Civil Engineering Reference
In-Depth Information
Life Cycle Energy Performance
Evaluation
Patxi Hernandez
The majority of energy used in buildings has been traditionally linked to their
operation (heating, cooling, lighting, etc.). Much attention has been directed to
assess and reduce this energy use, and future refurbishment projects might aim for
'zero-energy' buildings. As this goal is progressively approached, buildings
generally often employ an increasing amount of materials and systems, to the point
that the energy associated with these, the so-called embodied energy, can
constitute an important part of the building's life cycle energy use. For buildings
achieving 'zero-energy' use in operation, the embodied energy is indeed the only
life cycle energy use. Despite this, current building energy assessment methods,
and strategies from approaching 'zero-energy buildings' or 'nearly-zero-energy
buildings', frequently ignore the embodied energy component of building life
cycle energy use. This chapter presents the concepts and methodology to evaluate
life cycle energy performance of buildings, including embodied energy of the
different components, systems and processes. It also introduces the concept of 'net
energy ratio' (NER) to the built environment, presenting it as an indicator to
support optimization of building refurbishment strategies from a life cycle energy
perspective. A practical application is shown for the refurbishment of an Irish
typical house.
1 Introduction and Context
With buildings accounting for 40 % of the world's energy use, there is now a need
to aggressively limit their energy use in order to reduce the planet's energy-related
carbon footprint at the level called for by the Intergovernmental Panel on Climate
Change (IPCC) (World Business Council for Sustainable Development
2012
).
