Client:
Baugenossenschaft Oberricklingen e. G.
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Quellengrund, Hannover
Description
The existing structure contained 14 apartments, two of which were on the top floor next to an unheated attic. A comprehensive modernization was done using Passivhaus components in order to make the apartments more comfortable while also lowering renters' energy costs. Reducing heat bridging was given special attention. The old continuous balconies, which were creating cold and moisture-prone ceiling areas, were removed and replaced with large balcony towers in front of the facade. Due to their outdated technological condition, the top-floor apartments were dismantled as part of the modernization. Instead, the entire top floor is now used as an unheated drying loft. The top floor ceiling is insulated from above to Passivhaus standards. The stairwell walls adjacent to the unheated basement and attic areas have also been "dressed" for the weather; now, the stairwell is a warm area located entirely within the insulated building shell.
The new central heating system, which uses a condensing gas boiler, is housed in the basement. The walls separating the heating room from the unheated basement area are insulated, as are the exterior underground walls. The apartments are heated using the heaters already in place. The entire heating network is equilibrated hydraulically.
Parties involved
Design and construction management:
bauart Architekten
Building technology quality control:
Planungsbüro Peter Schmidt
Building data
Building type:
Apartment complex
Location:
Hannover-Limmer
Year of construction:
1958-1960
Modernization:
2010-2011
Residential units:
12
Heated usable space:
714 m²
Subsidies:
KfW, proKlima
Initial condition
Exterior Walls:
24 cm vertical coring brick masonry with plaster
Windows:
Windows with heat-insulating double glazing; 28-year-old skylight windows on top floor
Roof:
uninsulated collar beam roof
Basement ceiling:
Reinforced concrete with floating cement screed
Ventilation:
Ventilation through windows as well as through joints and cracks typically found in old buildings
Heating:
self-contained central gas heating systems built between 1977–2007, plus night-storage heaters and flow heaters on top floor
Modernization in detail
Exterior walls:
30 cm polystyrene composite thermal insulation system; quality: 0.035 W/(mK); HTC = 0.11 W/(m2K)
Windows:
synthetic-profile Passivhaus windows with heat-insulating triple glazing and stainless-steel glass spacers; HTC = 0.8 W/(m2K)
Top floor ceiling:
Uppermost ceiling insulated 24 cm thick from above; quality: 0.035 W/(mK), HTC = 0.13 W/(m2K)
Roof:
15 cm insulation between rafters; HTC = 0.25 W/(m2K)
Basement ceiling:
6 cm polyurethane insulation on underside of basement ceiling; quality: 0.025 W/(mK), HTC = 0.31 W/(m2K)
Interior walls adjoining unheated rooms:
12 cm polystyrene insulation; quality: 0.032 W/(mK), HTC = 0.23 W/(m2K)
Ventilation:
comfort-ventilation system with heat recovery in each apartment
Heating:
new central condensing gas boiler; 500-liter stratified storage tank; new distribution network to existing heaters
Air conditioning:
no active air conditioning
Measured values
AIRTIGHTNESS:
n50= 0.1,4 h-1
Calculated values
Calculation method: Passivhaus planning package; Initial values: Hannover building typology
HEATING ENERGY NEEDS:
BEFORE
150 kWh/(m²a)
AFTER
30 kWh/(m²a)
SAVINGS
80 %
TOTAL ENERGY NEEDS FOR HEATING,AIR CONDITIONING,DHW,ELECTRICITY:
BEFORE
Gas
231 kWh/(m²a)
Electricity
25 kWh/(m²a)
AFTER
Gas
60 kWh/(m²a)
Electricity
18 kWh/(m²a)
PRIMARY ENERGY NEEDS FOR HEATING,AIR CONDITIONING,DHW,ELECTRICITY:
BEFORE
324 kWh/(m²a)
AFTER
114 kWh/(m²a)
SAVINGS
65 %
CO2-EMISSIONS FOR HEATING,AIR CONDITIONING,DHW,ELECTRICITY:
BEFORE
72 kg/(m²a)
AFTER
26 kg/(m²a)
SAVINGS
64 %
