Water Conservation and the Water-Energy Nexus at Xavier University

Purchase PDF
Elyce Feliz
Xavier University in Cincinnati, Ohio.

In Brief

As Pope Francis’ recent encyclical on the environment has reminded us, “access to safe drinkable water is a basic and universal human right, since it is essential to human survival and, as such, is a condition for the exercise of other human rights.”1,2 Even in water-rich regions where water is “cheap,” careful attention to water conservation and pollution prevention is a moral necessity, helping us to respect this most essential resource while raising awareness of the lack of access to safe water around the globe. Xavier University in Cincinnati, Ohio is located in an area where water bills are relatively low, yet the area suffers from combined sewer overflow issues with associated water pollution. To tackle this problem, students developed a new model for assessing their water usage that, combined with energy savings, offers a bottom-up approach.

Key Concepts

  • Societies and organizations should analyze water and energy together. The “water-energy nexus” refers to the interconnections between water and energy, such as the energy cost of delivering water, the water cost of producing energy, and the entwined nature of energy and water infrastructures.

  • The need for water conservation across the globe is increasingly recognized. All of us should treat water as a precious resource, including those who live in relatively water-rich areas.

  • Xavier’s water-energy initiative benefited from the perspectives of a diverse group of individuals from multiple divisions and levels. Building a broad-based working group is critical to the success of innovative sustainability projects and can build system interconnections that improve sustainability efforts in the future.

  • In areas such as the energy cost of water usage, customizing standardized metrics to reflect local costs allows us to more accurately calculate environmental impacts and therefore make better decisions on related practices and policies.

The moral imperative of water sustainability is coming into focus, as witnessed by the work of global water activists and underlined by the recent statement from Pope Francis, “access to safe drinkable water is a basic and universal human right, since it is essential to human survival and, as such, is a condition for the exercise of other human rights.”1,2 The need for water conservation and the interconnections between water and energy (the “water-energy nexus”) are also gaining increased attention in the wake of a series of highly visible events, ranging from droughts (across a third of the United States, including long-term drought in California) to storms (impact of loss of power in Hurricane Sandy on water infrastructure). Increasingly, organizations will be seeking to analyze and address issues related to the water-energy nexus. The Department of Energy (DOE) recently formed a special team to issue a major report on the water-energy nexus. As the DOE team states, “It is time for a more integrated approach to address the challenges and opportunities of the water-energy nexus.”3

Universities as institutions are often major users of both water and energy and also have a unique capacity to inform society and raise awareness; many are working hard to reduce their energy and water footprints, both to reduce their costs and to use their research expertise to provide examples for other institutions.4 Xavier University’s 2010 Campus Sustainability Plan included water sustainability as a key element in overall campus sustainability and led to a number of water conservation measures.5 Recently, Xavier’s experience with their Energy Initiative led campus sustainability leaders to think about achieving similar results with water usage and to seek understanding of the water-energy nexus on campus.

How Energy Led to Water

In academic year 2013–14, a sustainability speaker series theme of “Energy Justice” focused the university’s attention on energy and included visits from energy experts such as Rocky Mountain Institute’s Amory Lovins and economist Jeremy Rifkin.6 Green building policies and practices that began in earnest in 2009 (construction of three buildings to LEED silver standards, including a central utility plant for heating and cooling systems) had reduced carbon intensity on campus but not the overall footprint. Inspired by Amory Lovins’ visit in the fall of 2013, a year-long Energy Initiative was funded by university President Father Graham, SJ at a cost of USD$120,000 and directed at uncovering immediate energy savings with a one-year payback, a challenging task on an already efficient campus. Energy consultant Ronald Perkins of Navasota, Texas (who had worked with Lovins in the past) helped Physical Plant staff and students identify problems and holistically analyze and solve them. This included workshops, walk throughs led by Perkins, and students who were appointed to be so-called “energy detectives” using an infrared camera and temperature/humidity pens to search for building leaks. As a result of these measures, Xavier achieved a five percent reduction of campus energy and met the one-year payback guideline from administration.


Xavier University
ECOS students, led by Mark Hanlon of Xavier University’s Physical Plant, explore the campus’ water-related infrastructure, such as the cooling tower depicted above.

This successful experience with energy was extended to include a water study. While water bills are relatively low in the region, there is currently a significant combined sewer overflow (CSO) problem in the area (leading to raw sewage flowing into waterways in periods of high rain), resulting in higher sewer bills and indicating an urgent environmental need for storm water management and water conservation.7 Water consultants assisted staff and sustainability interns as they collected data, developed a water footprint, and made project recommendations. As a follow-up to this analysis, Xavier students in a Natural Resource, Environmental, and Ecological Economics course customized the Environmental Protection Agency’s (EPA) Pollution Prevention Calculator to more accurately estimate the embedded energy in water delivered to Xavier’s campus.

Sustainability at Xavier University

Xavier’s 2010 Campus Sustainability Plan was developed after Xavier President Michael Graham, SJ joined more than 1,000 institutions in signing the American Colleges and University Presidents’ Climate Commitment,8 committing the University to carbon neutrality by 2030. To achieve this goal, a campus-wide Sustainability Committee was formed, a public sustainability speaker series was started, a Sustainability Director was hired, a number of Sustainability Faculty Fellows were funded, and by 2014, several interdisciplinary degrees in sustainability were launched to add to Xavier’s BS in Environmental Science: the BA in Economics, Sustainability and Society; BA in Land, Farming and Community; BSBA in Sustainability: Economics and Management; and MA in Urban Sustainability and Resilience.6 In 2015, a Sustainability Advisory Board for academic programs was formed, with prominent green leaders from private, public, and nonprofit sectors. The University has joined the Association for the Advancement of Sustainability in Higher Education (AASHE) and attends and presents at AASHE conferences. All efforts stress building commitment through involving a broad network of individuals on campus; working with community partners and sharing knowledge; and using campus as a laboratory for student learning and best practices.

A Collaborative Approach

This project used a systems thinking approach, so university students worked together with faculty, campus operations staff, and community partners in an integrated and experiential manner.9 This collaborative approach to tackling environmental and sustainability issues is a model that serves several valuable purposes simultaneously. Students in the Fall 2014 class had studied water as an economic resource and as a crucial element in local and global ecosystems via a general overview and abstract economic analysis.1,10,11 Studying water usage, storm water runoff, and nonpoint source water pollution issues right on their own campus, where they are personally using water by flushing toilets, using sinks and drinking fountains, and walking through landscaped grounds literally brought the discussion home to students. Students thus gained valuable knowledge and skills by working on real-world problems in an experiential learning methodology, while partners gained from the fresh perspectives and contributions of students. Faculty gained in-depth knowledge of relevant cases that can be communicated to future classes as well as community contacts that can assist them in staying up-to-date on cutting-edge applications.12


Xavier University
How a Combined Sewer System Works

Further, when campus operations and academic classes work together to improve the efficiency and environmental impact of their common campus, constructive relationships are formed and all parties achieve a better understanding of each other’s functions.13 From a systems thinking viewpoint, this introduced new interconnections to the system, which can serve as a basis for further improvements in the campus environment in the future.9 As a result of the water study, Xavier’s Sustainability Committee is now planning to report to the campus community regularly on water sustainability progress, thus solidifying the campus collaboration around water. This expands the foundation for further collaboration on other aspects of sustainability, assisting the University to fulfill and strengthen its sustainability commitments.

Water Footprint Study

The water study was undertaken in the summer of 2014. Water consultants Williams Creek Consulting worked with staff and sustainability interns to develop a baseline water footprint, that is, the total amount of potable water used and storm water runoff generated on the entire campus. The footprint was used as a basis for project recommendations, with the goal of moving Xavier’s campus closer to its long-term goal of Net Zero Water (where water use is minimized and offset by storm water infiltration, using best management practices in green infrastructure). Consultants, staff, and student interns did walk-through assessments of water use and storm-water management practices throughout campus, supplemented by desktop data analysis by consultants. Initial project recommendations were discussed in lively, open-ended workshops with faculty and staff and later refined by input from staff, faculty, students, and administration.


Xavier University
Mark Hanlon, Associate Director of Maintenance and Operations at the University’s physical plant, explains the control panel of one of the Univeristy’s largest chillers to a student.

The study documented the fact that more rainwater falls on the campus than is required to meet all of our current water usage. This generated a powerful learning moment for Xavier students, faculty, and administrators as they reflected on these facts: the campus receives all the water it needs from the sky, but instead, this rainwater drains away, contributing to the serious storm water runoff and combined sewer overflow issues in the region, while the campus then has to purchase all their water needs. Specifically, data from the water footprint study estimated Xavier’s current annual water use at 79.3 million gallons, with the majority associated with heating and cooling buildings (showing the importance of the water-energy nexus, since we normally focus on the energy aspects of heating and cooling). Additionally, 52 percent of Xavier’s 142-acre campus consists of impervious surfaces in the form of rooftops, parking lots, roads, and walkways. Based on the EPA’s Storm Water Management Model (SWMM), these impervious surfaces generate 85 million gallons of storm water runoff annually, greater than the usage of 79.3 million gallons. This implies a water surplus if all storm water could be captured, treated, and utilized. Since nonpotable water (water not suitable for drinking) can be used for irrigation for landscaping, the study indicated capturing rainwater for irrigation as a first step. The runoff from Xavier’s 930,000 square feet of rooftops alone has an annual rainfall capture potential of over 19 million gallons and would require minimal treatment for sediment prior to use for irrigation.

Other water footprint reduction opportunities identified by Williams Creek and interns include the following: rain gardens, xeriscaping (landscaping with little or no irrigation), air handler condensate reuse, replacement of domestic fixtures with EPA WaterSense® labeled products, and recommendations for operating pools and fountains with water conservation strategies in mind. For example, the Cintas Center, which holds events with over 10,000 attendees, has two cooling towers and nine air handler units. Air handler condensate represents a significant onsite water resource that is low in sediment, dissolved solids, hardness, and pathogens. Condensate is plentiful at the same time that cooling tower water demands are high, with an estimated 3 to ten gallons of condensate generated for every 1,000 square feet of conditioned space. To utilize this alternative water source, some plumbing alterations are required, and reused water may require disinfection and removal of copper (from contact with the cooling coil). Lastly, opportunities for green infrastructure implementation at Xavier’s campus were identified in landscaped areas where storm inlets could be raised to promote infiltration of storm water for shallow aquifer recharge, thus moving Xavier’s campus towards a Net Zero Water condition with associated carbon reductions.

Water-Energy Nexus Analysis by Students

In Fall 2014, over 40 Xavier undergraduate students took Professor Nancy Bertaux’s course in Natural Resource, Environmental and Ecological Economics. A subgroup of students, led by senior Mark Miller, undertook a class project to follow up on the water footprint study and ultimately reported results to all students in the class, plus attendees from Xavier administration and the Cincinnati water community. Students also participated in the University’s sustainability theme of “Water Justice” for the 2014–15 academic year, gaining the bigger picture on water resource issues by attending the speaker series and smaller dialogue sessions with P&G Vice President for Global Sustainability Len Sauers, water journalist Cynthia Barnett, and water activist Maude Barlow.6

Students explored the water-energy nexus on their own campus by researching embedded energy in the water delivered to Xavier’s campus. EPA’s Pollution Prevention Calculator’s water conservation tool was utilized to estimate the greenhouse gas impact of Xavier’s water usage.11 The calculator tool was then customized by incorporation of more granular data pertaining to Xavier’s campus. Working with expert guidance from John Hazlett of Williams Creek Consulting, and in partnership with Xavier University’s Physical Plant and Sustainability Director Ann Dougherty, students gathered data from local utilities serving the Xavier campus, customized the calculator, and compared results obtained by using the EPA’s Pollution Prevention Calculator versus results from the customized calculator (described in the appendix).14


AgriLife Today
One method of water conservation now employed by Xavier University is xeriscaping, or landscaping with little or no irrigation, as pictured.

Students learned that water footprinting is a rapidly developing field in need of (and approaching) standardized measurement and improved data collection. The water conservation tool contained in the standard EPA calculator includes parameters based on averages, reflecting the principle of diminishing feasibility (for every step of complexity in data collection, the data becomes disproportionately more complex to attain). For a single institution such as Xavier, modifications to the data collection tool can add accuracy without adding much complexity, given the institution’s easy access to its own data (e.g., organizational databases and water bills). The appendix outlines the specific procedures for customizing the EPA calculator’s water tool, which will allow other institutions to more accurately calculate the carbon impact of their water-energy nexus. Note that the EPA’s calculator converts data relevant to water conservation into greenhouse gas (GHG) emissions equivalents. It takes into account pumping, treatment, and distribution but not heating. There are three main parameters in the calculator: water conserved, conversion factor, and set energy expenditure per million gallons pumped, treated, and distributed. These are described in the appendix, including procedures to customize the calculator where applicable, and calculations performed for Xavier University are presented. Accounting for all adjustments, Xavier University’s emissions footprint was 37 percent lower than the estimate from the standard EPA calculator (23 percent coming from the conversion factor alone).

By customizing the calculator, institutions benefit from more accurate estimates. For example, if the institution is located closer to their water source than suggested by the generalized model, as was Xavier, they will enjoy a more accurate, lower water footprint, a welcome and nearly costless improvement in their green profile. Conversely, if local parameters are adverse compared to the generalized calculator, the institution could find their energy use is being significantly underestimated, causing them to enhance their carbon footprint mitigation strategies. Either way, the higher quality information will be helpful to institutions committed to reductions in their GHG emissions.

While the water-energy nexus analysis allowed Xavier to report lower GHG emissions due to a more accurate calculation, Xavier remains committed to pursuing water conservation with its associated energy conservation. Water is an abundant resource in the Cincinnati area, averaging 42 inches of rainfall annually, but as noted above, the region is challenged by serious storm water runoff and combined sewer overflow problems.7 Xavier also wants students to be aware that around the world and in parts of the US, water shortages are serious and chronic, with significant pricing and access problems that relate to issues of just distribution, as we teach our students to be “Men and Women For and With Others.” 1,2,10

Future Ideas on the Water-Energy Nexus: Use Local Geography


Julie Sweeney
The water study revealed that more rainwater falls on campus than is needed to meet all of the university’s water usage needs. Future projects such will aim to capture and recycle that rainwater to make Xavier University more sustainable.

The water study showed the benefits of Xavier’s previous water conservation efforts that included careful, drip irrigation and automatic moisture monitoring methods, installation of low-flow toilets and aerated sink faucets and showerheads in all new and renovated buildings, and tanks for slow discharge of storm water. The water study spurred action plans that will further increase water conservation and recharging of aquifers, while reducing storm water runoff, including reuse of condensation from HVAC systems and systematic increase in green infrastructure on campus, such as rain gardens and xeriscaping. With the water-energy nexus as inspiration, the University is now planning two further pilot projects that capitalize on the physical geography of the campus and could expand water-energy knowledge and awareness in the community:

1. Work with a local mechanical engineering company to design a turbine to use the high volume of rainfall and steep hillsides on campus to create energy. Two campus locations have been identified that have large parking lots that are adjacent to hillsides and drops of 20 feet or more, with minimum slope of 75 percent. In addition, rainfall to roofs on newer buildings flows to underground tanks for slow, gravity discharge to the region’s combined sewer system. Engineering and physics students will work with professors, the campus chief plumber, and mechanical engineers to implement their best design, exploring the following:

  • Can in-pipe or in-tank turbines take advantage of this flow during high rainfall events?
  • At what resistance would the turbine be set to not block but rather slow flow under different incoming flow rates?
  • What topographical “drops” and pipe geometries are necessary for such technologies to be used effectively?

2. Recycle rainwater on campus through use of rainwater barrels and solar panels for pumps. Locations with buildings that have downspouts in the right areas to connect to a rainwater barrel have been identified in three areas, and estimated costs for a project with 10 barrels, solar panels, pumps, drip irrigation, and engineering are USD $50,000. Rainwater from barrels would irrigate lawns around these areas, and solar panels for the pumps would conserve energy and reduce the campus carbon footprint. The barrels will need to be maintained over time—for example, emptying barrels prior to freezing temperatures in winter to avoid cracking. Total annual water yield, based on an estimated 20 gallons of harvested storm water per square foot of rooftop, would be 786,000 gallons for the three rooftops combined. Professors from Environmental Science, Physics and Economics would involve students with this project, including measuring pH, turbidity, and other aspects of water in the barrels; building a system to indicate water levels in the barrels; testing the most efficient way to move water from the barrels to the irrigation system; and tracking water, energy, and cost savings.

Putting the Water and Energy Conversations Together

Increasing attention is now being directed both at water sustainability, and at the connection or “nexus” between water and energy. A leading water journalist has observed:

The nation’s energy and water problems are remarkably similar. So are the solutions: focusing on the demand side rather than constantly growing the supply side will help save the nation’s water resources and billions of dollars. At the very least, we should put the water and energy conversations together.15

For Xavier, ‘putting the conversations together’ meant analyzing energy and water usage holistically. Sustainability initiatives of all kinds will increasingly incorporate more attention to issues related to water, and Xavier University’s experience in progressing from an energy focus to a water-and-energy focus will and should be replicated in other institutions who want to be a positive force for change on water. When water justice advocate Maude Barlow was asked how change will happen on water sustainability, she answered, “It’s going to come from the bottom up,” and to the question of who will do this, she said, “go home and look in the mirror.”16

Thanks to Xavier University President Michael Graham and Chief Financial Officer Maribeth Amyot for funding the Xavier Energy Initiative, including the water study. Thanks to students in the water-energy project group in the Fall 2014 Natural Resource, Environmental, and Ecological Economics class; Sustainability Interns, Summer 2014; and Energy Detectives, Spring 2015. Thanks to professionals Ron Perkins, Ted Blahnik, Don Reichman and Mark Hanlon, Chief Engineer David Lococo, Vice President of Operations Robert Sheeran, Provost Scott Chadwick, and to visiting speakers Amory Lovins, Jeremy Rifkin, Len Sauers, Cynthia Barnett, and Maude Barlow.

There are three main parameters in the calculator: water conserved, conversion factor, and set energy expenditure per million gallons pumped, treated, and distributed.14 (Institutions are advised to monitor the conversion factor periodically, as these can vary significantly as energy providers change sources of energy, for example from coal vs. natural gas.17)

1. Water Conservation. The institutional user’s monthly water bills provide all required data for this parameter.

2. Conversion Factor. The calculator includes an index of conversion factors collected by region. Users can contact their specific energy provider (in our case, Duke Energy) to determine the metric for a customized calculator. In our case, this metric proved to be critical. The regional default conversion factor in the standard calculator was 0.0008909 MTCO_2 e/kWh, but our research for Xavier University yielded a value of 0.00068199388 MTCO_2 e/kWh. This factor alone suggested a 23 percent decrease in estimated emissions compared to the standard calculator.

3. Set Energy Expenditure Factor. This is perhaps the most important parameter to customize. This value quantifies the kWh needed to pump, treat, and distribute a million gallons of water, and is set at 3,300 kWh per million gallons. Since Xavier University is closely situated to the Miller water treatment plant on the Ohio River, this estimate was high. Data from our water provider, Greater Cincinnati Water Works, yielded a value of 2714.117 kWh per million gallons. For users seeking to make the same adjustments, the following two-step process can be followed:

  • Contact local water pumping/treatment/distribution facilities and request the gallons and kWh associated with each process. In the case of Cincinnati, this is a single, municipally managed unit, but some institutions may need to contact several facilities, not necessarily municipally-owned.
  • Use data to calculate customized set energy expenditure per million gallons pumped, treated, and distributed, as follows:

The total energy expended per million gallons is:

kWh Total/gal Total

= kWh Raw/gal Raw + kWh Treatment/gal Treatment
+ kWh Distribution/gal Distribution

For institutions that receive water through more than water distribution pipeline (even if the water comes from the same treatment plant), this will only affect the distribution term in the equation above, which should be calculated using a weighted average in order to give appropriate representation to pipelines with asymmetric contributions. In this case, the distribution term will appear as the following equation with an index of i = a…n :

(kWhi Distribution/gali Distribution )2/(kWha Distributed/gala Distributed+…+ kWhn Distributed/galn Distributed)

Accounting for both the conversion factor adjustment and the adjustment to set energy expenditures, Xavier University’s emissions footprint was 37 percent lower than the estimate from the generalized EPA calculator (recall it was 23 percent lower due to the conversion factor alone).