Life Cycle Assessment
Putting high performance systems in newly constructed buildings will result in lower energy and maintenance costs over the life of the building. As our modeling tools are evolving, Rafn Company has been looking for ways to expand our use of Life Cycle Assessment tools. Following is a recap of a training session focused on capturing not only the cost of energy use but also the energy embodied in the materials that are used to construct those systems and everything within the constructed building. This is real cost of a building from cradle to grave.
This topic was presented by Kathrina Simonen, AIA, SE, LEED AP, Associate Professor, University of Washington, at SeaBEC's (Seattle Building Enclosure Council) 2015 Symposium in Seattle. Her presentation explained how to use Life Cycle Assessment to evaluate total energy usage in order to build a better building for true minimum carbon impact and energy cost savings.
Total Energy Use for a building = Operational Energy + Embodied Energy
Areas considered in the Life Cycle Assessment process include:
- Material Extraction
- Manufacturing & Production
- Maintenance & Reuse
- Disposal (cradle to grave)
- Recycling (cradle to cradle)
Operational energy is fairly straightforward to measure, but how do you accurately capture the cost of embodied energy? You use a computer of course. There are several software programs available to calculate these costs and some of them are even free.
Athena www.athenasmi.org Free
Etool www.etoolglobal.com Free
Tally www.choosetally.com $$
GaBi www.gabi-software.com $$$
SimaPro www.pre-sustainability.com/simapro $$$
The resulting Life Cycle Assessment report will be based on emissions that can be tracked. A methodology must be available to calculate. Items that are considered in an assessment include acidification, global warming potential, eutrophication, ozone depletion, photochemical ozone creation, and human health particulate matter. The result of these fall into two categories: ecosystem damage or human health damage. Some things not included are land use impacts, land use change, local impacts, habitat disruption, developing water use, and human health impacts, among others.
The basic formula for calculating the impact of a type of building material is the Quantity of Material in the Building X Environmental Impact = Total Environmental Impact of Building Materials. For example, the impact of 1,000kg of steel is calculated as 1,000kg X CO2e 0.43kg/kg steel = 430 kg CO2e.
Life Cycle Assessment can be a forward thinking, long term approach to saving energy and limiting the greenhouse effect on the environment. It may not always be practical to employ at this macro level, but it's an idea worth considering and supporting as we examine the products and systems used in constructing projects.