Method for Calculating Primary Energy Consumption under Japan’s Building Energy Standards (Non-residential Buildings)

The air conditioning equipment to be included in the calculations is as follows.

The following air conditioning equipment is not included in the calculation as air conditioning equipment.

Here, this calculation method determines the room heat load (total heat load) required to maintain the set temperature and humidity. While it estimates the humidification (or dehumidification) load itself, the calculation assumes that the total heat, including the load for humidification and dehumidification, is processed by the heat source device. Therefore, it does not provide a rigorous evaluation. To accurately assess the performance of a humidification system, it is necessary to separate sensible heat and latent heat and perform more precise calculations. However, this remains a topic for future consideration.

Figure 2.1.3.1 shows the calculation flow of energy consumption for air conditioning equipment. The calculation can be divided into two parts: a) room load calculation part, and b) energy consumption calculation part. The energy consumption of the air handling unit group, secondary pump group, and heat source group is calculated as a function of the loads handled by these units (assumed to be the air conditioning load, secondary pump load, and heat source load, respectively), and these loads can be obtained from the room load of each room. Figure 2.1.3.2 shows the process of calculating the load of each equipment from the room load. First, calculate the room load for each room. Next, calculate the total room load for each air handling unit group for each target room. And then calculate the air conditioning load for each air handling unit group by adding the outside air load to above room load. Similarly for the secondary pump group, calculate the total air conditioning load of the air handling unit group for which the relevant secondary pump group conveys chilled/hot water. And then, calculate the secondary pump load by adding the heat generation of the air conditioner fan to above air conditioning load. For a heat source group, calculate the total secondary pump load of the secondary pump group for which the relevant heat source group supplies heat. And then, calculate the heat source load by adding the heat generation of the secondary pump to above secondary pump load.

Although the heat generation by primary pumps should be included in the heat source load, the heat generation by primary pumps is not included in this calculation because it would require repetitive calculations, which would complicate the logic.

For weather data, use the Expanded AMeDAS Weather Data, reference year 1995 edition (based on 1980-1995 data). This weather data can be purchased from the website of Meteorological Data System Co., Ltd. ( here ).

The Buildling Energy Codes define climate zones (region 1-8), and specify the category of each city, ward, town, and village.

For each climate zone, the weather data to be used are specified in the table below. For example, for the region 1, the weather data file for "Hokkaido/Kitami" is used. The calculation method uses the outside air temperature, absolute humidity, direct normal irradiance, horizontal sky solar radiation, and horizontal long-wavelength radiation at date \(d\) and time \(t\) from the weather data file for the relevant representative location.

In addition, the values specified in the table below should be used for latitude \(lati\) and longitude \(longi\).

The cooling and heating seasons (cooling, intermediate, and heating seasons) on date \(d\), \(Season_{d}\) are specified as shown in the table below for each climate zone.

Note that it is assumed that rooms are "cooled" during the intermediate season in all regions.

First, calculated the daily average outside air temperature \(\theta_{AC,oa,d}\) on date \(d\) by the following formula.

Also, use the following formula to calculate the average outside air temperature by season.

Use the following formula to obtain the outside air enthalpies on date \(d\) \(H_{AC,oa,d,alltime}\), \(H_{AC,oa,d,daytime}\), and \(H_{AC,oa,d,nighttime}\).

\(C_{a}\) is the specific heat at constant pressure of dry air, \(C_{wv}\) is the specific heat at constant pressure of water vapor, and \(L_{w}\) is the latent heat of evaporation of vaporization.

The temperature setting of room i on date \(d\) \(\theta_{AC,room,i,d}\) is determined based on the heating and cooling seasons.

Inside air enthalpy during air conditioning on date \(d\), \(H_{AC,room,d}\), is calculated by the following formula. These values are the enthalpy when the set temperature and humidity are 22°C and 40% for the heating season, 24°C and 50% for the intermediate season, and 26°C and 50% for the cooling season.

The operating conditions and the operating time zone of the air conditioners should be determined based on the "Standard Room Use Conditions". Standard room use conditions are defined for each room use, and there are three "basic schedules (room use patterns 1, 2, and 3)" for each room use, and the basic schedule of each day is defined as the "calendar patterns". The start and end times of air conditioning are obtained from these "basic schedules" and "calendar patterns", and the operating status of the air conditioner is determined according to these values.

The calendar pattern is specified in "CALENDAR.csv", the calendar pattern used for each room use is specified in "ROOM_SPEC.csv", and the search key required when using the above files is specified in "ROOM_NAME.csv".

Retrieve the search key from ROOM_NAME.csv using the building use \(BuildingType\) and the room use \(RoomType_i\).

Obtain the calendar pattern code from ROOM_SPEC.csv using the search key.

Obtain the calendar pattern from ROOM_CALENDAR.csv using the date \(d\) and the calendar code.

Obtain the WSC pattern from ROOM_SPEC.csv using the search key.

Obtain the start and end times of air conditioning from ROOM_SPEC.csv using the search key.
There exist a total of eight air conditioning start and end times depending on the combinations of the calendar pattern (1, 2) and the time zone (1, 2).

Calculate the start and end times of air conditioning for each calendar pattern from the start and end times of air conditioning for each pattern and the WSC pattern.

Calculate the air conditioning start and end times on date \(d\), by using the calendar pattern on date \(d\) and the air conditioning start and end times for calendar patterns 1, 2, and 3.

Calculate the operating status of the air conditioner at date \(d\), time \(t\)by using the air conditioning start and end times on date \(d\).

If \(O_{AC,room,i,d,t}\) is True for at least one hour on date \(d\), then \(O_{AC,room,i,d,d}\) is True, otherwise it is False.

Calculate the operating time zone of the air conditioner using the air conditioning start and end times of calendar pattern 1.

First, retrieve the following four values from the database "ROOM_SPEC.csv" based on the room use of room i \(RoomType_{i}\).

According to the work intensity index \(HumanIndex_{i}\), determine the human body heat generation for room i \(q_{room,human,ref,i}\) from the table below.

Next, based on the room use of room i \(RoomType_{i}\) , retrieve the following three values from the database "ROOM_COND.csv". These are time-specific heat generation schedules specified separately for each "Basic Schedule (Room Use Pattern 1, 2, and 3)".

The basic schedule for each day is defined as a "calendar pattern". Therefore, based on the calendar pattern defined for each room use \(CalendarNum_{i}\) , the heat generation ratio for each time of day is determined.

The internal heat generation [Wh] of room i at date \(d\), time \(t\) is obtained by the following formula.

Calculate the value [Wh] by integrating these values over a 24-hour period.

The fresh outside air volume into room i is defined for each room use. Read the value in the "Outside air volume" field of "ROOM_SPEC.csv".

First, the inclination angle \(\theta_{env,slp,j}\) [°] and the azimuth angle \(\theta_{env,drct,j}\) [°] are specified according to the orientation of the envelope, etc. j belonging to room i \(D_{env,i,j}\), as in the following table.

The integrated direct solar radiation \(I_{dsr,j,d}\), the integrated sky solar radiation \(I_{isr,j,d}\), and the integrated long-wavelength radiation \(I_{nsr,j,d}\) to the envelope j on date \(d\) are calculated according to the azimuth and tilt angle of the envelope j as follows. Note that 0.5 in the formula is the sky view factor from a vertical surface, and 0.1 is the solar reflectance at the ground surface. Also, \(\theta_{j,d,t}\) is the angle between the normal of envelope j and the sun direction at date \(d\) time t, \(h_{sun,d,t}\) is the sun altitude at date \(d\) time t, and \(\theta_{sun,d,t}\) is the sun azimuth angle at date \(d\) time t. \(\eta_{j,d,t}\) is the angle-of-incidence characteristic of the envelope j at date \(d\) time t, which should be obtained by the following formula. \(\eta_{max}\) is the maximum value of \(\eta_{j,d,t}\), which is 0.89.

The sine and cosine values of the solar altitude \(h_{sun,d,t}\) [rad] and the solar azimuth angle \(\theta_{sun,d,t}\) [rad] at date \(d\), time \(t\)are calculated as follows. Note that the unit of angle in obtaining the sine and cosine is radian.

where \(del_{d}\) [rad] is the solar declination of date \(d\) and \(e_{d}\) [rad] is the equation of time on date \(d\), which is obtained from the following formula. The daynum(d) in the formula is the function to find the day of year of the date \(d\).

\(Tim_{d,t}\) [rad] is the hour angle at date \(d\) time t, which is obtained from the following formula. Where, time t is from 1 to 24.

Steady-state heat gain from the envelope is calculated separately for "steady-state heat gain due to temperature difference" and "steady-state heat gain due to solar radiation".

The steady-state heat gain per unit floor area due to temperature difference and long-wavelength radiation in room i on date \(d\) \(Q_{AC,room,tin,i,d}\) is determined by the following formula.

The daily integrated steady-state heat gain due to solar radiation in room i on date \(d\), \(Q_{AC,room,sin,i,d}\) is obtained by the following formula.

Calculate the heat gain due to internal heat generation.

In this calculation method, for simplicity, heat generations from room lighting, human body and equipment are treated as steady-state heat gain with no time delay. However, if date \(d\) is not air-conditioned day, both of these should be set to 0. Whether a day is air-conditioned day or not is defined by the standard room use conditions for each room use.

The daily integrated room load is calculated by calculating the daily integrated steady-state heat gain per unit floor area based on the envelope configuration of each room and multiplying it by the "factor for converting steady-state heat gain to room load".

First, calculate the cooling load due to temperature difference \(Q_{AC,room,tc,i,d}\)[Wh/(m²・d)], heating load due to temperature difference \(Q_{AC,room,th,i,d}\)[Wh/(m²・d)], cooling load due to solar radiation \(Q_{AC,room,sc,i,d }\)[Wh/(m²・d)], respectively. For convenience, the cooling load is expressed as a positive value and the heating load as a negative value, and \(Q_{AC,room,tc,i,d}≥0\), \(Q_{AC,room,th,i,d}≤0\), \(Q_{AC,room,sc,i,d}≥0\).

The coefficients for converting steady-state heat gain to room load \(\{a_{tc1,d},a_{tc2,d}\}\), \(\{a_{th1,d},a_{th2,d}\}\), and \(\{a_{sc1,d},a_{sc2,d}\}\) are defined by region, room use, cooling/heating season (cooling season, intermediate season, heating season), and the previous day’s air conditioning operation status.

Based on these loads \(Q_{AC,room,tc,i,d}\), \(Q_{AC,room,th,i,d}\), \(Q_{AC,room,sc,i,d}\) and the load due to internal heat generation \(Q_{AC,room,in,i,d}\), the daily integrated room load is calculated by following procedure.

Step 1) Find the following A and B.

Step 2) Find the following C and D.

The calculated C is the daily integrated room load (cooling) for room i \(Q_{AC,room,c,i,d}\)[Wh/( ^m2-d )] , and D is the daily integrated room load (heating) for room i \(Q_{AC,room,h,i,d}\)[Wh/( ^m2-d )]. However, if date \(d\) is not a air-conditioned day, these will both be 0. Whether a day is air-conditioned day or not is defined by the standard room use conditions for each room use.

The daily integrated room load handled by each air handling unit group is calculated by totalizing the room loads of the rooms where the air handling unit group handles the load.

Whether or not the air handling unit group i handles only outside air load \(OnlyOALoad_{AC,ahu,i}\) is False if the name of the air handling unit group i matches at least one of the names of the air handling unit group for handling room load of room r belonging to the air handling unit group i \(EquipmentName_{AC,ahu,room,i,r}\) , and True otherwise.

The daily integrated room load (cooling) \(Q_{AC,ahu,room,c,i,d}\) and daily integrated room load (heating) \(Q_{AC,ahu,room,h,i,d}\) of the air handling unit group i on date \(d\) are calculated by the following formula. For the air handling unit group that handles only outside air load, the daily integrated room load should be set to 0, and only the outside air load should be integrated as described below.

The operating hours of an air handling unit group are calculated as the total value of the used hours of the rooms in which the relevant air handling unit group performs air conditioning.

The operating hours of the air handling unit group i on date \(d\) \(T_{AC,ahu,i,d}\) is calculated by totalizing the operating status of the air handling unit group i at each time on a daily basis, assuming that the air handling unit group i is operating if any one of the rooms r that are air-conditioned by the air conditioner j belonging to the air handling unit group i, is performing air conditioning at each time.

First, calculate the operating status of the air handling unit group i at date \(d\), time \(t\)\(O_{AC,ahu,i,d,t}\). For a room air conditioned by the air handling unit group i, if \(O_{AC,room,r,d,t}\) is True in one room, then \(O_{AC,ahu,i,d,t}\) is True; if \(O_{AC,room,i,d,t}\) is False in all rooms, then \(O_{AC,ahu ,i,d,t}\) is False.

The operating hours of the air handling unit group i on date \(d\) \(T_{AC,ahu,i,d}\) is calculated by counting the number of hours for which \(O_{AC,ahu,i,d,t}\) is True on each day.

Next, calculate the cooling and heating operation hours of each air handling unit group. The daily integrated room load for each air handling unit group was calculated as above, but both the absolute values of the cooling room load and heating room load can be greater than zero on the same day. This means that both loads occur in a day, for example, the heating room load occurs in the morning, but the cooling room load occurs in the afternoon. However, since this calculation method calculates the daily integrated room load, it is not known at what time of the day the cooling room load and heating room load occurred. Therefore, it was decided to determine the cooling and heating operation hours by proportionally dividing the daily integrated air conditioning operation hours by the ratio of the absolute values of the cooling room load and the heating room load. However, the terms "cooling" and "heating" here indicate that the room load generated is the cooling (or heating) load. And the air conditioning load that is the room load plus the outside air load is not necessarily the cooling (or heating) load. In addition, as discussed in detail below, when the heat source system does not have a simultaneous cooling and heating supply function (i.e., it has a switching function between cooling and heating operations depending on the season), the heating load in the cooling and intermediate seasons and the cooling load in the heating season are assumed to be ignored without being processed (this is called the "unprocessed load").

The cooling operation hours \(T_{AC,ahu,c,i,d}\) and heating operation hours \(T_{AC,ahu,h,i,d}\) of the air handling unit group i are obtained by the following formula.

In the formula, "ceil" is a function that means to round up the decimal point and obtain an integer value.

Assume that the operating hours of the total heat exchanger \(T_{AC,ahu,aex,i,d}\) is the same as that of the air handling unit group i.

Calculate the outside air load handled by an air handling unit group.

First, calculate the outside air volume by air handling unit group i \(V_{AC,ahu,oa,i}\). The integrated value of the outside air volume by air handling unit group i to all rooms to be air conditioned \(V_{AC,room,oa,i,r}\) should be the outside air volume by air handling unit group i \(V_{AC,ahu,oa,i}\).

Next, calculate the supply airflow rate \(V_{AC,ahu,aex,i}\) [kg/s] of the total heat exchangers belonging to the air handling unit group i.

The daily average outside air enthalpy on date \(d\) is obtained by the following formula. If an air handling unit group runs all day, the daily average of outside air enthalpy is used; when it runs at night over several days, the night-time average of outside air enthalpy is used; and when it runs only during the day, the daytime average is used.

The operating time zone of a air handling unit group depends on the used time zone of the rooms to which they are connected. If the use time zones of all connected rooms are the same, the operating time zone of the air handling unit group is equal to it. However, if the use time zones differ depending on the connected room, it is considered as an "all-day operation" without depending on the combination of them.

The enthalpy difference between inside and outside is calculated by the following formula.

\(OnlyRoomLoad_{AC,ahu,i}\), which indicates whether the air handling unit group i handles only room load, is False if the name of the air handling unit group i matches at least one of the names of the air handling unit groups for handling outside air load of room r belonging to the air handling unit group i \(EquipmentName_{AC,ahu,oa,i,r}\). Otherwise, it is assumed to be True.

\(AutoChangeCtrl_{ahu,aex,i}\), which indicates whether the automatic ventilation switching function is enabled for the total heat exchangers of the air handling unit group i, is "Enabled" if the automatic ventilation switching function is enabled in at least one of the total heat exchangers of fan j belonging to the air handling unit group i. Otherwise, it is assumed to be "Disabled".

The outside air load of the air handling unit group i on date \(d\) \(q_{AC,ahu,oa,i,d}\) is calculated by the following formula. When calculating the outside air load, the load reduction effect is expected when each air handling unit group includes a total heat exchanger, but the calculation method differs depending on whether the total heat exchanger is equipped with an automatic ventilation switching function.

\(V'_{AC,ahu,aex,i}\) in the formula is the supply airflow rate of total heat exchangers belonging to the air handling unit group i, capped by the outside air volume, and is calculated by the following formula.

The \(\eta' _{ahu,aex,i}\) [-] in the formula is the total heat exchange efficiency of total heat exchangers belonging to the air handling unit group i corrected by considering the actual operating performance, and is calculated by the following formula \(C _{tol}\) is a coefficient related to the indicated value, \(C_{eff}\) is a coefficient related to the effective ventilation rate, and \(C_{bal}\) is a coefficient related to the balance between supply air volume and exhaust air volume.

\(\eta_{ahu,aex,i}\) [%] in the formula is the total heat exchange efficiency of total heat exchangers belonging to the air handling unit group i before correction, and you should adopt the worst total heat exchange efficiency among the total heat exchangers of fan j belonging to air handling unit group i.

\(C_{tol}\) is a coefficient considering the allowable range of indicated value specified in JIS B 8628:2003, \(C_{eff}\) is a coefficient considering the allowable range of effective ventilation rate in the same standard, and \(C_{bal}\) is the reduction ratio of the total heat exchange efficiency when the ratio of actual supply air volume and exhaust air volume is assumed to be 2:1 while considering the description (the use of a total heat exchanger should be considered only in such cases as where the exhaust air volume can be maintained at approximately 40% of the outside air volume) in the Building Equipment Design Standards (supervised by the Building Equipment and Environment Division, Government Buildings Department, Minister’s Secretariat, Ministry of Land, Infrastructure, Transport and Tourism). In practice, it is possible to obtain better total heat exchange efficiency by using the effective ventilation rate, and total heat exchange efficiency under the design conditions of the adopted model. However, at present, there are issues on how to specify these in the design documents and how to adjust and check the building equipment after construction and completion. Therefore, the calculation is based on a coefficient that assumes the safe side (lower efficiency) as described above.

Calculate the load reduction by outside air cooling control of the air handling unit group i on date \(d\).

First, calculate the design maximum outside air volume for air handling unit group i \(V_{AC,ahu,oacool,max,i}\) [kg/s]. If Form 2-7: (6) Design maximum Outside Airflow Volume is blank, \(V_{AC,ahu,oacool,max,i}\) is assumed to be 0.

Next, calculate the airflow rate during outside air cooling \(V_{AC,ahu,oacool,i,d}\). The supply airflow rate during outside air cooling should not exceed the design maximum outside airflow rate \(V_{AC,ahu,oacool,max,i}\).

The load reduction by outside air cooling control \(Q_{AC,ahu,oacool,i,d}\) is calculated by the following formula.

The daily integrated air conditioning load is calculated by adding the outside air load to the room load of each air handling unit group. In this calculation, consider the effect of introducing the "Control to Stop Outside Air Introduction During Preheating".

Calculate the daily integrated air conditioning load (cooling) using the following procedure.

Calculate the daily integrated air conditioning load (heating) using the following procedure. However, if only the outside air load is handled, the daily integrated air conditioning load (heating) is 0 because the outside air load is handled as the cooling load for processing purposes.

The load factor of an air handling unit group is determined by the air conditioning load (coil load) handled by relevant air handling unit group.

First, calculate the load factor in the cooling season of the air handling unit group i on date \(d\) \(L_{AC,ahu,mix,c,i,d}\) and the load factor in the heating season of the air handling unit group i on date \(d\) \(L_{AC,ahu,mix,h,i,d}\). In this calculation method, the daily average load factor is calculated using the daily integrated load, and then, the energy consumption is calculated assuming that the equipment operates at this constant load factor throughout a day.

where the function F in the above formula is defined as follows. The function \(floor(x)\) finds the largest integer smaller than or equal to x for a real number x. The function \(ceil(x)\) finds the smallest integer greater than or equal to x for a real number x.

The load factor during cooling operation and the load factor during heating operation of the air handling unit group i on date \(d\) are calculated by the following formula. In systems without simultaneous cooling and heating operation, the load factor is not set to 0 but to a small value ε (= 0.01) in order to calculate energy consumption assuming that the air conditioners are running at a low load rather than completely shutting down.

In addition, the presence or absence of simultaneous cooling/heating supply of heat source group i to which air handling unit group i belongs \(SimultenousCtrl_{AC,ref,i}\) obtains the value of Form 2-5: (2) Presence or Absence of Simultaneous Supply Function of Heating and Cooling by using the heat source group name (Form 2-7: (22) Cooling, (23) Heating) to which the air handling unit group i belongs as the search key.

Calculate the coefficients for calculating the energy saving effect due to airflow rate control.

The coefficient determined by the airflow rate control method of fan j belonging to the air handling unit group i \(f_{AC,ahu,c,i,j,d}\) is obtained by the following formula.

If the minimum airflow rate ratio of fan j belonging to the air handling unit group i \(L_{AC,ahu,i,j,min}\) is blank in Form 2-7, it should be \(L_{AC,ahu,i,j,min} = 100\).

where the function \(F_{AC,ahu,i,j}(L)\) is a fourth-degree polynomial expressed as the following formula.

The coefficient \(a_{i,j},b_{i.j},c_{i,j},d_{i,j},e_{i,j}\) is the coefficient representing energy consumption characteristic of each fan and is determined by the airflow rate control method \(FanCtrlType_{AC,ahu,i,j}\). If \(FanCtrlType_{AC,ahu,i,j}\) is not specified, it is assumed to be "constant airflow rate control".

<Explanation> This energy consumption characteristic was defined based on the results of a field survey conducted by the Ministry of Land, Infrastructure, Transport and Tourism (MLIT) in its 2011 and 2012 Building Standard Improvement Promotion Project, Survey Item 36: "Empirical Evaluation of Energy Saving Effects through Optimal Control of Air Conditioning Systems, etc." The variable airflow rate control refers to the control in which the rotational speed of the fan automatically changes according to the room temperature, etc., and does not cover manual switching of airflow rate, as is often the case with fan coil units and indoor units of packaged air conditioners. If variable airflow rate control is used, the minimum airflow rate ratio (ratio to the rated airflow rate) is set, and if the load factor falls below this minimum airflow rate ratio, the value of the coefficient at the minimum load factor where the load factor does not fall below the minimum airflow rate ratio \(f_{AC,ahu,i,j,min}\) is used for the load factor below that. If the load to be handled exceeds the rated capacity (overload), 1.2 is assumed for both constant and variable airflow rate control. Originally, in the case of an overload, the room temperature would deviate from the setpoint without the load being processed, but this calculation method does not reproduce this phenomenon and calculates energy consumption assuming that 1.2 times the rated power consumption was consumed to reach the set temperature and humidity (the load was processed) for the overload condition.

The rated power consumption of an air handling unit group should be the sum of the power consumption of the fans belonging to the relevant air handling unit group.

Calculate the power consumption of fans belonging to air handling unit group.

The power consumption in cooling operation \(E_{AC,ahu,c,i,j,d}\) and in heating operation \(E_{AC,ahu,h,i,j,d}\) of fan j in air handling unit group i are calculated by the following formula.

The power consumptions of the fan belonging to the air handling unit group i \(E_{AC,ahu,c,i,d}\) and \(E_{AC,ahu,h,i,d}\) are calculated by the following formula.

Calculate the heat generation by the fans of the air handling unit group.

The heat generations by the fans of an air handling unit group \(Q_{AC,ahu,heat,c,i,d}\) and \(Q_{AC,ahu,heat,h,i,d}\) are calculated by the following formula. Note that the heat generation should be included only when the type of air conditioner belonging to the air handling unit group i is "air conditioner".

where \(ACExists_{i}\) is a boolean value that is True if at least one of the air conditioner types of air conditioner j belonging to air handling unit group i \(ACType_{i,j}\) is "air conditioner", and is False otherwise.

Also, \(f_{fan,heat}\) is the fan heat generation ratio.

Calculate the power consumption of the total heat exchangers belonging to air handling unit group i.

The power consumption of a total heat exchanger belonging to the air handling unit group i \(E_{AC,ahu,aex,i,d}\) is calculated by the following formula.

Calculate the annual primary energy consumption of an air handling unit group.

The annual primary energy consumption of an air handling unit group \(E_{AC,ahu,i}\) is calculated by the following formula.

where \(E_{AC,ahu,c,i}\) and \(E_{AC,ahu,h,i}\) are calculated by the following formula.

where \(E_{AC,ahu,aex,i}\) is calculated by the following formula.

The load handled by each secondary pump group (secondary pump load) is calculated from the air conditioning load handled by the air handling unit group.

The load handled by each secondary pump group is calculated by totalizing the air conditioning load of the air handling unit groups to which the secondary pump groups supply chilled and hot water, and then adding up the effect of outside air cooling and the heat generated by the air conditioner fans. The subscript j indicates that the calculation should be done for the air handling unit group to which each pump group supplies chilled water.

In the above formula, -1 is used as the multiplier to reverse the sign of the heating load, which has been treated as a negative value, so that it becomes a positive value for the sake of convenience.

In systems where outside air cooling control is enabled, the fan heat generation is assumed to be 0 for days when outside air cooling control is enabled. This is because in a system where outside air cooling is effective, if all air conditioning load is handled by outside air introduction, the apparent air conditioning load is zero. And in this case, if the fan heat generation is added separately, a very small amount of load remains in the calculation, which has a large impact on the energy consumption of the heat source device and the secondary pump. To avoid this, in systems where outside air cooling control is enabled, fan heat generation is ignored for the days when outside air cooling control is effective.

The operating hours of a secondary pump group is calculated as the total value of the operating hours of the air handling unit groups to which the secondary pump group supplies chilled and hot water.

The operating hours of the secondary pump group i on date \(d\) \(T_{AC,pump,i,d}\) is calculated by totalizing the operating status of the secondary pump group i at each time during each day, assuming that the secondary pump group i is operating if at least one air handling unit group that supplies chilled/hot water is operating at each time point.

First, calculate the operating status of the secondary pump group i at date \(d\), time \(t\)\(O_{AC,pump,i,d,t}\). For an air handling unit group to which the secondary pump group i supplies chilled/hot water, if \(O_{AC,ahu,i,j,d,t}\) is True for at least one air handling unit group, then \(O_{AC,pump,i,d,t}\) is True, if \(O_{AC,ahu,i,j,d,t}\) is False for all air handling unit groups, then \(O_{AC,pump,i,d,t}\) is False.

The operating hours of the secondary pump group i on date \(d\) \(T_{AC,pump,i,d}\) is calculated by counting the number of hours for which \(O_{AC,pump,i,d,t}\) is True on each day.

The rated capacity of a secondary pump group is defined as the design flow rate multiplied by the design temperature difference.

The virtual rated capacity of secondary pump j belonging to the secondary pump group i [kW] is obtained from the rated flow rate and design temperature difference by the following formula.

Here, the design temperature difference \(\Delta \theta_{AC,pump,i}\) [K] is the temperature difference between the supply and return temperatures of the chilled and hot water to be supplied to the secondary-side air conditioning system (design value of the supply and return temperature difference).

Also, \(\rho_{w}\) is the density of water [kg/m³] and \(C_{w}\) is the specific heat of water at constant pressure [kJ/(kg-K)].

The virtual rated capacity of the secondary pump group i is the sum of the virtual rated capacities of the secondary pumps j belonging to the secondary pump group i.

Calculate the load factor of the secondary pump group i.

The load factor of the secondary pump group i on date \(d\) \(L_{AC,pump,i,d}\) is obtained by the following formula.

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

Calculate the number of pumps operating in the secondary pump group i. The number of pumps in operation varies depending on the Presence or Absence of control over the number of devices.

The calculation formula for the number of pumps operating in a secondary pump group differs depending on the Presence or Absence of control over the number of devices. Here, control over the number of devices is defined as a control in which there are two or more secondary pumps in a secondary pump group and the number of operating pumps is automatically adjusted according to the load.

The number of secondary pumps belonging to the secondary pump group i \(N_{AC,pump,i}\) is the x-th lowest number that has been input. (e.g., if 1st-3rd are input, it will be "3").

The function \(F_{pump,q,i}(n)\) means to totalize the virtual rated capacity up to the n-th secondary pump j belonging to the secondary pump group i. In a-2), the minimum number of operating secondary pumps N that satisfies the load of secondary pump group i on date \(d\) \(q_{AC,pump,i,d}\) is obtained.

Calculate the load factor of the single secondary pump j belonging to the secondary pump group i.

If there is no control over the number of devices, it is calculated as follows:

If there is control over the number of devices, it is calculated as follows.

where \(C_{i,j}\) is a boolean value that is True if the flow rate control method of the secondary pump j in the secondary pump group i is a "constant flow rate control", and False if it is a "variable flow rate control".

In b-2), \(q_{AC,pump,i,d,CWV}\) is the total amount of heat [kW] handled by the secondary pump j whose flow rate control method is a "constant flow rate control", \(q_{AC,pump,i,d,VWV}\) is the total amount of heat [kW] handled by the secondary pump j whose flow rate control method is a "rotational speed control", and \(N_{AC,pump,i,d,VWV}\) is the number of operating secondary pumps j whose flow rate control method is a "rotational speed control".

Calculate the coefficient determined by the flow rate control method.

The minimum flow rate ratio of the secondary pump j in the secondary pump group i \(L_{AC,pump,i,j,min}\) should be \(L_{AC,pump,i,j,min} = 100\) if the flow rate control method of the secondary pump j is a "constant flow rate control".

The coefficient determined by the flow rate control method of the secondary pump group i \(f_{AC,pump,i,j,d}\) is calculated by the following formula.

where the function \(F_{AC,pump,i,j}(L)\) is a fourth-degree polynomial expressed as the following formula.

The coefficient \(a_{i,j},b_{i.j},c_{i,j},d_{i,j},e_{i,j}\) is the coefficient representing energy consumption characteristic of secondary pump j and is determined by the flow rate control method \(PumpCtrlType_{AC,pump,i,j}\). If \(PumpCtrlType_{AC,pump,i,j}\) is not specified, the control method is assumed to be "constant flow rate control".

<Explanation> This energy consumption characteristic value was defined based on the results of a field survey conducted by the Ministry of Land, Infrastructure, Transport and Tourism (MLIT) in its 2011 and 2012 Building Standard Improvement Promotion Project, Survey Item 36: "Empirical Evaluation of Energy Saving Effects through Optimal Control of Air Conditioning Systems, etc." Here, the rotational speed control is defined as the control in which the pump rotational speed is automatically adjusted by an inverter or other means. If the rotational speed control is used, the minimum flow rate ratio (ratio to rated flow rate) should be set, and if the load factor falls below this minimum flow rate ratio, the load factor should be the coefficient at the minimum flow rate ratio. The reason for assuming that 1.2 times the rated power consumption is consumed during overload, is the same for the airflow rate control method for air handling unit group.

Calculate the power consumption of secondary pumps belonging to the secondary pump group.

The power consumption of the secondary pump group i on date \(d\) \(E_{AC,pump,i,d}\) is obtained by the following formula.

Calculate the heat generation of the pumps in the secondary pump group.

The heat generation of the secondary pump is calculated by the following formula.

And \(f_{pump,heat}\) is the heat generation ratio of the pump.

Calculate the annual primary energy consumption of a secondary pump group.

The annual primary energy consumption of a secondary pump group \(E_{AC,pump,i}\) is calculated by the following formula.

And \(f_{prim,e}\) is the coefficient that converts one kilowatt-hour of electricity into thermal energy.

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

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

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.

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.

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.

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.

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 \(StorageType_{i}\).

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.

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.

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.

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".

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.