At the beginning of the semester, most of what was known about water on campus could be characterized as heuristic observation. While these observations give good indications of where to look and what to examine, a more quantitative analysis is needed in order to make recommendations for an effective water conservation program. For example, a common perception among students, faculty, and staff is that the sprinkler system is very wasteful. We need to determine if that is in fact the case, or if that perception is simply a product of visibility rather than reality. Similarly, much has been made of the installation of flush-less urinals on the academic end. However, no indication was made regarding whether or not the savings from this modification constituted a significant portion of HMC’s total water usage. Of course, from an environmental standpoint, any reduction in water consumption is a positive, but there is another factor to be considered. Assuming that only a fixed amount of money is available to be spent on evaluation and conservation efforts, this work hopes to ensure that it is spent in the most beneficial way.
Understanding the end uses of water would also allow us to make educated decisions regarding various sustainability options. For example, if HMC were ever to undertake a large water project like the installation of cisterns1, then knowing how much of our water could come from unfiltered rainwater would be an important factor in both viability and design decisions.
The obvious first step is to find out how much total water is used on HMC’s campus. Before we can begin to break it down or identify problem areas, we simply need to know the aggregate amount of water that is pumped onto HMC’s campus every year. Beyond total supply, it becomes interesting to know where that water goes. End use break down of water usage can identify areas in which conservation will be the easiest or the most effective. In terms of this goal, we identify four main end uses of water: residential, academic, dining, and landscaping. Residential use consists of water used in the dorms by student residents. This use should consist primarily of shower, toilet, drinking, and miscellaneous washing tasks. Academic use is defined as water used in the academic and administrative buildings, with primary uses being restrooms, labs, and air conditioning. Dining use consists of water used in the preparation of food and dishwashing at the dining hall. Finally, landscaping use consists of water used for the irrigation of the landscaping throughout campus.
There are several reasons for finding out what the end uses of water are on HMC’s campus. The most prominent is to be able to identify problems or anomalies that may present opportunities for savings with minor changes. Also, the ability to identify the largest users of water will aid in determining where conservation efforts may be most effectively spent. Sewage is another reason to try to determine the end uses of water. In many places, sewage charges are based on the total water used. This is based on the reasoning that what goes in must come out. However, a campus that uses much of its water for landscaping that isn’t going back into the sewers may not need to be charged sewage for that water. Unfortunately, as noted previously, HMC is not charged by use for sewage, so this option is not available to us. Knowing how much of our water needs goes to indoor use and therefore needs to be treated will still help us determine the full cost of our water usage since sewage treatment also has financial and environmental costs, even if these are not passed on to us as an institution.
A good understanding of HMC’s water delivery system is required in order to determine the end uses of water. This includes the irrigation systems as well as the lines themselves and the metering situation. HMC recently underwent an overhaul of the irrigation system in conjunction with a clinic project on native landscaping techniques in 2000-2001. The clinic project looked at the evaporation and transpiration losses of plants as well as climate data in the region and made recommendations for a more water conscious landscaping program. The clinic team planted and metered a test garden just west of Atwood dormitory, which has served as a model for the new landscaping throughout much of campus. At that time, the team made recommendations regarding the new irrigation system, but no formal analysis has been made since it was installed. However, Mike Barber of HMC’s Facilities and Maintenance suggests that savings have been on the order of $30,000 per year based on the ratings of the sprinklers used and the replacements. The metering system and the water lines are crucial to understanding where the water comes from and where it goes. Currently, HMC has only meters installed by the water company for billing purposes. The locations of these meters and the accurate identification of what they service is the first step in identifying the end uses of water.
Although for this project we only separated water use into four categories, a major use of water at HMC are the cooling towers. In the future these should probably be a separate category. The cooling towers are part of the air conditioning systems for all of the buildings with central air: Parsons, Olin, Keck, Jacobs, Libra Complex, Kingston, Thomas Garrett, Platt, South, Linde Activities Center, Case, and Linde. HMC uses cooling towers that function based on evaporative cooling and so this may be a significant source of water usage. According to a report from the U.S. Department of Energy and the National Energy Technology Laboratory, evaporative cooling varies in the range of 10-30% evaporative loss from the circulation system [xxi]. Unfortunately, we have not been able to make independent estimates for the loss by the HMC cooling towers, so we have suggested metering the academic cooling towers separately.
4What We Currently Know About Water at HMC
Of the things we’d like to know about HMC’s water usage, some are easy to determine, but others are less readily available. Significant progress was made during the course of this work in the gathering of knowledge regarding water usage on HMC. However, there is much that remains to be found.