advanced building skins 14 | 15 June 2012 - lamp.tugraz.at - Graz ...

Advanced Building Skins
comply with the LEH-standard. The results indicated that the planned target values for space heating
had been achieved. The target-actual-comparison based on measured energy consumption showed
good matches in general for all housing estates. The consumption of useful energy was about on the
same level as the calculated demand values for space heating considering an actual indoor air
temperature of 23 °C and actual climate data. [1], [2], [4]
The PH standard saved about 30 kWh/(m².a) delivered energy on average compared with conventional
housing estates of the same construction period [1]. Many of the conventional reference buildings
already comply with LEH standard because of legal regulations for subsidized residential buildings.
Nevertheless, critical voices claim that PH might have a worse life cycle performance than LEH e.g.
due to higher electrical energy consumption for the ventilation system or due to higher ecological
effort for the production of the building skin. Therefore the main questions of this paper were:
How much environmental benefit is actually achieved by PH compared to conventional
residential complexes?
Impact of different insulation materials and different insulation thickness of external thermal
insulation composite systems (ETICS) on the life cycle performance?
1 Methodology
1.1 Life Cycle Assessment of Buildings and Building Materials
Building materials were investigated from cradle (raw materials extraction) to grave (dismantling and
end-of-life assessment). The methodology of the BNB system “Assessment System for Sustainable
Building” (BMVBS [6]) of the German federal ministry of transport, building and urban development
has been applied. This methodology is mandatory for federal buildings in Germany and the life cycle
assessment is consistent with the certification system of ÖGNI (Austrian sustainable building council)
and DGNB (German sustainable building council) as well as with EN 15978 and EN 15804.
According to this methodology a service life of 50 years is assumed for the assessment of residential
buildings and maintenance is taken into account by default values for the service life of building
materials.
The environmental impact was calculated with the database “Ökobau.dat 2009” [5] that is used for the
BNB, ÖGNI and DGNB certification and is based on the database of PE International and on EPD
datasets (environmental product declarations according to ISO 14025) verified by IBU (Institute
Construction and Environment e. V., Königswinter). As functional unit or service unit 1 m² gross floor
area with climatic conditioning according to OIB [3] was used. The conversion factors of the Austrian
building directive [3] have been used and are listed in table 1.
Table 1: Conversion factors for primary energy and greenhouse gas emissions [3]
Delivered energy Nonrenewable primary energy
kWh/kWh
- 2 -
CO2 emissions*
g/kWh
Electrical energy 2.15 617
Fossil gas 1.17 236
* The OIB directive [3] for the calculation of the energy certificate of buildings uses
CO2-emissions instead of CO2-equivalents as indicator for climate protection.
1.2 Description of Passive Housing Estate Mühlweg-C
The housing estate Mühlweg-C was completed in 2006 in Passive House standard with support of the
impulse program “Building of Tomorrow” of bmvit (Federal Ministry for Transport, Innovation and
Technology). The complex consists of four buildings with a mixed structure of massive timber and
concrete. 70 residential units have been realized with an eligible useable living area of 6748 m².