Embodied Energy 2 : Life Cycle Assessment
The Heritage Branch, Ministry of Tourism, Sport and the Arts, Province of British Columbia, is currently completing Life Cycle Assessments of two publicly-owned heritage buildings – the Emily Carr House in Victoria and Ridgeway Elementary School in Vancouver – in order to evaluate the environmental and economic implications of preserving heritage buildings.
Though the focus of the study is not on cultural values, they are an important aspect of heritage preservation and sustainable communities that set the context for environmental and economic analysis. As stated in Part 1 of this series (Spring 2007), the primary directive of this project is to develop a model that will evaluate heritage buildings over their whole life cycle.
From an environmental standpoint, Life Cycle Assessments quantify and justify the rehabilitation of heritage buildings. Life Cycle Assessments demonstrate the Association for Preservation Technology slogan "The Greenest Building is the Building that Has Already Been Built". Life Cycle Assessments recognize the embodied energy implications of preserving heritage buildings as counterparts to the operational energy savings of new 'green' buildings; they acknowledge that heritage buildings contribute to sustainable development.
Four steps in conducting a Life Cycle Assessment (LCA)
1. Goal and Scope Definition.
The life cycle of the building must first be defined in terms of its potential lifetime; its predicted use and maintenance; the possible repair, replacement or renovation of its components; and its final potential demolition and recycling. Furthermore, system boundaries must be set in terms of physical restrictions (the building envelope) and also life cycle process restrictions (which processes and aspects of the life cycle to include). Finally, a critical review process is also required to ensure that the data and processes specified are in keeping with the goals of the LCA and that the report will be consistent and impartial.
2. Inventory Analysis
This stage involves quantifying the relevant energy inputs and energy and emissions outputs of the defined system through data collection and calculation for each individual process.
3. Impact Assessment
- Category Definition: The environmental, social, and economic categories ("impact categories") addressed within the LCA.
- Classification: The input-output data collected in the inventory analysis are classified into the appropriate impact categories.
- Characterization: In each impact category, the allocated data is ranked in terms of its relative or potential importance. This serves to standardize the LCA results
- Weighting: After the data in each impact category has been characterized, the impact categories themselves are weighted or ranked in terms of their relative ethical, social, environmental and economic importance. The process of weighting is often used to determine a 'score' for the LCA that can be compared to the results of other buildings' LCAs.
4. Interpretation of results
This final step involves the identification of environmental, social, economic and cultural impacts and the resulting conclusions and recommendations. These conclusions and recommendations address the goal of the LCA.
As mentioned in my previous article, most Life Cycle Assessments do not take into account the embodied energy of buildings. However, the Athena Institute has recently released ATHENA Software Environmental Impact Estimator. Founded ten years ago, the Athena Institute is a not-for-profit organization that directs and undertakes research in conjunction with engineering firms that facilitates incorporating environmental considerations into the building design process. This is the only existing software to calculate the LCA of buildings in North America. Its mandate is to consider the environmental issues associated with constructing a building equally with traditional design issues, such as cost.
The Environmental Impact Estimator evaluates the 'cradle to grave' life cycle of a building in terms of the primary embodied energy (including calculating the 'upstream, pre-combustion' effects of creating and transporting energy), global warming potential, solid waste emissions, air and water pollutants, and natural resource usage. The ATHENA software, like other LCA methods, models the complete structure and envelope of the building (the system being considered). What differentiates the ATHENA software is that it also models maintenance and replacement effects in terms of the building type (residential, office building), location (in either Canadian or American regions), and a user defined total building lifetime.
Furthermore, it calculates the conversion between operational energy to primary energy (embodied energy) and the resulting carbon dioxide emissions.
Finally, the ATHENA software simulates the energy and environmental costs associated with the demolition of the building and the ensuing deposition of the building materials. After examining a trial version of the ATHENA Software for its suitability for the project, the full version will be used by the Heritage Branch as a valuable tool for evaluating the positive environmental implications in preserving heritage buildings.
The identified stakeholders for this project are:
Heritage Branch
Canada Green Building Council
BC Hydro
Clio Arts Associates Ltd. (managers of the Emily Carr House)
Association for Preservation Technology International (APT)
City of Victoria
Heritage BC
City Green (a not-for-profit environmental organization)
Parks Canada, Department of Heritage, Historic Places Initiative
British Columbia Building Policy Branch
These stakeholders recognize that heritage conservation, beyond supporting sustainable cultural development, also supports sustainable environmental,
economic, and social development.
