Client:
Kreissiedlungsgesellschaft Hannover mbH (KSG)
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Homannstrasse, Ronnenberg
Description
The building of the year 1958, which was located in Ronnenberg, was nearly in its original condition. The 45 years of using without any appreciable diversification got apparent. Both in visual aspects and in requirements of living comfort, insulation and efficient use of heating energy, the building didn’t meet the current entitlements. Missing insulation of exterior walls, roof and basement ceiling as well as a outdated heating system were the main reasons for high energy consumption.
Therefore, high standards were especially created for the insulation of exterior walls, roof and basement ceiling and even for the installation of passive house windows with 3-pane-glazing. For modernizing the heating system, a central condensing gas boiler with hot water tank was built in. Furthermore, the radiators were customized to the reduced heat demand through hydraulic adjustment. A central comfort ventilation system with heat recovery functions distributes each apartment with constant fresh air to and transports humidity of bathrooms and kitchens outside. A geothermal energy exchanger supports this system in preheating the outside air. Moreover, through the expansion of the attic space for two new apartments was created.
Involved parties
Design:
architects Freese und Reebe, Hanover, KSG, Hnnover
Quality management:
Büro für Bauphysik Horschler, Hannover Enakon Wolfenbüttel GmbH, Dipl.-Ing. Voigt
Building data
Building type:
Apartment house
Location:
Ronnenberg-Empelde
Year of construction:
1958
Modernization:
2004 - 2005
Residential units:
12
Heated usable space:
ca. 590 m²
Subsidies:
KfW, proKlima
Initial condition
EXTERIOR WALLS:
solid lightweight concrete exterior wall with a supplement of natural pumice
WINDOWS:
2-pane windows with double glazing, HTC = 2.7 W / (m2K)
ROOF:
Sloping ceiling and top ceiling uninsulated
BASEMENT CEILING:
uninsulated reinforced concrete ribbed ceiling
VENTILATION:
Window ventilation, as well as typical old building joints and cracks
HEATING:
each apartment is equipped with gas combi boilers for heating and hot water
Modernization in detail
EXTERIOR WALLS:
Insulating each exterioir wall with 20 cm composite heat insulation system, quality 0,035 W/(mK), HTC = 0,15 W/(m2K)
WINDOWS:
passive house windows with heat-insulating 3-pane-glazing, HTC = 0,79 W/(m2K)
ROOF:
With modernizing the building, two new residential units were created. The roof areas were insulated with 26 cm of mineral wool between the rafters, quality of 0,04 W/(mK), HTC = 0,18 W/(m2K)
BASEMENT CEILING:
Insulation of the basement ceiling from underneath with 10 cm polystrene insulation, quality of 0,04 W/(mK), HTC = 0,32 W/(m2K)
VENTILATION:
central ventilation system with heat recovery functions; installation in the basement in combination with a geothermics heat exchanger
HEATING:
central gas fired boiler with hot water tank
AIR CONDITIONING:
no active air conditioning installed
Measured values
AIRTIGHTNESS:
n50 = 0,62 h-1
Calculated values
HEATING ENERGY NEEDS:
BEFORE
150 kWh/(m²a)
AFTER
34 kWh/(m²a)
SAVINGS
77 %
TOTAL ENERGY NEEDS FOR HEATING,AIR CONDITIONING,DHW,ELECTRICITY:
BEFORE
Gas
236 kWh/(m²a)
Electricity
17 kWh/(m²a)
AFTER
Natural gas
65 kWh/(m²a)
Electricity
24 kWh/(m²a)
PRIMARY ENERGY NEEDS FOR HEATING,AIR CONDITIONING,DHW,ELECTRICITY:
BEFORE
308 kWh/(m²a)
AFTER
135 kWh/(m²a)
SAVINGS
56 %
CO2-EMISSIONS FOR HEATING,AIR CONDITIONING,DHW,ELECTRICITY:
BEFORE
68 kg/(m²a)
AFTER
31 kg/(m²a)
SAVINGS
54 %
