LCA: LCA for Buildings

Simulation of Buildings During Their Life Cycle

Use process:

1. Building operation

Building operation comprises all functions necessary to produce the interior climate (temperature, humidity, air quality) and the basic services (lighting, lifts, warm water). Simplified annual or monthly method : The energy needs are calculated by the CEN standard for heating, air change and warm water and by the Swiss standard SIA 380/4 for electrical energy needs. In the case of air conditioning there is no detailed calculation, the needs are estimated by the addition of different electricity consummations per m2 (air transport, air preparation etc.) Data from SIA 380/4. According to the precision needs and the availability of data, annual or monthly climatic data can be used. Detailed methods: If the simplified method is not sufficiently reliable, more detailed models can be applied. They need however a topological description and more constructive details than the cost element type construction description. Different types of dynamic simulation tools can be used.

2. Functional operation

Functional operation is more dependent on the activities than on the building itself. It includes all functions that take place inside a building which have a significant contribution to the energy and mass flows. For some of these activities complete LCA can exist, in most cases it is only possible to know the energy flows and the material flows. This allows to determine at least part of the upstream impacts (through energy) and the downstream impacts (through energy and waste category flows). Examples of LCA for functional operation are : Banking and office work, restaurants, hotels etc.. The transport resulting from the building use can also be estimated and divided into the following sections: - Transport of people from where they live to the building where they work (Person-km) - Transport of visitors and clients (Person-km and Ton-km) - Transport of organizations located in the building(Person-km and Ton-km) For all these transport process standard process data from OEKOINVENTARE can be used.

3. Disposal process

They include all activities from the point of collection of used components and waste In case of final deposit of a waste, this point is the deposit itself. The general question of allocation and detailed LCA of downstream process is still under discussion within SETAC and other bodies. There seems to be an agreement that there should be no bonus, but that the impacts should be allocated to the preceding process as long as there is no new use of the waste.

By new use we understand :

• a reuse of the same component or material at another site (in this case only the impacts due to transport and reinstallation will be allocated to the new use, the precedent use will only be allocated transport to the collection site). Example : Repainting, repair and reuse of old windows.
• recycling of a material or component. This means transformation and utilization generally in another function. The precedent use will only be allocated transport to the collection site. The new use will be allocated transformation. Example : Recycling of PS insulation as packing material.
• thermal recycling. The components or materials are burnt in a special installation. The precedent use will only be allocated transport to the collection site. The energy produced in the recycling plant will be allocated with the impacts produced by the combustion process.
• definitive deposit in special sites. The transport to the deposit site and the deposits impact will be allocated to the precedent use. There are data sets for the process of type c and d independent of the material (they include a general mix of materials).

  For a and b special LCA must be established (so called transfer functions). They exist for certain materials. As long as there are no LCA for all materials, the data sets of type c and d have to be used. The OEKOINVENTARE include such data sets.

  
  > References

  REGENER - (Regional planning for the development of renewable energies).first interim report, June 1995, Ecole des Mines - Paris

  Kohler N. (1994) et al : Energie- und Stofflussbilanzen von Gebäuden während ihrer Lebensdauer. Schlussbericht des Forschungsprojektes des Bundesamt für Energiewirtschaft. Lausanne/Karlsruhe 1994