13.+Environmental+Indicators+and+Metrics

Ryan Hazelwod, Shannon Reynolds, Andy Jensen, Courtney Flemming

13.1 Introduction
The process of measuring sustainability is accomplished through the introduction of tools that measure the benefits of installing sustainable practices and/or infrastructure. These tools are called sustainability indicators and metrics, and can fall into three categories; social, a harder to quantify gauge of a project’s effect on society, economic, an easily quantifiable measurement of a project’s financial impact, and environmental, an easily quantifiable, measurement of the effect on the ecosystem. The goal of this chapter is to introduce the reader to the idea, importance, and application of environmental indicators and metrics. This will be accomplished by defining environmental indicators and metrics through quotes and examples, looking at how the two relate to each other, discussing metric and indicator variability by project, showing how each can be classified, and lastly, describing, in detail, a limited number of popular indicators and metrics of commonly used frameworks.

13.2 Defining Environmental Indicator
Before delving into the discussion of environmental indicators and metrics, it is necessary to discuss their importance and form a working definition for both an indicator and a metric. The Environmental Protection Agency (EPA) defines environmental indicator as “ … a numerical value derived from actual measurements of a pressure, state or ambient condition, exposure or human health or ecological condition over a specified geographic domain, whose trends over time represent or draw attention to underlying trends in the condition of the environment [1].”In other words, an environmental indicator is a sign or measurement that conveys a message about the state of a particular environmental condition based on a trending set of data. Indicators should “represent an empirical model of reality, not reality itself, but they must, nonetheless, be analytically sound and have a fixed methodology of measurement [7].” One of the best natural environmental indicators, according to Mike Tyler, Associate Professor at the University of Adelaide, is frogs because they are the highest form of life to lay naked eggs in water [6]. This egg exposure makes them highly susceptible to changes in environment. An example of their application can be found in Santa Elena National Park near Monte Verde, Costa Rica where environmental changes have caused the loss of 20 frog species over the past 10 years [2]. Disappearance of species doesn’t necessarily point to what is causing the change in environment, but rather points to the fact that there is a change taking place. This relationship of indicators and data can be seen below in Figure 1. By making the species loss quantifiable, the occurrence of environmental changes becomes easier to draw attention to and communicate. In this instance, the overarching environmental indicator is biodiversity. By examining frog species as a facet of biodiversity, data, or more specifically the number of species, can be effectively communicated. Figure 1 – Information Pyramid [7]

13.3 Defining Environmental Metric
The Center for Sustainability at Aquinas College defines sustainability metrics as “… tools that measure the benefits achieved through the implementation of sustainability [3] ” and are comprised of two or more measures [8]. In other words, an environmental metric is a tool that measures the positive or negative effects of a project on the environment by evaluating two different measures. For instance, an example of metric that may be used to measure sustainability in Costa Rica would be amount of banana bags discarded per year by a farm compared to the year before. This example highlights how metrics can have little to no value if used improperly, or a great deal of value if used correctly. If this type of metric was applied to a banana farm that had no interest in conservation, it would be useless. To ensure that a metric is useful, Robert Eaton, chair of the Council of the National Academy of Engineering, says they should have the following characteristics [9]:

• They must address the needs of all stakeholders— community, government, and business.

• They must facilitate innovation and growth; continuous improvement must be the cornerstone.

• They must be harmonized at the local, state, national, and international levels.

• They must be fully compatible with existing business systems. If they do not add value, they will not support continuous improvement and will not be used.

• They must measure the right things—what is measured is what gets managed.

A metric for the previous example involving Santa Elena National Park could be measuring the biodiversity in the park before and after the addition of a new trail, building, or local water treatment facility. It should be stressed that a sustainability metric regarding infrastructure, like examining the effects of a water treatment facility on biodiversity, looks at the effects from infrastructure on the environment. By using metrics to analyze the effects of a project on the environment, solid, quantifiable conclusions can be drawn as to the influence, or lack thereof, of infrastructure.

13.4 Differentiating and Linking Indicators and Metrics
 From the two definitions, a clear distinction can be drawn between the two concerning sustainable infrastructure. An environmental indicator looks at a specific characteristic and reports a specific value or change over time. An environmental metric looks at indicator data and examines the relationship before and after the construction of infrastructure. In other words, metrics deal with a change in indicator data due to a change in the natural environment.

 The Institute for Sustainable Infrastructure Envision framework, a sustainability rating system for infrastructure, identifies sixty primary social, economic, and environmental indicators [4]. Inside each indicator, called a credit in the design manual, is a scoring scheme based on the metric for the indicator. A common example of this relationship would be focusing on the credit titled “Manage Stormwater” and setting a sustainability goal of restoring the runoff to predevelopment characteristics. Envision titles the metric for stormwater runoff “Infiltration and evapotranspiration capacity of the site and return to pre-development capacities” and awards increasing points for increased performance. The hierarchy of achievements starts with increased storage capacity and awards more points for extended storage capacity, sustainable stormwater management, and considers enhanced stormwater management being the highest level of sustainability. Full description of the intent, metric, and scoring can be found on pages 132-133 of the ISI Envision Design Manual 2.0.

 Envision, like other rating systems, uses the relationship between metrics and indicators to emphasize important factors in sustainability that are common throughout the scope of projects the ratings system covers. By linking the indicator and metric, goals can be easily established and communicated. For instance, pavement deterioration is a huge problem in Costa Rica, as seen in Figure 2, below [20]. To effectively communicate the benefits of different asphalts, road deterioration, or some other type of surface characteristic, need to be compared to the present methods. The indicator in this case would be the road way characteristic and the metric would be the performance comparison. By effectively relating the two, information can be effectively communicated.

Figure 2- Costa Rican Roadway Deterioration

13.5 Indicator and Metric Variance by Project
The use of environmental indicators and metrics can vary by project scope depending factors like purpose, funding, and location. For instance, while projects are in predevelopment, environmental metrics can be used for goal setting, comparison of alternatives, and representation of future changes. For existing projects, sustainable metrics can be used to convey changes and report progress. They can also be used on a wide variety of projects like roads, bridges, pipeline, and airports [4], to name a few. Indicators and metrics can be picked and modified to meet specific needs for each of these different projects. For example, consider a hotel that treats its own water for irrigation as in Figure 3, below. The main objective is to get the water clean enough so it can safely be used for irrigation before entering the ocean. The water does not have to be fit for human consumption, so treating and testing the water for drinking standards would be pointless and costly. It would also be futile to worry about indicators not pertaining directly to the project. In this way, indicators and metrics should be carefully selected and applied.

Figure 3 - Sand Filter in Coco Beach, Costa Rica

This being said, there is no standard method or metric for determining sustainability. A project’s goals, location, and purpose can influence the depth and focus of the environmental metrics applied. The Environmental Protection Agency (EPA) has three basic steps for determining indicators for green communities [5] that can be translated to be applicable to a wide variety of projects. The first step is to “Define your goals.” In other words, after determining where the project is, it is necessary to determine where the project would like to be afterward. Next, “Identify your target audience.” More specifically, identify the stakeholders and people of interest. Lastly, “Evaluate your indicators.” This can be done by voting and selection grid techniques. In other words, persons of interest can vote for the aspects they feel are most important.

A scenario examining the benefits of paving the road to Monte Verde, Costa Rica highlights the basic process. As the road stands, it is fairly narrow and bumpy by American standards. Video of the road can be found at []. Some possible goals for the road are decreased travel time between cities and increased tourism to Monte Verde and Santa Elena. The target audience would be land owners between the cities, commuters, and city planners. Some appropriate indicators, among others, would be vehicle miles traveled and forest impact. Evaluation of the indicators through voting would reveal how the design process should proceed. One option would be for the road to be as direct at possible to decrease vehicle miles traveled. This would lead to a design with little regard for roadway footprint and forest impact. Another option would be to design with minimal impact to the forest, as it is now. This type of design would lead to slightly higher miles traveled but less earthwork involved in construction. One other option would be to leave the road as is. Only through selection of appropriate indicators and proper determination of importance can the appropriate indicators and metrics be selected.

13.6 Types and Classification of Indicators
The wide variability and uses of indicators can make the typology a bit muddled for both the layperson and expert. To ease this problem the European Environmental Agency (EEA) has separated indicators in four simple groups by addressing a series of questions [10]:
 * What is happening to the environment and to humans? (Type A or //Descriptive Indicators//)
 * Does it matter? (Type B or //Performance Indicators//)
 * Are we improving? (Type C or //Efficiency Indicators//)
 * Are we on the whole better off? (Type D of //Total Welfare Indicators//)

Most indicators that are currently used look at present situations (descriptive indicators). They work by looking at an environmental issue with regard to a specific aspect of the Driver-Pressure-State-Impact-Response (DPSIR) framework, or a derivative of it. In short, the DPSIR framework looks at the relationship between the environmental system and the human system [10]. Below in Figure 4 the relationship between different aspects of the framework can be seen and more information on the DPSIR framework can be found at [11]. These descriptive indicators all represent the state as is and are further separated by the EEA into five classes: driving force, pressure, state, impact and response. Figure 4 - DPSIR Framework Relationships [11]

//Driving force indicators// “describe the social, demographic, and economic developments in societies and the corresponding changes in life styles, overall levels of consumption and production patterns [10].” Through population growth and sprawl, human pressures on their surroundings provoke changes in the environment. This, in turn, causes changes in production and consumption. An example of this type of indicator would be vehicle miles traveled (VMT). VMT can be used to assess highway efficiency, air quality, or potential gas tax revenue [12]. In San Jose, Costa Rica this indicator could be directed at public transportation to show how efficient privately run bus companies can be. //Pressure indicators// describe the release of pollutants into a system and/ or the use of land [10]. Theses physical and biological pressures on the environment show themselves by effecting the environment in a variety of ways. An example of a pressure indicator would be land use per gigawatt hour of power generated (Figure 5). This indicator is often used when comparing possible renewable energy alternatives. In Costa Rica, where renewable energy sources dominate the landscape, this type of indicator could be used to show why a geothermal plant can be considered more sustainable than wind power when looking at land use. Figure 5 - 30 Year Land Use [13]

//State indicators// describe a physical attribute of the environment like physical (temperature), chemical (air born pollutant), or biological (biodiversity) changes [10]. They can be extremely useful when trying to communicate a specific point. For instance in the Salt Lake valley, air pollution in the winter months can be a direct reflection of the need for cleaner, more sustainable energy sources. The Santa Elena frog example from earlier in the chapter is also a state indicator.

//Impact indicators// look how pressures on the environment that change the state of the environment affect social and economic functions [10]. This type of indicator accounts for a sequence of events. For example, global warming causes increased temperatures, which causes sea levels to rise and, in turn, decreases biodiversity. In San Jose where it rains almost every day during the rainy season, this type of indicator can highlight the effect on marine life caused be disposing of trash on the sidewalk without a receptacle.

//Response indicators// relay information as to how groups and individuals compensate, prevent, or adapt to changes in the environment [10]. This type of indicator can point out how society redirects consumption and production patterns based on availability, or how groups aim to raise the efficiency of products. An example of this type of efficiency indicator would be the amount of mixed solid waste recycling (Figure 6). In Costa Rica, where recycling is more ingrained in society, response indicators about recycling could be used to advocate for more recycling stations like the one seen in Figure 7.

Figure 6 - MSW Recycling Rates in the U.S. [14] Figure 7 – Costa Rica Recycling Station [17]

The above classes of indicators all look at the current state of the environment without regard to how it should be. On the other hand are //performance indicators//. They look at current conditions and compare them with a reference. The EEA describes them as “distance to target” assessments [10]. They are especially handy for groups or institutions responsible for management of pressures or states. National governments use them to show progress towards a goal or international mandate. As far as sustainability is concerned, they are extremely handy in communicating options or progress of infrastructure. An example of this type of indicator is amount of carbon offset. This is a key indicator in Costa Rica where renewable energy is highly utilized and sustainability is at the forefront of politics. In fact, the government of Costa Rica has pledged to be carbon-neutral by 2021 [15]. More information on why the small nation is able to strive for such an ambitious goal see [15].

For policy makers and government institutions, //efficiency indicators// are especially useful. They look at how options compare or how processes improve. This type of indicators can make use of one variable like miles per gallon of an automobile, or multiple variables like amount of CO2 produced by various types of transportation to move a person 100 miles [10]. The importance of efficiency indicators comes in the fact that they reflect progress and improvement of processes in terms of resources, emissions, or waste.

After the application of sustainable practices and the conserving of resources, //total welfare indicators// are used to examine if actual benefits and progress are attained. They look at how changes to the environment relate to overall social well-being. One example of this is the Index of Sustainable Economic Welfare (ISEW). The ISEW attempts to measure how economic activity increases quality of life [16]. For instance, it has adjustment factors to economic progress for climate change and depletion of resources. In other words, unlike other economic indicators like GDP the ISEW accounts for negative and positive changes to the environment.

The EEA classification system is just one way indicators can be classified. Like how indicators can be selected based on need, classification systems can delineate based on need as well. The EEA classification system is, however, fairly easy to understand and thorough, so relating it to sustainable infrastructure is particularly easy.

13.7 Types of Metrics
Environmental metrics, like indicators, have great variability in application and scope, while being a bit difficult to classify. Part of this difficulty is due to the wide variety of classification of systems already in place. One fairy concise scheme by Jin and High lays out four types of environmental performance metrics as they relate to chemicals [18]. With some broadening of context, the system can be used for all types of influences, not just chemicals. The four classes essentially cover the increasing complexity and sophistication of metric development.

The first and most basic class of metrics is non-site specific and non-influence specific [18]. More specifically, they can be translated across a wide spectrum of applications and don’t specifically measure one type of influence or pollutant. That is they measure emissions instead of specifically measuring CO2. These types of metrics are basically good for regulatory guidelines because they measure only if something is “good enough” without regard for improvement. An example of this type of metric would be waste flowrate into a river from a factory. The Reventazon River pictured below in Figure 8 is an example of where this type of metric isn’t well utilized. The river preceding the Cachi Dam has been polluted so much that the water isn’t suitable for human touch.

Figure 8 - Cachi Dam and Reventazon River

The second class of metrics is influence specific while providing no environmental information [18]. In other words, data is modified into equivalencies so it can be compared across a variety of sites without regard for the effect of the information. These metrics look at changes, but are not focused on the end result of the influence. They can be useful when examining safety or health, but are not suitable for sustainability because the context is ignored. For instance if a metric was designed to look at traffic volumes but ignored all environmental and safety impacts, it would be only partially useful when examining the feasibility of a road design. Also, a lot of toxicity metrics fall into this class.

The third class of metrics is influence specific while giving some relation to the environment [18]. This type of metric, like the second class of metrics, modifies information so it can be compared. At the same time, though, this class of metrics compares the value to some set of standards engrained in the metric. These standard conditions are developed to reflect generic circumstances. The shortcomings of this type of metric become apparent when comparing information from two extremely different locations. For instance if a metric was developed in San Jose examining the amount of pollution produced per bus rider, only a rough comparison could be made to systems in the United States because of differing emission standards and amounts of ridership. They are, however, useful when things like location, regulations, and other factors are equal. An example of this type of metric would be a town’s solid waste diversion rate before and after implementation of an expanded recycling program.

The fourth class of environmental metrics is influence and site specific [18]. In other words, this class of metrics is developed to measure something of interest at a specific location. This type of metric is extremely hard to translate to different locales because it is usually designed by an entity with a specific goal in mind about a specific place. An example of this type of this metric would be examining fish diversity in a bay due to changing water levels caused by the Arenal Dam Hydroelectric Intake Facility, below in Figure 9. No specific aspect of the metric is exclusive, but by narrowing location and influence the metric becomes basically useless outside of its exact intention.

Figure 9 - Arenal Dam Intake Facility

The classification of environmental metrics, like environmental indicators, can take many forms. The Jin and High system was highlighted because it shows that complexity and focus are the main delineators in classification. It would be nearly impossible to group metrics by what they examined because they could measure virtually anything.

13.8 Examples
It has already been well established that throughout various rating systems and projects different environmental indicators and metrics are used. From planning to post development analysis, these differing measures need to be selected based on necessity and purpose. Some rating systems and agencies have boiled down the possibilities to only include indicators and metrics they feel are most important for the given material. Below are three examples how different ratings systems use environmental indicators and metrics.

The Institute for Sustainable Infrastructure’s Envision rating system is composed of 60 different environmental, economic, and social indicators and metrics [3]. The rating system is designed to be applicable to a wide variety of projects and locations like dams, roads and wastewater treatment facilities. Inside the Climate and Risk category is a credit examining greenhouse gases. The indicator (credit) is titled //Reduce Greenhouse Gas Emissions// and the metric is “Life-cycle net carbon dioxide equivalent (CO2e) emissions.” The manual calls the project to at least complete a life-cycle carbon assessment and awards increasing points for percent reduction in carbon emission. The most points are awarded for a “net carbon negative” construction. As laid out in the manual, this could be achieved by planting trees or carbon sequestration. The Envision rating system includes this metric indicator combination because of its wide applicability to projects and importance to the environment.

The EPA has developed a list of indicators for communities to measure progress towards or away from becoming a Green Community [4]. Like the Envision framework, the EPA includes varying environmental, social, and economic examples. One of the indicators discussed is the amount of impervious surface. The purpose of this type of indicator is to manage stormwater impact. A possible metric for this indicator would be an increase in peak discharge caused by addition of impervious areas like parking lots. Increasing levels of sustainability could be achieved by making efforts to restore runoff to predevelopment levels. This could be achieved by greeenscaping or making runoff channels and storm sewers as large as the ones pictured below in Figure 10. These examples are photos from downtown San Jose where high levels of impervious area and rain make drastic need for runoff routing are necessary to avoid flooding.

Figure 10 - Costa Rican Roadway [21]

The LEED Certification for New Construction and Major Renovations is composed of different environmental indicators [19]. The intent of the framework is to promote more efficient and environmentally responsible buildings. Unlike the Envision system which looks at all types of infrastructure but buildings, LEED certifications hone in on one type of project. In this case it is the major construction of commercial buildings. This allows indicators to be tailored and more direct to the specific needs of the project. For instance, this certification looks at the use of certified wood as an indicator to sustainability. A possible metric for the predevelopment stage would be percentage of the buildings framing completed with environmentally sustainable wood. The intent of the credit is to promote environmentally sustainable forest management and building practices. By being able to refine the indicators and metrics to be project specific, LEED certifications have helped drive building sustainability as we know it.

13.9 Conclusion
Environmental indicators and metrics are priceless tools when evaluating sustainable infrastructure. To begin with, they allow designers to identify measurable ways of improving their design. When multiple options are possible, metrics help communicate the differences in options so decision makers can make a proper evaluation. For evaluators, multiple rating systems are in place for various types of projects. They often group important indicators and metrics together so the project’s stakeholders can identify sensitive areas. In this way, environmental indicators and metrics are the ruler and communication line for measuring sustainability.

13.10 References
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