U.S. Department of Energy - Energy Efficiency and Renewable Energy

Federal Energy Management Program – Water Efficiency

Case Study - Veteran Affairs Hospital

The FEMP SAVEnergy program performed a water audit on the Veterans Hospital in Portland, Oregon. The hospital is a large facility (1,363,000 ft²) with a wide range of aging water-related equipment that frequently experienced high volumes of water use. The annual consumption was determined from utility records to be 64.6 million gallons.

The audit collected data on water use rates and times of use for toilets, urinals, faucets, single-pass water-cooled equipment, cooling towers, boilers, irrigation equipment, sterilizers, dishwashers, and laundry equipment. Actual usage rates were compared with rates for newer commonly available equipment. The auditors determined how much water the new equipment would save and the cost to install it. Cost estimates were based on their experience with other similar projects and the estimates from local contractors. All new equipment recommended had a discounted payback period of 10 years or less. All costs, savings, and payback data is available for each measure in Table 1 at the end of this summary.

Domestic Measures

A total of 346 toilets and urinals in the hospital were found to each use 3.5-5 gallons of water per flush. Newer low-flush toilets use 1.6 gallons per flush and low flush urinals use about 1 gallon per flush; switching to new fixtures could save a significant amount of water.

Faucet water use in the facility ranged between 5-6 gallons per minute (gpm) of water, a much greater flow than is needed in a restroom. The auditors recommended installing faucets with flow rates of 2.5 gpm in all patient rooms and restrooms. Since the audit was conducted, a number of high-quality 1.5 gpm laminar flow faucets have become available. Laminar flow units are recommended for hospitals to prevent entrainment of germs and bacteria in the water stream. These low-flow units are usually sufficient for hand washing and offer an opportunity for increased savings.

Most of the hospital showers used 5-6 gpm of water, also much more than necessary. The auditors recommended replacement of 51 old showerheads with models having a flow rate of 2.5 gpm.

HVAC Equipment

The cooling tower makeup/blowdown/treatment is accomplished when the water level drops to a pre-set level. The system is set to maintain 8 to 10 cycles of concentration. This is an extremely water efficient approach since maintained cycles are based on testing of city and cooling tower water. The equipment can be modified to change the ratio of blowdown to makeup water if testing of city and tower water should warrant it.

It was also recommended that someone who maintains the cooling tower receive training in water efficient cooling tower water treatment. Additional training will allow the facility operator to verify the accuracy of the information and systems provided by the water treatment company.

Currently the boiler blowdown is carried out every night. The recommendations of the water treatment company were that the blowdown include about 5 seconds a night for the continuous blow and 10 seconds a night for the bottom blow. These recommendations by the water treatment company were based on knowledge of city water, testing of boiler water, and state requirements. According to the water treatment company the cycles of concentration in the boiler are maintained at 12 or more. This is a very water efficient approach.

Process Equipment

The medical vacuum pump and medical air compressor operate 24 hours a day and are cooled by a steady flow of fresh water. This single pass of water is a very expensive way to cool the equipment. There are at least three alternatives worth consideration. The first and second options would be to add a closed loop cooling system with the units placed on a process loop. The process loop could either be connected to the existing cooling towers or a secondary cooling system such as a heat pump. At the time of this audit the site was considering using a heat pump for this purpose. A third option would be to reuse this single pass water. Options for reuse could include boiler or cooling tower makeup water.

The larger water-cooled ice machines are candidates for replacement with air-cooled machines. For example, replacing a 400-pound capacity, water-cooled ice machine with an air-cooled (local or remote condenser) ice machine would have a simple payback of around 3 to 5 years at the current water and sewer rates.

The VA hospital has two different types of sterilizers. The ethylene oxide sterilizer uses 20 gpm, 9 hours a day for cooling. The steam sterilizers use an average of 7 gpm for cooling. At the time of the audit the hospital staff had planned to replace this unit with a sterilizer, which uses less water. Before replacing the sterilizer the following information should be obtained: the chamber size, the type/quantity requirements of items that need to be sterilized, and how the sterilizer will be loaded with equipment. The equipment sterilized by the ethylene sterilizer may not be able to handle exposure to steam and therefore some other type of non-steam but low water use sterilizer should be considered. It should be noted that there are now a number of add-on units for sterilizers that reduce water consumption; it is not always necessary to replace the entire unit.

Table 1: Water Efficiency Measures

Other Equipment

Improvements to the following equipment were considered, however, no cost-effective water efficiency opportunities were found. Irrigation system: Training and software are available that will allow a landscape irrigation person to schedule watering based on local evapotranspiration (ET) weather data, plant needs, and soil requirements. Expected savings from this approach are minimal because it would only apply to the lawn area, which is very small.

Recycling water in dishwashers, cart washers, and washing machines: All the dishwashers, cart washers, and washing machines already recycle water.