Florida Solar Energy Industries Assoc. Inc. EXhibil_ (WTG-1) 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 ot the authors and not necessarily those of the Florida Solar Energy Center. Florida Solar Energy IrldustnesAssoc

. Inc

. Exhibll_ (WTG- l ) &heW_ \



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

FSEC-PF-21S-90
Tim Merrigan Danny Parker



# Florida Solar Energy Center 300 State Road 401 Cape Canaveral , Florida 32920 Publi shed in ACEEE 1990 Summer Siudy on Energy Efficiency in Buildings. Views and opinions expressed here represen t those of the authors and not necessarily those ollhe Flori da Solar Energy Center.Dod<.el Nos 930548-EG
- 930551-EG Florida Solar Energy Industries Assoc., Inc. Exhibit

_ (WTG-l) SchedJIe 1 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 waterheating systems: conventional electric resistance. heatpump. desuperheater and solar hot water systems. Electrical consumptionfor electric resistance waterheaters averaged 8.3 kWh perday in Florida with an average water heating**~ystem** 

### efficiency of 82%. 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 of solar 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 of diversified demand to the utility winter peak and at least 0.2 kW to the summer peak. Solar bot water systems exhibited the most desirable demand profile relative to Florida utility coincident peak loads with a 0.7 kW per customer reduction 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 kW per customer reduction in the 

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

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

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


### INTRODUCTION Since 1982, Rorida's electric utilities have sold more electricity each year in the state than they have produced (Florida Public Service Commission 1985. 1989). Fortunately, this situation is the planned result of purchasing 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

. 

# .. full capacity. Unfortunately, when a high 

### demand for electricity occurs, Florida's utilities are severely limited in their ability to increase capacity beyood their own generation. Such a circumstance 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** ",ili,i

.." Ul

..r .. t1n2hlp tn nt_t in nllrt hecause the. Dod<.et NOS 930548· EG
- 930551
-EG Florida Solar Enefgy Industries Assoc

.. Inc

.**E~hibit** ( WTG-I) 

### Scheci.Ji91 Page2 ot12



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

Tim Merrigan and DaDDY Parker Fklrida Solar EDergy CeDler
£ighlY single family residences in Aorida were monitored 

### fer- 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 of four different waterheating systems: conventional elecDic resistance.beatpump, desuperheater and solar hot water systems. Electrical consumptionfor elecuic resistance waterheaters averaged 8.3 kWh perday in Rorida with an average water heating system efficiency of 82%. Desuperbeaters used an annual average of7.4 kWh per tby at an annual system efficiency of 110% and heat pump water beaters used 6.1 kWh per day at an average system efficiency of 153%

_ Elecbical use of solar hot water systems averaged 2.7 kWh 

### per day and the average system efficiency was 235%. Electric:al demand taken at IS-minute intervals showed electric resistance water heaters conuibute approximately 1.1 kW of diversified demand 10 the utility winter peak. and at least 0.2 kW to the summer peak. Solar bot wiler systems exlUbiltd the most desirable demand profile relative to Rorida utility coincident 

### peak loads with a 0.7 kW per customer reduction in the winter and a minimum 0

.2 kW per customer reduction in the summer. Desuperheatc:rs have the same 0.2 kW minimum peak demand reduction in the swruner and 0.2 kW per customer reduction in the winter. Heat pump water heaters exhibited approximately halfthe 

### peak: demands ofelecuic water heaters in the winter but were unable to reduce summer peak demand by any significant amount. Sinc:e elecuic water heaters iCC:Ount for approximately 2S percent ofthe utility winter 

### peak. demand per customer
. encouraging theuse of alternative water heating methods is beneficial to a winter-peaking utilit), in Aorida.


### INTRODUCTION Since 1982. Rorida's electric: utilities have sold more electricity each year in the state than they have produced (Florida Public Service Commission 1985

. 1989). Fortunately. this situation is the planned result of purchasing more economical power from elecuic utilities in the neighboring states ofGeorgia and Alabama

. Sinc:e the purchased power is more economical. the transmission lines that CatT)' this full capacity. UnfCl1UDately. when a high demand for elecuicilY occurs. Rorida's utilities are severely limited in their ability 

### to increase capacity beyood their own generation

. Such a circwnstance recently occurred on December 24. 1989 when a suong winter cold front quickly passed through the southeastern United States. The cold weather crealed a peak. demand for elccuicit)' that Florida!s ",;t;,i

...**~** ...,........ I1nllhl

... In """,.I in nlln**"'cau~** the

.

### transmission ofpurchased power was already at full capacity. The result was nwnerous large-scale service interruptions due to rotated cunailments and an understandable breakdown of overloaded equipment. The Slate's largest utility, Aorida Power and Light Company (FPL), experienced ademand 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 winterpeak demand without service interruptions is ofmajor concern to 

### Florida utilities. However, these utilities have historically used summer peak 

### demand as the basis for detennining a minimum capacity reserve margin. Winter peak demand is generally only considered in a loss-of-Ioad probability analysis for determining the need for new generating capacity (FPL 1989). The 1989 Chrisunas Eve power shortfall, however, emphasizes that any method to reduce peak demand

-- winter or summer - should be imponant to a utility's planning process, especially in a high growth Slate like Florida. One area for utility peak load management lies in the residential sector. Since 1970, residential electricity consumption has been approximately 50 percent of the total annual electricity use in the state ofAorida. 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 of these years. Waterheating accounts for approximatelNI

## perce~ of the residential electricity consumption Ui""FIOilda (FPL 1978). Over 99 percent ofthis energy is due to the use of electric resistance water heaters. Alternative water heating technologies

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

-- account for less i.han one percent ofthe domestic hot water (DHW) systems in the state (Aorida Governor's Energy Office -1981). Of course. these Dcx;;kel Nos 930548-EG
- 930551-EG Florida Solar Energy Industries Assoc., Inc. EXhibtl_ (WTG-l) SchedJIe 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 bot water delivered and the actual water use of the residences's bousebold. 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 bad 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. Under the sponsorship ofthe Florida public utility regulatory coounission, FSEC collected**time~** .. 

### of

-day performance data 

### for two 

### years (July 1982

- June 1984) 011 

### four types 

### ofDHW systems: 1. 

### Electric resistance water heaters (that met ASHRAE Standard 9OA-1980) 2. Heat pump water beaters 3. Solar hot water systems (with collectors that met ASHRAE Standard 93-1977) 4. Desuperheater water heaters. Twenty systems of each DHW type 

### were instru

### mented to detennine both their IS-minute electrical demand and 

### bot water energy use. TIle 

### systems were located in single-family residences in four major population areas of Florida: Jacksonville in 

### nonb Florida. OrlandolBrevard County in east central Aorida, the Tampa Bay region in west central b"ansmission ofpurchased power was already at full capacity. The result was numerous large-scale service interruptions due to rotated cunailments and an understandable breakdown of overloaded equipment. The Slate's largest utility, Aorida Power and Light Company (FPL). experienced a demand of close 10 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 sununer peak demands of 12.876 MW and 13,425 MW. respectively (FPL 1989)

. Clearly. the ability to supply the winterpeak demand without service interruptiom is of major coocem to Florida utilities. However. these utilities have historically used summer peak demand as the basis for determining a minimum capacity reserve margin. Winter peak demand is generally only coosidered in a loss-of-load probability analysis for determining !he 

### need for new generating capacity (FPL 1989)

. The 1989 Christmas Eve power shoruall, however. emphasizes that any method 10 reduce peak demand

-- winter or sununer - should be importan! to a utility's planning process, especially in a high growth state like Florida

. One area for utility peak load management lies in the residential sector. Since 1970. residential electricity comumption has been approximately SO percent of 

### the 

### total annual elecaicityuse in the state ofFlorida. In 1988, residential customers consumed over 

### 63 million megawatt-hours with 

### an armuaJ growth rate of over five percent for each of the preceding four years (FPSC 1989)

. nus growth rate exceeded the population growth rate by at least two percent for each of these years. 

### ....----:::, Water heating accounts ror approximatelNJ

## perce**~** of the residential electricity consumption lil'FTOfida (FPL 1978)

. Over 99 percent of lhis energy is due to 

### the use of elecuic resisWlCe water heaters

. Alternative water beating technologies - solar hoi water systems, heat pump water heaters. and desuperbeater units that recover the waste heal of the refrigerant in a residence 's air-conditioning equipment

-- account for less ihan one percent of the domestic hot water (DHW) systems in the state (florida Governor's Energy Oflice ' 1981). Of course, these Oocl\et Nos 93054&EG

- 930551-EG Florida Solar Energy Industries As$OC

.. Inc

. Exhibif

_ (WTG- l) 

# -, Page 3 0112

to operate 

### or to supply backup water healing when neither solar nor waste heal is available

. To evaluate the impact of alternative water heating technologies on the eledJic utility, it is necessary to measure the time-of -day electricity consumptioo or each system type in a number of occupied residences

. However, the electrical consumption of any 

### DHW method CIIl vary considerably depending on the temperature of (be hot waterdelivered and the actual water use of the residences's household. Unless a fairly large number ofhouses are measwed to eliminate the variance in these quantities

. itis also necessary to 

### measure !be bot water energy delivered by the 

### DHW system
. 'Ibis latter quantity can account for the variatioos in water temperature 

### as well 

### as volume and, therefore, can serve 

### as a commoo ground for comparison. 

## METHODOLOGY
A Florida solar energy researcb and testing institute (FSEC) bas bad an active 

### program in solar domestic hot water system field mcnitoring since 1978 (McCluney 1980; Block 1983). In ceder to compare the measured performance of solar systems with the performance of other types 

### of domestic hot water systems. the field monitoring program was expanded in 1982. Under the sponsorship ofthe Rorida public utility regulatory coounission. FSEC collected**time ~**  

### of

-day performance data 

### for two years (July 1982

_.. 

### June 1984) 00 

### four types 

### of DHW systems: I

. Elecoic resistance water beaters (that met ASIlRAE Standard 9OA-I980) 2. Heat pump water heaters 3. Solar hot water systems (with collectors that met ASIlRAE SWldard 93-1977) 4. Desuperheater water heaters

. Twenty systems of eacb DHW type were instrumen&.ed to 

### determine both their IS-minute electrical demand and hoi water energy use. TIle systems were located in single-family residences in four major population areas of Florida: Jacksonville in north Florida, Orlando/Brevard County in east cenual Florida, the Tampa Say regioo in west cenual

### Florida. 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 heat meter utilized aflow 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 (lOSS 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, controls, 

### and/or compressor ofan alternative DHW system. Standard single-phase 30 amp meters were used with pulse initiators that had a resolution of I watt hour (Wh). A solid-state demand recorder accumulated contact closure pulses from the kWh, Btu, and flow meters and stored them in IS-minute totals in its internal memory. These totals were routinely acquired by UOC""II"iOS :;1-.1V::>4o-t;.u

-- \J;)()::>::ll-t:.U Florida Solar Energy Industries Assoc., Inc, Exhibit

_ (WTG-1) Schedule 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 I 

### lists the 

### sample size, the average family size, the daily average bot water use, the daily average elecbic 

### 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. (Two elecbic and four beatpump water beaters were omitted from these averages because of instrumentation malfunctions 

### or hot water system equipment problems.) COP is defined as the 

### bot 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 profiles (based 

### on IS-minute intervals) for the 

### four DHW groups 

### for the 

### two-year period. 

### The hours 

### displayed are clock times. 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 housebold bot 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 G..)!pay (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 Water Heater (280.5) Solar Hot 20 3.1 53.8 2.7 2.35 Water Heater (203.9) DesuperhealCf 20 3.6 58.6 7.4 1.10 Unit (222.1 ) Aorida

. The systems were selected both to achieve a geographic balance of five 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 (Bw) meter was installed on each system. The heal meter 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 

### sensa 10 calculate the thermal energy change of the heated water befCl"e it is delivered to the household Lab«atory 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 (1055 k1) and I gal (3.8 L). A kilowatt-hour (kWh) meter was used 10 record 

### the resistance element energy 

### as well 

### as any 

### auxiliary energy used by the 

### pumps, controls. 

### amVor compressor of

### an alternative 

### DHW system. 

### Standard single-phase 30 amp meters were used with pulse initiators that had a resolution of I watt hour (Wh). A solid-state demand recorder accwnulated contact closure pulses from the kWh. Btu. and flow meters and stored them in 15-minute totals in its intemal memory. These tOLals were routinely acquired by**W()(; UII'O~**  ",..>U =>4o- l: l..>
- \;IJO:>:> I. t;.l.:i Florida Solar Energy IndustriesAssoc.. Inc

. Ed'li bit

_ (WTG- l )

""""'

. 1 Page4 0112

telephone interrogation of the demand recorders. b"ansferTed 10 a microcomputer. and stored on magnetic media for eventual data reduction. 

### RESULTS Table 

### 1lists the sample size

. the average family size. 

### the daily average bot water use, the daily average electric 

### use, and a dimensionless coefficient of 

### performance (COP) 

### for !be 

### four DHW 

### 'ypes for !be 

### two-year period 

### luly I. 1982 to 

### lune 30. 1984

. (Two elecUic and four beatpump water beaters were omitted from these averages because of insrrumentation malfunctions or hot water system 

### equi_g, problems.) COP 

### is defmed as !be bot water energy 

### use divided by the electrical energy consumption and is, 

### therefore, ameasW'e ofthe total 

### DHW system efficiency. 

### Figwe I displays the average daily electrical load profiles (based on IS-minute intervals) fer 

### the four DHW groups for !be 

### lWO-year period. The hours displayed 

### are clock

### times. rather lban 

### the year-round standard time 

### that is sometimes used in annual data acquisitioo projects subject 10 the hour offset of a sununerdaylight savings period. This approach was taken since household bot wiler 

### use generally corresponds to actual clock time, as seen by 

### the apparent awakening of the florida groups around 

### 6:00 

### a.m.

T.b,. 1

. Florida Group Si:es

.Annual Daily Average Hot Water Use. Electric Use. and Coefficient ofPerformance Sample Size 

### Family Hot Water Electric Coefficient No. of Size 

### Use Use of**S~stems** People Gal !1:llQa:l**(kWh/Da~l** Perronnance Electric 18 3

.6 55.7 8.3 0.82 Resistance (211.1) Heat Pump 16 3.9 74.0 6.1 1.53 Water Healer (280.5) Solar Hot 20 3

. 1 53

.8 2

.7 2

.35 Water Heater (203.9) Desuperhcat cr 20 3

.6 58

.6 7.' 1.10 Unit (222.1 )UOCl\et Nos**930~-tG** - 930551.EG Florida Solar Energy Industries Assoc

.. Inc. Exhibit

_ (WTG-1) Sched.J1e 1 PageS of 12

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



### Load factor is 

### a measure of how well the electtical capacity demanded from the utility is utilized by the 

### load over a period of time. for the 

### same peak 

### days. This bourJy coincident demand is 

### calculated by averaging &he 

### four 1S

### minute demands IbaI 

### 0CCUJ'J'ed 

### during the peak 

### hour. It is 

### important to DOle 

### in both 

### Table 3 and 

### Table 5 

### that 

### FPL was unable to meet abe 

### peak 

### demand on December 26, 1983 and bad 

### to rotate 

### CUJ1.Ijlments throughout their 

### service 

### uea. Hence, abe 

### FPL system peak 

### of &he 

### winter of 

### 1982-83 (January 

### 13• 

### 1983) bas been 

### included in these tables. 

### Figmes 2 through 

### 5 

### present the 

### average IS-minute demand profiles 

### for abe 

### four DHW syBtcm 

### types on abe 

### FPL wiD&er peak 

### day of February 

### 7. 1984. Figures 6 1brough 

### 9 

### presems the 

### same time-of-day 

### profl1es for the 

### Slimmer peak day of 

### July 

### 2S, 1983. These two days were selected for 

### presentation because they represent
-the 

### bighest utility system loads of all the 

### FPlr peak 

### days that did not have service intemlptions. 

## ANALYSIS Annual Electrical Use and Demand 

### The average electricity 

## use of 8.3 kWh 

### per day for the 

### electric resisWJCe water beater 

### group - with an 

### average family size of 

### 3.6 people

- compares f!lVorably with values oblained by other studies performed in 

### Florida. FPL determined 

### in a 

### 1976-77 study of 16S 

### customers that 

### a family 

### offour used 

### an average of 

### 10.2 kWh per 

### day (FPL 

### 1978). Florida 

### Power Corporatico detennined 

### in a 

### similar study lbat 

### a family 

### 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 improved insulation was required 

### co electrical wilei' bearers 

### in order to meet 

### the minimum beat lass rate 

### requiremcDlS 

### ofASHRAE Standard 

### 9OA-I980. The shape 

### of the 

### average daily eleeuical dmwJd 

### profile for electric resistance water beaters 

### as 

### seen in Figure 

### 1 is 

### also 

### CXlOSisleDt 

### wilb abe 

### results of previous SlUdies. 

### 1be twin 

### peats of mid- morning and 

### early eve:ning demand C:Ollespood 

### to 

### typical residential bot waJa' ute patUms 

### ofsbowering, food 

### preparatiOl1, and 

### cleanup (Perlman 

### and Mills 

### 1985; Gladban and 

### Wiebl 1986). As bot 

### water is withdrawn from the 

### lUnge tank, the 

### electric element turns 

### on wben the 

### warer &emperature drops Conventional electric Heal pump water healer Solar water heating system Desuperheater water heater



### Average Demand (kW) 

### Peak Demand (kW) 10 2 4 6 8 10

Noon Midnight 

### Average Daily Electrical Load

### Profilefor Four T)'Pes ofWattr Hearing Systems .6

.2

. .4

2 4 6 8 Midnight 

### Figure 1.



### Load Factor (%) 

# =

,- 

### Tables 

### 3 and 

### 4 indicate the 

### FPL winter 

### and 

### summer peak 

### days, respectively. and the hoor mat the peak 

### occurred. These same tables also contain each DHW system type's maximum IS-minute diversified demand that was coincident with the hour of the rD1 .,,,.,,pm nP-a-lc 

### The diversified 6O-minute The winter peak and sununer peak days chosen for data reduction are the 

### actual peak load days of Florida Power and 

### Light Company. in whose 

### service territory half of the 

### 80 systemS were located. 

### The other balf 

### ofme systems were located in 

### the service areas of Florida Power Corporation. Tampa Electric Company. and Jacksonville Elecaic Authooty. These 

### utilities either had the 

### same winter and summer peak load days as 

### FPL or their 

## Secondary system peaks occurred on these days. Table 2 

### presentS the 

### daily average IS-minute elecaical 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 average kilowatt demand over a designated period of time to the 

### maximum demand occurring in that period. E 

# .. ';i .8 

### "'" I/) ; Cl. '0 c: 

### " E 

# .. o


# .. CII



# .. > < 

# - 1.0

- -- 1 .1_:1 ••**~** Florida average daily electrical demand (July 1. 1982. 0 June 30

. 1984) Type 01 Sy.tem**~** 1

.0 Con"enlionat eteC:lric Heat pump .aler healer Solar Wiler heaUng .ytle", Desuperh

.. ler waler heller E 

## • ';

.8**~ ~**  

# · •**~ ~**  

### i .4 E ". 

## • Q

# ~**~=~~"--::-T-:--=;=:---: ~-;** **;- ~**  ;.. 'WO o .' : 0 c 2 • 6 8 10 2' 6 8 10 Midnight HOOf! Midnight 

### Figure 1. Averagt Dail y £ItcrricafLoad P,ojilt 

### fo, Four Typts

### ofWaItT Htat illg SYSltms
Table 2 

### presentS the diily 

### average I5-minute electrical demand

. the 

### average IS·mioute 

### maximum 

### demand and !be 

### daily load faclOr for 

### the four 

### DHW 

### types for the 

### twcry ear period

. 

### Load factor is 

### the 

### ratio

. expressed 

### as apercent ofthe 

### average kilOWlU demand over a designated 

### period of time to the maximum demand 

### occurring in that period

. 

### Load Factor (%) • 

### Average Demand (kW) P,ak Demand (kW) Load factor is a measure of how well the elecuical capacity 

### demanded from the 

### utility is utilized by the load over a 

### period of lime

. The winter 

### peak. and sununer 

### peak. days chosen for dau reduction are the actual 

### peak load days of Florida 

### Power and Light Company. in whose service territory 

### half of the 

### 80 systemS were located. 

### The other half of the systems 'Nert loclltd 

### in 

### the service areas of Acrida Power Corporation

. Tampa Electric Company. and Jacksonville Electric Authaity

. 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 winLel' and 

### summer peak. days. respectively. and the boor \hat the 

### peak occurred. These same tables alsocontain each OHW system type's maximum lS·minute diversified demand that was coincident with the hour of the rDT ."

..**~I**..", N':.Ilk

. The diversified 6()..minute U<X.>\e1 Nos.**9JO:wB c~**  - 930551

.EG FIoMa Solar Energy Industries Assoc

.. Inc. Exnibit_ (WT G-l) 

# """"'

., Page 5 0112

for Ihe same 

### peak. days

. 'Ibis bowiy coiodderu demand is calcula1ed by averaging lbc four 

### IS· minute drmands 1Iw occwred during the 

### peak bouT

. It 

### is imporwu to DOle in 

### boCh Table 3 and Table 

### 5 that Fi'L 

### was unable to meet the 

### peak. demand 00 December 26. 1983 IUd 

### bad to rDCate cwujlmeolS tbrougbout 

### Cbeir service 

### uea. Heoce
. lbe 

### FPL sy.tem peIk of lbc winter of 1982·83 

### (JIDUIly 13. 1983) bas

_ 

### iDcludcd in lbcse tables. 

### Figuros 2 lhrougb 5 

## presem lbc 

### avenge 15·miDute 

### demand prof ties for lbc four 

### DHW

_ type. 

### 011 the FPL 

### winIer peIk 

### day of February 7
. 1984

. 

### Filures 6 

### IIIrougb 9 praeDIS lbc 

### same time-oC-day 

### proflies for lbc

..",,_ 

### peak 

### day of 

### July 

### 25. 1983

. Tbese two 

### days 

### were ldecced fa 

### preseorarioo beuuse 

### they repn:sent 

### ihe bighest 

### utility 

### system loads of all 

### the FPL peIk 

### days ihat did not bav, service inte:n'Uptioas

. 

## ANALYSIS Annual Electrical Use and Demand 1be average elearicity

# use of 8.3 kWh 

### per day for the electric 

### resistance water beater group - with 

### an 

### average family 

### size of 

### 3.6 

### people

- 

### compares fllvorably with values 

### obcained by 

### other studies perform,d in Florida. FPL

### determined in. 1976-77 

### study of 165 CIIstomen lbal I 

### family 01 four used an 

### Iverlg' 0110

.2 kWh 

### per day (FPL 1978). 

### Aorida PowerCorporatioo

_ in I 

### similar srudy tIW a f

.. 

### -nily of three used an 

### avenge 01 8.4 kWh 

### per day and I 

### family of four 

### wed 11

.6 kWh 

### per day (FPC 1974). BolIl 

### studies

.... n: performed befor, 

### improved iDsulatioc was required 011 

### electrical 

### water beaten in order to meet 

### the minimum 

### beaI: 

# as rate 

### nquin:meDls of 

### ASHRAE $1_

### 9OA·I980

. The sbIpe of lbc 

### Iverage daily eiOClricai demand profile for**e~** resistlDC:e wlltr beaters IS seen in 

### Figure 1 

### is also CODSiSCCDI with 

### the results of 

### previous llUdies

. '!be 

### !wiD 

### peak> of mid- IIIOrDiag and Cltly 

### evczUn& demand CUiespood to typical residential boc: 

### waser ue patlans ofsbowerin.g. food 

## preparwoo. IUd cleanup**~** and Mills 1985; GladIwt and Wiebi 1986). As bot wiler is withdrawn frcm 

### the 

### aorage tank. !be 

### electric element turns 

### on wbeo &be water 

### umpc::rarure I!rops

__ _ .. .. ..1.:1••Docket Nos 930548-EG
- 930551-EG Florida Solar Energy Industries Assoc.• Inc. Exhibit_ (WTG-1) SchecilIe 1 Page 6 of 12



### Table 

### 2. Annual Average i5-MinUle Demand. Peak i5-MinuJe Demand. andLoad Faclor by Type of System Average Demand Peak Demand Load Factor (leW) (leW) 

### (%) 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 i5-MinUle Demand Coincident wilh FPL Winter**P~ak** Load

### (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 Heat Pump 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 of 666 MW



### Table 

### 4. Average i5-Minule Demand Coincident with FPL Summer Peak Load (60-Minute Nel) August 24, 1982 July 25, 1983 5-6 p.m. 5-6 p.m. Electric Resistance 0.74 kW 0.34 kW Heat Pump Water Heater 0.61 kW 0.37 kW SoIlU' Hot Water System 0.08 kW 0.02kW 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 of 50 percent.

LJ

..... n,,",n UllltP1"**hplItl"r~** had a 

### similar load factor average demand is 

### approximately 25 percent less. This reductioo is due to the higher annual average system efficiency of the 

### beat pump water beater

-- approxin:lately twice that of the 

### electric resistance water heaters. However, seven of the 20 heat pump Do:::Jo.eI Nos 93054&-EG
- 930551-EG Florida Solar Energy Industries Assoc., Inc

. Exhibil_ (WTG-l) 

# """""', Page 6 0112**T4b~** 

### 2. Annual Average 15-Minute Demand, Peak !5-Minule Demand, and 

### wad Factor by Type ofSyslem Average Demand Peak Demand Load Factor (!;Wl (!;Wl !%l 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**TtJb~** 

### J. Average JS-Minute Demand Coincuunl with FPL Wimer Peak Load

### (60-Miruue 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 Heat Pump 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 of 666 MW**Tab~** 

### 4. Average JS-MinuJe Demand Coincichnz with FPL 

### Summu Peak Load (60-MinuJe Nel) Augus' 24, 1982 July 25, 1983 5-6 p.m. ElecU"ic Resistance 0.74 kW Heat Pump Water Heater 0.61 kW Solar HOI Water System 0.08 kW Desuperheater Unit 0.14 kW

average demand ofthe element is exacUy one-halfof its average peak demand, resulting in an annu31. average load factor of 

### SO percenl.

u ...... n .......n**w"'~r** h

.....'

...r" had a similar load factor 5-6J2.m. 0.34 kW 0.37 kW 0.02kW 0.19 kW

average demand is approximately 25 percent less. This reductioo is due 

### to the higher annual average system efficiency of !.be beat pwnp water beater

- approximately twice that of the electric resistance waLer heaters. However, seven of the 20 heat pumpi)OCl\tll Nos 930548 EG
-- 930551·EG Florida Solar Energy Industries Assoc

.. Inc. Exhibit

_ (WTG·1) Schedule 1 Page 70112

Tabu 

### 5. Average 6O·Minute 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 O.64kW

• Unserved utility load of 666 MW

Tabu 6. Average 6O-Minute Demand Coincident with FPL Summer Peak Load(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-term 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 of solar 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. C'omhined with lhe 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. Desuperbeater 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 performance 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 of 54 percent and the average, iJoc"ul Nos**930~8** EG·· 93055I-EG Florida Solar Energy Industnes Assoc., Inc

. El<.hibil_(WTG·I) 

# """"", Page 701 12

Table S. A\"erage 6O·Minule Demand Coincident ·with FPL Winter Peak Load (60·Minule Net) lanuary 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 Resistancc Heat Pump Water 0.48 kW 0.36 kW 0.68 kW Heater Solar Hot Water 0.24 kW 0.59 kW 0.44 kW System Desuperheater Unit 0.63 kW 0.30 kW 0.64 kW

• Unserved utility load of 666 MW

Table 6. Average 6O-Minult Demand Coincident with FPL Summer Peak Load (60-Minule Nel) Augusl 24. 1982 July 25. 1983 5-6 p.m. Electric Resistance 0.58 kW Heat Pump Water Heater 0.51 kW Solar Hot Water System 0.06 kW Desuperheater Unit 0.04 kW

failures. indicating a problem with long·term reliability in 1982-84

. Solar hot water systemS operated with 

### the highest average electrical system efficiency and had the 10wesL average daily electrical demand p-ofile. However
. the solar system's annual load factor of 41 percent compares favorably with the electric resistance waler heater's load factor of 50 perceot This is surprising since the majority of 

### solar system owners turned off their st(l"age 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 thcse systems was that of the solar circulation pump as can be secn in the summer day average of Figure 9 for the six-hour period around noon.**C:nmhin~d** with the occasional winter use of the 5-6 p.m. 0.23 kW O.!7kW 

# om kW 0.07 kW

backup element. this electrical demand was consistent enough during the summer months to create a relatively high annual load factor. Desuperbeater unit owners also typically rumed off their backup electric clement during the sununer. However. 

### these units would only supply hot waler when there was a need f(l" air conditioning or, for those eleven desuperheaters lhat were instaUed on helt pumps, a need for beating and/or air conditioning. Surprisingly, even in Aorida, there are considerable periods of time when neither mode of space conditioning is required. 

### TIUs is reflected in the average two-year coeffacient of performance of 1.10 for desuperheaters. Although this COP is beuer than unity, it is not much higher than the efficiency for UI electric resistance waler healer. The annual load factor of 54 percent and the average.Docket Nos 930548-EG
- 930551·EG Florida Solar Energy Industries Assoc., Inc. Exhibit

_ (WTG-1) Schedule 1 Page8 of 12

Winter Peak Load Day: February 7, 1984 

### Solar water heating .y.tems

800 1200 1600 2000 2400

Hour of Day 400 

# - 7a 1800 "0 1600
--- --. ; 1400 E 1200.
-- _._- -.----- - III 

### o 1000 III '; 800 .5 ::IE 600
- 

### ----n-t--
...------- 400
- --.,-- 

## & 200- --iO-

__M III > 0 

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



### Conventional electric re.i.tance



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

# - 1800 ;- 1600 ; 1400 1200 1000 '; 800 c 

### j 600 It) 400 

# ... & 200 0 III > 

### < Figure 2. 

### Average Winter Peale Day Electrical Load ProfileforElectricResistance WaterHeaters Winter Peak Load Day: February 7, 1984 

### D
..up.rh.at.r water heate,..

800 1200 1600 2000 2400

Hour of 

### Day 400 Figun 4. 

### Average Winter Peak Day Electrical Load 

### Profilefor Solar Warers Heaters



# - - 1800
- ------------,--- ;- 1600
- -----------------: ; 1400
-**---------~-__t---'** 1200' 

### ------------f!--- o 1000
- 

### ----+-----_-...-.,...-' III '; 800
- -----1j---.,.-------,f,'------:T._-zt:- C 

### j 600 400- ---*- 

## & 200
-**~:"-'l** b-

.. -t--f;ji.1II 0 - _ilIioW

....._ III 0 

## _

..

## _- -

..

# __._-------- Winter Peak Load Day: February 7, 1984 

### He.t pump water heater.



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

# -



# - III 1800· "0 1600 c 1400 III E 1200 CII 0 1000 III '; 800 .5 600 ::IE It) 400 

# ... III 200 Cl III 0 CII > 

### < Figure 

### 3. Average Win/tr Peak Do)' Electrical Load Profilefor Heat Pump Waler Heaters Figu"; 5. 

### Average Winter PeaJc Day Electrical Load Profilef,?r Desuperheater Units 

### daily electrical demand as seen in 

### Figure I 

### also suggest that desuperbeater units 

### perfonn very similar to 

### electric resistance water heaters on 

### an annual basis. 

### Peak Day Demand Although both 

### the IS-minute and the 6O-minute coincident peak demands for each of the 

### DHW system types (found in 

### Tables 3lhrough 6) appear to vary considerably from one peak 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 

### wimer peak. 

### as evideDccd by tbe 

### fact Ihal FPL 

### system peak occurred at 

### a different boar OIl eacb 

### of the three 

### peat days. The peak 

### day electrical demand prof1les for each of the 

### DHW system types (found in 

### Figures 2lbrwgb 9) also 

### are higbly variable due to tbe 

### weather as well 

### as the bot water 

### use 00 tbat 

### day. Understandably, the 

### consumption of bot 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 

# '" ;; 1800**~** .; 1600**~** 1400 

# f. 1200 C 

# • 1000 '5 

# ••• .E 

# ••• 

# ,.**~** 

# ••• 

# - • 2•• 0> 

# • 

# • • 

# • • 

# .. Winler Puk L.oad Day: February 7

. 1984 Conv.ntional .I.ctric r••i.'ance



# • t

. . L

.

,. I"

400 800 1200 1600 2000 2400 Hour of Oay Fi,un 2.**A~ragt** Wimer Peak Day Elulricaf Load Profilt forEltctricRtsistaflct WattrHtattrs

_ WinIe, Pe.k 1.oad Day: February 7, 11184 

# = H•• t pump wat.r h••••,. 

### ;; 

## ------------------**~** 

# ,.

# ... ---

_ .--. 'D 1600 e 1400 

# • E 1200 

# • C 1000 J!! 

# , 

# ••• .E 

# ••• ,.**~** 

# - ••• • 2•• 0> 

# • 

# • • 

# • • 

# .. i .

. 

# • ••• ••• 1200 1600 ' 2000 2400 Hour of Oay ngurt 

### J
. Avtragt Winltr Ptak Day Eltclric al Load Profiltfor HtarPump Wattr Htattrs daily electrical demand as seen 

### in Figure 1 also suggest ahat desuperbuter

### units perform very sim.ilar to electric resistance water heaters 

### on an annual basis

. 

### Peak Day Demand AJthough both the lS·minute and the 6()..minUle coincident peale demands for each of the: DHW system lypeS (found in Tables 3 through 6) appeu to vary considerably (rom one peale day to another within the same season, it is important to note that these demands are highly dependent on the: weather Docket Nos 9Xl548·EG

- 9Xl5St·EG Fbrida Solar Energy Industries Assoc

.. Inc.**hibit** (WTG· 1) 

### SctI9d.Jiii1 Page8 01 1 2



## :F


# .. Winter Peak 1.oad Day: February 7, 1984 Sol.r .at.rh.aUng ayat.ma**~** 1800 'a 1600 e 

# E 1400 1200 

# • c 1000 J!! 

# • 

# ••**~. ·--** **---- rrt** **~i- ------~---­**  

# ....**--~ -,** **~** 200 ·**-,.---~ ~**  . . ...........JJ 

# • C 0 400 100 1200 1100 2000 2400 Hour ot Day 

### Firun 4. AwrD,t Winler Ptak Day Electrical Load Profiltlor Solar WattrS Heatlrs Wint.r P.ak Load Day: Februlry 7, 1884 

## i' D
.. uperh•• t.r •• ter h

.......



# ..**---------c------------- --** **---** 

# !. ,••• .**~ 1~0** **~-- ----------------------** **_c** ; 1400

-**-------- ------------_r** **-- -O**  

# E 1200 · 

## --------,----------'------f,----**~ 10~** **------ ~~** **---- --~** **-- _f~** **T" ~**  100 '**-- -----c** **+-,- ~~** **c_--_.** 

## :i**~** 

# - t • • 

# .. ••• ••• . -----,-0- 200 ·

### ~ti!j;

• . E 

# • 

# ... .oo 1200 1100 2000 2400


### Filurt S

_

Awra,t Winttr Ptak. 

### Day Eltctrical Load Profilt

## 10/DtsuptrMDttr Units foc 

### each day

_ 

### 1bi.s is especially true 

### in the case of !he wiDIu peak

. IS eviclcoccd by !he flCl 

### that FPL 

### system peak 

### occuned II • 

### diffe=t boor 00 

### eacb of lhc three 

### peak da}'$. 

### The peak day electrical dem,nd prom.. for cacb of tile 

### DHW system l)'JJes (found in 

### FiglRS 2 

## lbroulb 9)

_ ... bilhly variable due 10 &be 

### we&tber 

### u well IS (be bot water 

### use 00. 

### tba1 day. Understandably. the coosumption of bot wat.c:r IDd, therefore the demand for electricity, 

### was greater in the 

### winter than 

### in the summer. For instlDCe

. the average hot water consumption associlled withDocket Nos 930548-EG
- 930551-EG Florida Solar Energy Industries Assoc

.. Inc. Exhibit

_ (WTG-1) Sched.de 1 Page9 of 12



## o 400 200 ____ --.1. •

__

800 1200 1600 2000 2400

Hour of Day 400 

## ._---:-----_.- ._---- .-- Summer Peak Load Day: July 25. 1983 

### Solar water heating .y.'ems

600
- 400
- --------- 200
- 

# r-;

__••**Iba_~** __

0- 

## 1lj b 

## o 800-
-----

ClI en CIlI 

# ... ClI :- 

### < 

# - .:2 -; 1200 ;- 1000
- - --------- c: III E GI C ClI 

### 'S .5
It! 

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

### Conventional electric resistance



## o 400 800 1200 1600 2000 2400 Hour of Day 800 600 

# - "; 1200


# - 1000 III E ClI 

### c ClI 

### 'S 

# .= It! 

# ... ClI en III 

# ... ClI > 

### < Figure 6. 

### Average Summer Peak Day Electrical Load 

### ProfileforElectricResistance WaterHeaters Figure 8. 

### Average**S~r** 

### Peak Day Electrical Load 

### Profilefor Solar Walers Healers
Summer Peak L.oad Day: July 25. 1983


# - Heat pump water heater .ystems -; 1200-------

- 

# !



# __w';**t\~Lj'jfl.** 400 800 1200 1600 2000 2400 Hour of Day 'C 1000
- . c: CIlI E 800
- GI C 600
- GI 

### 'S .5 400 :IE It! 200· 

# ... GI en 0- CIlI 

# ... GI 0 :- 

### < Summer Peak Load Day: July 25.1983 

### -; De.up.rh••'er water h••t.,. 

## i 1200- ---------.,.------


# -

!



# -**-;-t~--** :

800 1200 1600 2000 2400

Hour of Day 400 

## o 800 600 400

ClI en III 

## ... ClI > 

### < 1000
- III E ClI 

### c ClI 

### 'S 

# .= It! 

# ...

Figure 7. 

### Average Summer Peak Day Electrical Load 

### Profilefor Heat Pump Water Heaters Figure 9. 

### Average SlU'J'JIner Peak Day Electrical Load 

### Profilefor Desuperheater Units 

### electtic resistance water heaters on the winter peak 

### day in 1984 (66.3 gallom or 251 L) was 27% greater than the 

### use on the peak 

### day (52.3 gallom or 198 L) during the previous summer. FurthennCl'e. the 

### average electtical consumption used to 

### heat each gallon ofbot 

### water shows large differences between winter and summer peak 

### days. On the 

### winter peak day. February 7. 

### 1984. electrical resistance systems used an average of 175 Wb to 

### heat each gallon of water. whereas only 119 Wh were used to heat each gallon on July 25. 1983. the summer peak 

### day. Thus. electrical consumption was 47% greater to 

### heat a 2iven volume ofwater on the winter peak 

### day. Most ofthe difference in electrical 

### consumption is 

### due to the 

### seasonal variatioo in 

### inlet water temperature to 

### the bot 

### water tank. Data 

### recorded over the last 

### two years at 

### FSEC show that iDlet 

### Wiler temperatures in 

### Central Florida 

### vary by 

### more than 

### 14 

### OF throughout the year 

### (Parker 1989). Also, since most 

### bot 

### wiler 

### beaters are loclleCl 

### in larqeB 

### in 

### FlOOda, 

### lower ambient temperab.lres 00 

### winter 

### peak days 

### iDcrease tank: 

### standby losses and 

### add 10 

### the daily bot 

### water beating electtical consumption. 'to evaluate the peak demand reduction potential of the 

### alternative water heating technologies. it is 

## F ;;**~** 1200**~** 1000 

# •**~** 800 

### o 600**~** 400**~ ~**  

# •**~** 

# • • 

# • • 

# " 200 

## o Summer Peak Load Day: July 25 , 1983 Conventional electric re.iatance



## o 

# . ;. jI

400 800 1200 1600 2000 2400 Hour ot Day Figur, 6. Alltrogr**S~r** Ptok Day Electrical Load 

### Pr o file /orElectricRe sistance WattrHeaters



# - •**~** 1200

### ~ 't:I 1000 c 

# • e 800 

# • o 

# • ;; .E :I**~ ~**  

# •**~** 

# • :;; 

## • 

# " 600 400 200 

## o SUmmer Peak Load Day: July 25 , 1983 H•• t 

### pump water h•• 

### ter arstem.

..



# _ ..



# _---

o 400 800 1200 1600 2000 2400 Hour 01 Day Figure 7. Avtrage Summer Pta); Do)' Electrical 

### Load Profilefor Heal Pump Wattr Heaters elecb'ic resistance water heaters on the winter 

### peak 

### <lay in 

### 1984 (66.3 gallons 

### or 251 L) was 27% gre...,r !han !he 

### use on the peal< 

### day (52.3 gallons 

### or 198 L) during the 

### previous swnmer. Furthermore, the 

### average electrical consumption used to beat 

### each gaUoo of bot 

### water shows large differences between winLet 

### and summer peak 

### days. On Ihe 

### winter peak 

### day, February 7
. 1984. electrical resistance sySlc:mS used an average of 175 Wb to beat each gallon of water, whereas only 119 Wh were used to heat each gallon onJuly 25. 1983. the summer 

### peak day. Thus

. electrical conswnption was 47% greater to heat a £iven volume ofwater on Lhe winter 

### peak day. Most 

# - " ;; ;J 

# .., c 

# • E 

# • 0 

# • ;; c 

## i**~ ~**  

# • 

# .. • • 

# • • 

# " 1200 Dod<.ec Nos93()548.-EG - 93055H G F

lorida Solar Energy lna..stries Assoc., Inc. Exhibit

_ (WTG-1 ) 

# """""', Page9 0112

Summ.r P••k Lo.d D.y: July 25. 1183 Solar .aterh•• tlng

# .,.t.me ._-_..

### - 

### - - - 

## - ._- 

## . ..

### _ ._ -- 1000

. - - - - - -- ..**.-** - . 100 · 600 · ..

## - .- 400 · 200 · 

# L,

• O ·


# -- 0 400 100 1200 1600 2000 2400 Hour of D.y Fitllrt 8. Awragt SJunmLr PtDk Day Eitctrical Load Profiltfor Solar Wattrs Htaltrs



# - "

.. 1200- ------.,-------

### ~ 

# .., 1000

- ' c 

# • E .00 · 

# • 0 600

-**~** 

# • c 400 

## i**~** 200 · 

# 1.., U;, 

# tl LtL**~** 

# • 

# .. O · 

# • • 

# • 0 400 100 1200 1800 2000 2'00 

# • 

# " Hour of D.y Fi,urt 9

. !.'1tragt**S~r** Peak. 

### Day Eltclricai Load PraftJtfor DtSllptrhetUtr Uniu of the 

### diffeJCDCe 

### in 

### e1ectric:a1 ccosumptioo is due to the 

### seuooal 

### variatioo 

### iD 

### iDlel water aempenture 10 

### the bot

# w_ WIlt. 

# n... rocudod 

### over the lISt two years It FSEC 

### sbow 

### dI.at iDld water temperatuJcs 

### in Ceulral 

### Flori<la vory by ""'" IIwI 

### 14 OF Ihrougbout IIIe 

### year (Parter 1989). 

### AlIa, IiDce '""'" 1>01 water beaI<rs

.. 

## loc:_ in 

## I...,.. in 

### Florida. lower ambient lempenlllreS OIl 

## .n- peak 

### days 

### iD=as<: 

### WlI: sundby losses IDd 

### odd to 

### the 

### daily bot 

### wiler beating electrical 

### coosumptioo.. 1:.0 evalualt the peak 

### demand reduction 

### poc.eotial of the ah.emative water heating teChnologies. it isnecessary to frrst test whether the 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. ResullS 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 detennine the difference in coincident peak demand between each technology and a base technology

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

### the service cunailmenlS 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 15-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 leW per customer. Heat pump water heaters contribute approximately 0.6 leW per customer reduction to winter peak demand. while desuperheaters are responsible for at least a 0.2 leW per customer reduction. Table 8 presenlS a similar analysis as Table 7 except that the diversified summercoincident peak 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 waler heaters may be Dochel Nos 930548-EG
-- 930551-EG Florida Solar Energy Industries Assoc., Inc. EXhibil_ (WTG-1) Schedule 1 Page 100112

as low as 0.25 leW per customer. one cannot claim more than a 0.2 leW summer peak 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 ooIy and does not consider any increase or reduction that may occur if the space conditioning load is affectedby the water heater operation. While most beat pump water heaters were located oulSide ofthe conditioned space ofa house, 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 load management because of the increasing level of residential

.electricity consumption and the ability of alternative waterheating technologies to reduce coincident peak demand. The common electric resistance water heater contributes approximately 1.1 leW per customer to the utility winter peak and at least 0.2 leW per customer to the summer peak. In 1988, the'c' total peak demand per customer at the time ofboth FPL's winter and summer 

### pea.ks was 4.2 leW (FPL 1989). Hence, electric water heaters are responsible for approximately 25 percent of the utility winter peak demand and only about 5 percent of the utility sumrner peak demand. However, recent circumstances in Florida indicate that the winter peak may become more important 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 leW per customer in the winter and a minimum of 0.2 leW per customer in the summer. Solar systems perform necessary to nrsttest whether the winter and sununer peak day electrical prolile of each technology was statistically diffcrenI 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 prontes. Results show«1 that the peak day prontes 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 leChnology and a 

### base technology

- the conventional electric resistance waler heaters. Table 7 presents this calculation for both the IS-minute and 6O-minute coincident winter peak demands found in Tables 3 

### and 

### 5. (The winter peak day of December 26. 1983 is omitted from Table 7 because of the service cunailments 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 ami 

### 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 

### S. 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 bot 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 presents a similar analysis as Table 7 except that the diversified sununercoincident peak demands from Tables 4 and 6 are used to detennine 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 thaI the 6O.minute COincident peak demand for electric resiS lance waier heaters may be DocJ,.m N os**930 S-** **·** 930551·EG Florida Solar Energy Indus tries Assoc

.. Inc

. Exhibit

_ (WTG· l ) 

# """"'

., Page 1 0 01 12

as low as 0.25 kW per customer. one cannot claim more than a 0

.2 kW summer peak reduction potential for these technologies. Table 8 also indicates no significant summer peak reduction potential for heat pump waler heaters. However. it is important to note that this analysis considers the peak demand reduction due to water heating roly and does DOt consider any increase or reduction that may occur if the space conditioning load is affectedby the water beater operation. While most beat pwnp water heaters were located outside ofthe conditioned space ofa bouse. there were some that were located inside such that their operatioo would increase the heating load in the winter and decrease the cooling load in the summer. This analysis does not consider any effcct that this contribution may have 

### had on overall residential 

### peak demaod. 

### CONCLUSIONS Residential water heating offers a significant potential for Rorida electric utility load management because of the increasing level of residential

.elecDicity consumption and the ability of alternative water heating technologies to reduce coincident 

### peak demand. The conunon elecDic resistance water heater contributes approximately 1.1 kW per customer to the utility winter peak and at least 0.2 

### kW per CUSIOmcr 10 the 

### summer peak. In 

### 1988. the', total 

### peak demand per customer at the time of both FPL's winter and swnmer 

### peaks was 4.2 kW (FPL 

### J989)

. Heoce, electric water heaters are responsible for approximately 25 percent of the utility winter 

### peak demand ami 

### ooIy about 5 percent ofthe 

### utility summer 

### peale demand. However. recent circumstances in Florida indicate that the winter 

### peale. may become more important than the sununer 

### peak in determining the need for new generating capacity

. FCX1Unately. alternative water heating teChnologies offer a means to reduce winter and sununer peak demand wilhout requiring controlled utility intervention or even significantly reducing load factor. Solar hot water systems exhibit 

### the highest coincident peale demand reduction of 0

.7 kW per customer in the winter and a minimwn of 0.2 kW per customer in the summer. Solar systems perfonnDo<::ket Nos 930548-EG
- 930551-EG Florida Solar Energy Industries Assoc., Inc. Exhibit

_ (WTG-1) SchedJIe 1 Page 11 ot 12

Table 7. Diversified J 5-Minule and 60-Minule Winter Peak Demand Reduction (kWper Customer)



### Electric Resistance

Heat Pump Water Heater

Solar Hot 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 IS·Minute and 60-Minute Summer Peak DemondReduction (kWper Customer)



### Electric Resistance

Heat Pump Water Heater

Solar Hot Water System
Desuperheater Unit August 24, 1982 July 25, 1983 Swnmer Peak 5-6 p.m. 5-6 p.m. Average IS-minute Base IS-minute Base IS-minute Base

••• aM ••••• 

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

## ------ 60-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 of performance of 2.35 and have an arulUal 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. Desuperheater units 

### can also provide the 

### potential of reducing coincident summer peak demand by a w'"

__ . __ .:_ 

## .L._ winter, only those units 

### that are installed 00 

### beat pwnps are capable of reducing electrical demand. 

### This- winter peak 

### demand 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

.....""hl\! turic-,. lluIl 

### of an electric resistance water Doc:kel Nos 93Q548·EG
- 930551 · EG Florida Solar Energy Industries Aswc., Inc

. Exnibil _(WTG

. l j """"'. 1 Page 11 at 12

Tabu 7. Divf'rsijif'd 15-Miflwf' and 60-Minute Wintf'r**P~ak D~mand** **R~ductiofl** (kW per Cu.nomer) 

### January 13. 1983 February 7. 19S4 WinLer Peak 8-9 a.m. 7-8 

### a.m. Average 15-nUnute Base 15-minute Base IS-minute 

### Base Electric Resistance 

# ------- 

# ----- --------- 6O-minute 

### Base 6O-minute Base 6O-minute 

### Base 0

.61 0.61 0.61 Heat Pump Water Heater 

# --- 0.59 0.50 

### O

.SS 0.68 0.63 0.66 Solar Hot Water System 

# -- 0.83 0.74 0.79 0.20 0.25 0.23 Desuperheater Unit 

### 0.44 0.54 0.49

Tabu 

### 8.**Div~rsified J5** **Miflut~** and**60-Miflut~** Summer Peak DemtJnd Reduction (kWper Cuswmer) 

### August 24. 1982 5-6 

### IZ.m. 15-minute Base Electric Resistance 6O-minute Base 

### 0.13 Heat Pump Water Heater 

### 0.07 0.66 Solar HOl Water System 

# --- 0

.52 0.60 Desuperheater Unit 

# --- 0.54

with 

### an average coefficient of performance 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. Desuperheater units can also provide the JX)tenlial of reducing coincident summer peak demand by a 

### July 25. 1983 Sununer Peak 5-6 

### IZ.m

. Average IS-minute Base IS-minute Base



# --- 6O-minute Base**6~minute** Base 

## .o.Q3 0.05 0.06 0.07 0.32 0.49



# -- --

0.22 0.37 0.15 038 0

.16 

### 0.35

winter. 

### mly 

### those wtits lhat 

### are installed 00 beat pumps are capable of reducing electrical demand

. This winter peak demand reduction is determined 

### to be al leasl 0.2 kW per customer. Desuperheaters also have an average COP of 1.10 and an annual load 

## r actor of 54 percent. Heal pwnp water heaters have a system efficiency

........hlv lwi

...", IhM of an electric resistance**wa~r**

### heater and operate at a load factor of 52 percent. .The winter peak coincident demand is approximately half that of an electric water heater so its winter demand reduction potential is 0.6 kW per customer. UnConunately, 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 perfonned in 1982 to 1984. If 

### these problems have been resolved. heat 

### pump waters also offer significant potential for reducing electric utility winter peak demand. ACKNOWLEDGEMENTS 

### The sponsorship of the Florida Public Service Commission. the suppon ofthe Florida Solar Energy Centermanagement, and the cooperationof

### Florida's electric utilities are gratefully acknowledged. The 

### FSEC projectstaff

- Charles Beach, Omar

### Hancock, Ross McCluney and Tom Tiedemann

-- also deserve both credit and thanks for their considerable work

### on the project The 

### dedicated assistance of 

### consultants Don Patzseh 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 determine the 

### thennal perfonnance of 

### solar collectors." American Society of Heating,**Refrigera~g,** 

### and Air-Conditioning Engineers, Inc., Atlanta, Georgia. ASHRAE. 1980. ANSIIASHRAE Standord 90A· 1980, 

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

### Air· Conditioning Engineers, Inc., Atlanta. Ge<xgia. ' Block, D. L. 1983. "Solar domestic hot water system four-year perfonnance results."**ProCt!~tJjngs** of 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.**'-',",,-"t;lll~uS** ::;';V::"Hl-!:l.i

- 930551-EG Florida Solar Energy Industries Assoc.• Inc EXhibit_ (WTG-1) SChedule 1 Page 1201 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 Service Commission. 1985. Research Deparunent. "Statistics ofthe Florida Electric Utility Industry 1984," Tallahassee, Florida. Florida Public Service Commission. 1989. Research Depanment, "Statistics ofthe Florida Electric Utility Industry 1988," Tallahassee, Florida. Gladhart. P.M., and Wiehl, 

### I.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 Solar Energy 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 in 

### central Florida." 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, Pan 2, pp. 657-679, Atlanta, Georgia. heater and operate at a load factor of 52 percent.

.The winter peak. coincidem demand is approximately half that of in electric water heater so its winter demand reduction p:1tential is 

### 0.6 kW per customer
. Unfortunately. 

### in the sununer. the: coincidtm peak. demand reduction of heat 

### pwnp water heaters 

### is negligible. Heat pump water heaters also demonstrated reliability problems when 

## me study was performed 

### to 1982 to 1984

. 

### Ifthese problenu have been resolved. beat pump waters also offer significant po&ential for reducing electric utility winter peak. demand.**ACKNO~DGEMENTS** 

### The sponsorship of the Florida Public Service Commission, the support ofthe Florida Solar Energy Centermanagement, and lhe cooperationofFlorida's elecDic utilities are grl1etully acknowledged. The FSEC

### project stall'

- Charles Beach. 

### Omar Hancock. Ross McCluney and Tom Tiedemann

- 

### &Iso deserve 

### both credi'

### and thanics for their considerable 

### worIc at the 

### projecl The dedicated assistance ofcomultants Don PalZSCh and Timothy Stryker. as well 

### as numerous FSEC graduate assiswus. is also acknowledged. Finally. the participating homeowners deserve special gratitude for their cooperation. Wi!bout their assistance. the project would not have been possible. REFERENCES ASHRAE. 1977. ANSJlASHRAESIDNlDrd93-1977. "Methods of testing to detennine the thermal performance of solar collectors." American Society of Heating.**Refrigera~g.** and Air..cooditioning Engineers

. Inc.• Atlanta. Georgia. ASHRAE. '980. ANSJlASHRAE SIDNlDrd 9OA

### 1980. "Energy comervatioo in new building design.

.. American Society ofHeating, Refrigerating. and AirConditiooing Engineers. Inc.• Atlanta, Geagia

... Block. D. 

### L. 1983. "Solar domestic hoc: water syslem fOUT-year performance results."**'prou~dings** 

### o/tht /983

### AnnualMuting.**A~r;can** 

### SolarEMrgy**Soci~ty.** Vol. 6. pp. 235·240. Minneapolis. MN. Florida Governor's Energy Office. 1981. "Florida Energy Data: 1960-1981 ." Tallahassee. Aorida

. ....""""""**I~"'~ ~~o** **[;\,i** - 930551 ·EG Florida Solar Energy Industries Assoc" Inc El(hibit_(WTG-l ) 

# -, Page 12d 12

FPC

. 1974. FJorida Power Corporation. "Water Heater Test Data," Technical Information No. 37. St Petersburg. Florida

. FPL
. 1978

. Florida Power and Light Company. "1978 Residential ElecDic Waler Heater Study." Miami

. Florida. FPL. 1989. Florida Power and Light Company. "Petition to Determine Need 

### fer Electrical Power Plant: 1993-1996." Miami. florida. Florida Public Service Commission. 1985. Research Depatanent. "Statistics ofthe florida Electric Utility Indusl/)' 1984," TaUahass

... Florid>- Florida Public Service Commission. 1989. Research Department. "Statistics ofthe Florida Electric Utility Indusl/)' 1988," Tallahassee. Florid>- Gladhart. P.M
.. and Wiehl. 

### 1.5. 1986. "Morul",e<! hot water 

### use: A 

### seasonal analysis. " 

### Procudings

- )986 SlU11IMr Sludy on**En~rgy Effici~ncy**  jn 

### BUildings

. American COWlcil for an Energy-Efficient 

### Economy. pp. 1.90-1.103. Merrigan. T. 1983

. "Residential conservation demmstration: Domestic hot water. Final repon." FSEC-CR-90-83. Florida Solar Energy Center, Cape Canaveral. Flcrida. Merrigan, T.• and Wang

. M. 1981. "BnJ meler dynamic 

# "st. Final 

### "pen." FSEC-CR-81-29(RD). Florida Solar Energy Center, Cape Canaveral, florida. McCluney. R
. 1980. "Annual perfonnlDCe of 

### 20 solarwaterheaters incentral Florida." FSEC-RM-80- 4, Florida Solar Energy Cemer. Cape: Canaveral. Florida. Parker. D.S. 1989. "Hot Wa"r Study: PI1ase I Final report." FSEC.cR-295-89. Florida Solar Energy Center. Cape Canaveral. Florida. Periman. M.• and Mills. B. "Development of residential hOl waler use patterns." ASHRAE 

### Transact jons, Vol. 91, Part 2. pp. 657-679, Atlanta, Georgia.