[ ]     encloses units of preceding symbol

$_E,COG     value of electricity produced by cogenerator daily

$_E,COG,M     value of electricity produced by cogenerator monthly

$_E,COG,Y     value of electricity produced by cogenerator annually

$_GAS,COG     cost of gas consumed by cogenerator daily

$_GAS,WH     cost of gas consumed by water heater daily

$_SAV     net periodic savings of using cogeneration

$_SAV,DAT     net annual savings based on electric bill data

C_COG     power rating specific cost of cogeneration energy system

C_E     cost of electricity

C_E,DAT     cost of electricity based on electric bill data

CER     carbon emissions reduction per day

CER_Y     carbon emissions reduction per year

C_G     cost of natural gas

C_P,W     constant-pressure specific heat of water

E_COG     electrical energy output of cogenerator per day

     power rating of cogenerator

E_COG,Y     electrical energy output per year of cogenerator

f(x)     probability density function

h_C     mass specific enthalpy of cold water

h_H     mass specific enthalpy of hot water

h_T     mass specific enthalpy of mixed water

HV_GAS     volume specific heating value of natural gas

IRRI     internal rate of return on investment

LF     load factor of cogenerator

LF_MAX     maximum load factor of cogenerator

m_C     mass of cold water

m_H     mass of hot water

m_T     mass of mixed water

n     number of data points

Q     thermal energy input rate

Q_EXH     thermal energy output of cogenerator exhaust per day

Q_GAS,COG     natural gas energy input to cogenerator per day

Q_GAS,WH     natural gas energy input to water heater per day

Q_R     energy transmitted from hot side to cool side of heat exchanger per day

RT_MAX      maximum daily runtime of cogenerator

SPBP     simple pay back period of cogeneration system

SPBP_DAT     simple pay back period based on electric bill data

T_C     temperature of cold water

T_H     temperature of heated water

t_m     hours of runtime per month of the cogenerator

T_T     temperature of mixed water

t_period     time period of interest

t_y     hours of runtime per year of the cogenerator

V_GAS,COG     volume of natural gas used by cogenerator per day

V_GAS,WH     volume of natural gas used by water heater per day

V_NG     volume of natural gas consumed per day

V_W      hot water volume demand per day

V_W,Y     probable annual hot water capacity

x     daily hot water usage

x_C      mass fraction of water that is cold

x_H      mass fraction of water that is hot

x_o     particular daily hot water usage

Y     cogenerator life length in years

Z     normalized hot water demand per day

D$_GAS,Y     increase in gas expenditure on cogenerator over water heater per year

DT_W     water temperature increase

F     cumulative normal distribution in days per year

F(Z)     cumulative normal distribution in percent

F_o     number of days per year the hot water demand is less than or equal to x_o

h_E     gas-to-electric conversion efficiency of cogenerator

h_R     heat recovery efficiency

h_WH     water heater efficiency

m_LN     natural-log-based variance of data

r_W      density of water