the shaft the windows are inserted with simple new jambs, avoiding to different formal decoration. Slat blinds have been inserted into the new thermal coating. Windows on the court side have been replaced and changed in size (no heritage protection).

All the intervention has been discussed with the "City Picture Commission".

Existing window U-value Glass [W/m2K]: 2,5 New window U-value Glass[W/m2K]: 0,6 Existing window U-value Frame [W/m2K]: 2,0 New window U-value Frame [W/m2K]: 1,4
More Details
Existing window type Casement window
Existing glazing type Double
Existing shading type Outer shutter
Approximate installation year 1980
New window type Casement window
New glazing type Triple
New shading type Outer shutter
New window solar factor g [-] 0,45

Other interventions

ROOF

GROUND FLOOR

MEASURES TO INCREASE AIRTIGHTNESS

ROOF

Several requirements of the City Picture Commission had to be met. The challenge was to operate a 6-storey residential building with 12 apartments as completely as possible with solar energy in the protected zone of Basel-Stadt. The entire heat energy requirement (hot water, heating, home ventilation and auxiliary energy) is covered exclusively by the solar energy on the roof of the building.

The protection constraints exist only on the street side (north pitch). The south pitch of the roof was completely covered with solar thermal and photovoltaic panels. The north pitch was re-proposed with the dimensions of the previous one, with formal alignments with the neighbour buildings. Two dormers larger than those present in the circumstances have been proposed and accepted by the commission. The roofing of the two dormers was covered with photovoltaic panels.

U-value (pre-intervention) [W/m2K] 2 U-value (post-intervention) [W/m2K] 0.1
More Details
Original roof build-up
Tiles - Plain tiles and Sheet metal:
10 mm
Other - Wood board:
22 mm
Other - Wood stud:
160 mm
Retrofitted roof build-up
Other - Sun collector:
50 mm
Other - battens and counter battens:
85 mm
Other - Wood fiber board:
50 mm
Other - Rafter blow out with cellulose:
1 mm
Other - Woodlath:
30 mm
Other - Plasterboard:
15 mm
GROUND FLOOR

The wooden beamed ceiling against unheated basement rooms were insulated (cavities filled with insulation plus on the bottom a continuous insulation layer).

No restrictions regarding this element.

U-value (pre-intervention) [W/m2K] 2.4 U-value (post-intervention) [W/m2K] 0.15
More Details
Original groundfloor build-up
Finish - Floor:
15 mm
Other - Board:
25 mm
Other - Wood beam:
160 mm
Retrofitted groundfloor build-up
Other - Floor:
20 mm
Other - Board:
30 mm
Insulation - Insulation:
400 mm
Other - Wooden Board:
20 mm
MEASURES TO INCREASE AIRTIGHTNESS

A centralized ventilation with heat recovery, typical of the Minergie buildings, was added to the building, but a tightness test was not carried out.

Airtightness (pre-intervention) [ach@50Pa] 0 Airtightness (post-intervention) [ach@50Pa] 0

HVAC

HEATING

VENTILATION

DOMESTIC HOT WATER

HEATING

The total heat energy demand (hot water, heating, ventilation and auxiliary energy) is covered exclusively by the solar energy on the roof of the building.

For the heating system there were no particular protection conditions, except for the laying of panels on the roof.

More Details
New primary heating system New secondary heating system
New system type Solar thermal panels with storage (tank 40'000 l) with integrated heat-exchanger. Heat pump
Fuel Sun Electricity
Distribuition system Radiators Radiators
Nominal power about 13 kW (34.5 m2 - production 530 kWh/m2a) kW 14,5 kW
VENTILATION

A centralized ventilation with heat recovery, typical of the Minergie buildings, was added to the building, but a tightness test was not carried out.

The intervention for ventilation was done entirely internally without repercussions on the façade. The air intakes pass in the subsoil of the court.

More Details
Original roof build-up New ventilation system
Type ventilation system Centralized
Type flow regime Overflow
Heat recovery Yes
Humitidy recovery No
Nominal power 0,9 kW
Electric power 0,31 kW
Control system Airfox
DOMESTIC HOT WATER

Thermal panels with storage (tank 40'000 l) with integrated heat-exchanger.

For the domestic hot water there were no particular protection conditions, except for the laying of panels on the roof.

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

RENEWABLE ENERGY SYSTEMS

SolarThermal

Photovoltaic

SolarThermal

Solar thermal panels with storage (tank 40'000 l) with integrated heat-exchanger.

Several requirements of the cityscape commission for façade and roof design had to be met. In this case solar panels have been integrated in the south pitch which hasn't any requirements of protection.

Thermal collectors from Ernst Schweizer AG Type: AV 23 light flat collector Total 34.5 m2 integrated in the roof area.

More Details
SolarThermal System
Type Flat collector
Collector area 34,5 m²
Elevation angle 30,0
Azimuth 156,0
Overall yearly production 18200,0 kWh
Heating_contribuition 2400,0 kWh
DHW contribuition 15810,0 kWh
Cooling contribuition 0,0 kWh
Photovoltaic

Three different types of modules and integrated models have been used: -Sanyo HIP 195 with integrating System INDACH (Roof and garret south) -Sanyo HIP 245 (Garret north) -Special execution (Window lintel garret south)

Several requirements of the cityscape commission for façade and roof design had to be met. In this case PVpanels have been integrated in the south pitch which hasn't any requirements of protection and on the dormers roofs on the north pitch. This solution has been discussed and accepted by the Commission.

The PV mounting system for in-roof solutions offers the utmost independence in the selection of solar modules with minimum installation effort. The tiles-tightness of the system is achieved by a safe construction solution that drains the rainwater from top to bottom as with conventional tiles.

More Details
Photovoltaic System
Type Monocrystaline
Collector area 63,7 m²
Total nominal power 13,0 kW
Elevation angle 30,0
Azimuth 156,0
Overall yearly production 9000,0 kWh
Heating contribuition 9000,0 kW
DHW contribuition 0,0 kW
Cooling contribuition 0,0 kW
Lighting contribuition 0,0 kW

Energy Efficiency

Energy Performance
Energy performance certificate: No
Voluntary certificates: Plus-Wärmeenergiehaus (more than ZEB)
Energy Use
Heating
Primary Energy 50 kWh/m2.y
Documents:
C13 003 Datenbaltt und Kennzahlen.pdf
Data sheet
Diagramme_1.pdf
Bilanz
C11 202 Energiefluss#A5BDB0.pdf
Energy flow 2011

Consumption_estimation_Before: 190 kWh/m2.y
Consumption_estimation_After: 35 kWh/m2.y

Primary Energy
Consumption_estimation_Calculation_method: Steady state simulation (e.g. EPC, PHPP)
Documents:
G-09-08-20 Viriden.pdf
Swiss solar price publication

Consumption_estimation_Before: 210 kWh/m2.y
Consumption_estimation_After: 50 kWh/m2.y
Measured Parameters
Internal Climate
Type_of_monitoring: Punctual
Description: All energy production and consumption are recorded.

Internal Climate

Temperature

Only adjustable via room thermostats at the radiators.

Indoor Air Quality

Installation of a controlled apartment ventilation, where each apartment can be set separately.

Daylight

-

Acoustic Comfort

Requirement according to SIA 181 - Fulfills the minimum to increased requirements.

Artifact Conservation

-

Costs

Financial Aspects

Energy costs are CHF 0.00 (All energy for heating and hot water is produced in the building in the balance itself).

Investment Costs
Total investment costs
5.0 Mio CHF (total)
Amount includes: BKP 1 to 5: demolition, buildings, solar systems, surrounding and additional costs.

Cost of energy related interventions:
CHF 500’000.- (total)
Amount includes: Insulation, plants (Heatpump, PV panels, solar thermal, ventilation)
Running Costs
Total annual energy cost
0 (total)

Annual heating cost
0 (total)
(includes DHW) Yes

Annual electricity cost
145 (per m2)

Lifecycle cost
Maintenance costs per year approx. 28'000.- (PV plant yield approx. CHF 8'000.-).

Environment

Greenhouse Gas Emissions
Methodology_used: Greenhouse gas according to SIA D 0216 Efficiency path
Documents:
G-09-08-20 Viriden_1.pdf
emissions_at_use_stage_before_intervention: 69 kg/y per m2
emissions_at_use_stage_after_intervention: 8 kg/y per m2
emissions_before_use: NA
Building_Lifetime: 40
Life Cycle Analysis
Methodology_used: 2000 Watt Society
Documents:
Diagramme.pdf
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