Shower Monitor and Alarm System
The severe drought underway in California makes water use reduction a high priority. In the case of showering, water use reduction also results in electricity or gas savings which is of direct importance to the Investor Owned Utilities like SDG&E. The technology studied here is mounted in-line with a showerhead and emits audible and visual alarms when a targeted shower duration is exceeded. These alarms give strong cues to the occupant to stop showering while not restricting the flow in any manner.
The researchers installed 8 such devices in all the showers in a freshman dormitory at USD. The researchers installed identical 2.5 gallon per minute (GPM) showerheads on all 8 showers. The researchers placed opaque neoprene sleeves on the devices for the roughly 1 month baseline period and disabled the alarms. The researchers removed the sleeves and enabled the alarms for the roughly 0.5 month retrofit period. During both periods, shower length and mixed water temperature were logged. For the retrofit period, a consistent target shower duration of 8 minutes was chosen after reviewing the baseline data and determining that it would save roughly 15% water savings maximum. After fielding some isolated student complaints near the end of the retrofit period, the length was increased to 10 minutes on two of the showers (showers 7 & 8).
Analyzing this data, the average water volume savings per shower was about 11%. Also, roughly 16,820 gallons were consumed during the 1-month-long baseline period with an average temperature of 100 °F. Using the equation from Appendix B: Measurement & Verification Plan with an energy factor (EF) of 0.751 and cold water temperature of 70 °F2, the annual gas savings for the building are about 72 therms. At the current USD water rate of $3.75 per HCF, sewage rate of $5.16 per HCF, gas rate of $0.86298 per therm, and at two possible product price points, combined gas and water cost savings are shown in the report. Please note that payback period would roughly double if only gas savings were considered.