u ..........."v• •-'1.);;, ::.1..)UJo.+O Lv ;J,Jv:,,;.; I Lv 

# f Flonda Solar Energy Industries Assoc. In

.... Exhibit

_ (WTG-l) Schedule 1



# Electrical 

# Use, Efficiency, 

# and Peak Demand of Electric 

# Resistance, Heat Pump, Desuperheater, 

# and Solar Hot Water Systems

FSEC-PF-215-90

Tim Merrigan Danny Parker



# Florida Solar Energy Center 300 

## State Road 401 Cape Canaveral, Florida 32920
Published in ACEEE 1990 Summer Study on Energy Efficiency in Buildings. Views and opinions expressed here represent those of the authors and not necessarily those of the Florida Solar Energy Center. 

# . . U\Jl...h.L:••-.u;;, ::1..,)UJo+O Lv**:J, l\** **.,)** I L v 

# f Flonda Solar Energy Industries Assoc , In

..... Exhibit _ (WTG

-l) Schedule 1



# Electrical Use, Efficiency, and Peak Demand of Electric Resistance, Heat Pump, Desuperheater, and Solar Hot WaterSystems

FSEC-PF-21S-90

Tim Merrigan Danny Parker



# Florida Solar Energy Center 300 State Road 401 Cape Canaveral, Florida 32920
Published in ACEEE 1990 Summer Study on Energy Efficiency in Buildings

. Views and opinions expressed here represent those of the authors end not necessarily those of the Florida Solar Energy Center.Docl\et Nos 930548-EG

- 930551-EG Florida Solar Energy Industries Assoc., Inc. Exhibit_ (WTG-l) SchedJlel Page 2 of 12



### ELECTRICAL USE, EFFICIENCY, AND PEAK DEMAND OF ELECTRIC RESISTANCE, HEAT PUMP, DESUPERHEATER, AND SOLAR HOT WATER SYSTEMS

Tim Merrigan and Danny Parker Florida Solar Energy Center

Eighty 

### single family residences in Florida were monitored for two years in order to 

### collect data on water heating electrical energy consumption, efficiency, and time-ofday demand. The homes were divided into equally sized samples offour different waterheating systems: conventional electricresistance,heatpump, desuperheaterand solar hot water systems. Electrical consumptionforelectric resistance waterheaters averaged 8.3 kWh perday in Florida with an average waterheating**~ystem** 

### efficiency of82%. Desuperheaters used an annual average of7.4 kWh per day at an annual system efficiency of 110% and heat pump water heaters used 6.1 kWh per day at an average system efficiency of 153%. Electrical use ofsolar hot water systems averaged 2.7 kWh 

### per day and the average system efficiency was 235%. Electrical demand taken at IS-minute intervals showed electric resistance water heaters contribute approximately 

### 1.1 kW ofdiversified demand to 

### the utility winter peak and at least 0.2 kW to the summerpeak. Solarhot water systems exhibited the most desirable demand profile relative to Florida utility coincident peak loads with a 0.7 kW percustomerreduction in the winter and a minimum 0.2 kW per customer reduction in the summer. Desuperheaters have the same 0.2 kW minimum peak demand reduction in the summer and 0.2 JeW per customer reduction in the winter. Heat pump water heaters exhibited approximately halfthe 

### peak 

### demands ofelectric water heaters in the winter but were unable to reduce swmner peak: 

### demand by any significant amount. Since electric waterheaters accountfor approximately 25 percent ofthe utility winter peak demand percustomer, encouraging the use ofalternative water heating methods is beneficial to a winter-peaking utility in Florida.



### INTRODUCTION
Since 1982, Florida's electric utilities have soldmore electricity each year in the state than they have produced (Florida Public Service Commission 1985. 1989). Fortunately. this situation is the planned result ofpurchasing more economical power from electric utilities in the neighboring states ofGeorgia and Alabama. Since the purchased power is more economical. the transmission lines that carry this power from the 

### neighboring states are generally at full capacity. Unfortunately, when a high 

### demand for electricity occurs, Florida's utilities are severely limited in 

### their ability to 

### increase capacity beyond their own generation. Such a circwnstance recently occurred on December 24, 1989 when a strong winter cold front quickly passed through the southeastern United States. The cold weather created a peak demand for electricity that Florida's utilities were unable to 

### meet, in 

### part because the Dodlet Nos 930548
-EG

- 930551
-EG Florida Solar Energy Industries Assoc

.. Inc

. Ex

hibi t _ (WTG-l) SchedJlel Page2 of 12



### ELECTRICAL USE, EFFICIENCY, AND PEAK DEMAND OF ELECTRIC RESISTANCE, HEAT PUMP, DESUPERHEATER, AND SOLAR HOT WATER SYSTEMS

Tim Merrigan and Danny Parker Florida Solar Energy Center

Eighty 

### single family residences in Florida were monitored for two years in 

### order to 

### collect data on water heating electrical energy consumption, efficiency, and time-ofday demand. The homes were divided into equally sized samples offour different waterheatingsystems: conventional electricresistance,heatpump,desuperheaterand solar hot water systems. Electrical consumptionforelectricresistance waterheaters averaged 8.3 kWhperday in Florida with an average waterheating**~ystem** 

### efficiency of82%. Desuperheaters used an annual average of7.4 kWh per day at an annual system efficiency of 110% and heat pump water heaters used 6.1 kWh per day at an average system efficiency of 153%. Electrical use ofsolar hot water systems averaged 2.7 kWh 

### per day and the average system efficiency was 235%. Electrical demand taken at IS-minute intervals showed electric resistance water heaters contribute approximately 1.1 kW ofdiversified demand to 

### the utility winter peak and at least 0.2 kW to the summerpeak. Solarhotwater systems exhibited the most desirable demand profile relative to Florida utility coincident peak loads with a 0.7 kW percustomer reduction in the winter and a minimum 0.2 kW percustomer reduction in the summer. Desuperheaters have the same 0.2 kW minimum peak demand reduction in the summer and 0.2 leW per customer reduction in 

### the winter. Heat pump water heaters exhibited approximately halfthe peak 

### demands ofelectric water heaters in the winter but were unable to reduce summer peak 

### demand by any significant amount. Sinceelectric waterhealers accountfor approximately 25 percent ofthe utility winter peak demand percustomer, encouraging the use ofalternative water heatingmethods is beneficial to a winter-peaking utility in Florida.



### INTRODUCTION**~** 

### Since 1982.Florida'selectricutilitieshave soldmore electricity each year in the state than they have produced (Florida Public Service Commission 1985. 1989). Fortunately. this situation is the planned result ofpurchasing more economical power from electric utilities in the neighboring states ofGeorgia and Alabama

. Since tile purchased power is more economical. the transmission lines that carry this power from the neighboring stales are generally at full capacity. Unfortunately, when a high 

### demand for electricity occurs, Florida's utilities are severely limited in 

### their ability to 

### increase capacity beyond their own generation. Such a circwnstance recently occurred on December 24, 1989 when a strong winter cold front quickly passed through the southeastern United States. The cold weather created a peak demand for electricity that Florida's utilities were unable to meet. in 

### part because thetransmission ofpurchased power was already at full capacity. The result was numerous large-scale service interruptions due to rotated curtailments and an understandable breakdown of overloaded equipment. The state's largest utility, Rorida Power and Light Company (FPL), experienced a demand of close to 16,000 megawatts (MW), a level that was not expected until 1998! FPL had forecast a 1989- 90 winter peak demand of approximately 13,500 MW

-- based in part on the previous winter and summer peak demands of 12,876 MW and 13,425 MW, respectively (FPL 1989). Clearly, the ability to supply the winterpeakdemand without service interruptions is ofmajor concern 

### to Florida utilities. However, these utilities have historically used summer peak demand as the basis for determining a minimum capacityreserve margin. Winter peak demand is generally only considered in a loss-of-load probability analysis for determining the need for new generating capacity (FPL 1989). The 1989 Christmas Eve power shortfall, however, emphasizes that any method to reduce peak demand

-- winter or sununer - should be imponant to a utility's planning process, especially in a high growth state like Rorida. One areafor utility peak loadmanagement lies in the residential sector. Since 1970, residential electricity consumption has been approximately 

### 50 percent of the total annual electricityuse in the state ofFlorida. 

### In 1988, residential customers consumed over 63 million megawatt-hours with an annual growth rate of over five percent for each of the preceding four years (FPSC 1989). This growth rate exceeded the population growth rate by at least two percent for each ofthese years. ./**-~** Waterheating accounts for**approximatel~** 1 perceny of the residential electricity consumption (FPL 1978). Over99 percent ofthis energy is due to the use of electric resistance water heaters. Alternative water heating technologies

- solar hot water systems, heat pump waterhearers, and desuperheater units that recover the waste heat ofthe refrigerant in a residence's air-conditioning equipment

-- account for less lhan one percent ofthe domestic hot water (DHW) systems in the state (Rorida Governor's Energy Office 1981). Of course, these water**heatin~** alternatives still reQuire electricity Docket Nos 930548-EG

- 930551-EG Florida Solar Energy Industries Assoc., Inc. Exhibit

_ (WTG-l) Schedule 1 Page 3 of 12



### to operate or 

### to supply backup water heating when neither solar nor waste heat is available.
To evaluate the impact of alternative water heating technologies on the electric utility, it is necessary to measure the time-of-day electricity consumption of each system type in a number of occupied residences. However, the electrical consumption of any DHW method can vary considerably depending on the temperature ofthe hot waterdelivered and the actual water use of the residences's household. Unless afairly large number ofhouses are measured to eliminate the variance in these quantities, it is also necessary to measure the hot water energy delivered by the DHW system. This latter quantity can account for the variations in water temperature as well as volume

.and, therefore, can serve as a common ground for comparison. 

## METHODOLOGY
A Florida solar energy research and testing institute (FSEC) has had an active program 

### in solar domestic hot water system field monitoring since 1978 (McCluney 1980; Block 1983). 

### In order to compare the measured performance ofsolar systems with the performance of other types of domestic hot water systems, the field monitoring program was expanded in 1982. Underthe sponsorship ofthe Floridapublic utility regulatory commission, FSEC collected**time~** .. of

-day performance data for two years (July 1982·' June 1984) on four types ofDHW systems: 1. Electric resistance water heaters (that met ASHRAE- Standard 90A-1980) 2. Heat pump water heaters 3. Solarhot water systems (with collectors that met ASHRAE Standard 93·1977) 4. Desuperheater water heaters. Twenty systems of each DHW type were instrumented to detennine both their IS-minute electrical demand and hot water energy use. The systems were located in single-family residences in four major population areas of Florida: Jacksonville in north Rorida, Orlando/Brevard County in**ea~t** central Rorida. the Tampa Bay region in west central Rorida. and Broward/Palm Beach counties in south transmission ofpurchased power was already at full capacity. The result was numerous large-scale service interruptions due to rotated curtailments and an understandable breakdown of overloaded equipment. The state's largest utility, RoridaPower and LightCompany (FPL), experienced a demandof close to 16,000 megawatts (MW), a level that was not expected until 1998! FPL had forecast a 1989- 90 winter peak demand of approximately 13,500 MW

-- based in part on the previous winter and summer peak demands of 12.876 MW and 13,425 MW, respectively (FPL 1989). Clearly,the ability to supplythe winterpeakdemand without service interruptions is ofmajor concern 

### to Florida utilities. However. these utilities have historically used summer peak demand as the basis for determininga minimum capacityreservemargin. Winterpeak demand is generally onlyconsidered in a loss-of-Ioad probability analysis for determining the need for new generating capacity (FPL 1989). The 1989 Christmas Eve power shortfall. however. emphasizes that any method to reduce peak demand

-- winter or sununer - should be imponant to a utility's planning process, especially in a high growth state like Rorida. Oneareaforutilitypeakloadmanagementlies inthe residential sector. Since 1970, residential electricity consumption has been approximately 

### 50 percent of the total annual electricityusein the stateofFlorida. 

### In 1988, residential customers consumed over 63 million megawatt-hours with an annual growth rate of over five percent for each of the preceding four years (FPSC 1989). This growth rate exceeded the population growth rate by at least two percent for each ofthese years.**~** ./**-~** Waterheating accounts for**approximatel~**1perceny of the residential electricity consumption 

## ifii::'roi1da (FPL 1978). Over99percent ofthis energy is due to the use of electric resistance water heaters. Alternative water heating technologies

- solar hot water systems,heat pump waterhearers. and desuperheater units that recover the waste heat ofthe refrigerant in a residence's air-conditiOning equipment

-- account for less lhan onepercent ofthe domestic hot water (DHW) systems in the state (Rorida Governor's Energy Office 1981). Of course. these water**heatin~** alternatives still reQuire electricity DOCket Nos 930548·EG

- 930551-EG Florida Solar Energy Industries Assoc., Inc. Exhibit

_ (WTG-l) Schedule 1 Page 3 of 12



### to operate or 

### to supply backup water heating when neither solar nor waste heat is available.
To evaluate the impact of alternative water heating technologies on the electric utility. it is necessary to measure the time-of-day electricity consumption of each system type in a number of occupied residences. However, the electrical consumption of any DHW method can vary considerably depending onthetemperatureofthehotwaterdeliveredandthe actual water use of the residences's household. Unless afairly largenumberofhouses aremeasured toeliminatethevarianceinthesequantities. itis also necessary to measure the hotwaterenergy delivered by the DHW system. This latter quantity can account for the variations in water temperature as well as volume

.and, therefore, can serve as a common ground for comparison. 

## METHODOLOGY
A Florida solar energy research and testing institute (FSEC) has hadanactive program 

### insolardomestic hot water system field monitoring since 1978 (McCluney 1980; Block 1983). 

### Inorderto compare the measured performance ofsolar systems with the performance of other types of domestic hot water systems, the fieldmonitoringprogramwas expanded in 1982. UnderthesponsorshipoftheFloridapublic utility regulatory commission, FSEC collected**time~**.. of

-day perfonnance data for two years (July 1982 -' June 1984) on four types ofDHW systems: 1. Electric resistance water heaters (that met ASHRAE- Standard 90A-1980) 2. Heat pump water heaters 3. Solarhot water systems (withcollectorsthatmet ASHRAE Standard 93-1977) 4. Desuperheater water heaters. Twenty systems of each DHW type were instrumented to detennine both their IS-minute electrical demand and hot waterenergyuse. The systems were located in single-family residences in four major population areas of Florida: Jacksonville in north Rorida. Orlando/Brevard County in**ea~t** central Rorida, the Tampa Bay region in west central Rorida. and BrowardIPalm Beach counties in southFlorida. The systems were selected both to achieve a geographic balance offive systems ofeach type in each population region and to reflect relatively similar family sizes (Merrigan 1983).
To measure the hot water energy delivered by the system. a heat (Btu) meter was installed on each system. The heatmeter utilized a flow meter located in the cold water supply line to the hot water storage tank, as well as both a cold and hot water temperature sensor to calculate the thermal energy change of 

### the heated water before it is delivered 

### to the household. Laboratory tests on the flow meter indicated flow accuracies within 2.5% of the true mass flow over long time periods. Similar tests on the heat calculation indicated an accuracy of within 5% of the true energy flow (Merrigan 1981), with resolutions of 1000 Btu (l055 kJ) and 1 gal (3.8 L).
A kilowatt-hour (kWh) meter was used to record the resistance element energy as well as any auxiliary energy 

### used by the pumps, conuols, and/or compressor ofan alternative DHW system. Standard single-phase 30 amp meters were used with pulse initiators that had a resolution of 1 watt hour (Wh).
A solid-state demand recorder accumulated contact closure pulses from the kWh, Btu, and flow meters and stored them in 15-minute totals in its internal memory. These totals were routinely acquired by UOC"l:!t 1'<05 :1.ju:>4o-t:1.>

-- \:IJO:>:>l-cU Florida Solar Energy Industries Assoc

.. Inc. Exhibil_ (WTG-1) Sct1edJ1e 1 Page4 of 12

telephone interrogation of the demand recorders, transferred to a microcomputer. and stored on magnetic media for eventual data reduction. 

### RESULTS
Table 1 lists the sample size, the average family size, the daily average hot water use, the daily average electric usc, and a dimensionless coefficient of performance (COP) for the four DHW types for the two-year period July I, 1982 

### to June 30. 1984. (Two electric andfour beatpump waterbeaters were omitted from these averages because of instrumentation malfunctions or hot water system equipment problems.) COP is dermed as the hot water energy use divided by the electrical energy consumption and is, therefore, a measure ofthe total DHW system efficiency. Figure 1 displays the average daily electrical load profiles (based on IS-minute intervals) for 

### the four DHW groups for the two-year period. The hours displayed are clocktimes. rather than 

### the year-round standard time that is sometimes used in annual data acquisition projects subject to the hour offset of a summer daylight savings period. This approach was taken since household hot water use generally corresponds to actual clock time, as seen by the apparent awakening of 

### the Florida groups around 

### 6:00 

### a.m.

Table 1. Florida Group Sizes. Annual Daily Average Hot Water Use. Electric Use. and Coefficient ofPerformance
Sample Size Family Hot Water Electric Coefficient No. of Size Use Use of Systems People Gal (L)/Day (kWh/Pay) Performance Electric 18 3.6 55.7 8.3 0.82 Resistance (211.1) Heat Pump 16 3.9 74.0 6.1 1.53 WaterHeater (280.5) Solar Hot 20 3.1 53.8 2.7 2.35 Water Heater (203.9) Desuperheater 20 3.6 58.6 7.4 1.10 Unit (222.1 ) Florida. The systems were selected both to achieve a geographic balance offive systems ofeachtype in each population region and to reflect relatively similar family sizes (Merrigan 1983)

. To measure the hot water energy delivered by the system, a heat (Btu) meter was installed on each system. Theheatmeterutilized aflow meter located in the coldwater supply line to the hot water storage tank, as well as both a cold and hot water temperature sensor to calculate the thermal energy change of 

### the heated water before 

### it is delivered to the household. Laboratory tests on the flow meter indicated flow accuracies 

### within 2.5% of the true mass flow over long time periods. Similar tests on the heat calculation indicated an accuracy of within 5% of the true energy flow (Merrigan 1981), with resolutions of 1000 Btu (l055 kJ) and I gal (3.8 L).
A kilowatt-hour (kWh) meterwasused to record the resistance element energy as well as any auxiliary energy 

### used by the pumps. conuols. and/or compressorofanalternative DHWsystem. Standard single-phase 30 amp meters were used with pulse initiators that had a resolution of 1 watt hour (Wh)

. A solid-state demand recorder accumulated contact closure pulses from the kWh. Btu. and flow meters and stored them in 15-minute totals in its internal memory. These totals were routinely acquired by**vQ(;" ~I** **S** :1.:1U04o-t:u

-- \:KlOool

-t:U Florida Solar Energy Industries Assoc

., Inc

. Exhibit

_ (WTG-l) SctledJIe 1 Page4 of 12

telephone interrogation of the demand recorders. transferred to a microcomputer, and stored on magnetic media for eventual data reduction. 

### RESULTS
Table 1lists the sample size. the average family size. the daily average hot water use. the daily average electric use. and a dimensionless coefficient of performance (COP) for the four DHW types for the two-year period July 1. 1982 to June 30, 1984. (Twoelectricandfourheatpumpwaterheaters were omitted from these averages because of instrumentation malfunctions or hot water system equipment problems.) COP is defined as the hot water energy use divided by the electrical energy consumption and is. therefore

. ameasure ofthe total DHW system efficiency. Figure 1 displays the average daily electrical load proflles (based on IS-minute intervals) for 

### the four DHW groups for the two-year period. The hours displayed are clocktimes.rather than 

### the year-round standard time that is sometimes used in annual data acquisition projects subject to the hour offset of a summerdaylight savings period. This approach was taken since household hot water use generally corresponds to actual clock time. as seen by the apparent awakening of 

### the Florida groups around 

### 6:00 

### a.m.

Table 1

. 

### Florida Group Sizes, Annual DailyAverage Hot Water Use,Electric Use,and CoeffiCient ofPerformance
Sample Size Family Hot Water Electric Coefflcient No. of Size Use Use of**S~stems** People Gal (LllDa:z:: !kWh/Da:z::l Performance Electric 18 3.6 55.7 8.3 0.82 Resistance (211.1) Heat Pump 16 3.9 74.0 6

.1 1.53 WaterHeater (280.5) Solar Hot 20 3.1 53.8 2.7 2.35 Water Heater (203.9) DesuperheatCf 20 3.6 58.6 7.4 1.10 Unit (222.1)LJOCl\et Nos**930!:>48-~G** - 930551-EG Florida Solar Energy Industries Assoc

.. Inc. Exhibit

_ (WTG-1) ScheciJle1 Page 5 of 12

Type 01 System Florida average daily electrical demand (July 1. 1982.· June 30.1984)



### Figures 

### 2 through 

### 5 

### present the 

### average IS-minute demand profiles for the four 

### DHW system types 

### on the 

### FPL winter peak day of February 

### 7, 1984

. Figures 

### 6 tbrough 

### 9 presents the 

### same time-of-day profiles for the 

### summer peak 

### day ofJuly 25, 1983. These 

### two days were selected for presenlation because they represent the 

### bighest utility system loads of all the FPL peak days that did not have service interruptions.

The average electricity use of 

### 8.3 kWh per day for the electric resistance water heater group - with an average family size of 3.6 people

-- compares**f~vorably** 

### with values obtained by other studies performed

### in Florida. 

### FPLdetermined in a 1976-77 study of. 165customers that 

### a family of

### four used 

### an average of 10.2 kWh 

### per day (FPL 1978). Florida PowerCorporationdetermined

### in a similarstudythat 

### a f:mrily of 

### three used 

### an average of 

### 8.4 kWh per day and a family of four used 

### 11.6 kWh per day (FPC 1974). Both studies were performed before improvedinsulation was 

### required"on electrical water heaters in order to 

### meet the minimum beat 

### loss rate requirements ofASHRAE Standard 9OA-1980. for the same peak days. This hourly coincident demand is calculated by averaging the 

### four 15- minute demands 

### Ihat occurred 

### during the peak 

### hour. It 

### is important to note 

### in both Table 

### 3 and 

### Table 

### 5 that FPL was unable to 

### meet the 

### peak demand 

### on December 26. 1983 and bad to rotate curtailments 

### throughout their service 

### area. Hence. the 

### FPL system peak of the winter of 1982-83 (January 13• 1983) bas 

### been included in these 

### tables

.



## ANALYSIS
Annual Electrical Use and Demand

The 

### Shape of the average daily electrical demand profile for electric resistance Wiler beaters as seen in 

### Figure 1 is also 

### c:oosisteDt with the 

### results of previous studies. 

### 1be twin peaks 

### ofmid- 

### morning and 

### early evening demand 

### correspond to typical residential bot 

### wateruse patterns 

### ofshowering, food preparation. and cleanup (Perlman 

### and Mills 1985; Gladhart and 

### Wiehl 1986). As bot 

### Wiler is withdrawn from the storage tank. the 

### electric element turns on when the water 

### temperature drops

.....Inw thl' Lank 

### thermostat 

### setting. The annual daily Convenlio'nal electric Heal pump water heater Solar water healing system Desuperheater water heater



# -'-
.,.-.,...............

### .... 8 10 2 4 6 8 10 Noon Midnight Average Daily Electrical Load Profilefor Four Types o/WaterHeating Systems .6

.2

. .4

246 Midnight 

### Figure 

### 1.

Table 2 presents the 

### daily average IS-minute electrical demand. the average IS-minute maximum demand and the daiIy load factor for the four DHW types for the two-year period. Load factor is the ratio, expressed as apercent, ofthe average kilowatt demand over a designated period of time to the maximum demand occurring in that period. Load Factor (%) 

# = Average Demand (kW) Peak Demand (kW) Load factor is a measure ofhow well the electrical capacity demanded from the utility is utilized by the load over aperiod oftime. The winter peak and summer peak days chosen for data reduction are the actual peak load days of Florida Power and LightCompany. in 

### whose service territory half of the 80 systems were located. The other halfofthe systems were located

### in the service areas ofFlorida Power Corporation. Tampa Electric Company, and Jacksonville Electric Authority. These utilities either had the same winter and summer peak load days as FPL or their secondary system peaks occurred on these days. Tables 3 and 4 indicate the FPL winter and summer peak days, respectively. and the hour that the peak occurred. These same tables alsocontaineach DHW system type's maximum IS-minute diversified demand that was coincident with the hour of the FPL system peak. The diversified 6O-minute 

## I.-

-- ._..1.:_ T

..

## ""'Ar' "**~nA** f-. Florida average daily electrical demand (July 1. 1982.· June 30.1984) Type 01 System**~ ~**  1.0 Convenlio'nal electric Heat pump water heater Solar water heating system Desuperheater water heater

I\> DI 

## '" 

# -'-
.,.-.,...............

### .... t**Ol+-~~~--~-r~~~~--~ ~**  2 4 6 8 10 Midnight 

### Figure 1. Noon Midnight Average Daily Electrical Load Profilefor Four Types o/WaterHeating Systems


### Table 2 presents the 

### daily average IS-minute electrical demand. the average IS-minute maximum demand and the daily load factor for the four DHW types for the two-year period. Load factor is the ratio. expressed as apercent. ofthe averagekilowatt demand over a designated period of time to the maximum demand occurring in that period. Load Factor (%) 

# = Average Demand (kW) 

### Peak Demand (kW) 

### Load factor is a measure ofhow well the electrical capacity demanded from the utility is utilized by the load over aperiod oftime. The winter peak and summer peak days chosen for data reduction are the actual peak load days of FloridaPower and LightCompany, in

### whose service territory half of the 80 systems were located. The other halfofthe systems were locatedin the service areas ofFlorida Power Corporation, Tampa Electric Company, and Jacksonville Electric Authority. These utilities either had the same winter and summer peak load days as FPL or their secondary system peaks occurred on these days. Tables 3 and 4 indicate the FPL winter and summer peak days, respectively, and the hour that the peak occurred. These same tables alsocontaineachDHW system type's maximum IS-minute diversified demand that was coincident with the hour of the FPL system peak. The diversified 6O·minute 

## I . -

--____._..I!_ 'T'

..

## "'Ar' (**~nA** f-. LJOCl\et Nos**930!:>48·~G** - 930551·EG Florida Solar Energy Industries Assoc., Inc. Exhibit

_ (WTG·1) Sc:heciJ1e1 Page 5 of 12



### for the same peak days. This hourly coincident demand is calculated by averaging the four 15· 

### minute demands Ihal occurred 

### during the peak

### hour. It

### is important to note 

### in both Table 3 and 

### Table 5 that FPL was unable to 

### meet the 

### peak demand 

### on December 26, 1983 and bad to 

### rotate curtailments 

### throughout their service area. Hence, the 

### FPL system peak of the winter of 1982-83 (January 13, 1983) bas 

### been included inthese 

### tables. Figures 2 through 

### 5 

### present the 

### average 1S-minute demand profiles for the four DHW system types on the 

### FPL winter peak day of February 

### 7, 1984

. Figures 

### 6 tbrough 

### 9

### presents the 

### same time-of-day profiles for the SU11lIDeI' 

### peak 

### day ofJuly 25, 1983. These 

### two days were selected 

### for presenlation because they represent the 

### bighest utility system loads of aU the FPL peak days that did not bave service interruptions. 

## ANALYSIS
Annual Electrical

### Use and Demand The average electricity use of 

### 8.3 kWh per day for the electric resistance water beater group - with an average family size of 3.6 people

-- compares**f~vorably** 

### with values obtained by other studies performedinFlorida. FPLdetermined in a 1976-77 study of. 165 

### customers that 

### a family of

### four used 

### an average of 10.2 kWh 

### per day (FPL 1978). Florida PowerCorporationdetermined

### ina similarstudythat 

### a f:mrily of

### three used 

### an average of 

### 8.4 kWh per day and a family of four used 

### 11.6 kWh per day (FPC 1974). Both studies were performed before improvedinsulation was 

### required'onelectrical water heaters in order to 

### meet the 

### minimum beat 

### loss rate requirements ofASHRAE Standard 9OA-1980.
The 

### sbape of the average daily electrical demand profile for electric resistance Wiler beaters as seen**~** 

### in 

### Figure 1 is also 

### c:oosisteDt with the results 

### of previous sbldies. The 

### twin peaks 

### ofmid- 

### morning and 

### early evening demand 

### correspond to 

### typical residential bot 

### wateruse patterns 

### ofshowering,food preparation. and cleanup (Perlman 

### and Mills 1985; Gladbart and 

### Wiehl 1986). As bot 

### Wiler is withdrawn from the storage tank, the 

### electric element turns on when the water 

### temperature drops

.....Inw thl' tank 

### thermostat seuing. The annual dailyDocket Nos 930548-EG

- 930551-EG Florida Solar Energy Industries Assoc

.. Inc. Exhibit

_ (WTG-1) SChedJIe 1 Page60f12

Table 

### 2. AnnualAverage I5-Minute Demand. Peak IS-MinUle Demand. andLoad Factor by Type of System 

### Average Demand Peak Demand Load Factor (leW) QsW) (%) 

### Electric Resistance 0.34 0.68 50 Heat Pump Water Heater 0.25 0.48 52 Solar Hot Water System 0.11 0.27 41 Desuperheater Unit 0.31 0.57 

### 54

Table 

### 3. Average IS-Minute Demand Coincident with FPL Winter PeakLoad (60-Minute Net) 

### January 13, 1983 December 26, 1983 February 7, 1984 9 a.m. 9-10 a.m.· 7-8 a.m.. Electric 1.14 kW 1.26 kW 1.36 kW Resistance HeatPump Water 0.53 kW 0.56 kW 0.75 kW Heater Solar Hot Water 0.46 kW 0.88 kW 0.73 kW System Desuperheater Unit 0.94 kW 0.62 kW 1.11 kW

• Unserved utility load of666 MW

Table 

### 4. Average IS-Minute Demand Coincident with FPL Summer PeakLoad (60·Minute Net) 

### August 24, 1982 July 25, 1983 5-6 p.m. 5-6 p.m. Electric Resistance 0.74kW 0.34 kW Heat Pump Water Heater 0.61 kW 0.37 kW Solar Hot Water System 0.08 kW 0.02 kW Desuperheater Unit 0.14 kW 0.19 kW

average demand ofthe element is exactly one-halfof its average peak demand. resulting in 

### an annual average load factor of50 percent. Heat pump water heaters had a similar load factor



### . 

# . average demand is approximately 25 percent less. This reduction is due to 

### the higher annual average system efficiency of the 

### beat pump water beater

-- approximately twice that of the electric resistance water heaters. However, seven ofthe 20 heat pump Ul"IM**hp"lpr~** in**thi~ ~I\ldv**  

### exnerienced comoressor Docket Nos 930548-EG

- 930551·EG Florida Solar Energy Industries Assoc

.. Inc. Exhibit

_ (WTG-1) SchedJ\e 1 Page60f12

Table 

### 2. AnnualAverage I5-Minute Demand. Peak IS-MinUle Demand. andLoadFactor by Type of System 

### Average Demand Peak Demand Load Factor (!W} (!W} !%} Electric Resistance 0.34 0.68 50 Heat Pump Water Heater 0.25 0.48 52 Solar HotWater System 0.11 0.27 41 Desuperheater Unit 0.31 0.57 54

Table 

### 3. Average IS-Minute Demand Coincident with FPL Winter PeakLoad (60-Minute Net) 

### January 13, 1983 December 26, 1983 February 7, 1984 9 a.m. 9-10 a.m.· 7-8 a.m.. Electric 1.14 kW 1.26 kW 1.36 kW Resistance HeatPump Water 0.53 kW 0.56 kW 0.75 kW Heater Solar HotWater 0.46 kW 0.88 kW 0.73 kW System Desuperheater Unit 0.94 kW 0.62 kW 1.11 kW

• Unserved utility load of666 MW

Table 

### 4. Average IS-Minute Demand Coincident with FPLSummer PeakLoad (60-Minute Net) 

### August 24, 1982 July 25, 1983 5-6 p.m. 5-6 p.m. Electric Resistance 0.74kW 0.34 kW Heat Pump Water Healer 0.61 kW 0.37 kW Solar HotWater System 0.08 kW**~** 

### 0.02 kW Desuperheater Unit 0.14 kW

averagedemand oftheelement is exactly one-halfof its average peak demand, resulting in 

### an annual average load factor of50 percent. Heat pump water healers had a similar load factor



### . 

# . 0.19 kW

average demand is approximately 25 percent less. This reduction is due to 

### the higher annual average system efficiency of the 

### beat pump water beater

-- approximately twice that of the electric resistance water heaters. However, seven ofthe 20 heat pump \1I"IM**hp~lpr~** in**Ihi~ ~I\ldv**  

### exnerienced comoressorUocl\el Nos 930548 EG

-- 930551·EG Florida Solar Energy Industries Assoc., Inc. Exhibit

_ (WTG-1) Schedule 1 Page 7of 12



### Table 

### 5. Average 60-MinUle Demand Coincident with FPL Winter Peak Load (60-Minute Net) January 13, 1983 December 26, 1983 February 7, 1984 8-9 a.m. 9-10 a.m.· 7-8 a.m. Electric 1.07 kW 0.90 kW 1.18 kW Resistance Heat Pump Water 0.48 kW 0.36 kW 0.68 kW Heater Solar Hot Water .0.24 kW 0.59 kW O.44kW System Desuperheater Unit 0.63 kW 0.30 kW 0.64 kW

• Unserved utility load of 666 MW



### Table 6. 

### Average 6O-Minute Demand Coincident with FPL Swnmer PeakLoad (60-Minute Net) August 24, 1982 July 25, 1983 5-6 p.m. 5-6 p.m. Electric Resistance 0.58 kW 0.23 kW Heat Pump Water Heater 0.51 kW 0.17 kW Solar Hot Water System 0.06 kW 0.01 kW Desuperheater Unit 0.04 kW 0.07 kW

failures, indicating a problem with long-tenn reliability in 1982-84. Solar hot water systems operated with the highest average electrical system efficiency and had the lowest average daily electrical demand profile. However, the solar system's annual load factor of 41 percent compares favorably with the electric resistance water heater's load factor of 50 percent This is surprising since the majority ofsolar system owners turned off their storage tank's backup electric element and relied on the solar system to 

### supply whatever hot water they needed during the summer months. The only electrical consumption for these systems was that of the solar circulation pump as can be seen in the summer day average of Figure 9 for the six-hour period around noon. Combined with the occasional winter use of the backup element, this electrical demand was consistent enough during the summer months to create a relatively high annual load factor. Desuperheater unit owners also typically turned off their backup electric element during the summer. However, these units would only supply hot water when there was a need for 

### air conditioning or, for those eleven desuperheaters that were installed on heat pumps, a need for beating and/or air conditioning. Surprisingly, even in Florida, there are considerable periods of time when neither mode of space conditioning is required. This is reflected 

### in the average two-year coefficient of perfonnance of 1.10 for desuperheaters. Although this COP is better than unity, it is not much higher than the efficiency for an electric resistance water heater. The annual load factor of54 percent and the average Uocl\el Nos 930548 EG·· 930551·EG FloridaSolar Energy IndustriesAssoc., Inc. Exhibit

_ (WTG-1) Schedule 1 Page 7of 12



### Table 5. Average 60-MinUle Demand Coincident with FPL Winter Peak Load (60-MinUle Net) January 13, 1983 December 26, 1983 February 7, 1984 8-9 a.m. 9-10 a.m.· 7-8 a.m. Electric 1.07 kW 0.90 kW 1.18 kW Resistance Heat Pump Water 0.48 kW 0.36 kW 0.68 kW Heater Solar HOl Waler .0.24 kW 0.59 kW O.44kW System Desuperheater Unit 0.63 kW 0.30 kW 0.64 kW

• Unserved utility load of 666 MW



### Table 

### 6. Average 6O-Minure Demand Coincident with FPL Swnmer PeakLoad (60-Minute Net) August 24, 1982 July 25, 1983 5-6 p.m. Electric Resistance 0.58 kW HeatPump Water Heater 0.51 kW Solar Hot Waler System 0.06 kW Desuperheater Unit 0.04 kW

failures, indicating a problem with long-tenn reliability in 1982-84. Solar hot water systems operated with the highest average electrical system efficiency and had the lowest average daily electrical demand profile. However. the solar system's annual load factor of 41 percent compares favorably with the electric**~** 

### resistance water heater's load factor of 50 percent This is surprising since the majority ofsolar system owners turned off their storage tank's backup electric element and relied on the solar system to 

### supply whatever hot water they needed during the summer months. The only electrical consumption for these systems was that of the solar circulation pump as can be seen in the summer day average of Figure 9 for the six-hour period around noon. Combined with the occasional winter use of the 5-6 p.m. 0.23 kW 0.17 kW 0.01 kW 0.07 kW

backup element, this electrical demand was consistent enough during the summer months to create a relatively high annual load factor. Desuperheater unit owners also typically turned off their backup electric element during the summer. However. these units would only supply hot water when there was a need for 

### air conditioning or. for those eleven desuperheaters that were installed on heat pumps, a need for beating and/or airconditioning. Surprisingly, even in Florida, there are considerable periods of time when neither mode of space conditioning is required. This is reflected 

### in the average two-year coefficient of perfonnance of 1.10 for desuperheaters. Although this COP is better than unity, it is not much higher than the efficiency for an electric resistance water heater. Theannual load factor of54percent and the averageDod<.et Nos 930548-EG

- 930551-EG Florida Solar Energy Industries Assoc., Inc. Exhibit

_ (WTG-l) Sd1edu1e 1 PageS of 12

800 1200 1600 2000 2400

Hour of Day 400 Winter Peak Load Day: February 7. 1984 Solar water heating ayatem• -. .!! 0; 

## 1aoo. 

# !. "Cl 1600· ---'-- 1400 

# e 1200.

__ 4_ ••

_ -.------ QI 

### o 1000 QI 

### 'E 

## aoo .E 600

-**--~__i_T+-** __

## !__------- 400-**--~­** 200- --+- 

### E 0 -

.....

# _-.1

QI 

# < 0 I " !-

"

, f: 

### ,. Winter Peak Load Day: February 7, 1984

Conventional electric realatance



## o 400 800 1200 1600 2000 2400 Hour of Day -. 1800 :; 1600 1400 1200 1000 

### 'E aDo c 

## ii 600 It) 400 

# - 200 0 111 > 

### e:r:
Figure 

### 2. Average Winter Peak Day Electrical Load Profile forElectricResistance WaterHealers Figure 

### 4. Average Winter Peale Day Electrical Load Profilefor Solar Waters Healers

800 1200 1600 2000 2400

Hour of Day 400 Winter Peak Load Day: February 7, 1984


### -. .!! De.uperheater water heatera 0; 1800

- -------------.-- :; 1600

- ---------....,..----- 

### I; 1400

- ----....,..-------"-----t-- 1200- 

## -----------+--- C 1000

- 

### ----+-----..----W--.-' QI 

### :i 800

-**-----th,--~-----:T_~&:_** C 

## i 600 It) 400

- ---f!- 

# - 200

-**~b-l.-l;i!i-tt** 

### E 0 - EiliI.iU"-:;;U;;O QI 

# < 0 r**.~** -'._-



# _...

# __._---------

.------- 

# --_
....

# __..

# _----- Winter Peak Load Day: February 7, 1984 Heat pump water heater.



# c=':,."f.!£l:**~~_Ii** o 400 800 1200 1600' 2000 2400 Hour of Day -. 0; 1800 ' 

# !. "Cl 1600 c 1400 III E 1200 \I) 0 1000 111 

### 'E 800 

### .E 600 It) 400 

# - 111 200 Cl'l III 0 111 > 

### e:r:
Figure 

### 3, Average Winter Peak Day Electrical Load Profilefor Heat Pump Water Heaters Figure 

### 5. Average Winter Peak Day Electrical Load Profilefor Desuperhealer Units daily 

### electrical demand as seen in 

### Figure I also suggestthatdesuperheater units 

### perfonnvery similar to 

### electric resistance water heaters on 

### an annual basis. Peak Day Demand Although both the IS-minute and the 6O-minute coincident peale 

### demands for each of the DHW system types (found in 

### Tables 3 through 6) appearto vary considerably from one peale 

### day to another within the same season, it is important to 

### note that these demands are highly dependent on the weather for each day. This is 

### especially ttue in the 

### case of the 

### winter peak, IS 

### evidenced by the 

### fact that 

### FPL system peak 

### occurred at • 

### different hour 00 

### each of the three peak

### days. 1bepeak

### day electrical demand 

### profiles for each 

### ofthe 

### DHW system types 

### (found in 

### Figures 2 tbrough 

### 9) also 

### are highly variable 

### due to the 

### wel1her IS 

### well as the bot water 

### use 00 

### that day. 

### Understandably, the 

### consumption ofbot water 

### and, therefore the 

### demand for electricity. was greater in 

### the winter than in 

### the summer. For instance, the 

### average hot water consumption associated with 

# --**~** 'i 1800


### == :; 1600 ; 1400

### ~ 1200 

### o 1000 CI 

### 'E aoo 

## .: 600 ::E It') 400 

# - CI 200 01 III 0 

# .. CI > <I: Winter Peak Load Day: February 7, 1984 

### Conventionalelectricreal.tance

0 400 800 1200 1600 2000 2400 Hour of Day Figure 

### 2. Average Winter Peak Day Electrical Load Profile forElectricResistanceWaterHealers



# -**~** 'i 

# !. 1800 · "CI 1600 ; 1400

### ~ 1200

### ~ 1000 

### 'E 800 

### .E ::E 600 400**~** 200**~** 0 CI > <I: Winter Peak Load Day: February 7, 1984 

### Heatpumpwaterheater.



## o 400 800 1200 1600' 2000 2400 Hourof Day Figure 

### 3. Average Winter Peak Day Electrical Load Profilefor Heat Pump Water Heaters 

### daily electrical demand as seen in Figure I also suggestthatdesuperheaterunits 

### performvery similar to 

### electric resistance water heaters on 

### an annual basis. Peak Day Demand Although both the IS-minute and the 6O-minute coincident peale 

### demands for each of the DHW system types (found in Tables 3through 6) appearto vary considerably from one peak 

### day to another within the same season, it is important to 

### nOle that these demands are highly 

### dependent on the weather 

# -- .!! Dod<.et Nos 930548
-EG

- 930551
-EG Florida Solar Energy Industries Assoc

.,Inc

. E

x hibit

_ (WTG

-l) Sd1edu1e 1 PageS of 12

'i 1800

. 

# !. Winter Peak Load Day: February 7, 1984 

### Solarwaterheating .y.tem•

"CI 1600 · --

_ ._. ; 1400 

# f 1200 · 

### o 1000 CI 

### 'E 800 

### .E ::E 600

-**--~~~---~------------** It') 

# -**~** 200

- --+- 

### E O

- ......**-~** CI**~** 0 400 800 1200 1600 2000 2400 Hourof Day Figure

### 4. Average Winter Peak Day Electrical Load Profilefor Solar Waters Heaters WinterPeakLoad Day: February7, 1984


# - .!! 

### De.uperheaterwat.rh.at.r. 'i**1800 ----------------------~----** 

## ~**1600 -------------~------­**  ; 1400-**--------~--------~--~---­** 

### E CI 

## o CI 

### 'S c 

### j It') 

# - CI 01 «I 

# ... CI > <I: 1200

- 1000

- 800 · 600 400

- 200

-

0- 0 400 800 1200 1600 2000 2400 Hourof Day Figur, S. Average Winter Peak Day Electrical Load Profilefor DesuperiJeater Units 

### for each day. This is 

### especially ttue in 

### the case of the winter peak, IS 

### evidenced by the 

### fact that 

### FPL system peak occuned at • 

### different hour OIl 

### each of the threepeak

### clays

. 1bepeak 

### day electrical demand 

### profiles for each 

### ofthe 

### DHW system types 

### (found in 

### Figures 

### 2 through 

### 9) also 

### are highly variable 

### due to the 

### weather IS 

### well IS 

### the hot water

### use 00 

### that day. Understandably, the 

### consumption ofbot water 

### and, therefore the 

### demand for electricity, was greater in 

### the winter than in the summer. For instance, the 

### average hot water consumption associated withDocket Nos 930548--EG

- 930551-EG Florida Solar Energy IndustriesAssoc., Inc. Exhibit_ (WTG-1) Schedule 1 Page9 of 12

---....:.----_.**-~--** - ... Summer Peak Load Day: July 25, 1983 Soler water heating systems

800 1200 1600 2000 2400

Hour of Day 400 

## ca 1200 .-----.------.--- .-'"-- '

.... '._.0_

.. '-

- 

# !. 't:l 1000
- ------.-.----**~.----.** c 

# E 800- CII 600
- -----,----- 

### :; .E 400
- ---------- :1:

### ~enCII**200------~** , ell 0 -

__

# W~;;;_' fiiRa"'_--:.

__ t 0 

# ,. < 2000 2400 Summer Peak Load Day: July 25. 1983 Conventional electric resistance 

# - iii 1200 

# :=



# 't:l 1000 c co E 800 CII 0 CII 600 

### :; c :1: 400 L/') 

# ... 200 CII en co 0 

# .. CII > 

### < Figure 6. 

### Average SummerPeakDay Electrical Load 

### Profile forElectricResistance WaterHeaters Figure 8. 

### Average SJI11UnerPeakDay Electrical Load 

### Profilefor Solar Warers Heaters
Summer Peak Load Day: July 25, 1983 

# - Heat pump water heater systems iii 1200 -. --.----- . --..----- Summer Peak Load Day: July 25, 1983 'jjj' De.uperheater water he.te" 

## i 1200· ---------,,--------, 

# := 

# -

o 800 1200 1600 2000 2400 Hour of Day 400 't:l 1000·

. C ell E 800· CII 0 600. CII 

### 'S .E 400 

### :IE L/') 200
- 

# ... CII en 0- ell 

# .. CII 0 

# ,. < 800 1200 1600 2000 2400

Hour of Day 400 

## o 800

200 600 400 1000 co E CII 

### o CII 

### :; .E :1: L/') 

# ...

Figure 7. 

### Average Summer Peak DayElectrical Load 

### Profilefor Heat Pump Water Heaters Figure 9. 

### Average SJI11UnerPeoJc Day Electrical Load 

### Profilefor Desuperhealer Units
electric resistance water heaters on the winter 

### peak day in 1984 (66.3 gallons or 251 L) was 27% greater than the use on the 

### peak day (52.3 gallons or 198 L) during the previous summer. FurtherrnCl'e. the average electrical consumption used to heat each gallon ofhot water shows large differences between winter and summer 

### peak days. 

### On the winter 

### peak day. February 7, 19.84, electrical resistance systems used an average of 175 Wh to heat each gallon of water. whereas only 119 Wh were used to heat each gallon onJuly 25.1983, the summer 

### peak day. Thus. electrical consumption was 47% greater to heat a £iven volume ofwateron the winter 

### peak day. Most ofthe difference 

### in 

### electrical consumption is 

### due to the 

### seasonal 

### variatiOll in 

### iDlet 

### water temperature to 

### the bot water tank. 

### Data recorded over 

### the last two years at

### FSEC show that 

### iDlet 

### watertemperatures in 

### Central Florida vary by 

### more than 14 

### OF throughout 

### the year 

### (Parker 1989). 

### Also, since most bot 

### water heaters are located 

### in 

### ganges in 

### Florida. 

### lower ambient tempetJtures OIl 

### winter peak 

### days increase tank standby losses 

### and 

### add to the daily bot 

### water heating electrical coosumption.
To evaluate the 

### peak. demand reduction potential of the alternative water heating technologies. 

### it is 

# -**~** iii 

# :=



# - 't:I c 10 E CII 0 CII 

### :; c :l: L/') 

# ... CII en 10


## ... CII > 

### < 1200 1000

800 600 400 200

0 0Summer Peak Load Day: July 25. 1983 Conventional electric re.istance

400 800 1200 1600 2000 2400 Hour of Day 

### Figure 6. 

### Average SummerPeakDay Electrical Load 

### ProfilejarElectricResistance WaterHealers
Summer Peak Load Day: July 25. 1983 

# -**~** Heat pump water heatersystems iii 1200 -. --.----- . --..-----

### ~**~** 1000 10 E 800 CII 

### o CII 

### :; .E :l: L/') 

# ... 600 400 200



## o o 400 800 1200 1600 2000 2400 Hour of Day 

### Figure 7. 

### Average Summer Peak DayElectrical Load 

### Profilejor Heat Pump Water Heaters
electric resistance waterheaters on the winter

### peak dayin 1984(66.3 gallons or 251 L) was 27% greater than the use on the 

### peak day 

### (52.3 gallons or 198

### L) during the previous summer. FurtherrnCl'e. the average electrical consumption used to heat each gallon ofhotwater shows large differences between winter and summer

### peak days. 

### On the winter 

### peak day. February 7. 19.84. electrical resistance systems used an average of 175 Wh to heat each gallon of water. whereas only 119 Wh were used to heateach gallononJuly 25.1983. the summer

### peak day.Thus. electrical consumption was 47% greater to heat a £iven volumeofwateronthe winter

### peak day. Most

### ~ Docket Nos 930548--EG

- 930551-EG Florida Solar Energy IndustriesAssoc.• Inc. Exhibit_ (WTG-1) Schedule 1 Page9 of 12

Summer Peak Load Day: July 25. 1983 

## ca 1200 .------------.--- .-'"-- "-,-

..

# _.0_

..'-

- !. 't:I 1000

- ------.--.----**~.----.** c 

# E 800- , . ---.....:.----.**-~--** - ... CII

### ~ 600-

### --------~-------- :; .E :l: 400-

-----------------**~ 200-------4~--r·** **--~'-------~----** 

# g o.
__

# ~Lui~==n.' 

# •.**~~**

# __**~_** t 0 400 800 1200 1600 2000 2400 Hour of Day :0- 

### < Figure 8. 

### Average SU11IInerPeakDay Electrical Load 

### Profilefor Solar Waters Heaters Summer Peak Load Day: July 25. 1983

., Desuperheaterwater he.ters 

## i**1200·------------------~------~** 

# := 

# - 't:I C 10 E CII 0 CII 

### 'S .E :IE L/') 

# .. CII en 10 

# ... CII > 

### < 1000·

. 800· 600. 400 200

-

O·0 400 800 1200 1600 2000 2400 Hourof Day 

### Figure 9. 

### Average SU11IInerPeoJc Day Electrical Load 

### ProfilejorDesuperhealer Units ofthe 

### difference 

### in electrical consumption 

### is due to the 

### seasonal variatiOll 

### in inlet water temperature to 

### the botwater

### tank.. Datarecorded over

### the last two years atFSEC

### showthat

### inlet watertemperatures in Central Floridavarybymore than 14

### OF throughout 

### the year (Parker 1989). 

### Also, siDee most bot water 

### heaters are 

### Iocared in ganges 

### in Florida, 

### lower ambient tempetatures OIl 

### winter peak days increase tank standby losses 

### and 

### add to the daily bot water heating electrical coosumption.
To evaluate the 

### peak. demand reduction potential of the alternative water heating technologies. 

### it isnecessary to ftrst test whetherthe winter and summer peak day electrical profile of each technology was statistically different from the same peak day electrical profile of the electric resistance water heaters. Since the distributional shapes of the electrical demand are non-normal, a Wilcoxon ranksum test was performed to compare the profiles. Results showed that the peak day profiles of the alternative technologies were statistically different from conventional resistance systems at the 99.99 percent confidence level.
To calculate actual peak demand reduction, it is necessary to determine the difference in coincident peak demand between each technology and a base technology

- the conventional electric·resistance water heaters. Table 7 presents this calculation for both the IS-minute and 6O-minute coincident winter peak demands found inTables 3 and 5. (The winter peak day of December 26, 1983 is omitt.ed from Table 7 because of 

### the service curtailments that occurred on this day.) Table 7 also includes the average value of the coincident peak demand reductions of the two fully-served FPL winter peak days of 1983 and 1984.
As evident from Table 7, the coincident peak demand reduction on the two winter peak days is much more consistent than the individual winter peak demands of Tables 3 and 5. While the coincident peak demand reduction based on 60- minute intervals varies slightly from the IS-minute value, this is simply the result of averaging over a longer time period. Table 7 indicates that solar hot water systems exhibit the largest winter demand reduction of approximately 0.7 kW per customer. Heat pump water heaters contribute approximately 0.6 kW per customer reduction to winter peak demand, while desuperheaters are responsible for at least a 0.2 kW per customer reduction.
Table 8 presenlS"a similar analysis as Table 7 except that the diversified summercoincidentpeak demands from Tables 4 and 6 are used to determine the demand reduction for each alternative DHW system type. Table 8 indicates that 

### both solar hot water systems and desuperheaters are able to reduce summer peak demand considerably. However, since Table 6 reveals that the 6O-minute coincident peak demand for electric resistance water heaters may be Doc"et Nos 930548-EG

-- 930551-EG Florida Solar Energy Industries Assoc" Inc. Exhibit

_ (WTG-1) Schedule 1 Page 10 of 12

as low as 0.25 kW per customer, one cannot claim more than a0.2 kW summerpeak reduction potential for these technologies.
Table 8 also indicates no significant summer peak reduction potential for heat pump water· heaters. However, it is important to note that this analysis considers the peak demand reduction due to water heating only 

### and does not consider any increase or reduction that may occur 

### if the space conditioning load is affectedby the waterheater operation. While most beat pump water heaters were located outside ofthe conditioned space ofahouse, there were some that were located inside such that their operation would increase the heating load in the winter and decrease the cooling load in the summer. This analysis does not consider any effect that this contribution may have had on overall residential peak demand. 

### CONCLUSIONS
Residential water heating offers a significant potential for Florida electric utility loadmanagement because of the increasing level of residential ,electricity consumption and the ability ofalternative waterheating technologies to reduce coincidentpeak demand. The conunon electric resistance water heater contributes approximately 1.1 kW per customer to the utility winter peak and at least 0.2 kW per customer to the summerpeak. In 1988, the' C' total peak demand per customer at the time ofboth FPL's winter and summer peaks was 4.2 kW (FPL 1989). Hence, electric waterheaters are responsible for approximately 25 percent of 

### the utility winter peak demand and only about 5 percent of

### the utility summer peak demand. However, recent circumstances in Florida indicate that the winter peak may become more imponant than the summer peak in determining the need for new generating capacity. Fortunately, alternative water heating technologies offer a means to reduce winter and summer peak demand without requiring controlled utility intervention or even significantly reducing load factor. Solar hot water systems exhibit the highest coincident peak demand reduction of 0.7 kW per customer in the winter and a minimum of 0.2 kW per customer in the·summer. Solar systems perform necessary to ftrst test whetherthe winter and summer peak day electrical profile of each technology was statistically different from the same peak day electrical profile of the electric resistance water heaters. Since the distributional shapes of the electrical demand are non-normal, a Wilcoxon ranksum test was performed to compare the profiles. Results showed that the peak day profiles of the alternative technologies were statistically different from conventional resistance systems at the 99.99 percent confidence level.
To calculate actual peak demand reduction, it is necessary to determine the difference in coincident peak demand between each technology and a base technology

- the conventional electric·resistance water heaters. Table 7 presents this calculation for both the IS-minute and 6O-minute coincident winter peak demands found inTables 3 and 5. (The winter peak day of December 26, 1983 is omitted from Table 7 because of 

### the service curtailments that occurred on this day.) Table 7 also includes the average value of the coincident peak demand reductions of the two fully-served FPL winter peak days of 1983 and 1984.
As evident from Table 7, the coincident peak demand reduction on the two winter peak days is much more consistent than the individual winter peak demands of Tables 3 and 5. While the coincident peak demand reduction based on 60- minute intervals varies slightly from the IS-minute value, this is simply the result of averaging over a longer time period. Table 7 indicates that solarhot water systems exhibit the largest winter demand reduction of approximately 0.7 kW per customer. Heat pump water heaters contribute approximately 0.6 kW per customer reduction to winter peak demand, while desuperheaters are responsible for at least a 0.2 kW per customer reduction.
Table 8 presenlS"a similar analysis as Table 7 except thatthe diversified sununercoincidentpeakdemands from Tables 4 and 6 are used to determine the demand reduction for each alternative DHW system type. Table 8 indicates that 

### both solar hot water systems and desuperheaters are able to reduce summerpeak demand considerably. However, since Table 6 reveals that the 6O-minute coincident peak demand for electric resistance water heaters maybe Doc"et Nos 930548-EG

-- 930551-EG Florida Solar Energy Industries Assoc., Inc. Exhibit

_ (WTG-1) Schedule 1 Page 10 of 12

as low as 0.25 kW per customer, one cannot claim more than a0.2kW summerpeakreduction potential for these technologies.
Table 8 also indicates no significant summer peak reduction potential for heat pump water·heaters. However, it is important to note that this analysis considers the peak demand reduction due to water heating only 

### and does not consider any increase or reduction that may occur 

### if the space conditioning loadis affectedbythe waterheateroperation. While most beat pump water heaters were located outside oftheconditionedspaceofahouse, therewere some that were located inside such that their operation would increase the heating load in the winter and decrease the cooling load in the summer, This analysis does not consider any effect that this contribution may have had on overall residential peak demand. 

## CONCLUSIONS
Residential water heating offers a significant potentialforFlorida electricutility loadmanagement because of the increasing level of residential

.electricity consumption and the ability ofalternative waterheatingtechnologies toreduce coincidentpeak demand. The conunon electric resistance water heater contributes approximately 1.1 kW per customer to the utility winter peak and at least 0.2 kW per customer to the summerpeak. In 1988, the' c' total peak demand per customer at the time ofboth FPL's winter and summer peaks was 4.2 kW (FPL 1989). Hence, electric waterheaters are responsible for approximately 25 percent of 

### the utility winter peak demand and only about 5 percent of

### the utility summer peak demand. However, recent circumstances in Florida indicate that the winterpeakmay become more imponant than the summer peak in determining the need for new generating capacity. Fortunately, alternative water heating technologies offer a means to reduce winter and summer peak demand without requiring controlled utility intervention or even significantly reducing load factor. Solar hot water systems exhibit the highest coincident peak demand reduction of 0.7 kW per customer in the winter and a minimum of 0.2 kW per customer in the·summer. Solar systems performDocket Nos 930548-EG

- 930551-EG Florida Solar Energy Industries Assoc., Inc. Exhibit_ (WTG-1) SchedJIe 1 Page 11 of 12



### Table 

### 7. Diversified IS-Minute and60-MinUle Winter Peak DemandReduction (kWper Customer)



### Electric Resistance

Heat Pump Water Heater

SolarHot Water System

Desuperheater Unit January 13. 1983 February 7, 1984 Winter Peak 8-9 a.m. 7-8 a.m. Average IS-minute Base IS-minute Base IS-minute Base

.-------- .--.------ --------- 

### 60-minute Base 60-minute Base 6O-minute Base 0.61 0.61 0.61



### ------ 

# ---- -----

0.59 0.50 0.55 

### 0.68 0.63 0.66

------ 

# --- ----

0.83 0.74 0.79 0.20 0.25 0.23



### ------ ------ 

### ----

0.44 0.54 0.49

Table 

### 8. Diversified I5-Minute and 60-Minute Sununer Peak DemandReduction (kWper Customer)



### Electric Resistance

Heat Pump Water Heater

Solar Hot Water System

Desuperheater Unit August 24, 1982 July 25, 1983 Summer Peak 5-6 p.m. 5-6 p.m. Average IS-minute Base 15-minute Base IS-minute Base



### ------.-- 

# -------- --------- 6O-minute Base 60-minute Base 60-minute Base 0.13 -0.03 0.05



### ------ 

# ---- ------

0.07 0.06 0.07 0.66 0.32 0.49



### ------ 

## ---- -----

0.52 0.22 0.37 0.60 0.15 0.38



# ----- 

# -- ----

0.54 0.16 0.35

with an average coefficient ofperformance of 2.35 and have an annual load factor of 41 percent. In comparison, an electric resistance water heater has an average COP of 0.82 and a load factor of 50 percent. Desu.perheater units 

### can also provide the potential of reducinJ:t coincident summer peak demand by 

### a winter, only ltlose units 

### that are installed on beat pumps are capable of reducing electrical demand. 

### This winterpeakdemand reduction is determined to be 

### at least 0.2 kW per customer. Desuperheaters also have an average COP of 1.10 and an annual load factor of 54 percent. Heat pump water heaters have a system efficiency _L'-_

..**_-~--** 

### """'_t _r "_**1Io1~h"i,.. r~ci4::t~nrp**  water Docket Nos 93054B

-EG

- 930551-EG Florida Solar Energy Industries Assoc

., Inc. Exhibi t _ (WTG-l) Sched.J1e 1 Page 11 of 12



### Table 

### 7. Diversified IS

-Minute and60-Minute Winter Peak DemandReduction (kWper Customer) 

### January 13. 1983 February 7, 1984 Winter Peak 8-9 a.m. 7-8 a.m. Average 15-minute Base 15-minute Base 15-minute Base Electric Resistance .-------- .--.------ --------- 

### 60-minute Base 60-minute Base 6O-minute Base 0.61 0.61 0.61 Heal Pump Water Heater ------ 

# ---- ----- 0.59 0.50 0.55 

### 0.68 0.63 0.66 SolarHotWater System ------ 

# --- ---- 0.83 0.74 0.79 0.20 0.25 0.23 Desuperheater Unit 

### ------ ------ 

# --- 0.44 0.54 0.49

Table 

### 8. Diversified I5-Minute and60-Minute Sununer Peak DemandReduction (kWper Customer) 

### August 24, 1982 5-6 Q.m. 15-minute Base Electric Resistance 

### ------.-- 60-minute Base 0.13 Heat Pump Water Heater 

### ------ 0.07 0.66 Solar Hot Water System 

### ------ 0.52 0.60 Desuperheater Unit 

# ----- 0.54

with an average coefficient ofperfonnance of 2.35 and have an annual load factor of 41 percent. In comparison, an electric resistance water heater has an average COP of 0.82 and a load factor of SO 

### percent.**Des~perheater** 

### units 

### can also provide the potential of reducinJ:t coincident summer peak demand by 

### a July 25, 1983 Summer Peak 5-6 Q.m

. Average IS-minute Base IS-minute Base



# -------- --------- 60-minute Base 60-minute Base -D.03 

### 0.05



# ---- ------

0.06 0.07 0.32 0.49



# ---- -----

0.22 0.37 0.15 0.38



# -- -----

0.16 0.35
winter, only**~ose** 

### units 

### that are installed on beat pumps are capable of reducing electrical demand

. 

### This winterpeak demand reduction is determined to be 

### at least 0.2 kW per customer. Desuperbeaters also have an average COP of 1.10 and an annual load factor of 54 

### percent. Heat pump water heaters have a system efficiency

_L'-

_ ..**-- ~--**  ,,\..._. _t" "_**a.l~t-r'r-- r~4::iCl:t!lnrp**  water

### heater and operate at a load factor of 52 percent. .The winter peak coincidentdemand is approximately half that of an electric water heater so its winter demand reduction potential is 0.6 leW per customer. Unfonunately, in the summer, the coincident peak demand reduction of heat pump water heaters is negligible. Heat pump water heaters also demonstrated reliability problems when the study was performed in 1982 to 1984. If 

### these problems have been resolved. heat 

### pump waters also offer significant potential for reducing electric utility winter peak demand.**ACKNO~DGEMENTS** 

### The sponsorship of the Florida Public Service Commission. the suppon ofthe 

### FloridaSolarEnergy Centermanagement. and thecooperationofFlorida's electric utilities are gratefully acknowledged. The FSEC projectstaff

- Charles Beach. OmarHancock. Ross McCluney andTomTiedemann

-- also deserve both creditand thanks for theirconsiderable workon the project The dedicated assistance ofconsultants Don Patzsch and Timothy Stryker. as well as numerous FSEC graduate assistants. is also acknowledged. Finally. the participating homeowners deserve special gratitude for their cooperation. Without their assistance. the project would not have been possible. REFERENCES ASHRAE. 1977. ANSIIASHRAEStandard93-/977, 

### "Methods of testing to detennine 

### the thermal performance ofsolar collectors." American Society of Heating. Refrigerating, and 

### Air-Conditioning Engineers, Inc.• Atlanta. Georgia. ASHRAE. 1980. ANSI/ASHRAE Standard 90A

### 1980. "Energy conservation in new building design." American Society ofHeating. Refrigerating. and 

### AirConditioning Engineers. Inc.• Atlanta, Georgia. Block. D. L. 1983. "Solar domestic hot water system four-year performance results." Procee(/jngs o/the 

### 1983 AnnualMeeting, American SolarEnergy Society, 

### Vol. 6. pp. 235-240, Minneapolis, MN. Florida Governor's Energy Office. 1981. "Florida Energy Data: 1960-1981," Tallahassee. Florida.**v",,""'I~US** ",JUOOll:H:::G

- 930551-EG Florida Solar Energy Industries Assoc.• Inc. Exhibit

_ (WTG-1) Schedule 1 Page 12eX 12



### FPC. 1974. Florida Power Corporation, "Water Heater Test Data," Technical Information No. 37. St Petersburg, Florida.
FPL. 1978. Florida Power and 

### Light Company. "1978 Residential Electric Water Heater Study." Miami. Florida.
FPL. 1989. Florida Power and Light Company. "Petition to 

### Detennine Need for Electrical Power Plant: 1993-1996." Miami, Florida. FloridaPublic ServiceCommission. 1985. Research Department. "Statistics ofthe Florida Electric Utility Industry 1984." Tallahassee. Florida. FloridaPublic Service Commission. 1989. Research Department. "Statistics ofthe Florida Electric Utility Industry 1988." Tallahassee. Florida. Gladhan, P.M.• and Wiehl, ].S. 1986. "Monitored hot water use: A seasonal analysis." Proceedings

- 1986 Summer Study on Energy Efficiency in 

### Buildings. 

### American Council for anEnergy-Efficient Economy. pp. 1.90-1.103. Merrigan, T. 1983. "Residential conservation demonstration: Domestic hot 

### water. Final report" FSEC-CR-90-83. Florida SolarEnergy Center, Cape Canaveral, Florida. Merrigan. T.• and Wang. M. 1981. "BTU meter dynamic test. Final report" FSEC-CR-81-29(RD), Florida Solar Energy Center. Cape Canaveral. Florida. McCluney. R. 1980. "Annual performance of 20 solarwaterheaters incentralFlorida." FSEC-RM-80- 4. Florida Solar Energy Center. Cape Canaveral, Florida. Parker. D.S. 1989. "Hot Water Study: Phase I Final repon." FSEC-CR-295-89, Florida Solar Energy Center. Cape Canaveral. Florida. Perlman, M.. and Mills, B. "Development of residential hot water use patterns." ASHRAE Transactions. 

### Vol. 91, Part 2. pp. 657-679. Atlanta. Georgia. heater and operate at a load factor of 52 percent. .The winter peale coincidentdemand is approximately half that of an electric water heater so its winter demand reduction potential is 0.6 kW per customer. Unfonunately, in the summer. the coincident peale demand reduction of heat pump water heaters is negligible. Heat pump water heaters also demonstrated reliability problems when the study was performed in 1982 to 1984. If

### lhese problems have been resolved. heat 

### pump waters also offer significant potential for reducing electric utility winter peak demand.**ACKNO~DGEMENTS** 

### The sponsorship of the Florida Public Service Commission. the supponofthe 

### FloridaSolarEnergy Centermanagement, and thecooperationofFlorida's electric utilities are gratefully acknowledged. The FSECprojectstaff

- Charles Beach,OmarHancock, Ross McCluney andTomTiedemann

-- also deserve bothcreditand thanksfor theirconsiderable workon the project The dedicated assistance ofconsultants Don Patzsch and Timothy Stryker. as well as numerous FSEC graduate assistants, is also acknowledged. Finally. the participating homeowners deserve special gratitude for their cooperation. Without their assistance, the project would not have been possible. REFERENCES ASHRAE. 1977. 

### ANSIIASHRAEStandard93-1977, "Methods of testing to detennine 

### the thermal performance ofsolar collectors." American Society of Heating, Refrigerating, and 

### Air-Conditioning Engineers. Inc., Atlanta, Georgia. ASHRAE. 1980. 

### ANS/IASHRAE Standard 90A1980, "Energyconservation in newbuilding design." American SocietyofHeating,Refrigerating, and

### AirConditioning Engineers, Inc.• Atlanta, Georgia. Block. D. L. 1983. "Solar domestic hot water system four-year performance results." 

### Proceedjngs o/the 1983

### AnnualMeeting.AmericanSoJarEnergy Society, Vol. 6. pp. 235-240, Minneapolis. MN. Florida Governor's Energy Office. 1981. "Florida Energy Data: 1960-1981," Tallahassee. Florida. 

### v"'"'''',,**I~US** ::tJUOOII:)-t::G

- 930551-EG Florida Solar Energy IndustriesAssoc.• Inc. Exhibit

_ (WTG-l) Schedule 1 Page 12eX 12



### FPC. 1974. Florida Power Corporation. "Water Heater Test Data," Technical Information No. 37. St Petersburg. Florida.
FPL. 1978. Florida Power and 

### Light Company. "1978 Residential Electric Water Heater Study." Miami. Florida.
FPL. 1989. Florida Power and Light Company, "Petition to 

### Determine Need for Electrical Power Plant: 1993-1996." Miami. Florida. FloridaPublicServiceCommission. 1985. Research Department. "Statistics ofthe FloridaElectric Utility Industry 1984." Tallahassee, Florida. FloridaPublic ServiceCommission. 1989. Research Department. "Statistics ofthe Florida Electric Utility Industry 1988," Tallahassee, Florida. Gladhan, P.M., and Wiehl. ].S. 1986. "Monitored hot water use: A seasonal analysis." 

### Proceedings

- 1986 Summer Study on Energy Efficiency in 

### Buildings. American CouncilforanEnergy-Efficient Economy. pp. 1.90-1.103. Merrigan. T. 1983. "Residential conservation demonstration: Domestic hot 

### water, Final report" FSEC-CR-90-83. Florida SolarEnergyCenter, Cape Canaveral. Florida. Merrigan. T.• and Wang. M. 1981. "BTU meter dynamic test. Final report" FSEC-CR-81-29(RD). Florida Solar Energy Center. Cape Canaveral. Florida. McCluney, R. 1980.

..Annual performance of 20 solarwaterheaters incentralFlorida."FSEC-RM-80- 4. Florida Solar Energy Center. Cape Canaveral, Florida. Parker. D.S. 1989. "Hot Water Study: Phase I Final repon," FSEC-CR-295-89, Florida Solar Energy Center, Cape Canaveral. Florida. Perlman. M.. and Mills. B. "Development of residential hot water use patterns." 

### ASHRAE Transactions. Vol. 91. Part 2. pp. 657-679. Atlanta. Georgia.