Civil Engineering Reference
In-Depth Information
where the objective is a building whose primary energy use in operation plus the
energy embedded in materials and systems over the life of the building is equal or
less than the energy produced by renewable energy systems within the building.
The use of this definition could substitute or expand current definitions of 'net
zero-energy buildings' or 'near-zero-energy buildings', including a life cycle
perspective. The actual lack of data on embodied energy, which makes difficult the
immediate application of the presented methodology, has been pointed out.
However, as data become increasingly available, for example with the uptake of
EPDs, the methodology described could be useful for policy making, including
further development of building regulations and schemes as building energy rat-
ings. The concept of 'NER' as a life cycle energy indicator for use within building
energy analysis has also been introduced, as an indicator which allows comparing
building refurbishment options and specification decisions, in between them and
also with other options such as building integration of renewable energies. This
indicator has the potential to make clearly visible the true impact of design
decisions influencing energy use over the full life cycle of a building.
The adoption of an accepted dataset of embodied energy values and service life
of building components and systems is the main difficulty in the application of the
proposed methodology for life cycle energy evaluation. Some data sources have
been presented, and there is a good development in this area as new regulations
such as the Construction Product Regulation requires the declaration on sustain-
able use of natural resources. The service life of buildings, products and systems is
another of the main assumptions that must be applied when using the proposed
methodology. A more detailed lifetime prediction for different building types and
for different components and products should be used when available. Future
improvement in data availability is particularly necessary for HVAC and renew-
able energy systems, including their maintenance phase, area on which very
limited data are available within existing databases.
Further research is also needed to evaluate potential trade-offs between oper-
ational and embodied energy efficiency of buildings at local or regional level,
considering in detail the issues of climate, energy mix, production processes,
transport issues, etc.
References
Adalberth K (1997a) Energy use during the life cycle of buildings: a method. Build Environ
32:317-320
Adalberth K (1997b) Energy use during the life cycle of single-unit dwellings: examples. Build
Environ 32:321-329
Ardent F, Beccali G, Cellura M, Lobrano V (2005) Life cycle assessment of a solar thermal
collector. Renew Energy 30:1031-1054
Asif M, Currie J, Muneer T (2007) Comparison of aluminium and stainless steel built-in-storage
solar water heater. Build Serv Eng Res Technol 28:337-346
