Starting point and Motivation
In the life cycle assessment of a building two phases are essential: the production of the building materials for construction and renovation on the one hand, the operation of the building on the other hand. Up to now these life phases of a building are assessed with two different methods in Austria:
- the operating energy within the framework of the energy performance certificate (short EAW)
- the manufacturing energy with the so called ‘Oekoindex’
So far a combined assessment of operation and construction of buildings isn’t intended neither in the framework of the energy performance certificate nor within the ecological building assessment via Oekoindex.
Moreover the evaluation of the building construction is mostly limited to the thermic relevant building components (namely ‘OI Bilanzgrenze’ BG0 or BG1). Although some of the building assessment systems (like klimaaktiv, TQB, KGA) up to now do consider the thermic non relevant building components (underground parking, basements, etc.) like with ‘OI BG3’, the broad implementation of a more comprehensive building assessment fails due to the missing tools to track and evaluate the building components aside the energy performance certificate with as little effort as possible. In addition other building components like unconditioned staircases, access balconies, balconies and adjoining buildings as well as building equipment systems are not taken into consideration even in the ‘OI Bilanzgrenze BG3’.
Contents and Objectives
The project „HEROES – Houses for energy and ResOurceEffiecient Settlements” was set up to develop a method to oppose the building operation to the building construction consistently. This allows gathering and displaying the “ecological usefulness” of measures to improve the energetic building quality in operation (higher insulation thickness, PV systems etc.) with keeping track of the higher efforts.
Further a simplified calculation method should be developed which allows to include HVAC systems and building components which are not already assessed in the energy performance certificate into the ecological evaluation. Ideally this should be done with as little effort as possible. To reach this goal a simplified calculation model for these building components has to be developed and integrated into the programmes which are participating in the project and calculate values for the energy performance certificate and ecological parameters.
The contents will be accessible with the following software soulutions:
- ‚ArchiPHYSIK 15‘ (http://www.archiphysik.at/)
- ‚AX3000 Energieausweis‘ (https://www.ax3000-group.de/energieausweis/)
- ‚baubook ökobilanz‘ for buildings (www.baubook.info/eco2soft)
For the mutual consideration of building operation- and construction the respective calculation and accounting basics (conversion factors, life cycle assessment (LCA) methods) were analysed and methodically equilibrated. Moreover the determining factors, which essentially influence the mutual consideration of building operation and construction, were examined. Hereby especially the consideration of the service lifetime, the definition of the reference area and the selection of the evaluation indicators were investigated.
As basis for the simplified calculation of building components, which are not yet included in the energy performance certificate, three family homes, eight types of the so called KliNaWO project and five apartment houses (multiple apartments) were recorded and assessed in detail. As a result the relevance of the respective building components can be expressed.
The first step was to calculate a surface and a mass balance of the identified building components. In a second step these were assigned to the building components and the building materials. During both steps parameters, which were relevant for the results, were outlined. These served as guidelines for the calculation of default values.
The share of building service facilities to the overall life cycle assessment were also analysed on the basis of exemplary building LCA. Simultaneously the building service components/systems were systemized and grouped and different variants were established. For the relevant systems guide values and conservative default values were derived.
The OI calculations using the system borders BG0 and BG1 for simplified measurement takes 50 % on average of the ecological total expenditures (building services excluded) into account. The balance limit BG3 already takes on 85 % on average of the ecological expenditures. Nevertheless the consideration of building components, which were not assessed up to now, can have a crucial influence on the overall evaluation of buildings. In addition especially the building components which are not yet assessed show room for improvement. In contrast the simplified service-lifetime-model doesn’t lead to serious change in the ecological building assessment.
The simplified calculation methods and default-building components, for not yet in the energy performance certificate assessed building components, which were developed within the project, allow a significant simplification of the overall assessment of buildings.
The project points out that the mutual consideration of building operation and construction should be done with absolute values instead of using relative (site-related) values. This is especially true if also building components should be included which are not included in the energy performance certificate. Whereas if buildings with different size and cubing want to be compared (for example within the ecological building certification) a separated examination of operation and construction, with the respective surfaces, seems more suitable.
Prospects and Suggestions for future research
For new housing construction the developed results of the project provide a useful basis and simplification to assess and analyse buildings in their entirety. An expansion of the method to other building types (industrially used, schools, hospitals, etc.) is possible and recommended.
For residential buildings it could be shown that the described broad building accounting can influence the assessment results decisively. The more the not yet incorporated building components do have a considerable potential for optimization. This potential should be further investigated by continuing research activities.
In the at hand project only the current simplified service lifetime model of the OI calculations has been investigated. To what extent a detailed service lifetime concept would influence the building assessment should be further analysed. In doing so especially the verifiability of the building assessment- and support systems should be of importance.