2.7 Heat Source Group: Heat Source Characteristics

2.7 Primary Energy Consumption of Heat Source Group

The heat source group specification is input into Form 2-5 "Heat Source Input Sheet", wherein the heat source group i should be specified as follows, depending on presence or absence of the input in Form 2-5: (10) Rated Cooling Capacity and Form 2-5: (10) Rated Heating Capacity.

1) If values are entered only into Form 2-5: (10) Rated Cooling Capacity, and Form 2-5: (10) Rated Heating Capacity is blank,
the operation mode of the relevant heat source group i is assumed to be "cooling source". The name of heat source group i is the same as the character string entered in Form 2-5: (1) Heat Source Group Name, and its performance is the value entered in the "Cooling source" field of Form 2-5.

2) If Form 2-5: (10) Rated Cooling Capacity is blank and values are entered only into Form 2-5: (10) Rated Heating Capacity,
the operation mode of the heat source group i in question is assumed to be "heating source". The name of the heat source group i is the same as the character string entered in Form 2-5: (1) Heat Source Group Name, and its performance is the value entered in the "Heating source" field of Form 2-5.

3) If values are entered both for Form 2-5: (10) Rated Cooling Capacity and Form 2-5: (10) Rated Heating Capacity,
there are two generated heat source groups: one heat source group whose performance is the value entered in the "Cooling source" field of Form 2-5 and the operation mode is "cooling source", and another heat source group whose performance is the value entered in the "Heating source" field of Form 2-5 and the operation mode is "heating source". The name of these heat source groups should be the same as the string entered in Form 2-5: (1) Heat Source Group Name (i.e., there are two heat source groups with different operating modes).

In other words, in the above case 3), even if there is physically only one heat source device, the calculation is based on the assumption that there are separate cooling sources producing chilled water, and heating sources producing heating water.

Table 93. Input

Variable Name	Description	Unit	Reference
\(Q_{AC,ref,c,i,rated}\)	Rated cooling capacity of the heat source group	kW/device	Form 2-5: (10) Rated Cooling Capacity
\(Q_{AC,ref,h,i,rated}\)	Rated heating capacity of the heat source group	kW/device	Form 2-5: (10) Rated Heating Capacity

Table 94. Output

Variable Name	Description	Unit	References
\(CtrlMode_{AC,ref,i}\)	Operation mode of the heat source group	cooling/heating source	2.7.2, 2.7.4

a) If the rated cooling capacity is positive and there is no rated heating capacity (not entered),
( \(Q_{AC,ref,c,i,rated} > 0 \land Q_{AC,ref,h,i,rated} \mbox{ is nothing}\) )

\[ CtrlMode_{AC,ref,i} = \mbox{cooling source} \]

b) If there is no rated cooling capacity (not entered) and the rated heating capacity is positive,
( \(Q_{AC,ref,c,i,rated} \mbox{ is nothing} \land Q_{AC,ref,h,i,rated} > 0\) )

\[ CtrlMode_{AC,ref,i} = \mbox{heating source} \]

c) If the rated cooling capacity is positive and the rated heating capacity is positive,
( \(Q_{AC,ref,c,i,rated} > 0 \land Q_{AC,ref,h,i,rated} > 0\) )

Perform the calculation twice, assuming that one heat source group i has two virtual heat sources.

\[ CtrlMode_{AC,ref,i}= \begin{cases} \mbox{cooling source} & ,(calculation for 1st device) \\ \mbox{heating source} & ,(calculation for 2nd device) \end{cases} \]

d) In other cases,
It is an error.

2.7.1 Heat Loss in Thermal Storage Tank

Calculate the increase in heat load due to heat loss in thermal storage tank.

Table 95. Input

Variable Name	Description	Unit	Reference
\(Q_{AC,ref,ts,i,cap}\)	Thermal storage tank capacity of heat source group	MJ	Form 2-5: (5) Thermal Storage Capacity
\(StorageType_{i}\)	Operation mode of the thermal storage system of the heat source group i (water thermal storage (mixed type), water thermal storage (stratified type), ice thermal storage, additional storage, none)	-	Form 2-5: (4) Operation Mode

Table 96. Output

Variable Name	Description	Unit	References
\(Q_{AC,ref,ts,i,d}\)	Heat loss from thermal storage tank in the heat source group i on date \(d\)	MJ/d	2.7.2
\(ThrmlStrg_{AC,ref,ts,i}\)	Presence or Absence of thermal storage tank in the heat source group	Present ・ additional/Present ・thermal storage/None	2.7.2, 2.7.4.1, 2.7.15

First, the presence or absence of a thermal storage tank \(ThrmlStrg_{AC,ref,ts,i}\) is calculated by the following formula.

\[ ThrmlStrg_{AC,ref,ts,i} = \begin{cases} \mbox{none} & ,(StorageType_{i} = \mbox{none} \lor \mbox{not entered}) \\ \mbox{Present・additional} & ,(StorageType_{i} = \mbox{additional}) \\ \mbox{Present・thermal storage} & ,(\mbox{otherwise}) \end{cases} \]

The heat loss from the thermal storage tank of the heat source group i on date \(d\) \(Q_{AC,ref,ts,i,d}\) is calculated by the following formula.

And \(f_{ref,ts,loss}\) is the heat loss coefficient of the thermal storage tank.

a) If there is a thermal storage tank ( \(ThrmlStrg_{AC,ref,ts,i} = \mbox{Yes,heat storage}\) ),

\[ Q_{AC,ref,ts,i,d} = f_{ref,ts,loss} \times Q_{AC,ref,ts,i,cap} \]

b) If there is no thermal storage tank ( \(ThrmlStrg_{AC,ref,ts,i} = \mbox{No} \mbox{Yes, follow-up}\) ),

\[ Q_{AC,ref,ts,i,d} = 0 \]

2.7.2 Heat Source Load

The heat source load handled by each heat source group is calculated by totalizing the pump load of the secondary pump group to which the heat source group supplies chilled and hot water. And then add pump heat generation, and additionally, for systems with thermal storage tank, add heat loss of thermal storage tank. For a heat source device, similar to pumps, calculations are performed assuming that there are separate cooling source systems supplying chilled water and heating source systems supplying hot water.

Table 97. Input

Variable Name	Description	Unit	Reference
\(Q_{AC,ref,ts,i,cap}\)	Thermal storage tank capacity of heat source group	MJ	Form 2-5: (5) Thermal Storage Capacity
\(ThrmlStrg_{AC,ref,ts,i}\)	Presence or Absence of thermal storage tank in the heat source group	Present ・ additional/Present ・thermal storage/None	2.7.1
\(StorageType_{i}\)	Operation mode of the thermal storage system of the heat source group i (water thermal storage (mixed type), water thermal storage (stratified type), ice thermal storage, additional storage, none)	-	Form 2-5: (4) Operation Mode
\(Q_{AC,pump,j,d}\)	Secondary pump load of secondary pump group j on date \(d\)	MJ/d	2.6.1
\(Q_{AC,pump,heat,j,d}\)	Heat generation of pump in secondary pump group j on date \(d\)	MJ/d	2.6.9
\(Q_{AC,ref,ts,i,d}\)	Heat loss from thermal storage tank in the heat source group i on date \(d\)	MJ/d	2.7.1
\(CtrlMode_{AC,ref,i}\)	Operation mode of the heat source group	cooling/heating source	2.7

Table 98. Output

Variable Name	Description	Unit	References
\(Q_{AC,ref,i,d}\)	Heat load of heat source group i on date \(d\)	MJ/d	2.7.4.4, 2.7.7, 2.7.15

First, calculate \(Q_{AC,ref,base,i,d}\) defined by the following formula. \(\sum_ {j}\) represents that each heat source group is to be totalized for the secondary pump group j that supplies chilled or hot water.

a) For cooling source system ( \(CtrlMode_{AC,ref,i} = \mbox{cooling source}\)),

\[ Q_{AC,ref,base,i,d} = \sum_{j} \left( Q_{AC,pump,j,d} + Q_{AC,pump,heat,j,d} \right) \]

However, if \(Q_{AC,pump,j,d}=0\), then \(Q_{AC,pump,heat,j,d}=0\).

b) For heating source system ( \(CtrlMode_{AC,ref,i} = \mbox{heat source}\)),

\[ Q_{AC,ref,base,i,d} = \sum_{j} \left( Q_{AC,pump,j,d} - Q_{AC,pump,heat,j,d} \right) \]

However, it is only for the secondary pump group j satisfying \(Q_{AC,pump,j,d}>Q_{AC,pump,heat,j,d}\).

Next, the heat source load is calculated by taking into account the heat dissipation from the thermal storage tank. However, the heat load for heat storage should not exceed the total heat storage capacity multiplied by the total heat storage efficiency.

a) If the heat is stored ( \(ThrmlStrg_{AC,ref,ts,i} = \mbox{Present・thermal storage}\)) and \(Q_{AC,ref,base,i,d} \neq 0\)),

\[ Q_{AC,ref,i,d} = \min\!\left( Q_{AC,ref,base,i,d} + Q_{AC,ref,ts,i,d}, \ f_{ref,ts,eff} \times Q_{AC,ref,ts,i,cap} \right) \]

b) Other than above,

\[ Q_{AC,ref,i,d} = Q_{AC,ref,base,i,d} \]

where \(f_{ref,ts,eff}\) is the thermal storage tank efficiency, which is determined by the thermal storage tank type. The thermal storage tank type is determined by the operating mode of the thermal storage system \(StorageType_{i}\).

Thermal storage tank type	Thermal storage tank efficiency
Water thermal storage (mixed type)	0.8
Water thermal storage (stratified)	0.9
Ice thermal storage	1.0

2.7.3 Operating Hours of Heat Source Group

The operating hours of a heat source group are calculated as the total value of the operating hours of the secondary pump groups that convey the chilled and hot water generated by the relevant heat source group.

Table 99. Input

Variable Name	Description	Unit	Reference
\(O_{AC,pump,j,d,t}\)	Operating status of the secondary pump group j at date \(d\), time \(t\)	Boolean value	2.6.2

Table 100. Output

Variable Name	Description	Unit	References
\(T_{AC,ref,base,i,d}\)	Standard operating hours of the heat source group i on date \(d\)	h/d	2.7.6, 2.7.7, 2.7.15

The standard operating hours of the heat source group i on date \(d\) \(T_{AC,ref,base,i,d}\) is calculated by totalizing the operating status of the heat source group i at each time on each day, assuming that the heat source group i is operating if at least one secondary pump group for conveying chilled and hot water generated by the heat source group i is operating at each time point. The subscript j indicates that the total value is obtained for the secondary pump group to which each heat source group is connected.

First, obtain the operating status of the heat source device group i at date \(d\), time \(t\)\(O_{AC,ref,i,d,t}\). For a secondary pump group to which the heat source group i supplies chilled and hot water, if \(O_{AC,pump,i,d,t}\) is True for any one secondary pump group, then \(O_{AC,ref,i,d,t}\) is True; if \(O_{AC,pump,i,d,t}\) is False for all secondary pump groups, then \(O_{AC,ref,i,d,t}\) is False.

The standard operating hours of the heat source group i $T_{AC,ref,base,i,d} $ is calculated by the following formula.

\[ T_{AC,ref,base,i,d} = \text{count}\!\left\{ \; t \,\mid\, O_{AC,ref,i,d,t} = \text{True} \right\} \]

2.7.4 Temperature of Heat Source Water, etc.

Calculate the temperature of the heat source water, etc. (e.g., cooling water temperature for water-cooled systems, outside air temperature for air-cooled systems) to estimate the performance of the heat source device.

Table 101. Input

Variable Name	Description	Unit	Reference
\(RefType_{i,j}\)	Heat source device model of the heat source device j belonging to the heat source group	-	Form 2-5: (6) Heat Source Device Model
\(CtrlMode_{AC,ref,i}\)	Operation mode of the heat source group	cooling/heating source	2.7
\(\theta_{AC,oa,i,j,d}\)	Average outside air temperature during operating time zone of the heat source device j belonging to the heat source group i on date \(d\)	℃	2.7.4.1
\(\theta_{AC,wb,i,j,d}\)	Wet-bulb temperature of the heat source device j belonging to the heat source group i on date \(d\)	℃	2.7.4.2
\(\theta_{AC,cw,i,j,d}\)	Cooling water temperature of the heat source device j belonging to the heat source group i on date \(d\)	℃	2.7.4.3
\(\theta_{AC,w,c,i,j,d}\)	Daily average heat source water temperature from the geothermal heat exchanger during cooling operation of the heat source device j belonging to the heat source group i on date \(d\)	℃	2.7.4.4
\(\theta_{AC,w,h,i,j,d}\)	Daily average heat source water temperature from the geothermal heat exchanger during heating operation of the heat source device j belonging to the heat source group i on date \(d\)	℃	2.7.4.4

Table 102. Output

Variable Name	Description	Unit	Reference
\(\theta_{AC,ref,base,i,j,d}\)	Temperature of the heat source water, etc. of the heat source device j belonging to the heat source group i on date \(d\)	℃	2.7.8, 2.7.11

The temperature of the heat source water, etc. of the heat source device j belonging to the heat source group i on date \(d\) \(\theta_{AC,ref,base,i,j,d}\) is calculated by the following formula.

The cooling mode of the heat source device j belonging to the heat source group i \(CoolingType_{i,j}\) is specified for each heat source device model \(RefType_{i,j}\). However, for geothermal systems, heat source device models that fall under geothermal types 1 through 5 should be considered as "closed loop", and heat source device models that fall under geothermal types A through G should be considered as "open loop".

a) If \(CoolingType_{i,j}\) is water-cooled,

\[ \theta_{AC,ref,base,i,j,d} = \begin{cases} \theta_{AC,cw,i,j,d} & ,(CtrlMode_{AC,ref,i} = \mbox{cooling source}) \\ 15.5 & ,(CtrlMode_{AC,ref,i} = \mbox{heating source}) \end{cases} \]

b) If \(CoolingType_{i,j}\) is air-cooled,

\[ \theta_{AC,ref,base,i,j,d} = \begin{cases} \theta_{AC,oa,i,j,d} & ,(CtrlMode_{AC,ref,i} = \mbox{cooling source}) \\ \theta_{AC,wb,i,j,d} & ,(CtrlMode_{AC,ref,i} = \mbox{heating source}) \end{cases} \]

c) If \(CoolingType_{i,j}\) is geothermal (closed loop),

\[ \theta_{AC,ref,base,i,j,d} = \begin{cases} \theta_{AC,wc,c,i,j,d} & ,(CtrlMode_{AC,ref,i} = \mbox{cooling source}) \\ \theta_{AC,wc,h,i,j,d} & ,(CtrlMode_{AC,ref,i} = \mbox{heating source}) \end{cases} \]

d) If \(CoolingType_{i,j}\) is geothermal (open loop),

\[ \theta_{AC,ref,base,i,j,d} = \begin{cases} \theta_{AC,wo,c,i,j,d} & ,(CtrlMode_{AC,ref,i} = \mbox{cooling source}) \\ \theta_{AC,wo,h,i,j,d} & ,(CtrlMode_{AC,ref,i} = \mbox{heating source}) \end{cases} \]

e) Other than the above,

\[ \theta_{AC,ref,base,i,j,d} = \theta_{AC,oa,i,j,d} \]

If the monthly heat source water temperature is evaluated under the optional evaluation system, it should be possible to read in the optional heat source water temperature and perform the calculation. In this case, the heat source water temperature \(\theta_{AC,ref,base,i,j,d}\) is determined according to what month the date \(d\) belongs to. The number of days in each month should be as follows.

Table 103. Number of days per month

January	February	March	April	May	June	July	August	September	October	November	December
31	28	31	30	31	30	31	31	30	31	30	31

2.7.4.1 Daily Average Outside Air Temperature

Calculate the daily average outside air temperature for calculating the energy consumption of heat source device.

Table 104. Input

Variable Name	Description	Unit	Reference
\(\theta_{AC,oa,d}\)	Daily average outside air temperature on date \(d\)	℃	2.2.3
\(CtrlMode_{AC,ref,i}\)	Operation mode of the heat source group	cooling/heating source	2.7
\(ThrmlStrg_{AC,ref,ts,i}\)	Presence or Absence of thermal storage tank in the heat source group	Present/Absent	2.7.1
\(ClimateZone\)	Climate zone of the location of the building subject to evaluation	-	Form 0: (5) Regional Categories in Buildling Energy Codes

Table 105. Output

Variable Name	Description	Unit	Reference
\(\theta_{AC,oa,i,j,d}\)	Average outside air temperature during operating time zone of the heat source device j belonging to the heat source group i on date \(d\)	℃	2.7.4.2, 2.7.4

The daily average outside air temperature is calculated by the following formula. However, if the heat source group includes thermal storage tank, the heat source device is assumed to operate at night, and the daily average outside air temperature minus 5°C is used as the average outside air temperature during operating time zone.

\[ \theta_{AC,oa,i,j,d} = \begin{cases} {\mathrm{F}}(\theta_{AC,oa,d}) & ,(ThrmlStrg_{AC,ref,ts,i} = \mbox{Present}) \\ {\mathrm{F}}(\theta_{AC,oa,d} - 5) & ,(ThrmlStrg_{AC,ref,ts,i} = \mbox{Absent}) \end{cases} \]

where the function \({\mathrm{F}}(T_{o})\) is defined by the following formula.

\[ {\mathrm{F}}(T_{o}) = {\mathrm{floor}}(T_{o}/5) \times 5 + 2.5 \]

However, the following upper and lower limits should be set for \(\theta_{AC,oa,d}\) by region and cooling/heating source. If the upper limit is exceeded, the value should be the upper limit; if the value is below the lower limit, the value should be the lower limit.

Table 106. Lower and upper limits of outside air temperature

Climate zone \(ClimateZone\)	Lower limit of heating source	Upper limit of heating source	Lower limit of cooling source	Upper limit of cooling source
Region 1	-15	15	0	30
Region 2	-15	15	0	30
Region 3	-10	20	5	35
Region 4	-10	20	5	35
Region 5	-10	20	5	35
Region 6	-10	20	5	35
Region 7	-10	20	5	35
Region 8	5	35	5	35

2.7.4.2 Wet-Bulb Temperature

Calculate wet-bulb temperature from the average outside air temperature during operation.

Table 107. Input

Variable Name	Description	Unit	Reference
\(ClimateZone\)	Climate zone of the location of the building subject to evaluation	-	Form 0: (5) Regional Categories in Buildling Energy Codes
\(\theta_{AC,oa,i,j,d}\)	Average outside air temperature during operating time zone of the heat source device j belonging to the heat source group i on date \(d\)	℃	2.7.4.1

Table 108. Output

Variable Name	Description	Unit	Reference
\(\theta_{AC,wb,i,j,d}\)	Wet-bulb temperature of the heat source device j belonging to the heat source group i on date \(d\)	℃	2.7.4, 2.7.4.3

\[ \theta_{AC,wb,i,j,d} = a_{wb} \times \theta_{AC,oa,i,j,d} + b_{wb} \]

\(a_{wb},b_{wb}\) is the wet-bulb temperature conversion coefficient and the values are shown in the following table.

Table 109. Wet-bulb temperature conversion coefficient table

Climate zone \(ClimateZone\)	\(a_{wb}\)	\(b_{wb}\)
1,2	0.8921	-1.0759
3,4,5,6,7	0.9034	-1.4545
8	1.0372	-3.9758

2.7.4.3 Cooling Water Temperature

Calculate the cooling water temperature from the wet-bulb temperature.

Table 110. Input

Variable Name	Description	Unit	Reference
\(\theta_{AC,wb,i,j,d}\)	Wet-bulb temperature of the heat source device j belonging to the heat source group i on date \(d\)	℃	2.7.4.2

Table 111. Output

Variable Name	Description	Unit	Reference
\(\theta_{AC,cw,i,j,d}\)	Cooling water temperature of the heat source device j belonging to the heat source group i on date \(d\)	℃	2.7.4

Convert wet-bulb temperature to cooling water temperature using the following formula. \(a_{cw}\) is the cooling water temperature conversion coefficient and is set to +3.0.

\[ \theta_{AC,cw,i,j,d} = \theta_{AC,wb,i,j,d} + a_{cw} \]

2.7.4.4 Heat Source Water Temperature from Geothermal Heat Exchanger (closed loop)

Calculate the cooling water return temperature from the ground based on the type of geothermal heat exchanger.

Table 112. Input

Variable Name	Description	Unit	Reference
\(GroundHEType_{i,j}\)	Type of geothermal heat exchanger (1-5) of the heat source device j belonging to the heat source group	-	Form 2-5: (6) Heat Source Device Model
\(Q_{AC,ref,i,d}\)	Heat load of heat source group i on date \(d\)	MJ/d	2.7.2
\(\theta_{AC,oa,d}\)	Daily average outside air temperature on date \(d\)	℃	2.2.3
\(\theta_{AC,oa,ave}\)	Annual average outside air temperature	℃	2.2.3
\(\theta_{AC,oa,c,ave}\)	Average outside air temperature during cooling	℃	2.2.3
\(\theta_{AC,oa,h,ave}\)	Average outside air temperature during heating	℃	2.2.3

Table 113. Intermediate Variable

Variable Name	Description	Unit
\(\theta'_{wc,h,i,d}\)	Difference between the period average heat source water temperature during the heating season and the annual average outside air temperature	℃
\(\theta'_{wc,c,i,d}\)	Difference between the period average heat source water temperature during the cooling season and the annual average outside air temperature	℃
\(k_{h,i,d}\)	Coefficient	-
\(k_{c,i,d}\)	Coefficient	-
\(R_{Q,i,d}\)	Ratio of the annual maximum daily integrated heating load to the annual maximum daily integrated cooling load	-

Table 114. Output

Variable Name	Description	Unit	Reference
\(\theta_{AC,wc,c,i,j,d}\)	Daily average heat source water temperature from the geothermal heat exchanger during cooling operation of the heat source device j belonging to the heat source group i on date \(d\)	℃	2.7.4
\(\theta_{AC,wc,h,i,j,d}\)	Daily average heat source water temperature from the geothermal heat exchanger during heating operation of the heat source device j belonging to the heat source group i on date \(d\)	℃	2.7.4

Calculate the cooling water return temperature from the ground \(\theta_{AC,w,c,i,d}\) and \(\theta_{AC,w,h,i,d}\) based on the type of geothermal heat exchanger. Here, the coefficients \(a_{h,i,j},b_{h,i,j},c_{h,i,j},d_{h,i,j},a_{c,i,j},b_{c,i,j},c_{c,i,j},d_{c,i,j}\) are determined by the type (1-5) of geothermal heat exchanger of the heat source device j in the heat source group i according to the table below.

\[ \theta_{AC,wc,h,i,j,d} = k_{h,i,j,d} \times (\theta_{AC,oa,d} - \theta_{AC,oa,h,ave}) + \left(\theta_{AC,oa,ave} + \theta'_{wc,h,i,j,d} \right) \]

\[ \theta_{AC,wc,c,i,j,d} = k_{c,i,j,d} \times (\theta_{AC,oa,d} - \theta_{AC,oa,c,ave}) + \left(\theta_{AC,oa,ave} + \theta'_{wc,c,i,j,d} \right) \]

\[ \theta'_{wc,h,i,j,d} = a_{h,i,j} \times R_{Q,i,d} + b_{h,i,j} \]

\[ \theta'_{wc,c,i,j,d} = a_{c,i,j} \times R_{Q,i,d} + b_{c,i,j} \]

\[ k_{h,i,j,d} = c_{h,i,j} \times R_{Q,i,j,d} + d_{h,i,j} \]

\[ k_{c,i,j,d} = c_{c,i,j} \times R_{Q,i,j,d} + d_{c,i,j} \]

Table 115. Coefficient \(a_{h,i,j},b_{h,i,j},c_{h,i,j},d_{h,i,j},a_{c,i,j},b_{c,i,j},c_{c,i,j},d_{c,i,j}\)

Type	1	2	3	4	5
\(a_{h,i,j}\)	8.0278	13.0253	16.7424	19.3145	21.2833
\(b_{h,i,j}\)	-1.1462	-1.8689	-2.4651	-3.091	-3.8325
\(c_{h,i,j}\)	-0.1128	-0.1846	-0.2643	-0.2926	-0.3474
\(d_{h,i,j}\)	0.1256	0.2023	0.2623	0.3085	0.3629
\(a_{c,i,j}\)	8.0633	12.6226	16.1703	19.6565	21.8702
\(b_{c,i,j}\)	2.9083	4.7711	6.3128	7.8071	9.148
\(c_{c,i,j}\)	0.0613	0.0568	0.1027	0.1984	0.249
\(d_{c,i,j}\)	0.2178	0.3509	0.4697	0.5903	0.7154

\(\theta_{AC,oa,ave}\) is the annual average outside air temperature [°C], \(\theta_{AC,oa,c,ave}\) is the average outside air temperature during the cooling season [°C], and \(\theta_{AC,oa,h,ave}\) is the average outside air temperature during the heating season [°C]. These temperatures are determined as follows according to climate zones.

Regional Category	1	2	3	4	5	6	7	8
\(\theta_{AC,oa,ave}\)	5.8	7.5	10.2	11.6	13.3	15.7	17.4	22.7
\(\theta_{AC,oa,c,ave}\)	16.8	17	18.9	19.6	20.5	22.4	22.1	24.6
\(\theta_{AC,oa,h,ave}\)	-3	-0.8	0	1.1	3.6	6	9.3	17.5

\(R_{Q,i,j,d}\) is calculated by the following formula.

\[ R_{Q,i,j,d} = \frac{ \left| Q_{AC,ref,c,i,d}^{MAX} \right| - \left| Q_{AC,ref,h,i,d}^{MAX} \right| }{ \left| Q_{AC,ref,c,i,d}^{MAX} \right| + \left| Q_{AC,ref,h,i,d}^{MAX} \right| } \]

where \(Q_{AC,ref,h,i,d}^{MAX}\) is the annual maximum daily integrated heating generation of the heat source group i and \(Q_{AC,ref,c,i,d}^{MAX}\) is the annual maximum daily integrated cooling load of the heat source group i. Specifically, these are calculated as follows.

1) If the heat source group i is a "cooling source" and there exists a heat source group k that is a "heating source" with the same heat source group name,

\[ Q_{AC,ref,c,i,d}^{MAX} = \max_{d}(Q_{AC,ref,i,d}) \]

\[ Q_{AC,ref,h,i,d}^{MAX} = \max_{d}(Q_{AC,ref,k,d}) \]

2) If the heat source group i is a "cooling source" and there exists no heat source group that is a "heating source" with the same heat source group name,

\[ Q_{AC,ref,c,i,d}^{MAX} = \max_{d}(Q_{AC,ref,i,d}) \]

\[ Q_{AC,ref,h,i,d}^{MAX} = \max_{d}(Q_{AC,ref,i,d}) \]

3) If the heat source group i is a "heating source" and there exists a heat source group k that is a "cooling source" with the same heat source group name,

\[ Q_{AC,ref,c,i,d}^{MAX} = \max_{d}(Q_{AC,ref,k,d}) \]

\[ Q_{AC,ref,h,i,d}^{MAX} = \max_{d}(Q_{AC,ref,i,d}) \]

4) If the heat source group i is a "heating source" and there exists no heat source group that is a "cooling source" with the same heat source group name,

\[ Q_{AC,ref,c,i,d}^{MAX} = \max_{d}(Q_{AC,ref,i,d}) \]

\[ Q_{AC,ref,h,i,d}^{MAX} = \max_{d}(Q_{AC,ref,i,d}) \]

2.7.4.5 Heat Source Water Temperature from Geothermal Heat Exchanger (Open Loop)

Calculate the cooling water return temperature from the ground based on the type of geothermal heat exchanger (open loop).

Table 116. Input

Variable Name	Description	Unit	Reference
\(ClimateZone\)	Climate zone of the location of the building subject to evaluation	-	Form 0: (5) Regional Categories in Buildling Energy Codes
\(GroundHEType_{i,j}\)	Type of geothermal heat exchanger (A-F) of the heat source device j belonging to the heat source group	-	Form 2-5: (6) Heat Source Device Model

Table 117. Intermediate Variable

Variable Name	Description	Unit
\(\theta'_{wo,c}\)	Well water tank temperature correction value to be applied during cooling operation for Types C and F (types that returns heat source water to the well water tank after heat exchange)	℃
\(\theta'_{wo,h}\)	Well tank temperature correction value to be applied during heating operation for Types C and F (type that returns heat source water to the well tank after heat exchange)	℃
\(\theta'_{hex,c}\)	Heat exchanger temperature correction value to be applied during cooling operation for types D, E, and F (types in which heat is exchanged by the heat exchanger)	℃
\(\theta'_{hex,h}\)	Heat exchanger temperature correction value to be applied during heating operation for types D, E, and F (types in which heat is exchanged by the heat exchanger)	℃
\(\theta_{AC,wo,ave}\)	Average annual outside air temperatures applied to the calculation of well pumping temperature for geothermal heat exchangers (open loop)	℃
\(\theta_{wo,m}\)	Monthly well pumping temperature	℃
\(\theta'_{AC,wo,m}\)	Monthly groundwater temperature correction value	℃

Table 118. Output

Variable Name	Description	Unit	Reference
\(\theta_{AC,wo,c,i,j,m}\)	Daily average temperature of the heat source water from the geothermal heat exchanger (open loop) during cooling operation of the heat source device j belonging to the heat source group i in month	℃	2.7.4
\(\theta_{AC,wo,h,i,j,m}\)	Daily average temperature of the heat source water from the geothermal heat exchanger (open loop) during heating operation of the heat source device j belonging to the heat source group i in month	℃	2.7.4

The monthly cooling water return temperature from the ground \(\theta_{AC,wo,c,i,j,m}\) and \(\theta_{AC,wo,h,i,j,m}\) are calculated by the following formula based on the type of geothermal heat exchanger (A to F). Note that Types A and B and Types D and E have the same cooling water return temperature.

\[ \theta_{AC,wo,c,i,j,d} = \theta_{wo,m} + \theta'_{wo,c} + \theta'_{hex,c} \]

\[ \theta_{AC,wo,h,i,j,d} = \theta_{wo,m} + \theta'_{wo,h} + \theta'_{hex,h} \]

Here, the well water tank temperature correction value \(\theta'_{wo,c}\), \(\theta'_ {wo,h}\) and the heat exchanger temperature correction value \(\theta'_{hex,c}\), \(\theta'_ {hex,h}\) should be determined by the table below according to the type of geothermal heat exchanger (A to F) of the heat source device j belonging to the heat source group i.

Table 119. Temperature correction value \(\theta'_{wo,c},\theta'_{wo,h},\theta'_{hex,c},\theta'_{hex,h}\)

Type	A	B	C	D	E	F
\(\theta'_{wo,c}\)	0	0	6	0	0	6
\(\theta'_{wo,h}\)	0	0	-4	0	0	-4
\(\theta'_{hex,c}\)	0	0	0	3	3	3
\(\theta'_{hex,h}\)	0	0	0	-2	-2	-2

The monthly well pumping temperature \(\theta_{wo,m}\) is calculated by the following formula. Here, the annual average outside air temperature \(\theta_{AC,wo,ave}\) and the monthly groundwater temperature correction value \(\theta'_{AC,wo,m}\) are determined by the climate zone as follows.

\[ \theta_{wo,m} = \theta_{AC,wo,ave} + \theta'_{AC,wo,m} \]

Table 120. Annual average outside air temperature \(\theta_{AC,wo,ave}\), Monthly groundwater temperature correction \(\theta'_{AC,wo,m}\)

Regional Category		1	2	3	4	5	6	7	8
\(\theta_{AC,wo,ave}\)		5.8	7.5	10.2	11.6	13.3	15.7	17.4	22.7
\(\theta'_{AC,wo,m}\)	January	4	1.9	1.3	0.6	0.1	1.5	1.7	0
	February	3.9	1.8	1	0.2	-0.3	1.3	1.4	0
	March	4.2	2	1.4	0.8	0.4	1.7	1.7	0
	April	4.6	2.3	1.9	1.5	1.2	2	2	0
	May	4.9	2.5	2.3	2.1	1.9	2.4	2.3	0
	June	5.1	2.6	2.5	2.5	2	2.7	2.6	0
	July	5.2	2.6	2.8	2.9	2.1	3.1	3	0
	August	5.4	2.7	3	3.3	2.2	3.4	3.3	0
	September	5	2.5	2.6	2.7	1.8	2.9	3	0
	October	4.7	2.3	2.2	2.1	1.4	2.4	2.6	0
	November	4.3	2.1	1.8	1.5	1	1.9	2.3	0
	December	4.2	2	1.5	1.1	0.6	1.7	2	0

2.7.5 Rated Capacity of Heat Source Group

Calculate the rated capacity of a heat source group.

Table 121. Input

Variable Name	Description	Unit	Reference
\(N_{AC,ref,i,j}\)	Number of the heat source devices j belonging to the heat source group	Number of devices	Form 2-5: (8) Number of Devices
\(q_{AC,ref,i,j,rated}\)	Rated capacity of the heat source device j belonging to the heat source group	kW/device	Form 2-5: (10) Rated Cooling/Heating Capacity

Table 122. Output

Variable Name	Description	Unit	Reference
\(q_{AC,ref,i,rated}\)	Rated capacity of the heat source group	kW	2.7.6

The rated capacity of the heat source group i \(q_{AC,ref,i,rated}\) is the sum of the rated capacity of the heat source devices j belonging to the heat source group i.

\[ q_{AC,ref,i,rated} = \sum_{j=1} \left( q_{AC,ref,i,j,rated} \times N_{AC,ref,i,j} \right) \]

2.7.6 Corrected Rated Capacity Taking Into Account Heat Release From Thermal Storage Tank

Calculate the corrected rated capacity taking into account the heat dissipation from the thermal storage tank.

Table 123. Input

Variable Name	Description	Unit	Reference
\(StorageType_{i}\)	Operation mode of the thermal storage system of the heat source group i (water thermal storage (mixed type), water thermal storage (stratified type), ice thermal storage, additional storage, none)	-	Form 2-5: (4) Thermal Storage System Operation Mode
\(RefType_{i,j}\)	Heat source device model of the heat source device j belonging to the heat source group	-	Form 2-5: (6) Heat Source Device Model
\(N_{AC,ref,i,j}\)	Number of the heat source devices j belonging to the heat source group	Number of devices	Form 2-5: (8) Number of Devices
\(q_{AC,ref,i,j,rated}\)	Rated capacity of the heat source device j belonging to the heat source group	kW/device	Form 2-5: (10) Rated Cooling/Heating Capacity
\(q_{AC,ref,i,rated}\)	Rated capacity of the heat source group	kW	2.7.5
\(T_{AC,ref,base,i,d}\)	Standard operating hours of the heat source group i on date \(d\)	h/d	2.7.3

Table 124. Output

Variable Name	Description	Unit	Reference
\(q'_{AC,ref,i,j,rated}\)	Corrected rated capacity of the heat source device j belonging to the heat source group	kW	2.7.8
\(q'_{AC,ref,i,rated}\)	Corrected rated capacity of the heat source group	kW	2.7.7, 2.7.9, 2.7.12

First, if the heat source group includes a thermal storage tank and the first heat source device to operate in additional operation is a "heat exchanger", the apparent heat source handling capacity (corrected rated capacity) is calculated assuming the additional operation hours is 8 hours. The \(\max_{d}(T_{AC,ref,base,i,d})\) in the formula means that for each day’s operating hours, the maximum operating hours of the day is used.

a) If \(StorageType_{i} = \mbox{additional}\) and \(RefType_{i,1} = \mbox{heat exchanger}\),

\[ q'_{AC,ref,i,j,rated} = \begin{cases} q_{AC,ref,i,j,rated} \times N_{AC,ref,i,j} \times \frac{8}{\max_{d}(T_{AC,ref,base,i,d})} & ,(j = 1) \\ q_{AC,ref,i,j,rated} \times N_{AC,ref,i,j} & ,(otherwise) \end{cases} \]

\[ q'_{Ac,ref,i,rated} = q_{Ac,ref,i,rated} + \left(q'_{AC,ref,i,1,rated} - q_{AC,ref,i,1,rated} \right) \]

b) In cases other than a),

\[ q'_{AC,ref,i,j,rated} = q_{AC,ref,i,j,rated} \times N_{AC,ref,i,j} \]

\[ q'_{Ac,ref,i,rated} = q_{Ac,ref,i,rated} \]

2.7.7 Load Factor Ranges for Heat Source Group

Calculate the load factor of a heat source group.

Table 125. Input

Variable Name	Description	Unit	Reference
\(ThrmlStrg_{AC,ref,ts,i}\)	Presence or Absence of thermal storage tank in the heat source group	Present ・ additional/Present ・thermal storage/None	2.7.1
\(Q_{AC,ref,i,d}\)	Heat load of heat source group i on date \(d\)	MJ/d	2.7.2
\(T_{AC,ref,base,i,d}\)	Standard operating hours of the heat source group i on date \(d\)	h/d	2.7.3
\(q'_{AC,ref,i,rated}\)	Corrected rated capacity of the heat source group	kW	2.7.6

Table 126. Output

Variable Name	Description	Unit	Reference
\(L_{AC,ref,i,d}\)	Load factor range for the heat source group i on date \(d\)	-	2.7.9, 2.7.12, 2.7.16

The load factor range for the heat source group i on date \(d\) \(L_{AC,ref,i,d}\) is calculated by the following formula. The load factor range of a heat source group that has a thermal storage tank and perform thermal storage operation should always be 1.0.

a) If \(ThrmlStrg_{AC,ref,ts,i}\) is \(\mbox{Present ・thermal storage}\),

\[ L_{AC,ref,i,d} = 1.0 \]

b) Other than the above,

\[ L_{AC,ref,i,d} = \begin{cases} \mathrm{F}\left( \dfrac{Q_{AC,ref,i,d}}{q'_{AC,ref,i,rated}} \times \dfrac{1000}{3600} \times \dfrac{1}{T_{AC,ref,base,i,d}} \right) & ,(T_{AC,ref,base,i,d} \neq 0) \\ 0 & ,(T_{AC,ref,base,i,d} = 0) \end{cases} \]

The function F is defined in the same way as for an air handling unit group and a secondary pump group as follows.

\[ \mathrm{F}(L) = \begin{cases} \dfrac{\mathrm{floor}(L \times 10)}{10} + 0.05 & ,(0 < L \leq 1.0) \\ 1.2 & ,(1.0 < L) \\ 0 & ,(L \leq 0) \end{cases} \]

2.7.8 Maximum Capacity

Calculate the maximum capacity of a heat source device using the maximum capacity characteristics.

Table 127. Input

Variable Name	Description	Unit	Reference
\(q'_{AC,ref,i,j,rated}\)	Corrected rated capacity of the heat source device j belonging to the heat source group	kW	2.7.6
\(\theta_{AC,ref,base,i,j,d}\)	Temperature of the heat source water, etc. of the heat source device j belonging to the heat source group i on date \(d\)	℃	2.7.4
\(a_{ref,q,i,j},b_{ref,q,i,j},c_{ref,q,i,j},d_{ref,q,i,j},e_{ref,q,i,j}\)	Coefficient of maximum capacity characteristic of the heat source device j belonging to the heat source group	-	A.4
\(\theta_{ref,q,i,j,min},\theta_{ref,q,i,j,max}\)	Minimum and maximum temperatures of maximum capacity characteristic of the heat source device j belonging to the heat source group	℃	A.4

Table 128. Output

Variable Name	Description	Unit	Reference
\(q_{AC,ref,i,j,max,d}\)	Maximum capacity of the heat source device j belonging to the heat source group i on date \(d\)	kW	2.7.9, 2.7.15, 2.7.12

The maximum capacity of the heat source device j belonging to the heat source group i on date \(d\) \(q_{AC,ref,i,j,max,d}\) is calculated by the following formula.

\[ q_{AC,ref,i,j,max,d} = q'_{AC,ref,i,j,rated} \times \mathrm{F_{ref,q,i,j}}(\theta_{i,j,d}) \]

where the function \({\mathrm{F_{ref,q,i,j}}}\) is defined by the following formula.

\[ \mathrm{F_{ref,q,i,j}}(\theta_{i,j,d}) = a_{ref,q,i,j} \times \theta_{i,j,d}^{4} + b_{ref,q,i,j} \times \theta_{i,j,d}^{3} + c_{ref,q,i,j} \times \theta_{i,j,d}^{2} + d_{ref,q,i,j} \times \theta_{i,j,d} + e_{ref,q,i,j} \]

\[ \theta_{i,j,d} = \begin{cases} \theta_{ref,q,i,j,min} & ,(\theta_{AC,ref,base,i,j,d} < \theta_{ref,q,i,j,min}) \\ \theta_{AC,ref,base,i,j,d} & ,(\theta_{ref,q,i,j,min} \leq \theta_{AC,ref,base,i,j,d} \leq \theta_{ref,q,i,j,max}) \\ \theta_{ref,q,i,j,max} & ,(\theta_{ref,q,i,j,max} < \theta_{AC,ref,base,i,j,d}) \end{cases} \]