In North America, the ATHENA Impact Estimator for Buildings is the only software tool that is designed to evaluate whole buildings and assemblies based on internationally recognized life cycle assessment (LCA) methodology.
Using the Impact Estimator, architects, engineers and others can easily assess and compare the environmental implications of industrial, institutional, commercial and residential designs — both for new buildings and major renovations. Where relevant, the software also distinguishes between owner-occupied and rental facilities.
The Impact Estimator puts the environment on equal footing with other more traditional design criteria at the conceptual stage of a project. It is capable of modeling 95% of the building stock in North America, using the best available data.
The Estimator takes into account the environmental impacts of:
- Material manufacturing, including resource extraction and recycled content
- Related transportation
- On-site construction
- Regional variation in energy use, transportation and other factors
- Building type and assumed lifespan
- Maintenance and replacement effects
- Demolition and disposal
Although the Impact Estimator doesn’t include an operating energy simulation capability, it does allow users to enter the results of a simulation in order to compute the fuel cycle burdens, including pre-combustion effects, and factors them into the overall results.
Complex Results in a User-friendly Format
Although LCA is a complex process, the Estimator has been designed for ease of use.
The first step is to enter required information such as geographic location (the user selects the most representative North American city), building life and whether it’s owner occupied or a rental property (this affects maintenance and replacement schedules), and, if desired, annual operating energy values by energy form.
Pre-set dialogue boxes prompt users to describe the different assemblies — by requesting the width, span and live load of a floor assembly, for example — that together form a conceptual building design.
The Impact Estimator then instantly provides cradle-to-grave implications in terms of:
- Global Warming Potential
- Acidification Potential
- Human Health Respiratory Effects Potential
- Ozone Depletion Potential
- Photochemical Smog Potential
- Eutrophication Potential
- Fossil Fuel Consumption
Note that the first six impact measures listed above are based on mid-point impact estimation methods developed by the US EPA and reported in their Tool for the Reduction and Assessment of Chemical and Other Environmental Impacts (TRACI, 2012 version).
As design data is entered for each assembly, the software builds a “tree” of information so that each individual assembly can be identified and viewed easily. The tree can also display, as a value or percentage, the impact of each assembly in terms of a selected measure such as global warming potential. This allows users to track the effects of each assembly as it’s added, or to quickly pinpoint what is causing a particular environmental effect.
Detailed LCA Results
Results from an individual design can be seen in summary tables and graphs by assembly group and life cycle stage. Detailed tables and graphs show individual energy use by type or form of energy, and emissions by individual substance.
Flexible Comparison of Alternate
Accommodating multiple comparisons at once, the Impact Estimator allows users to change the design, substitute materials, and make side-by-side comparisons for any one or all of the environmental impact indicators. It also lets users compare similar projects with different floor areas on a unit floor area basis.
“End of Life” (Demolition) Module
The “End of Life” module simulates demolition energy and final disposition of the materials incorporated in a building. The whole area of solid waste is in flux. Until a consensus within North America is reached in the area of solid waste, the Impact Estimator for Buildings will continue to calculate the materials and energy consumed during the “End of Life” life cycle stage but will not determine the physical amount of material that actually goes to landfill.
Structural materials have a demolition energy per physical unit of material associated with them. All materials have a percentage that goes to landfill associated with them. The location (city) has an average distance to landfill associated with it. These values are used in conjunction with the amount of material in the building at the end of life to calculate the following:
- the material and energy used to demolish all structural material
- the physical amount of material that is destined for landfill. Note that this is not reported as land emission at this time pending a North American consensus as mentioned above.
- the material and energy used to transport to landfill the material that is destined for landfill. Note that all remaining material is assumed at this time to remain on site, again pending a North American consensus.
How it works: Software User Guide
For more detailed information, please see the User Guide document, which explains what the software does and how it does it. The software’s embedded databases are also explained, highlighting their use within the tool.
The Impact Estimator is a Visual C# (C-Sharp) application. It is PC-compatible but can also be run on a Mac system with appropriate Windows capability.
Highlights of Version 4
The Impact Estimator’s greatly increased functionality and flexibility allows design teams to:
Define complete envelope systems. Version 4 users can define complete envelope systems, save them, and then reuse them on any project.
Choose multiple envelope materials. With the introduction of the Custom Wall Assembly, Version 4 users can now specify multiple structural (e.g., double stud wall) and envelope materials (e.g., two or more types of insulation plus other envelope components) for each individual wall that makes up a building.
Specify columns and beams. In Version 4, you now specify the number of columns and the number of beams in a grid system. The grid can either be a complete column and beam system employing non-load bearing infill walls, or a modified grid using an exterior load bearing wall with interior columns and beams.
Select exterior and interior doors. The Impact Estimator now includes wood, steel and aluminum exterior and interior doors, offering seven different configurations in all, both with and without glazing.
Export to Excel. The output tables can now be directly exported to Excel or PDF instead of having to first export as a text file and then import into Excel.
Note: The Impact Estimator is not an engineering design tool. It is a tool that allows users to express a design in simple terms in order to assess the environmental implications of their choices.
Software is subject to a license agreement.