Wastewater treatment plants typically have one or more administration buildings that could benefit from the following energy-efficiency measures. These measures cost nothing or only a little, are easy to implement, and utilize proven technologies.
Turning things off
Turning things off seems simple, but remember that for every 1,000 kilowatt-hours (kWh) you save by turning things off, you’ll save $100 on your utility bill (assuming average electricity costs of 10 cents per kWh).
Computers and monitors. Computers and other electronic equipment can contribute up to 20 percent of overall energy consumption. You can gain significant energy savings by verifying that computer power-management settings are enabled on individual computers and monitors, forcing them to enter sleep mode after a specified period of inactivity. Effective power-management settings can cut a computer’s electricity use roughly in half, saving up to $75 annually per computer. Although most computers are now shipped with some sort of power management settings enabled, those settings can be disabled or made less effective, or they can be made more rigorous to maximize energy savings. For more information, the US Environmental Protection Agency (EPA) offers detailed instructions on Energy Star’s The Business Case for Power Management page.
Other office equipment and plug loads. Like computers, devices such as printers, fax machines, and coffeemakers often have energy-reduction settings that can yield substantial energy savings. Additionally, consider using smart power strips with occupancy sensors, which are an easy way to shut off often-forgotten energy users such as printers, monitors, desk lamps, and radios.
Lights. Lights should be turned off when not in use, but many people forget to take this step. When properly installed, occupancy sensors and timers can do this for you. A no-cost option is to simply train staff to turn off lights as part of their closing procedures (you can also help by posting a notice that identifies the locations of light switches).
Chilled-water drinking fountains. Water fountains generally don’t need to provide ice-cold water 24 hours a day unless it’s required for health reasons. In most cases, you can turn off the cooling systems in drinking fountains.
Vending machines. Refrigerated vending machines typically operate 24/7, using 2,500 to 4,400 kWh per year and adding to cooling loads in the spaces they occupy. Timers or occupancy sensors can yield significant savings because they allow the machines to turn on only when a customer is present or when the compressor must run to maintain the product at the desired temperature.
Walk-through audits. For facilities that don’t operate constantly, one method to identify energy-efficiency opportunities is a walk through the facility after hours. Much of the equipment that is left on overnight or over the weekend in an empty building is a good candidate for saving energy by switching it off. Consider recruiting volunteers from each shift as monitors.
Motors. Identify motors that are operating unnecessarily and shut them down. This could be as simple as ceiling fans running in unoccupied spaces or as complicated as cooling tower fans still running after target temperatures have been met.
Turning things down
Some equipment cannot be turned off entirely but can be turned down to save energy.
HVAC temperature setbacks. During closed hours, turn down temperature settings during heating seasons and turn them up in cooling seasons. Programmable thermostats make temperature setbacks a reliable option.
Peripheral and back rooms. Make sure that HVAC settings in rarely used offices and other peripheral rooms are at minimum settings.
Window shades and blinds. During warm weather, blinds can block direct sunlight and reduce cooling needs; in the winter, opening the blinds on south-facing windows will let in sunlight to help heat the space.
Optimizing operations and maintenance
Given all the moving mechanical parts in a wastewater treatment plant, it’s very important to remember that regularly scheduled operations and maintenance (O&M) can keep equipment running smoothly and delivering energy savings.
Check motors. Mechanical problems are the main cause of premature failures of electric motors. Routinely lubricating motors, checking for clean and adequate ventilation, and ensuring that motors aren’t suffering from a voltage imbalance will help them achieve their full-life potential while simultaneously minimizing their energy consumption.
Inspect fans, bearings, and belts. A thorough inspection of fan blades, bearings, and belts at least once a year can prevent failure and maintain efficiency. During the inspection, fan blades should be cleaned, bearings should be checked for adequate lubrication, and belts should be adjusted and changed if needed.
Conduct a recommissioning audit. Professionals who are trained in identifying wastewater treatment O&M and capital opportunities offer audits similar to the walk-through audit described above, but focused on identifying a broader set of opportunities (not just turning equipment off). The audit typically lasts up to a day, and ends with the delivery of a report detailing potential savings measures, plus estimated costs and benefits. The audit is often done in conjunction with benchmarking, which involves collecting facility energy use data, billing data, and facility comparison data. Recommissioning audits identify efficiency measures that will restore the overall plant performance to original design levels, but they do not delve into specifics about the performance of process systems.
