7-i 

CHAPTER 7. ENERGY AND WATER USE ANALYSIS

TABLE OF CONTENTS

7.1 INTRODUCTION .............................................................................................................. 7-1

7.2 ANNUAL ENERGY CONSUMPTION............................................................................. 7-1

7.2.1 Equipment Class Energy Use and Harvest Rate Capacity ...................................... 7-2

7.2.2 Utilization Factor .................................................................................................... 7-2

7.3 ANNUAL WATER CONSUMPTION............................................................................... 7-3

LIST OF TABLES

Table 7.2.1 Total Annual Energy Usage ...................................................................................... 7-3

Table 7.3.1 Total Annual Water Consumption ............................................................................ 7-4
7-1 

CHAPTER 7. ENERGY AND WATER USE ANALYSIS

7.1 INTRODUCTION

This chapter presents the U.S. Department of Energy’s (DOE’s) analysis of annual 

energy and water usage at various efficiency levels of automatic commercial ice makers. These 

estimated values of annual energy consumption (AEC) in kilowatt-hours per year (kWh/yr) and 

annual water consumption (AWC) in gallons of water per year are key inputs to the life-cycle 

cost and payback period analysis (chapter 8 of the preliminary technical support document 

(preliminary TSD)) and national impacts analysis (chapter 10 of the preliminary TSD).

The goal of the energy use analysis is to generate a mean value and a range of energy use 

values that reflect actual use of an automatic commercial ice maker in commercial applications. 

Actual energy usage in the field often differs from that estimated by the test procedure because 

of variations in the system capacities chosen to serve the estimated load, operating conditions, 

user behaviors, and other factors. The remainder of this chapter discusses the methodology used 

to estimate the annual energy and water consumption for representative sized units for each 

automatic commercial ice maker equipment class.

7.2 ANNUAL ENERGY CONSUMPTION

For the preliminary analysis, DOE estimated the AEC for every combination of 

equipment class and efficiency level considered in the analysis. Estimated energy use per 100 

pounds of ice, assumed equipment utilization factor, and rated maximum daily harvest rates for 

each combination are used to calculate a daily energy consumption value for the ice-making 

related function of the equipment. In addition to the ice-making related energy consumption, 

estimated daily standby energy usage is also added to yield a total energy consumption value for 

a single 24-hour period. Multiplying the sum of the daily ice-making related energy and standby 

energy use by 365 results in the total AEC for each specific equipment class and efficiency level 

combination. 

For automatic commercial ice makers, the equation for AEC is: 

AECi,j = (Ei,j ÷ 100× Hi × Ui + SEi × (1 – Ui)) × 365

Eq. 7.1 

Where: 

AECi,j = calculated annual energy consumption for equipment class i, at efficiency level j

(kWh/year), 

Ei,j = estimated energy use for equipment class i, at efficiency level j (kWh/100 lb ice), 

Hi = harvest rate for equipment class i (pounds of ice produced per 24 hours), 

Ui = assumed utilization for equipment class i (percent of time producing and harvesting ice), 

and

SEi= estimated “standby” energy use for equipment class i (kWh/24 hours). 
7-2 

7.2.1 Equipment Class Energy Use and Harvest Rate Capacity 

For each equipment class, a baseline energy use value is estimated, noted as Efficiency 

Level 1. Level 1 is the initial value against which energy saving percentages are based. A more 

complete breakdown of how the incremental percentage savings values are derived is also 

described in chapter 5 of the preliminary TSD. Harvest rate capacity, which provides a 

representative value for the pounds of ice that can be produced for each ice-making equipment 

class, does not vary by efficiency level within an equipment class. The values used as estimates

for energy use (Ei,j), and harvest rate (Hi) are taken from the engineering analysis presented in 

chapter 5 and are designed to be representative of a given equipment class. 

7.2.2 Utilization Factor 

Ice-making equipment is not assumed to be making ice 24 hours out of every day. 

Instead, a utilization factor (Ui) is used as the estimate for the percent of time the ice maker is 

actively producing ice. In the preliminary analysis, this value is consistent across all equipment 

classes and efficiency levels, and is estimated at 50 percent. The complement to the amount of 

time the ice-making equipment is actively producing is the time that the ice-making equipment is 

not actively producing or harvesting ice. Energy used during non-producing periods is referred to 

as standby use energy. Preliminary test data indicates that standby use represents an extremely 

small level of usage. As a conservative assumption, DOE used a value of 5 watts for all 

equipment classes, but believes the average value is actually lower. The standby loss assumption

yields a daily energy consumption of 0.12 kWh/24 hours. 

Calculated values for each equipment class and available efficiency levels are provided in 

Table 7.2.1. For each equipment class listed, AEC for the maximum available energy efficiency 

levels are also included in the table, and are found in column with the highest numbered 

efficiency level for that equipment class.
7-3 

Table 7.2.1 Total Annual Energy Usage 

Equipment Class* 

Total Annual Energy Usage

kWh/year

EL 1** EL 2 EL 3 EL 4 EL 5 EL 6 EL 7

IMH-W-Small-B 4,292 3,865 3,695

IMH-W-Med-B 7,825 7,044

IMH-W-Large-B 10,972 9,877 9,767

IMH-A-Small-B 5,639 5,078 4,797 4,516

IMH-A-Large-B 9,366 8,432 7,964 7,497

RCU-Small-B 11,328 10,310 9,632 9,462

RCU-Large-B 13,983 12,727 11,889 11,680

SCU-W-Small-B 2,310 2,150 1,967 1,853 1,761

SCU-W-Large-B 4,183 3,892 3,559 3,351 3,143 3,018 2,560

SCU-A-Small-B 3,635 3,382 3,093 2,913 2,732 2,624

SCU-A-Large-B 3,599 3,349 3,062 2,884 2,705

IMH-W-Small-C 11,848 10,665 10,074 9,483 8,891 7,945

IMH-W-Large-C 9,329 8,399 7,933 7,468 7,096

IMH-A-Small-C 5,849 5,266 4,975 4,684 4,392 4,101

IMH-A-Large-C 11,519 10,370 9,795 9,220 8,645 8,070 7,495

RCU-Small-C 12,158 11,272

RCU-Large-C 15,078 13,979 12,594

SCU-W-Small-C***

SCU-W-Large-C 3,471 3,350

SCU-A-Small-C 3,635 3,382 3,093 2,985

SCU-A-Large-C 5,387 5,012 4,583 4,314 4,046 3,778 3,456

*See chapter 5, Tables 5.2.1 and 5.2.2, for a description of these abbreviations. 

** EL = efficiency level; EL1 is the baseline efficiency level; EL2 through EL7 represent increased efficiency levels. 

*** DOE was not able to identify any existing products of this equipment class in ice maker databases. Hence, this 

equipment class was not analyzed, directly or by extrapolation.

7.3 ANNUAL WATER CONSUMPTION

DOE estimated the AWC for each ice-making equipment similar to the method used for 

calculating the AEC, the difference being that for the preliminary analysis DOE assumes that 

water consumption, potable or condenser, does not vary with efficiency levels within a given 

equipment class. Results for this method, therefore, are only provided at the equipment class 

level. To calculate the AWC, first the estimated potable water use and condenser water use per 

100 pounds of ice are summed to provide a total water use per 100 pounds of ice. Factoring the 

total water use per 100 pounds of ice produced with the assumed equipment utilization factor and 

representative maximum daily harvest rates yields a total daily water use figure for each 

equipment class. Multiplying the daily use values by 365 days in a year provides the total AWC. 

For automatic commercial ice makers, the equation for AEC is: 

AWCi = (PWi + CWi) ÷ 100× Hi × Ui × 365 

Eq. 7.2 

Where: 

AWCi = calculated total annual water consumption for equipment class i (gal/year), 

PWi = estimated potable water use for equipment class i (gal/100 lb ice), 
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CWi = estimated condenser water use for equipment class i (gal/100 lb ice), 

Ui = assumed utilization for equipment class i (percent of time producing and harvesting ice), 

and

Hi = harvest rate for equipment class i (pounds of ice produced per 24 hours). 

Estimates for the potable water and condenser water use to produce 100 pounds of ice 

come from preliminary TSD chapter 5, Engineering Analysis, and are summarized in Table 

7.3.1. 

Table 7.3.1 Total Annual Water Consumption 

Equipment Class* 

Condenser 

Water Use

gal/100 lb

Condenser 

Water Use

gal/yr**

Potable 

Water Use

gal/100 lb

Potable 

Water Use

gal/yr**

Total 

Water Use

gal/100 lb

Total 

Water Use 

gal/yr*

IMH-W-Small-B 156 85,410 22 12,045 178 97,455

IMH-W- Med -B 148 229,585 21 32,576 169 262,161

IMH-W-Large-B 137 375,038 20 54,750 157 429,788

IMH-A-Small-B 0 0 22 12,045 22 12,045

IMH-A-Large-B 0 0 20 29,200 20 29,200

RCU-Small-B 0 0 21 26,828 21 26,828

RCU-Large-B 0 0 20 54,750 20 54,750

SCU-W-Small-B 165 33,124 29 5,822 194 38,946

SCU-W-Large-B 165 90,338 28 15,330 193 105,668

SCU-A-Small-B 0 0 30 6,023 30 6,023

SCU-A-Large-B 0 0 26 9,490 26 9,490

IMH-W-Small-C 110 160,600 12 17,520 122 178,120

IMH-W-Large-C 110 200,750 12 21,900 122 222,650

IMH-A-Small-C 0 0 12 6,789 12 6,789

IMH-A-Large-C 0 0 12 21,900 12 21,900

RCU-Small-C 0 0 12 15,330 12 15,330

RCU-Large-C 0 0 12 32,850 12 32,850

SCU-W-Small-C*** — — — — — —

SCU-W-Large-C 110 60,225 12 6,570 122 66,795

SCU-A-Small-C 0 0 12 2,409 12 2,409

SCU-A-Large-C 0 0 12 6,570 12 6,570

*See chapter 5, Table 5.2.1 and 5.2.2, for a description of these abbreviations.

**Total number is adjusted by the appropriate utilization factor.

***DOE was not able to identify any existing products of this equipment class in ice maker databases. 

Hence, this equipment class was not analyzed, directly or by extrapolation.