EcoCalculator Quickstart
Background
The Athena EcoCalculator for Assemblies provides instant LCA results for commonly used building structure and envelope assemblies. Results are based on detailed assessments previously conducted by Athena experts using the Athena Impact Estimator for Buildings. Assemblies are complete systems, such as a wall or roof system, composed of individual products and⁄or pre-assembled building components. The EcoCalculator can be used for new construction projects, retrofits and major renovations, and for industrial, institutional, office or residential designs, either to compare specific assemblies or to assess all of the assemblies in a structure.
Choose your Version
The residential version applies to single family residential buildings: detached, semi–detached, or row houses. The commercial version is suitable for industrial, institutional or office buildings.
The EcoCalculator is regionalized; after selecting the commercial or residential version, select the city or climatic region reflecting the building’s location. The following North American cities are currently available: Atlanta, Calgary, Halifax, Los Angeles, Minneapolis, Montreal, New York City, Orlando, Ottawa, Pittsburgh, Quebec City, Seattle, Toronto, Vancouver, and Winnipeg. Alternatively, select a standardized USA Zone 3 or Zone 6. Other Southwest and Central regions will be added in the future.
In the EcoCalculator for Commercial Assemblies, choose a low or high–rise version.
Using the EcoCalculator
The first step is to select an assembly sheet from one of the following categories:
- Foundations and footings
- Columns and beams
- Intermediate floors
- Exterior walls
- Windows
- Interior walls
- Roofs
The number of assemblies in each category varies widely depending on the possible combinations of layers and materials. Within the exterior wall category, for example, there are nine basic wall types, seven cladding types, three sheathing types, four insulation types and two interior finish options. The number of assemblies for exterior walls represents all viable combinations of these options.
The list of combinations can be lengthy and is thus shown as collapsed by type. Collapsed lists can be expanded or closed using the + or – signs in the far left column of the spreadsheet.
Columns and beams can be confusing. You need only enter the supported floor and/or roof areas in the yellow column.
Selecting Assemblies and Generating Building Scale Results
Assemblies are assessed in terms of a range of performance measures, including global warming potential, embodied primary energy (fossil fuel depletion), pollution to air and water and weighted resource use. The measures are explained in more detail in the Definitions & Assumptions document.
Each sheet contains the following key to the color coding in the cells:
Yellow highlighted areas show required inputs
Green highlighted areas show constant information
Blue highlighted areas show outputs calculated by the spreadsheet
You need only enter information in yellow colored cells in order to generate results.
Having selected a major assembly category, in the yellow column you enter the total square footage of each type of assembly that you plan to use in your building. Percentages are calculated automatically when you enter the square footage for individual assemblies selected in any category. You can select multiple assemblies within a category; the total will indicate their combined environmental impact. There are no limits to the number of assemblies permitted, but the “percent of total” must add up to 100 within a category.
The smaller set of blue cells toward the top of the sheet keep a running total for the building as a whole.
Comparing to Averages
At the top of the column of green cells for each measure (e.g., for global warming potential), there is a cell that shows the average performance for that assembly category (e.g., for all low rise exterior walls in a warmer climate zone). This allows different assemblies to be compared to the average at a glance, with results lower than the average preferred.
Assemblies are assessed in terms of a range of performance measures:
- Fossil Fuel Consumption
- Weighted Resource Use
- Global Warming Potential
- Acidification Potential
- Human Health Respiratory Effects Potential
- Eutrophication Potential
- Ozone depletion Potential
- Smog Potential
In the EcoCalculator for Residential Assemblies, energy use and global warming potential are highlighted in pink to emphasize their importance as critical environmental issues that will increasingly affect the design of buildings and the selection of building materials.
To develop results, the user indicates the square footage (or metreage for Canadian regions) represented by selected assemblies. Users can evaluate multiple assembly types within a category (e.g., exterior walls), in which case their impact measurements will be combined to arrive at a total environmental impact for that category.
Design results are available in tabular form and show real time changes as the inputs are adjusted by the user. This allows different assembly options to be considered in light of their environmental impacts and provides the information necessary to make informed, scientifically–based choices.
Ensuring Fair Life Cycle Comparisons
The EcoCalculator is able to generate instant LCA results because each preset assembly has already undergone a lengthy assessment using the Athena Impact Estimator for Buildings.
The results take into account:
- Resource Extraction and Processing
- Product Manufacturing
- On–site Construction of Assemblies
- All Related Transportation
- Maintenance and Replacement Cycles Over an Assumed Building Service Life
- Structural System Demolition and Transportation to Landfill
Operating energy effects can be included in whole building LCA using the Impact Estimator, but are not included in the EcoCalculator. Where the tool is used as part of a green building rating system, these effects are covered elsewhere.
To ensure fair comparisons between assemblies, the following assumptions were made:
- Results are presented on a per unit area basis (e.g., per square foot), but the underlying analyses were done on a whole building basis and actually took into account much larger quantities, such as 1,000 linear feet of wall of a defined height with an assumed window-to-wall ratio.
- Installation for all assemblies was assumed to utilize components and loadings typical for central areas of the United States.
- It was assumed that all assemblies would be used in “owner occupied office buildings” (in the Commercial version) or “single family residences” (in the Residential version) with a 60-year lifespan; building type and ownership assumptions affect the maintenance and repair/replacement schedules of relevant building envelope materials (e.g., roofing membranes, claddings and window systems).
- Other specific assumptions covered factors such as:
– concrete strength and flyash content;
– gypsum board type and thickness with latex paint;
– live load for all intermediate floors, columns and beams, and roofs;
– bay sizes;
– column heights;
– external wall thicknesses depending on construction system;
– stud size/strength and spacing; and
– sheathing and decking materials. - Results are presented on a per unit area basis (e.g., per square foot), but the Impact Estimator software actually took into account much larger quantities, such as 1,000 linear feet of wall.
- Installation for all assemblies was assumed to utilize components and loadings typical for central areas of the United States.
- It was assumed that all assemblies would be used in “owner occupied office buildings” with a 60-year lifespan—which affects the maintenance and repair/replacement schedules of relevant building envelope materials (e.g., roofing membranes, claddings and window systems).
- Other specific assumptions covered factors such as:
- Window-to-wall ratio
- Concrete strength and flyash content
- Gypsum board type and thickness with latex paint
- Live load for all intermediate floors, columns and beams, and roofs
- Bay sizes
- Column heights
- External wall thicknesses depending on construction system
- Stud size/strength and spacing
- Sheathing and decking materials
