Client:
Hufnagel family
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Slevogtweg, Hanover
Description
The previous owners have refurbished the 2,5-floor house at the end of the 90s from inside in personal contribution and equipped the exterior walls with a 8 cm thick heat insulation system. The asymmetric gabled roof was situated in its original condition and had a little dormer to the north side. In the course of time, the windows were refurbished as 2-disc-insulating glass with plastic frame. Annual energy need including water heating amounted recently to 260 kWh per m² living space.
The roof truss had to be demolished due to the installation of two large dormers. Thereby, the thermal protection could be optimized by the rebuilding it with boardwalk carriers. In front of the existing exterior wall insulation, a new design in lightweight wood was elevated with larch cladding and anchored to the house. The windows of the south and west facades have been enlarged to French doors to let more light into the rooms. Each window was substituted through new larch wooden windows with heat insulating 3-pane-glazing. The addition was demolished and rebuilt. The heating received a condensing gas boiler witht some solar space heating support. Each floor was equipped with a comfort ventilation system with heat recovery. The basement ceil was insulated from underneath.
Involved parties
Design:
Lindener Baukontor, client
Execution:
Co. Heinrichs, Herford (carpentry; addition roof truss), Co. Klauenberg, Hanover (carpentry; windows and oriel), Co. Corona Solar, Hannover (heating and solar heating, comfort ventilation system)
Building data
Building type:
Two-family house with possible division into three residential units
Location:
Hanover-List
Year of construction:
1952
Modernization:
2002 - 2006
Residential units:
3
Heated usable space:
224 m2
Subsidies:
KfW, Land Niedersachen, BAFA, proKlima
Initial situation
EXTERIOR WALLS:
ca. 40 cm brickwork with 8 cm thermal insulation system, HTC ? 0.4 W / (m2K)
WINDOWS:
Mix of wooden and plastic windows with double glazing, HTC window ? 3 W/(m2K)
ROOF:
uninsulated rafter roof with 5 cm thick underlay wood wool board, HTC ? 1.8 W / (m² K)
BASEMENT CEILING:
uninsulated box tile ceiling
VENTILATION:
Window ventilation, as well as typical old building joints and cracks
HEATING:
Gas low temperature boiler with a capacity of 24 kW, year of completion 1987; the heat distribution network was expanded in the course of time, depending on the upgrade progress without hydraulic balancing
Modernization in detail
EXTERIOR WALLS:
Elevation of a prefabricated lightweight timber wall planked with a diffusible fiberboard and externally provided with larch cladding, insulated with 20 cm cellulose insulation, quality of 0.04 W / (mK); the existing thermal insulation system is still in use, HTC = 0.14 W / (m2K)
WINDOWS:
Enlargement of the window area in the south and west facades and installation of larch wood windows with 3-pane glazing, HTC = 0.8 - 1.1 W / (m2K), roof windows with 3-pane glazing, HTC = 1,0 W/(m2K)
ROOF:
Installation each of a dormer on the south and north side of the roof, new roof framework with 40 cm wooden walkway supports, topside permeable fiberboard, underside particle board, in between a total of 40 cm cellulose insulation, quality of 0.04 W / (mK) were blown in, HTC = 0.12 W / (m2K)
BASEMENT CEILING:
Insulating the basement ceiling from underneath with overall 10 cm polystyrene insulation, quality mainly 0.035 W / (mK), HTC = 0.35 W / (m2K)
VENTILATION:
Each floor is equipped with a comfort ventilation system with heat recovery
HEATING:
central buffer storage (650l) with integrated gas burner (condensing boiler) combined with 10 m2 flat plate collectors for solar space heating and water heating
AIR CONDITIONING:
no active air conditioning installed
Measured values
AIRTIGHTNESS:
n50 = 1,4 h-1
Calculated values
Calculation method: Passivhaus planning package; Initial values: Hannover building typology
HEATING ENERGY NEEDS:
BEFORE
160 kWh/(m²a)
AFTER
37 kWh/(m²a)
SAVINGS
77 %
TOTAL ENERGY NEEDS FOR HEATING,AIR CONDITIONING,DHW,ELECTRICITY:
BEFORE
Gas
257 kWh/(m²a)
Electricity
20 kWh/(m²a)
AFTER
Natural gas
46 kWh/(m²a)
Electricity
24 kWh/(m²a)
PRIMARY ENERGY NEEDS FOR HEATING,AIR CONDITIONING,DHW,ELECTRICITY:
BEFORE
341 kWh/(m²a)
AFTER
104 kWh/(m²a)
SAVINGS
70 %
CO2-EMISSIONS FOR HEATING,AIR CONDITIONING,DHW,ELECTRICITY:
BEFORE
75 kg/(m²a)
AFTER
24 kg/(m²a)
SAVINGS
68 %
