Client:
Dr. Ulrich Stiebel
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Schaufelderstraße, Hannover
Description
During the "chaos days" of the mid-90s, the plundering of a supermarket within it brought the building a sad kind of fame. Its combination of completely outdated building technology, unattractive apartment layouts, high energy costs, and lack of comfort drove would-be renters away, and the building fell into ever-greater disrepair. After the renovation work, the building is hardly recognizable anymore. Intelligent planning made it possible to expand its total living space and usable area from 1,709 to 2,100 square meters. For example, the roof was converted into an attractive additional story of living space. The building's post-modernization heating energy needs are just 15 kWh/(m2a) – around 70 percent under current standards for new constructions. This reduction was achieved with the help of top-quality insulation, minimization of heat bridges, improved airtightness of the building shell, and the incorporation of highly efficient ventilation equipment with heat recovery. Passivhaus building standards create ideal conditions in which to use two efficient heat pumps as heat supply sources. But that is not all the building's roof has a photovoltaic system with a total of 110 modules, which generates almost as much electricity as the heat pumps require. The property was extremely well-received on the rental market: new renters can now be found for vacated apartments within a very short amount of time. The building's operating costs total just 54 percent of the averages calculated by the German Renter's Association. Energy price increases have a negligible influence on total rent prices.
Parties involved
Design:
PassivHausKonzepte,
Dipl.-Ing. Architect
Rainer Wildmann
Building data
Building type:
Residential and commrcial building
Location:
Hannover-Nordstadt
Year of construction:
around 1950
Modernization:
2005-2007
Residential units:
32 apartments, of which 4 handicapped-accessible; 2buisness units
Heated usable space:
2.100 m²
Subsidies:
KfW, dena-Modellprojekt, proKlima
Initial condition
Exterior Walls:
plastered solid-brick masonry; HTC ?1.3 W/(m2K)
Windows:
Wooden windows with heat-insulating double glazing; HTC = 2.8 W/(m2K)
Roof:
uninsulated concrete ceiling on top floor; HTC ? 2.9 W/(m2K)
Basement ceiling:
20 cm concrete ceiling; HTC ?1.5 W/(m2K)
Ventilation:
Ventilation through windows as well as through joints and cracks typically found in old buildings
Heating:
some self-contained central gas heating systems; some electrically- powered night storage heaters
Modernization in detail
Exterior walls:
Ground floor exterior walls: 10 cm composite thermal insulation system; quality: 0.032 W/(mK); HTC = 0.24 W/(m2K) Exterior walls on upper floors: 22 cm composite thermal insulation system; quality: 0.032 W/(mK); HTC = 0.13 W/(m2K)
Windows:
new Passivhaus windows with heat-insulating triple glazing; HTC = 0.8 W/(m2K)
Roof:
36 cm mineral wool insulation between rafters; quality: 0.035 W/(mK), HTC = 0.11 W/(m2K)
Basement ceiling:
new construction to hold insulation: OSB slabs on wooden lightweight beams, filled in with cellulose filling material; quality: 0.040 W/(mK); HTC = 0.12 W/(m2K)
Ventilation:
one comfort-ventilation system with heat recovery per unit
Heating:
two separate water-to-water heat pump systems which use the same well system as their energy source: surface heating provided by one 13-kW heat pump with a low flow temperature; heating elements using heating water supplied through a 22-kW heat pump; drinking water heated in a two-step process
Measured values
AIRTIGHTNESS:
n50= 0.63 h-1
Calculated values
Calculation method: Passivhaus planning package; Initial values: Hannover building typology
HEATING ENERGY NEEDS:
BEFORE
230 kWh/(m²a)
AFTER
15 kWh/(m²a)
SAVINGS
93 %
TOTAL ENERGY NEEDS FOR HEATING,AIR CONDITIONING,DHW,ELECTRICITY:
BEFORE
Gas
173 kWh/(m²a)
Electricity
153 kWh/(m²a)
AFTER
Electricity
25 kWh/(m²a)
PRIMARY ENERGY NEEDS FOR HEATING,AIR CONDITIONING,DHW,ELECTRICITY:
BEFORE
592 kWh/(m²a)
AFTER
43 kWh/(m²a)
SAVINGS
93 %
CO2-EMISSIONS FOR HEATING,AIR CONDITIONING,DHW,ELECTRICITY:
BEFORE
129 kg/(m²a)
AFTER
10 kg/(m²a)
SAVINGS
92 %
