eMerging Technologies Source Municipal Water (Potable) HVAC Condensate Cooling Tower Blowdown Storm Water, Roof Runoff Storm Water, Grade Runoff Debris None None Low Low Medium Suspended Solids Very Low Very Low Medium Medium Medium Dissolved Inorganics Low Very Low Medium Low Variable Dissolved Organics Very Low Very Low Low Low Variable Microbes Very Low Very Low Low Low Medium Table 2: Comparison of selected nonpotable water sources to potable sources. electrical energy use in the U.S. On a global basis, the water/wastewater sector accounts for about 1.5% of CO2 emissions and about 5% to 7% of greenhouse gas emissions. Commercial buildings in the U.S. account for about 18 quads of energy consumption. Space heating, lighting, and space cooling are the top three energy consuming applications. Any recovery and reuse of water used in space cooling could contribute to a net reduction in commercial building energy and water demand.14 Market Potential Drivers for adoption of technologies to reduce use of potable water for landscape irrigation purposes include the potential cost savings associated with use of alternative water sources. Results from a comprehensive assessment of the economics of condensate collection from air-handling units indicates that the water rate charged by the local water utility is key to the economic viability of condensate collection.15 Starting with a set of 47 U.S. cities and considering weather data and cost of water for each city, the study identified four locations in which the payback period for an air-handling unit condensation collection unit was three years or less: Honolulu; Miami; New Orleans; and Orlando, Fla. Each of these cities is associated with an annual condensate water potential of 7 gallons per cfm of outdoor air (56 L per L/s of outdoor air) annually. Water rates in these locations ranged from $4.82/thousand gallons to $10.75/thousand gallons ($1.27/thousand L to $2.84/thousand L). The study assumed a simple system that drains the air-handling unit condensate sump into a small tank and then pumps that water to a simple reuse application. August 2012 www.info.hotims.com/41642-47 78 ASHRAE Journal