Although it is widely understood that energy and water are the world’s two most critical resources, their vital interconnections and vulnerabilities are less often recognized. This farsighted talk offers a new, holistic way of thinking about energy and water—a big picture approach that reveals the interdependence of the two resources, identifies the seriousness of the challenges, and lays out an optimistic approach with an array of solutions to ensure the continuing sustainability of both.

This presentation brings the water-energy nexus to the building scale discussing tradeoffs that are made on projects. For example, focusing on energy efficiency using evaporative cooling or irrigated landscape for shading saves electricity locally, but at a higher water use which, in turn uses energy at a municipal level to treat and pump that water. Conversely, air-cooled equipment eliminates cooling tower water use, but at lower efficiency therefore using more electricity which uses water at the power plant. Similar to the “site” versus “source” discussion for energy use, the water energy nexus brings this consideration to water use.

Electricity generation generally consumes water, meaning energy efficiency reduces water consumption. Evaporative cooling offers substantial energy efficiency gains but consumes water on site, and the impact of evaporative cooling is largest in arid regions which are susceptible to droughts. Net water consumption for evaporative cooling depends on the regional generation mix, water quality, weather conditions, and the water-use efficiency for particular evaporative equipment. This presentation explores total water-use scenarios including a detailed analysis of a theoretical worst-case scenario where all water for evaporative cooling uses energy-intensive desalination, the results of which suggest that evaporative cooling is energy and cost effective.

Proposed ASHRAE Standard 212 is a Method of Test for determining the energy and peak electricity demand savings associated with adding evaporative pre-coolers to packaged HVAC equipment. The standard measures the evaporative effectiveness of a pre-cooler as a function of face velocity and weather conditions, as well as the water consumption required to produce that effectiveness. This presentation will discuss the current content of the standard, as well as the rationale for how and why different parameters are measured within the standard. It will also include preliminary test results for different pre-cooler technologies.

Several manufacturers have recently introduced hybrid vapor-compression/evaporative cooling solutions that incorporate the advantages of multiple cooling components into variable speed, multi-mode equipment. These technologies may utilize indirect evaporative cooling, exhaust air heat recovery, desiccant dehumidification (or other components) in combination with vapor compression. This presentation summarizes findings from several laboratory tests, and more than 30 monitored installations of different hybrid air conditioning solutions. It focuses on practical issues in design and commissioning that help ensure performance in operation. In most cases these strategies can reduce full-load cooling demand by more than 40%. Some systems deliver annual savings of 65% or more.

With an increasing focus on use of refrigerants with a low GWP (Global Warming Potential), one such refrigerant muscling its way back onto the scene is R-718, better known to most by its chemical formula, H₂O. This presentation focuses on two distinct uses of evaporative cooling technologies. The first case investigates DEC for a commercial office building. The second case investigates Indirect Evaporative Cooling for a laboratory building with stringent humidity control requirements. The results indicated combined chiller and fan energy savings greater than 60%. The IEC improved overall energy and water efficiency while providing significant first cost savings.

Water-cooled chillers have for years been the most energy efficient and cost effective means of addressing large cooling loads as is recognized by ASHRAE 90.1. However, as the price of water has increased and the performance of air-cooled chillers have improved those lines have begun to blur. It is no longer clear that the lowest total cost ownership for cooling applications over 300 tons resides with water cooled chillers. This session explores all the factors related to comparing chiller plants including: performance curves, climate, altitude, water quality, first cost and operating cost (water, energy, maintenance, and treatment).

This presentation explores evaporative cooling technologies that can vastly reduce onsite energy use of building systems. Systems explored include direct and indirect airside systems, as well as evaporative pre-filters at condensers. These new systems are compared on an energy and cost basis to conventional air-cooled systems or hydronic systems with a conventional plant and cooling tower. A case study compares the benefits of different systems in climates across the United States to examine the benefits available in different regions.

As water scarcity and utility prices increase, building water consumption is an increasingly important aspect of sustainability and efficiency. For buildings where water-efficient fixtures and cooling system upgrades have already been made, the final step toward ‘net zero’ water consumption is capture, treatment, and re-use of onsite and auxiliary water sources. This presentation provides an overview of onsite auxiliary water sources, treatment systems and other equipment required for various uses, and the site energy implications of net zero water buildings

Stone 34, a 130,000 sq. ft. mixed-use commercial office building, exceeded the aggressive performance standards of Seattle’s Living Building Pilot. The requirements of this program include achieving at least three of the seven petals in the "Living Building Challenge" plus showing a reduction in annual energy usage by 75% when compared to CBECS data, a reduction in potable water usage by 75% and re-use of at least 50% of storm water that hits the site. The Living Building Pilot requires validated performance after 12 continuous months of operation, and both the design team and ownership team faced financial penalties if the building failed to meet the program targets. This paper will explain the "bookend approach" that the design and ownership team used to ensure that the occupied building met the performance requirements.

This research project examines the complexity of conveyor dishwashers, benchmarking water and energy use of old and new dishwashers operating in facilities and identifying strategies to sustain the savings potential of high-efficiency machines. The catalyst for this study was receiving funding from Metropolitan Water District’s Innovative Conservation Grant Program and co-funding from Pacific Gas and Electric Company. These machines are the most water and energy intensive appliances in commercial kitchens with older dishwashers using two to three times their anticipated hot water use when factoring in the manufacturer’s specifications of rinse flow rate and tank volume.

Buildings consume 25% of global water and are responsible for 40% of the total world annual energy consumption. Buildings account for 72% end-use electricity in the U.S. with the largest portion spent for cooling and heating of buildings. The key issues for the future of building industry are related to saving of water and energy consumption, and delivering environmental benefits. The objective of this study is to quantify cooling/heating energy saving and rainwater saving due to vertical gardening in buildings by using controlled experiments and building energy modeling.

Engineers often work on projects in areas where they have not worked before. When that happens, how do we decide whether the incoming water should be used as-is or treated for domestic use? Should it be softened? Should only hot water be softened? Should soft and raw water be blended? If so, in what ration? Is RO needed for some applications? This presentation introduces a spreadsheet that may become an ASHRAE tool offering that will help engineers to make those decisions based on something more than what the building next door does.

Specifying the water usage ratio for HVAC equipment is an increasing goal in high performance building designs. This session introduces the concept of saturation indices for heat transfer systems, and demonstrate the tools available for predicting water consumption, water treatment control limits and chemical treatment directives. Presenters explore how the indices can be utilized to develop a successful water treatment program which balance water consumption and equipment life. This seminar provides the engineer, owner and operator with the tools and understanding necessary, for an efficient HVAC system, regardless of local makeup water quality 

Cooling towers used by water source systems can consume up to 50% of a site’s potable water. Owners and design-professionals must cut down on CTs that reject waste heat for space cooling by the power of evaporation. Towers consume water, chemicals, and lots of electricity; producing wastewater unqualified to pass through treatment plants. Can anything take their place? YES! Distributed GSHP systems provide thermal leverage on reduced power demand; reducing cooling tower water wastage by 50% - 70% and electric consumption by 60%. Explore how a GX-based Distributed Energy System enables solutions to Energy/Water Nexus challenges.

This presentation focuses on a geothermal sourced chiller plant in Florida, and a distributed geothermal heat pump installation near Los Angeles, both in operation for several years, originally slated for cooling towers. Attendees will see in both cases the methodology and rationale by which architects, engineers and owners worked together to choose to eliminate their cooling towers, and reaping remarkable water savings along with energy savings and an array of other tangent benefits.

With the ever changing climate we are experiencing in the world, Cashman Equipment is doing their part to conserve water and energy by using a Geo-Thermal system to cool their corporate facilities. They are using 30% less water than conventional systems utilizing two (2) 250 ton cooling towers as a supplemental cooling to the loop used by the heat pumps. The original calculations showed an approximate savings of $46,000.00 over the conventional DX cooling. Yes, as hot as Las Vegas is, we are running efficiently with massive well field below the desert heat.

Interest in waste water heat recovery in the residential and commercial sectors has increased significantly in recent years. Integration of heat pumps with these systems introduces the possibility to use the recovered heat freely. However, integration of heat pumps also makes these systems more complicated. For the system designer, this means that knowledge regarding the influence of design parameters on the system performance over both the short- and long term is needed. This seminar presentation looks into how different parameters influence the system performance when using heat pumps; a few examples of heat exchangers are also introduced.

Today’s evolving market for GeoExchange systems continues to develop solutions that are compatible with large buildings in urbanized areas where site areas for a traditional ground heat exchanger are extremely limited. For both new construction and retrofit situations, alternatives to a ground loop may exist such as waste water systems that recycle non-potable water. In fact, there are over 3500 municipalities with some level of recycled water distribution networks. These untapped resources offer both viable performance solutions and higher potential installation and operation cost savings. This presentation covers such a system at the Denver Museum of Nature & Science.

This presentation highlights the findings of a case study of a recycled water heat pump (RWHP) system installed at the Denver Museum of Nature and Science in Denver, Colorado. The RWHP system utilizes the recycled water from the City’s water system as the heat sink and source for the heat pump. This case study is based on the analysis of measured performance data, maintenance records, construction costs, and engineering calculation of the energy consumption of conventional central heating, ventilation, and air-conditioning (HVAC) systems providing the same level of space conditioning as the demonstrated RWHP system.

This presentation covers the background and history of legionellosis and the conditions in building water systems that amplify it. The key parts of ANSI/ASHRAE Standard 188-2015 are summarized to give the audience a conceptual framework and sources of more in depth knowledge are given. Compliance requirements, health care facility requirements, the necessary building survey to assess the risk of LD, the key elements of a WMP (water management plan), control points, and the verification and validation requirements. The design, documentation, operation & maintenance of building water systems by the program team of knowledgeable persons is stressed.

ASHRAE 191P is a proposed standard setting minimum performance requirements for mechanical and process systems as well as a required water balance analysis for all water sources and sinks within a building and site. The presentation briefly discusses the history of the standard, define scope of how this standard interacts with other standards such as plumbing and irrigation standards, and highlight key requirements of each section covering everything from cooling towers to vivarium animal watering systems. Finally, examples of whole building water balances are shared to demonstrate how to apply the standard for different building types.

Tomorrow’s kitchen will take advantage of new technical innovations in food service equipment to be smaller, faster, more flexible and more efficient. Water, like electricity and natural gas, is a mission critical component of any restaurant operation. Efficient cooking and sanitation technologies as well as regimented maintenance programs can drastically reduce water and energy costs and maximize profits. This session presents examples of new technologies that can maximize output, while minimizing energy and water use and fulfilling the evolving demands of the 21st century commercial kitchen.

Ice making machines are ubiquitous in commercial foodservice. Ranging from cube, to nugget and flake-type machines, the installed base represents one of the largest inventories of foodservice equipment. A field study of ice machines in eight restaurants confirmed that the actual ice making (i.e., compressor operation) was coincident with utility peak periods. The measured duty cycles, combined with actual electric load profiles, demonstrated the potential for off-peak operation of these ice machines. A second field study demonstrated a dramatic (34%) reduction in energy use. Furthermore, the operation of the new machine shifted OFF had no impact on the foodservice operation.

Overview and results of an extensive project that seeks to modernize hot water system design and operation are discussed. The speaker discusses a study that monitored use from generation to point of use in a restaurant. Details will be provided on the original system’s energy and water use, delivery performance and overall efficiency. Updates on the design, installation and monitoring of the replacement system will be covered. The study was conducted to understand the limitations of conventional design and ways to remediate performance issues through a redesign that utilizes decentralized water heating, optimized distribution systems, and innovative dishwashers.

This presentation is a case study of a QSR prototype design that evolved from 2005 to 2015 to result in a 16.7% reduction in electric use, a 1.4% reduction in natural gas use, and a 19% reduction in water use compared to the 2005 prototype. The energy savings were evaluated using energy model simulations and spreadsheet calculations that take into account changes operation as well as energy improvements in the design over the 10 year period. The steps taken to achieve these savings are presented.

In the commercial sector, energy is used to pump and heat water for domestic and other uses, and water is often critical to HVAC equipment. In certain building types, the usage of water can have a major impact on a building’s demand and performance. Collecting information water usage in commercial buildings is an important step towards a better understanding of the relationship between water and energy. This presentation discusses the collection of water usage data in the 2012 Commercial Buildings Energy Consumption Survey (CBECS): reporting rates by important building characteristics, an evaluation of data quality, and discussion of results.

Commercial buildings represent a sizable use of water from U.S. public water systems, include the largest accounts in many jurisdictions, and utilize water for many processes and end uses ripe for efficiency improvements. Yet water conservation efforts haven’t made the same headway in commercial buildings as in the residential sector. This presentation reviews what is known about water use in the commercial sector, discusses gaps in current knowledge and how an inability to describe the variation observed in water use limits water efficiency potential and summarizes recent efforts by EPA’s WaterSense and ENERGY STAR programs to bridge this gap.

Water is generally overlooked as a source of savings for facilities. The cost of producing and delivering water continues to climb, making it ripe for savings opportunities under energy saving performance contracts. Prisons often have a relatively high usage per inmate. This presentation looks at a recent prison project where prioritizing water conservation resulted in water, sewer, energy and O&M savings, which helped fund significant capital improvements. Water meter data was used to identify a baseline utility profile and achieve substantial domestic water system improvements. Finally, the presentation discusses adopting utility monitoring programs after implementing water system improvements.

As humid air blows past cooling coils in the air-conditioning process, moisture in the air condenses and is routed away from buildings and disposed of as waste. This ‘nuisance’ water is being seen as a new sustainable strategy that contributes toward net zero installations and increases resilience in urban areas. As condensate recovery becomes a more acceptable alternate source to satisfy water demands, understanding potential necessary condensate treatment is important. Treatment methods should be considered based on need, efficacy, cost, safety and long-term maintenance. The case studies provided include examples of implementation, considerations, and lessons learned for condensate collection strategies.