Environmental Engineering Reference
In-Depth Information
The IChemE metrics
The British Institute of Chemical Engineers (IChemE) has developed a set of sustainability
metrics based on environmental, economical, and social indicators. The metrics have been
primarily designed for the chemical processing industry; however, they are completely
applicable to the food-processing industry.
The complete procedure to calculate the metrics is explained in an iCemE document titled
“The Sustainability Metrics: Sustainable Development Progress Metrics Recommended for
Use in the Process Industries.” The procedure provides spreadsheets for intermediate
calculations of all the elements included in each indicator. The metrics are presented in three
groups that reflect environmental burdens, economic markers, and social impact. The environ-
mental indicators are based on the impact of net energy used per kilogram of product, net
energy used in reference to the added valued, fraction of raw materials recycled, net water
consumed, land impact, hazardous raw materials, and environmental burden. The environmen-
tal burden is calculated with the method of environmental burden index approach developed by
the former Imperial Chemistry Industries (ICI), which is based on the following equation:
EB
=∑
W
×
PF
[4.6]
i
n
i,n
Where:
●
EB
i
= the environmental burden category (e.g., global warming)
●
W
n
= weight of emissions of the substance “n” emitted
●
PF
i,n
= potency factor for species “n” for impact category “i”.
Environmental burdens are defined for global warming, ozone depletion, photochemical
smog, atmospheric acidification, water acidification, aquatic oxygen demand, aquatic
eco-toxicity, and human health. The reader can find more details on ICI environmental
burdens by consulting the comprehensive paper published by Wright et al. (1997). The
economic aspect is based on value added generated, return on capital, taxes paid, hires per
number of employees, gross margin per number of employees, training expenses, and so on.
Social impact is evaluated by accounting aspects such as benefits as percentage of payroll,
percentage of lost hours in relation to total of worked hours, ratio of income plus benefits
of the top 10 percent versus the bottom 10 percent, number of legal actions, number of
complaints, and so on.
Transportation indicators
Transportation indicators account for the distance that the food product travels from the place
of production to the location where it is consumed. There are two formulas that are widely
used to calculate the food miles embedded in a food product: the Weighted Average Source
Distance (WASD) and the Weighted Total Source Distance (WTSD) (Hill, 2008). WASD
formula is normally used for fruits, vegetables, and single-ingredient food products. WASD
computes the amount of food transported and the distance it travels from the production to the
consumption place. Because products are not produced at just one location, the total food
miles traveled by a food item is calculated by averaging distances from all sources to reach the
final destination. WASD is calculated with the formula (Pirog and Benjamin, 2005):
∑
(m(k)
×
d(k))
[4.7]
WASD
=
∑
m(k)
