Single-family home in Dorfen
Construction Due to their low degree of compactness, free-standing single-family homes place high demands on the energy performance of constructional and technical components. The U-values of the thermal envelope must be around 0.1 W/m2K, or sometimes even lower. In this project, these demands have been fulfilled at very low cost and in combination with a very simple standard in the fit-out. A reinforced concrete ground slab with load-bearing perimeter insulation below forms the base of the building. All other structural elements were built as a lightweight timber construction. Since a decision was made to construct the exterior walls without an installation cavity, the wood frame elements were very inexpensive owing to the small number of layers. Instead, the electrical installations have been incorporated in the insulation plane. To meet the high requirements concerning airtightness, the wall elements were equipped with airtight sockets and installation pockets before arriving on site. These work processes required a great deal of experience and accuracy, as it would have been extremely difficult to remedy any leakages determined during the blower-door pressure test after having erected the walls. The floor is a Brettstapel panel with a conventional screed finish. For cost reasons OSB panels, which would have been required anyway for stiffening purposes, have been used for the interior fit-out. Because the same material has been used for the flooring, the appearance of the interior is extremely uniform and only interrupted by the door and window openings. Building services The building services are located inside the thermal envelope in two small plant rooms stacked on top of each other in the north-eastern corner. A gas condensing boiler was installed with a solar collector plant to provide domestic hot water and support the heating system. The mechanical ventilation unit with a heat recovery system uses a brine heat exchanger for frost protection purposes in winter. A ground heat exchanger would have been very expensive without the construction of a basement storey. Due to the open layout, the air ducts have only been incorporated in the ancillary rooms. The heat is supplied to the rooms through a heating water circuit and radiators. This means that the air volume can be set and controlled independently from the heating.
4
3 5
2 5
1
6 5.10
3 1
6
2
5
5 5
5
5
a
b 4 solar collectors for the provision of hot water and heating 5 radiators 6 brine heat exchanger
1 gas boiler 2 500 l buffer heat store 3 comfort ventilation unit with heat recovery
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outside air supply air extract air exhaust air heating 5.11
Building data Use residential Areas 161 m2 113 m2 409.3 m2
floor space index (FSI) gross volume (V) A / V ratio A weighted /TFA
0.36 611.7 m3 0.67 3.11
roof ground slab glazing-to-floor area ratio (glazing/TFA)
0.1 W/m2K 0.07 W/m2K 0.213
wall window: Uw-value g-value
0.1 W/m2K 0.708 W/m2K 0.61
Energy performance data
PHPP
space heat demand primary energy heat supply rate GWP (CO2 equivalent)
13.8 kWh/m2a 115.5 kWh/m2a 86 % 28.2 kg/m2
heat load ventilation system blower-door test 1/h (50 Pa)
10.3 W/m2 central 0.29
Heat supply system
gas condensing boiler
energy carrier photovoltaic plant
natural gas not installed
solar collector plant (coverage rate)
49 %
gross floor area (GFA) treated floor area (TFA) thermal envelope area (A) U-values [W/m2K]
Particularities frost protection layer with brine circuit 5.12
51