Internal Loads
Internal loads add thermal load to a space. People, Lights, and Miscellaneous Loads are added in this section. These loads contribute heat to the space and may consume energy.
Template Loads
Internal loads are automatically applied to each space based on the selected Room Type and are able to be enable by default. To disable a template Internal Load, uncheck the Enabled checkbox. When disabled the row is crossed out in this view.
Add People Load
The people internal load defines the heat gain from occupancy. Standard library members that include typical occupancy densities from NREL and heat gain per activity type per ASHRAE HOF 2013.
Name
Entered name for the internal people load from its library member.
Percent Floor Area
The percent floor area that receives the loads applied. This input impacts load to space only when people/area is used for units.
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Default: 100%
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Typical Range: 0 to 100%
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Min Max: 0 to 100
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Units: %
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Type
Specify the activity level undertaken by the people in the room.
It determines the amount of sensible and latent heat gain per person in the room under design conditions. The available options are taken from the ASHRAE Handbook of fundamentals 2013, chapter 18.
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Default: Per ASHRAE HOF2013
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Typical Range: NA
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Min Max: NA
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Units: NA
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Density
Specify the design population of people in the space.
It can be defined as a total number of people, an amount of area per person (i.e. ft.2/person, m2/person), or an amount of people per area (people/ft.2, people/m2). A value of "0" in combination with any of the units will be interpreted as zero people.
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Default: Per NREL table 4 Occupancy by space type
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Typical Range: 1 to 5000
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Min Max: 1 to 5000
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Units: people; ft2/person; m2/person; people/sq ft; people/m2
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Schedule
Schedules define the 24-hour percentage profiles for the variable loads in the room, such as people, lights, miscellaneous equipment, ventilation, infiltration, and more. The % Value entries for each hour in the schedule act as direct multipliers on the corresponding design value
For example, a schedule can be created to define the amount of heat gain due to lighting in a room if the amount of lighting for a room is entered as 250 Watts. This value is considered the design value for that room (i.e., the 100% value). If the schedule selected for the lighting in this room reads 50% for the period between 1 p.m. and 2 p.m., the lighting load in the room during that period is 125 Watts (or 50% of 250 Watts). The percentage of a given load present during time of space and coil peaks depends on the value entered in the associated schedule for that month and hour, as well as the cooling methodology selected. Choose a standard member from the Schedules Library supplied with the program or a custom schedule in the library.
Add Light Load
The lighting internal loads define the heat gain from internal lighting. They are applied to the zones in the Room Properties screen. The program has standard library members that include typical lighting densities and heat gains.
Name
Entered name for the internal lighting load.
Percent Floor Area
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Default: 100%
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Typical Range: 1 to 100%
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Min Max: 1 to 100
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Units: %
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The percent floor area that will have the loads applied.
Type
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Default: Per ASHRAE HOF 2013
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Typical Range: NA
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Min Max: NA
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Units: NA
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Defines the type of lighting load that is applied to the space. It determines the amount of heat gain associated with the lighting fixtures under design conditions. The available options are taken from the ASHRAE Handbook of fundamentals 2013, chapter 18.
Density
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Default: Per ASHRAE HOF 2013 depending on the space type
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Typical Range: 0.5 to 2 W/sq•ft (5.38 to 21.5 W/m2)
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Min Max: 0 to 100,000
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Units: W, W/ft2, W/m2, W/person, W/fixture
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Defines the design lighting density. It can be defined as a total number of watts in the zone, lighting power per zone floor area (i.e. W/sq. ft.) or lighting power per person (i.e. W/person)
Schedule
Schedules define the 24-hour percentage profiles for the variable loads in the room, such as people, lights, miscellaneous equipment, ventilation, infiltration, and more. The % Value entries for each hour in the schedule act as direct multipliers on the corresponding design value
For example, a schedule can be created to define the amount of heat gain due to lighting in a room if the amount of lighting for a room is entered as 250 Watts. This value is considered the design value for that room (i.e., the 100% value). If the schedule selected for the lighting in this room reads 50% for the period between 1 p.m. and 2 p.m., the lighting load in the room during that period is 125 Watts (or 50% of 250 Watts). The percentage of a given load present during time of space and coil peaks depends on the value entered in the associated schedule for that month and hour, as well as the cooling methodology selected. Choose a standard member from the Schedules Library supplied with the program or a custom schedule in the library.
Add Miscellaneous Equipment Load
These library members are created to define the heat gain from various plug loads. They are applied to the room in the Room Properties screen. The program has standard library members that include typical miscellaneous load densities and heat gains. These loads are categorized by fuel type: Electric, Gas, Hot Water, IT Equipment, Steam and Other.
The Miscellaneous Loads library member details screen displays the fields that must be defined for each Miscellaneous Load library member.
Name
Entered name for the miscellaneous load.
Percent Floor Area
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Default: 100%
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Typical Range: 0 to 100%
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Min Max: 0 to 100
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Units: %
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The percent floor area that will have the miscellaneous loads applied. This input impacts load to space only when load/area is used for units.
Type
Defines the type of lighting load that is applied to the space. It determines the amount of heat gain associated with the lighting fixtures under design conditions. The available options are taken from the ASHRAE Handbook of fundamentals 2013, chapter 18.
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Default: Per ASHRAE HOF 2013
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Typical Range: NA
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Min Max: NA
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Units: NA
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Density
Defines the design maximum input to the equipment. It can be defined as a total number of watts or Btu, load per zone floor area, or load per person.
This value is a property of the selected Equipment Type and is defined in the Library. However, this value can be overridden directly on the Create Rooms or Internal Load Template screens, if desired.
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Default: Per ASHRAE HOF 2013 depending on the space type
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Typical Range: NA
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Min Max: -10,000 to 10,000,000
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Units: W, W/ft2, W/m2, W/person, W/fixture
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The Energy Consumption Value must be entered in combination with Energy Consumption Units.
A heat gain need not be associated with equipment.
Schedule
Schedules define the 24-hour percentage profiles for the variable loads in the room, such as people, lights, miscellaneous equipment, ventilation, infiltration, and more. The % Value entries for each hour in the schedule act as direct multipliers on the corresponding design value
For example, a schedule can be created to define the amount of heat gain due to lighting in a room if the amount of lighting for a room is entered as 250 Watts. This value is considered the design value for that room (i.e., the 100% value). If the schedule selected for the lighting in this room reads 50% for the period between 1 p.m. and 2 p.m., the lighting load in the room during that period is 125 Watts (or 50% of 250 Watts). The percentage of a given load present during time of space and coil peaks depends on the value entered in the associated schedule for that month and hour, as well as the cooling methodology selected. Choose a standard member from the Schedules Library supplied with the program or a custom schedule in the library.
Fuel Type
Fuel Type is used to tell the program what utility type is being used to produce the given internal load. If left blank, the miscellaneous equipment defined will not consume any energy.
Input Considerations:
Utility Type can be modified only from the library.
Electric and Gas
Heat Gain
Peak heat gain in the space.
Latent Fraction
The amount of latent heat given off by the miscellaneous load. It affects the moisture balance within the zone. Enter the value as a decimal.
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Default: 0
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Typical Range: 0 to 1
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Min Max: 0 to 1
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Units: %
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Radiant Fraction
The amount of long-wave radiant heat being given off by the miscellaneous load. This value is multiplied by the total energy consumed by the load to give the amount of long wavelength radiation gain. Enter the value as a decimal.
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Default: 0
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Typical Range: 0.1 to 0.2
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Min Max: 0 to 1
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Units: %
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Fraction Lost
The amount of heat which is “lost” and does not impact the zone energy balances. It might correspond to energy converted to mechanical work or heat that is vented to the atmosphere. Enter the value as a decimal.
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Default: 0
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Typical Range: 0 to 1
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Min Max: 0 to 1
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Units: %
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Note: The total sum of the Latent, Radiant and Lost Heat percentages must be 100% or less.
Account only for energy use: This checkbox allows the user to select in the project if a miscellaneous load will only spin the meter and will not add any load to the space.
Hot Water
Peak Flow Rate
The peak demanded hot water flow rate. It can be defined as a total flow rate, a flow rate per floor area or flow rate per person.
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Default: 2.5 gpm
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Typical Range: -10000000 to 10000000
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Min Max: -10000000 to 10000000
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Units: gpm, gpm/person, gpm/sq ft, m3/s; m33/s/person, m3/s/m2
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Entering Water Temperature
The supply hot water temperature at the tap.
Leaving Water Temperature
The leaving cold water temperature.
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Default: 55
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Typical Range: Entering 32 to 150°F (0 to 66°C); Leaving 80 to 200°F (26 to 94°C)
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Min Max: 32 to 150°F; 0 to 66°C
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Units: °F; °C
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IT Equipment
Electric Consumption
The design maximum input to the IT equipment when fully loaded. It can be defined as the number of watts per unit or watts per area or load per person.
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Default: Per ASHRAE HOF 2013 depending on the equipment type
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Typical Range: NA
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Min Max: -10,000,000 to 10,000,000
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Units: W, W/ft2, W/m2, W/person
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Number of Units
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Default: 1
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Typical Range: NA
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Min Max: 0 to 10,000,000
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Units: NA
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The total number of units that have the electric consumption from the previous field.
Fan Powered percentage
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Default: 0
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Typical Range: 0 to 1
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Min Max: 0 to 1
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Units: %
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The percentage of the total power input that corresponds to the cooling fans. Enter the value as a decimal.
Steam and Other
Heat Gain
Peak heat gain in the space.
Latent Fraction
The amount of latent heat given off by the miscellaneous load. It affects the moisture balance within the zone. Enter the value as a decimal.
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Default: 0
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Typical Range: 0 to 1
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Min Max: 0 to 1
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Units: %
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Radiant Fraction
The amount of long-wave radiant heat being given off by the miscellaneous load. This value is multiplied by the total energy consumed by the load to give the amount of long wavelength radiation gain. Enter the value as a decimal.
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Default: 0
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Typical Range: 0.1 to 0.2
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Min Max: 0 to 1
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Units: %
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Fraction Lost
The amount of heat which is “lost” and does not impact the zone energy balances. It might correspond to energy converted to mechanical work or heat that is vented to the atmosphere. Enter the value as a decimal.
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Default: 0
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Typical Range: 0 to 1
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Min Max: 0 to 1
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Units: %
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Note: The total sum of the Latent, Radiant and Lost Heat percentages must be 100% or less.
Account only for energy use: This checkbox allows the user to select in the project if a miscellaneous load will only spin the meter and will not add any load to the space.
Add Stand Alone Water Heater
Add water heater in a space to consume utilities and impose space loads due to jacket/tank losses. Refer to the library item to see more details about this equipment type.
Name
Entered name for the water heater load.
Type
The library item applied as Stand Alone Water Heater.
Default Value: Stand Alone Water Heater from the library
Density
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Default: Per ASHRAE HOF 2013 depending on the space type
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Typical Range: 0.5 to 2 W/sq•ft (5.38 to 21.5 W/m2)
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Min Max: 0 to 100,000
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Units: W, W/ft2, W/m2, W/person, W/fixture
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Defines the design lighting density. It can be defined as a total number of watts in the zone, lighting power per zone floor area (i.e. W/sq. ft.) or lighting power per person (i.e. W/person)
Schedule
Schedules define the 24-hour percentage profiles for the variable loads in the room, such as people, lights, miscellaneous equipment, ventilation, infiltration, and more. The % Value entries for each hour in the schedule act as direct multipliers on the corresponding design value
For example, a schedule can be created to define the amount of heat gain due to lighting in a room if the amount of lighting for a room is entered as 250 Watts. This value is considered the design value for that room (i.e., the 100% value). If the schedule selected for the lighting in this room reads 50% for the period between 1 p.m. and 2 p.m., the lighting load in the room during that period is 125 Watts (or 50% of 250 Watts). The percentage of a given load present during time of space and coil peaks depends on the value entered in the associated schedule for that month and hour, as well as the cooling methodology selected. Choose a standard member from the Schedules Library supplied with the program or a custom schedule in the library.
Efficiency
Thermal Efficiency of the water heater.
Flow Rate
Peak flow demand of the water heater.
Flow Rate Units
Units applied to the peak Flow Rate input.
Default: gpm
Options: gpm, gpm/sqft, gpm/person, m3/s