Considerations for Energy Efficient Showers in Hot-Humid Climates

Abstract

Measurements have been conducted on four low-flow showerheads currently recommended by utilities. These measurements were made to determine expected cost savings in two prison installations, based on water savings, sewer savings, and energy savings. Current shower flowrates of 2.5 gpm were reduced to 1.95 gpm without affecting shower quality. Three heads tested will provide total annual savings of $12,337 at Prison 1 and $11,036 at Prison 2, or over $35 per showerhead compared with the showerheads currently being used by the prisons. The estimated payback is less than two months. The savings determined are about one-third the estimate made before testing, since the low flow heads tested require that supply water temperatures be approximately 10 F higher than standard heads to achieve comparable temperatures in the spray pattern. This is because of evaporative cooling by the aerating shower nozzles. Further study also indicated lower shower water usage than initially estimated due to shorter inmate shower times. Over 80% of the savings projected will be due to reduced water and sewer costs. Further testing to determine whether very low flow heads exist which do not require elevated supply temperatures are recommended.