REDUCE HOT WATER DEMAND
Install low-flow showerheads: The Energy Policy Act of 1992 limits showerheads to 2.5 gpm (9.5 lpm) at 80 psi water pressure (550 kPa). In areas with municipal water and reasonable water pressure, a high quality, 1.5 gpm showerhead will probably be adequate. In rural areas with well water and variable water pressure, a 2.0 gpm showerhead will probably be adequate. Buy a well-designed product to ensure satisfactory performance). Install water-efficient faucet aerators: In residential bathrooms, install faucet aerators that deliver 0.5 gpm (1.9 lpm). For kitchens, a higher-flow faucet or retrofit aerator is probably needed for filling pots. The legal limit is 2.5 gpm (9.5 lpm). “Laminar-flow” faucets create the look and feel of a much fuller flow (these produce a hollow cylinder of water). Install foot or knee controls for faucets: Foot- or knee-activated faucet controls for kitchen sink faucets can save significant quantities of water (including hot water), along with adding convenience. A number of products are available. Install water-efficient clothes washers: The best horizontal-axis washers use less than half as much water per cubic foot of capacity as standard vertical-axis washers. A few vertical-axis washers do nearly as well. There have been dozens of advanced water-saving washers introduced in the past several years. To qualify for the GreenSpec Directory, a clothes washer can use no more than 9.5 gallons per cubic foot (1,270 l/m3) of capacity. Install water-efficient dishwashers: Water- and energy-efficient dishwashers today use as little as 4.5 gallons (17 l) of water per load. The Energy Factor (EF) of dishwashers is a fairly good indicator of water efficiency, since approximately 90% of the energy use of a dishwasher is for heating the water. To qualify for a listing in the GreenSpec Directory, a dishwasher must have an EF of at least 0.60.IMPROVE SYSTEM EFFICIENCY
Fix plumbing leaks: Leaky faucets or showerheads can waste tremendous quantities of hot water. Turn down water heater thermostat: Turning down the water heater thermostat to 120°F (49°C) can reduce standby losses to some extent, but this conservation strategy is overrated. Lower temperatures also raise concerns about Legionnaire’s Disease. Insulate storage water heater: Insulating a hot water tank can significantly reduce standby heat loss. Insulating an electric water heater is easier than insulating a gas water heater, because venting of the electric model is not required. Separate tanks used for indirect water heating can also be well insulated. Insulate hot water pipes: Water sitting in insulated hot water pipes between uses will not cool down as quickly, so hot water use will be reduced some of the time. Significant savings result from use of a recirculation system. Install heat traps: Heat traps are one-way valves or piping loops that reduce the thermosiphoning of hot water within hot water delivery pipes. Some water heaters may incorporate heat traps; if not, the heat traps can be added at the time a water heater is installed. Install a Metlund™ system: The proprietary Metlund Demand system can save water and boost the overall efficiency of a water heating system.CAPTURE HEAT THAT'S USUALLY LOST
Install a drain-line heat exchanger: The GFX™ system is a very simple heat exchanger for capturing some of the heat in water that’s going down the drain. More sophisticated (and expensive) wastewater heat exchangers are available for commercial/industrial applications. Capture waste heat from power-generation equipment: Microturbines and fuel cells are ideal candidates for cogeneration or combined heat and power (CHP). These processes of generating electricity also generate considerable waste heat that can be captured with a heat exchanger system. Capture waste heat from compression-cycle refrigeration equipment: Refrigerators, heat pumps, and air conditioners can sometimes be modified with heat exchangers to capture waste heat. Referred to as desuperheaters, these devices are not widely available but can be a source of free energy—particularly where there are large refrigeration loads or when air conditioners are in heavy use during the summer. Capture waste heat from ventilation air: Heat pumps can be used to extract heat from ventilation air in larger buildings. A high-rise condominium project in Portland, Oregon is being designed to get about 70% of its domestic hot water in this way.
