Help: My Analysis
This section enables two types of analysis: Contribution and Comparison. The Instructions section below gives details on how to analyze and interpret your scenarios.
Instructions
Contribution:
A contribution analysis is performed on one scenario. It presents many pie charts that highlight the purchasing categories that contribute most to overall expenditures and to a variety of environmental impact categories. A contribution analysis can be performed on one scenario at a time. If multiple scenarios are selected for a contribution analysis, the first scenario will be analyzed.
A contribution analysis can be used to prioritize purchases. It shows the purchasing categories that have the largest environmental impact in a purchasing scenario, and perhaps the most potential for 'greening' a purchasing portfolio.
Comparison:
Scenarios can be compared on various environmental impact categories. The first scenario is used as a baseline reference, and the scores of all other scenarios are given as a percentage of the baseline reference scenario. At least two scenarios must be selected in order to perform a comparison.
Absolute:
|absolute| The total impact of a scenario is expressed. Use this analysis option to determine total physical pollution or impact. If you would like to compare scenarios, use the relative comparison option discussed above.
Impact Categories
Impact categories used are from the ecoindicator99 method. Please see the Eco-indicator website for more information.Data & Calculation
The data used by PIE are a mixture of the US Input/Output Database by Sangwon Suh, PhD and Eco-Indicator characterization factors by PRE Consultants.
Units
Tons Equivalent (Tons -eq)
Tons (Short) equivalent are used for the respiratory organics, respiratory inorganics, and the climate change impact categories. They are provided in
terms of a reference substance. For example, Carbon Dioxide is the reference substance for the climate change category. Other gases, such as methane
and Nitrous Oxide are expressed as Carbon Dioxide with respect to their Global Warming Potential. More information on the concept of reference substances is available here
The reference substance for respiratory organics is VOCs, and it is Nitrogen Oxides (NOx) for respiratory inorganics.
DALYS
"Disability Adjusted Life Years" is a measure of human health impact. For more information see the Eco-Indicator website.
PDF*m2*yr
"Potentially Disappeared fraction" is a measure of ecological impact. For more information see the the Eco-Indicator website.