Low-Income Water and Energy Program

Low-Income Water and Energy Program

Justification for assumptions and source documentation

A. Assumption of appliance usage:

All usages were an estimate from the direct user. They were asked to estimate the usage for:

1. Commercial dishwasher; racks per day

2. Commercial Clothes washer: loads per week

3. Ice machine for the estimate is size

4. Steam Cooker

5. Oven lbs. cooked

6. Sprayer use

7. Faucet and shower

8. Dishwasher cycles

9. Loads per week

B. Commercial Dishwasher calculations: Energy Star

Calculator: Used for all usage calculations that were not changed.

C. Commercial and Non-commercial Clothes washer size:

4.8 cu. Ft. is an average that came from the following: This is an average size of the washers we would use for this project.

Specific option used for cost purposes:

ENERGY STAR Qualified Clothes Washer Eligibility

Only front and top-loading clothes washers with capacities greater than 1.6 ft3 and less than 6.0 ft3; and are not definedas Combination All-In One Washer-Dryers or Residential Clothes Washers with an Optional Dry Cycle are eligible forENERGY STAR Certification.

1.6 ft3 + 6.0 ft3/2 = 3.8 ft3

D. Estimate of ice machine production: ACEEE

Ice machines are categorized as self-contained units (SCU), ice-making head units (IMH)or remote condensing units (RCU). Self-contained ice machines are units with the ice makercombined with an integral storage bin. These units are smaller in size than ice making head unitsand have capacities less than 250 pounds of ice per 24 hours. Ice making head units are modularmechanisms that can be combined with each other on top of a separate storage bin. Head unitshave capacities ranging from 200 to 1,900 pounds of ice per 24 hours. Storage bins are typicallysized to hold 12 hours’ worth of ice production. The third category is remote condensing units.Remote condensing units are machines with the condenser mounted in a remote location,typically on the roof.

Assumption of H2O per 100 lbs. of ice made: Alliance for Water Efficiency

There are two basic equipment designs: air-cooled refrigeration units and water cooled refrigeration units. The air-cooled units are usually more water efficient; while the water cooled units are usually more energy efficient. Both types vary greatly in water efficiency, even within its own design type. The water efficiency is measured by the industry in “gallons of water per 100 lbs (45.36 kg) of ice”. Perfect water efficiency would equate to 11.97 gallons (45.3 L) of water to produce 100 lbs (45.36kg)of ice. Most ice makers’ water use ranges between 18 to 200 gallons (68 L to 756.9 L) of water per 100 lbs (45.36 kg) of ice. This represents a water efficiency range of 66% to only 5%. Thus, 34% to 95% of the water used is dumped down the drain. The water varies for several reasons.

E. Estimate of typical shower water temperature, lbs/gal: South Carolina Gas and Electric

Incoming potable water temperature is assumed to be 50°F (10°C). Formost uses, the water heater temperature setting is 120°F (49°C), butcan be as high as 140°F (60°C). For an end use such as a shower, atypical temperature of 105°F (41°C) is achieved with a combination ofhot and cold water. To determine how much of a temperature rise isneeded, subtract the incoming water temperature from the desired output temperature. Note thatthis same methodology can be applied to process water requirements for commercial or industrialapplications.

Calculating BTU Requirements

A BTU is defined as the amount of heat required to raise the temperature of one pound of waterone degree Fahrenheit. Since a gallon of water weighs 8.34 pounds, the gallon per minute flowrate can be converted to pounds for the specified time use, and then converted back to BTU.

F. Water Sense Sprayer rate estimate:EPA Water Sense

The manufacturer shall specify a maximum flow rate value (i.e.,rated flow rate) of the pre-rinse spray valve. This specified valuemust be equal to or less than 1.28 gallons per minute (gpm) [4.8liters per minute (Lpm)].

G. Dishwasher electric and water consumption: Energy Star

Dishwashers Key Product Criteria

Equipment Capacity Current Criteria

Standard ≥ 8 place settings + six serving pieces

≤ 270 kWh/year

≤ 3.5 gallons/cycle

Compact < 8 pace settings + six serving pieces

≤ 203 kWh/year

≤ 3.10 gallons/cycle

The current ENERGY STAR criteria for dishwashers became effective January 29, 2016.

Specific Maytag dishwasher specifications used: