shower timer savings calculations
Step 1 find cost per gallon$2.80 fresh water + $2.80 waste water = $5.60 per 1000 gallons $5.60 / 1000 = $0.0056 per gallon |
Step 2 find daily gallon usage10 mins x 3 people showering x 2 gpm = 60 gallons used per day before timer 4 mins x 3 people showering x 2 gpm = 24 gallons used per day after timer |
Step 3 find the difference in gallons used60 - 24 = 36 gallons savings |
Step 4 find the cost savings in water36 x $0.0056 = $0.2016 water savings per day |
Step 5 find the number of heated gallons of water saved36 x 60% = 21.6 gallons of heated water per day |
Step 6 find the number of degrees of heating water140 water heater temp - 57.5 cold water temp = 82.5 degrees |
Step 7 multiply the number of degrees by the 8.337 BTUs it takes to heat one gallon of water one degree8.337 BTUs x 82.5 degrees to raise by = 687.8025 BTUs to heat 1 gallon to desired temp |
Step 8 take into account the hot water heater efficiency687.8025 BTUs / 85% = 809.1794 |
Step 9 multiply your efficiency adjusted BTUs by the number of gallons to be heated809.1794 BTUs x 21.6 gallons to heat = 17,478.2750 BTUs per day |
Step 10 convert BTUs to therms17,478.2750 / 100,000 = 0.1748 therms per day |
Step 11 covert therms to kilowatt hours for electric water heaters0.1748 therms per day x 29.3071 KWh per therm = 5.1229 KWh per day |
Step 12 find the cost of heating water with electric5.1229 daily KWh use * $0.118 cost per KWh = $0.6045 per day savings |
Step 13 add the water and electric savings$0.6045 daily electric savings + $0.2016 daily water savings = $0.8061 daily savings |
Step 14 find yearly and lifetime savings in dollars with electric$0.8061 x 365 = $294.23 yearly savings with electric $294.23 x 5 year estimated life = $1,471.13 estimated lifetime savings with electric |
Step 15 find yearly and lifetime electric savings5.1229 kWh/day x 365 days/year = 1,869.9 yearly KWh savings 1,869.9 x 5 year estimated life = 9,349 lifetime KWh savings |
Step 16 find yearly and lifetime water savings36 gallons daily water savings x 365 = 13,140 gallons yearly water savings 13,140 x 5 year estimated life = 65,700 lifetime water savings $0.2016 daily water savings x 365 days = $73.58 yearly water savings |