SEDAC ENERGY SMART TIPS Pools

Swimming pools and spas have become energy cost for a given category differ a) standard features in hotels, motels, because energy per unit cost for natural apartment complexes, health clubs, gas is lower than for electricity. This subdivisions, and municipal recreation breakdown gives an indication of possible facilities, but they can be large energy areas for improvement. Generally users. Thankfully there are several speaking, pool water heating and space measures available to reduce energy cooling/heating make up a significant consumption. portion of energy consumption, in addition to pumping, ventilation, and The Smart Energy Design Assistance lighting. The category labeled ‘Other’ Center (SEDAC) has examined facilities includes miscellaneous loads like with pools and spas and has categorized computers and other office equipment. primary savings into four groups: b) pool evaporation, pool water heating, Naturally, the percentages of these dehumidification and ventilation, and categories will vary from one facility to pool filtration pumping. Savings can also another and drastically from an indoor be achieved through typical building to an outdoor pool; but, nevertheless, recommendations, including lighting and these charts illustrate how SEDAC tries to building envelope improvements. subdivide total energy consumption by end use. Indoor and outdoor pools have common and unique energy consumption This fact sheet examines how pools lose issues. Both need heating and filtration, heat, how to reduce that heat loss, how yet dehumidification is exclusive to to efficiently heat pool water, and what indoor pools and spas. Figure 1 shows additional ventilation and mechanical how energy was used at a natatorium issues facility operators may want to Figure 1. Energy Breakdown for examined by SEDAC. Energy use and examine for energy conservation. a) indoor pools, b) outdoor pools

The Smart Energy Design Assistance Center performs energy assessments on various building types. Each building type has different energy requirements. SEDAC’s Energy Smart Tips help building operators identify energy cost reduction measures. SMART ENERGY DESIGN ASSISTANCE CENTER PROVIDING EFFECTIVE ENERGY STRATEGIES FOR PUBLIC AND PRIVATE BUILDINGS IN ILLINOIS ENERGY STAR®’S 7 STEPS OF WATER HEATING

ENERGY MANAGEMENT The method used to heat pool water is an important 1 Make a Commitment consideration. Options are electric resistance, electric Recognize that the economic, environmental and political heat pumps, gas fired boilers, solar thermal and using impacts of energy consumption are sufficient motivation waste heat. Electric resistance heaters are the most to change our energy use patterns. expensive to operate. If electricity is the only resource available, focus on high-efficiency heat pumps. Heat 2 Assess Performance pumps are rated by their coefficient of performance Make a personalized accounting of energy use and (COP) and pool heaters range from approximately 3 costs. Benchmark your facility by comparing its energy to 6. The higher the COP, the more efficient the unit performance with similar sites. is. A COP of 5.0 is five times more efficient than an electric resistance heater. Both gas fired boilers and 3 Set Goals heat pumps come in many different efficiencies, so Review your objectives and constraints. Establish priorities shop prudently. Table 1 shows the results of a SEDAC and set measurable goals with target dates. analysis of various heating systems for an outdoor pool in Chicago. Note that the type of heating system 4 Create an Action Plan can significantly impact utility costs. Define the technical steps. Apply proven methods to increase energy efficiency or get specialized guidance. Assign roles and resources. Consider rolling savings from POOL HEATING SAVINGS EXISTING ELECTRIC 85% 95% ANALYSIS ELECTRIC HEAT PUMP EFFICIENT EFFICIENT earlier efforts into future, more complex initiatives. RESISTANCE COP = 4.0 GAS HEATER GAS HEATER Annual consumption 310,380 kWh 77,595 1,245 MBtu 1,114 MBtu Annual operating costs $31,985 $7,746 $14,025 $12,548 5 Implement Action Plan Savings over electric resistance - $23,239 $17,960 $19,437 Install equipment and change operational procedures. Table 1. Utility costs for various pool heating systems (compiled by SEDAC) Establish a maintenance schedule. Train equipment operators and building occupants on the changes. Track Consider heating your pool with solar energy. and monitor conditions. Employing solar thermal may not eliminate the need for a heater, but can significantly reduce the amount 6 Evaluate Progress of time it has to operate. The collector area needed is Compare current performance to established goals. anywhere from 50 to 100% of pool surface area. The Understand what worked well in order to identify best further south you are, the more cost effective these practices. Adjust procedures and goals, and schedule the systems become. Finally, waste heat can also be used next evaluation. to heat pools. If you have a chiller or dehumidification equipment that is rejecting heat through a cooling 7 Recognize Achievements tower, why not reject this heat to the pool instead Provide internal recognition for the efforts and through a plate-and-frame heat exchanger or water- achievement of individuals, teams, and facilities. Seek to-water heat pump? Other sources of waste heat may external recognition from government agencies, media, also be available but may require thinking outside the or third party organizations. box. Table 2 provides ASHRAE recommendations for pool water temperatures. Lower temperatures are preferable for competitive swimming while higher temperatures are preferable for therapy and pools used by the elderly. Raising water temperature by only 1°F will increase energy costs an additional 10 to 30%, depending on your location. If the pool is used intermittently, reduce the heater thermostat setting during unused periods. Install a timer or a control system to automate the hours of operation.

TYPE OF FACILITY AIR TEMP. WATER TEMP. Competition 78°F to 85°F 76°F to 82°F Diving 80°F to 85°F 80°F to 90°F Elderly Swimmers 84°F to 90°F 85°F to 90°F Hotel 82°F to 85°F 86°F to 92°F Recreational 75°F to 85°F 75°F to 85°F Therapeutic 80°F to 85°F 85°F to 95°F Whirlpool/Spa 80°F to 85°F 97°F to 104°F ENERGY STAR®’s steps for energy management. Table 2. Recommended pool temperatures (ASHRAE) Descriptions have been modified by SEDAC staff. POOL EVAPORATION Swimming pools lose energy in a variety of ways, but, as illustrated in HOW MUCH WATER IS LOST THROUGH EVAPORATION? Figure 2, evaporation is by far the For an indoor aquatics facility that has a 25 x 20 yard pool with 80°F water, 82°F largest source of energy loss for both interior air at 50% relative humidity, water loss is equal to 216 pounds of water indoor and outdoor pools. According per hour or approximately 26 gallons per hour. Each pound of 80ºF water that to the Department of Energy, the single evaporates takes 1,048 Btu of heat out of the pool . This means that every most effective means of reducing pool hour 226,368 Btu, or approximately $2-3 are lost due to evaporation. If pool heating costs is to cover the water covers are deployed during unoccupied hours, this component of heat loss is surface when not in use. This step can virtually eliminated. Assuming the same conditions, the same losses would generate savings of up to 50–70%. For occur from an outdoor pool, except there is no need for dehumidification indoor pools, an additional benefit of equipment to deal with the evaporated water. pool covers is that less evaporation requires less dehumidification, exhaust, and addition of chemicals. Detailed results from a study of pool evaporation rates conducted by a program funded by DOE - Reduce Swimming Pool Energy Costs (RSPEC) can be found at: http://www.rlmartin. com/rspec/whatis/studies.htm. SEDAC analyzed outdoor pool covers for a client in Chicago and found that they are extremely cost effective a) b) when used with an electric resistance Figure 2. Pool energy loss characteristics, a) outdoor, b) indoor heating system. If applied to a pool with a more efficient heating system, also the most expensive. Exterior pool the pool, and they reduce the amount absolute cost savings are reduced, but covers need to be UV stabilized. Some of debris that lands in the pool, thus still represent up to a 40% savings. covers primarily inhibit evaporation reducing cleaning tasks. For various while others offer the additional reasons including aesthetics, odd pool Two other important considerations benefit of having insulating properties shapes, or long open periods with include how the pool cover is deployed or act as solar heaters and heat the short closed times, pool covers may (manually, semi-automatically, or pool if left on during the day. not always be desirable. So for outdoor automatically), and the material it is pools, strategically placed wind breaks made from. Naturally, pool covers Additionally, pool covers reduce can reduce air movement across the that automatically deploy and retract the amount of makeup water and surface of the pool, thereby reducing are the most convenient, but they are chemicals that must be supplied to evaporation rates. POOL FILTRATION PUMPING

Maintaining the quality of pool water properly-sized high efficiency pumps requires pumps which consume and electric motors. This upgrade electricity. “Turnover” is the rate at can be made either when replacing which pool water needs to be filtered, older pumps and motors in an and it occurs when the amount of existing pool or when designing new water equal to the volume of the pools. Motors use many times their pool is pumped through the filtration initial cost in electrical consumption system. Turnover rates are dictated over their life and can often consume by the Illinois Department of Public several times their cost in the first Health (Table 3). The number of year alone. The energy savings from turnovers that occur in a pool can be a high efficiency motor can pay for calculated by dividing the volume of itself in a very short time. pool (gallons) by the flow rate (gal/ min). Furthermore, the pool water must be pumped through filters and TYPE OF POOL TURNOVER RATE TURNOVERS/DAY treated with bactericides 24 hours a Diving Pools 8 hours or less 3 or more day to ensure good water quality. Wading Pools & Areas, 2 hours or less 12 or more Plunge Pools & Areas, and Lazy Rivers To reduce pool operating costs, All Other Pools 6 hours or less 4 or more electrical consumption can be significantly lowered by using Table 3. State of Illinois Pool Turnover Requirements SEDAC WHO WE ARE

SEDAC is sponsored by the Illinois Department of Commerce and Economic Opportunity in partnership with investor-owned utilities to achieve energy efficiency savings in ENERGY SAVING TIPS FOR INDOOR POOLS buildings. VENTILATION SPACE TEMPERATURE SEDAC is an applied research unit Ventilation of indoor pool areas is critical for Maintaining the proper balance between of the School of Architecture at maintaining acceptable indoor air quality, air and water temperature directly impacts the University of Illinois at Urbana- occupant comfort, and humidity control. user comfort and energy consumption. It Champaign. ASHRAE Standard 62-2007: Ventilation For is recommended to set air temperature to Acceptable Indoor Air Quality requires a two degrees above pool water temperature. The 360 Energy Group is a collaborative minimum outdoor air rate of 0.48 CFM/SF Air temperature should be less than water partner working with SEDAC. Support based on the area of the pool and deck, and a temperature only in pools with high water minimum outdoor air rate of 8.0 CFM/person temperature requirements, such as pools is also provided by the Energy based on occupancy for spectator areas (when that cater to the elderly, therapy pools, and Resources Center at the University of spectators are present). The Standard also whirlpools. In these cases, air temperature Illinois at Chicago. states that higher rates may be required for should be set in the mid 80s since higher humidity control. The ASHRAE HVAC Systems temperatures could cause occupant and Applications Handbook also recommends 4 discomfort. High water temperature and to 6 air changes per hour (ACH) for therapeutic low air temperature can greatly increase SEDAC PROGRAMS pools and pools with no spectator facilities, and evaporation rates and should be accounted for 6 to 8 ACH for pools with spectator areas. The when designing the dehumidification system. Energy Assessment design of these ventilation systems is critical for As previously stated, pool covers can eliminate energy efficiency. most evaporation, thus allowing temperature Public Sector Retro-Commissioning setbacks during unoccupied periods without Due to evaporation, indoor pool environments increased evaporation penalties. New Construction Design need constant dehumidification. During Assistance occupied times, outdoor air ventilation should DEHUMIDIFICATION be set to minimum code-approved levels and Because of extensive dehumidification Public Sector New Construction increased based on the number of occupants, requirements for indoor pool climate control, Incentive Review and during unoccupied periods outdoor there are several dehumidification strategies to air flow may be closed. TheASHRAE HVAC choose from with distinctly different first-cost Public Housing Efficient Living Handbook recommends that interior relative and operating cost characteristics. Rather than humidity (RH) levels be maintained between rejecting heat from the refrigeration system to Training and Outreach 40-60%. If relative humidity is below 50%, the exterior, several dehumidification systems evaporation rates from the pool and human recover this heat to pre-heat ventilation air or Energy Incentive Guidance body increase, and a relative humidity above to heat pool water. The design of ventilation 60% may pose mold and building material systems for natatoriums can be complex and degradation problems. It is also recommended must take into account many considerations to maintain a slight negative pressure in the including: proper air flow across building interior environment to keep warm moist air surfaces to avoid condensation problems, from migrating into building assemblies and to draft-free distribution for occupant comfort, prevent pool odors from seeping into adjacent and minimized air velocities across the surface spaces. of the pool to reduce evaporation rates. ENERGY SMART RESOURCES FOR SWIMMING POOLS Managing Swimming Pool Water Moisture Load Calculation Temperature for Energy Efficiency www.dehumidifiercorp.com/catalog/loadcalc.pdf www.energysavers.gov/your_home/water_ heating/index.cfm/mytopic=13300 Solar Pools energy.sandia.gov/index.htm Natatorium Dehumidification Design Manual www.nauticadehumid.com/nautica_PDFs/ DOE Reduce Swimming Pool Energy Costs MAY 2012 NATATORIUM DEHUMIDIFIER DESIGN MANUAL.pdf www.rlmartin.com/rspec/ www.SEDAC.org | 1-800-214-7954 | [email protected] Smart Energy Design Assistance Center 1 Saint Mary’s Road, Champaign, IL 61820