Case Studies and White Papers

Co-generation Application at a Health Club

Full service health clubs, defined as those that are equipped with pools and spas, tend to have unique energy consumption patterns. Such facilities require high constant thermal inputs to maintain state mandated temperatures of 84° F pool and 104° F spa (State of Massachusetts). These clubs, many of which were built around 1970 (at the beginning of the social trend toward better fitness) usually feature a 20 yard by 10 yard pool and a six person spa. Older clubs in particular are still utilizing much of their original equipment, which is inefficient by current standards. The large surface area of the pool acts as a natural radiator and requires a large input of energy to maintain the legal temperature. In today’s economic climate, losing energy through inefficient heating is quite literally pouring money down the drain.

These conditions can be improved, and costs can be reduced. Any health club that maintains pool and spa equipment and incurs total energy costs of $200,000+ per year should consider a co-generation application.


A privately owned health club in Worcester County, MA was built circa 1970 and is housed in a metal frame structure that is typical of many such facilities. It currently has over 5,000 members. The club features indoor and outdoor (seasonal) swimming, an indoor spa, fitness, gymnasium, aerobics, and stationary cycling areas, along with four tennis courts that are enclosed in a separate heated, inflatable structure.

The club also has a child care facility and several other businesses that sublet space. The facility utilizes over $250,000 per year of energy costs (2005 – 2006 period). These costs are rapidly escalating and management needs to remediate the situation. The facility is presently constrained to use #2 heating oil as no natural gas service is presently available for the immediate location. The club recently contacted SES for a thorough energy audit and analysis.


The club’s high thermal load immediately suggests the use of co-generation as a means for possible energy savings. A co-generator is simply an electrical generator that captures the waste heat from the generator prime mover, and uses it in other processes in the facility. This capture and utilization of waste heat is the key to understanding the economics of these machines.

For example, assume that the club requires 6,250 gallons of #2 heating oil per month for space and water heating and 57,600 kWh of electricity to run the facility.

They key to understanding the co-generation opportunity is to realize that a central generating station (i.e.: the electric company’s equipment) must purchase 1,420 gallons of fuel oil equivalent and combust it to provide energy to drive a turbine, which in turn, drives an electrical generator. In this process the generating station loses 910 gallons equivalent or approximately 64% of the energy of the fuel as unrecoverable waste heat. The remaining 36% (511 Gallons) is converted to electricity and sold to the club. But the club pays for 100% of the processing costs…in other words, the health club pays for the electric company’s inefficiencies.

                Monthly Energy Costs Before Cogeneration: 

Fuel Oil: 6,250 gallons @ $2.60 per gallon   = $16,250
Electricity: 57,600 kWh at kWh rate of 0.12 = $6,912
Total Energy Costs                                          = $23,162