Client:
Energiekonzept GmbH & Co. KG
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Hauptstraße 7, Wennigsen
Description
Before the modernization
The building, which dates back to 1900, last underwent major renovations in 1961; however, neither thermal insulation nor efficient heating and ventilation technology were included in that renovation work. When the new owners began doing comprehensive energetic modernization work on it in 2008, the 775-square-meter building had been empty for three years.
The modernization
Today, every aspect of the modernized residential and commercial building in central Wennigsen is perfectly coordinated: members of several generations live side by side under one roof, and residential life harmonizes with work and business life. Having completely gutted the building, implemented a new handicapped-accessible and senior-appropriate room concept, and consistently incorporated Passivhaus components, the owners now have an efficient and comfortable overall system with practically zero CO2 emissions. The showpiece structure currently includes three apartments, an office, and two shops. Passivhaus windows, high-quality insulation, and a comfort-ventilation system with heat recovery have allowed the owners to reduce building heating energy consumption from 150,000 kilowatt hours per year to just 14,000. A clever design feature uses the hair dryers in the ground-floor salon to everyone's benefit: the heat they produce is directed into the comfort-ventilation system and used to heat cold supply air without using additional energy. An old masonry wall and exposed sections of foundation help keep memories of the original building alive.
Parties involved
Planning:
PBS PlanungsBüro Schmidt
Building data
Building type:
Residential and commercial building
Location:
Wennigsen
Year of construction:
circa 1900
Modernization:
2008
Units:
3 apartments
1 office and 2 stores
Heated living space:
775 m²
Subsidies:
Region Hannover, KfW
Initial condition
Exterior Walls:
36 cm double masonry walls; HTC ?1.5 W/(m2K)
Windows:
Mixture of single-pane and thermal-glazed windows; HTC ? 2.5 –5 W/(m2K)
Roof:
uninsulated rafter roof
Basement ceiling/ Floor plate:
no insulation
Ventilation:
Ventilation through windows as well as through joints and cracks typically found in old buildings
Heating:
20-year-old oil heater; water heated via electric flow heater
Modernization in detail
Exterior walls:
24–40 cm polystyrene composite thermal insulation system, quality: 0.032 W/(mK); insulated vertical coring brick also used in some places HTC= 0.1– 0.14 W/(m2K)
Windows:
new Passivhaus windows: heat-insulating triple glazing in wood-aluminum frames with plastic glass spacers; HTC = 0.8 W/(m2K) plus new skylight windows with heatinsulating triple glazing
Roof:
Rafter roof with extra panels, 36 cm cellulose insulation in total, plus 5 cm wooden softboard plates; HTC = 0.12 W/(m2K)
Basement ceiling/ Floor plate:
Areas with new floor construction: 8 cm polyurethane insulation, quality: 0.022 W/(mK); 4 cm footfall sound insulation, quality: 0.040 W/(mK)
Ventilation:
central comfort ventilation system offering 87 % heat recovery
Heating:
new wood-pellet block heating station; one 9 kW electric heating rod serves as a reserve system; heat distribution via heating elements with high heat transfer ratios, plus radiant heating panel in office ceiling
Measured values
AIRTIGHTNESS:
n50= 0.58 h-1
Calculated values
Calculation method: Passivhaus planning package; Initial values: Hannover building typology
HEATING ENERGY NEEDS:
BEFORE
190 kWh/(m²a)
AFTER
18 kWh/(m²a)
SAVINGS
91 %
TOTAL ENERGY NEEDS FOR HEATING,AIR CONDITIONING,DHW,ELECTRICITY:
BEFORE
Electricity
32 kWh/(m²a)
Oil
263 kWh/(m²a)
AFTER
Pellets
49 kWh/(m²a)
Electricity
21 kWh/(m²a)
TOTAL GENERATED ENERGY (AFTER):
WOOD PELLET BLOCK HEATING STATION
Electricity
5.100 kWh/(a)
PV SYSTEM
Electricity
6.400 kWh/(a)
PRIMARY ENERGY NEEDS FOR HEATING,AIR CONDITIONING,DHW,ELECTRICITY:
BEFORE
377kWh/(m²a)
AFTER
23 kWh/(m²a)
SAVINGS
94 %
CO2-EMISSIONS FOR HEATING,AIR CONDITIONING,DHW,ELECTRICITY:
BEFORE
100 kg/(m²a)
AFTER
6 kg/(m²a)
SAVINGS
94 %
