Life cycle observation
The life cycle of a building consists of three phases: construction, utilisation and deconstruction. In the current assessment of buildings, however, the entire life cycle plays no decisive role since both the monetary and energetic assessment have each been restricted to only one phase up to now. Whilst the construction phase is decisive for the costs, only the utilisation phase is referred to for the energetic balance. However, this way of looking at things must be reviewed for efficient resource utilisation and the entire life cycle analysed.
When carrying out an energy consumption balance for a building, it is now time for the energy expenditure for raw materials, erection, recycling and disposal to be considered as well. At the beginning of the Energy Conservation Regulations (EnEV) and its predecessor - the thermal insulation regulations - the energy consumption for thermal heat during the utilisation phase considerably exceeded the energy requirement for its setting up, but now the latest versions of the EnEv result in considerably reduced energy consumption during utilisation. This means that the energy consumption for construction and deconstruction is no longer considered as insignificantly low, and that the energy consumption over the entire life cycle should be included in the balance in future.
Even with respect to monetary evaluation, getting away from the observation of only one single phase - in this case construction - is required. In view of increased and increasing energy costs, building construction is no longer the sole main cost factor. The costs during the utilisation phase, e.g. thermal heat, nowadays form a considerable proportion – something which means that an extension of observation over the entire life cycle is necessary in this sector as well. In view of the high energy prices, this would also increasingly lead to measures for improving energy efficiency.
At present, increased costs for equipment integrating renewable energies or costs for an energetically-optimised building envelope, are not economical given the current fixation on construction costs. However, they become so if occupancy costs are incorporated. VDI Directive 2067 represents an approach to a more comprehensive balancing of costs in which energy costs in addition to costs for maintenance and renewing equipment in the technical building services, such as heating, are also taken into account in addition to the construction costs.
Deconstruction, the last phase of the building life cycle, has hardly been considered up to now. If, however, one considers the enormous resource consumption of the construction industry and the simultaneous shortage of raw materials, the deconstruction outlay and recyclability of materials must also be taken into account in terms of a comprehensive examination in the future. This comprises both drawing up a deconstruction and recycling concept as early as the planning phase before construction of a building, and also the development and optimisation of deconstruction technologies and recyclability.
This is aimed at efficient use of materials together with other parameters such as raw material type and CO2 balance for the materials used. If it is possible to extend energy efficiency across the entire life cycle of a building and also consider material efficiency at the same time, resource efficiency is even possible in the material-intensive construction industry.