The
need for consideration of lifecycle greenhouse gas implications of building
energy retrofits is becoming more accepted and lifecycle GHG is increasingly being
used as an evaluation metric for building energy retrofit projects, estimating
the net climate impact of intervention options. However such studies are not
without weaknesses, lack of standardisation means that they are rarely
comparable. Additionally, they are often weakened by unclear assumptions;
arbitrary boundary setting; variable data quality; indifference to temporal
issues; and poor communication of results. This paper presents a comparative
assessment on the use of four standards to evaluation the greenhouse gas
implication of building energy retrofits, viz.
·
ISO 14044:2006 Environmental management - Life cycle
assessment - Requirements and guidelines;
·
PAS 2050:2011 Specification for the assessment of the
life cycle greenhouse gas emissions of goods and service;
·
Greenhouse Gas Protocol Product Life Cycle Accounting
and Reporting Standard;
·
EN 15978:2011 Sustainability of construction works -
Assessment of environmental performance of buildings - Calculation method.
The
papers explores the commonalities and differences between the methodologies
required by the standards, in such areas as: boundary setting; cut-off
thresholds; allocation; date provenance and quality; capital goods; carbon
storage; temporal issues; etc. The
role of appropriate product category rules to provide for a common approach is
examined and the meaning for lifecycle GHG determination for building retrofits
is discussed.