Calculation of DesignBuilder Output from EnergyPlus Report Variables

At the end of an EnergyPlus simulation DesignBuilder reads the EnergyPlus output file eplusout.eso. The format of this file is described in EnergyPlus documentation. The table below explains how the raw EnergyPlus output is processed to create DesignBuilder output. The Environmental/Comfort Output column refers to the data shown in DesignBuilder output screens. EnergyPlus Report variable column data shows report variable names with the units in square brackets. The units should be omitted when using the report variables in IDF data. The Area column indicates the zone, surface, component etc.

 

Environmental/Comfort Output

EnergyPlus Report Variable

Area

Notes*

Internal air temperature

Zone Mean Air Temperature [C]

ZoneId

 

Internal radiant temperature

Zone Mean Radiant Temperature [C]

ZoneId

 

Internal operative temperature

 

ZoneId

0.5 x (Zone Mean Air Temperature + Zone Mean Radiant Temperature)

Relative Humidity

Zone Air Relative Humidity [%]

ZoneId

 

Fanger PMV

FangerPMV

PEOPLE ZoneId

 

Pierce PMV ET

PiercePMVET

PEOPLE ZoneId

 

Pierce PMV SET

PiercePMVSET

PEOPLE ZoneId

 

Pierce Discomfort Index (DISC)

PierceDISC

PEOPLE ZoneId

 

Pierce Thermal Sens. Index (TSENS)

PierceTSENS

PEOPLE ZoneId

 

Kansas Uni TSV

KsuTSV

PEOPLE ZoneId

 

Discomfort hrs (summer clothing)

Time Not Comfortable Summer Clothes [hr]

PEOPLE ZoneId

 

Discomfort hrs (winter clothing)

Time Not Comfortable Winter Clothes [hr]

PEOPLE ZoneId

 

Discomfort hrs (all clothing)

Time Not Comfortable Summer or Winter Clothes [hr]

PEOPLE ZoneId

 

Fabric and ventilation

Glazing heat gain

Window Heat Gain [W] - Window Heat Loss [W] - Window Transmitted Solar [W]

SurfaceId

Window Transmitted Solar is subtracted so that Glazing heat gain represents the transfer of all heat through the window excluding beam and diffuse short-wave solar heat effects. This makes it more comparable with the opaque surface conduction results.

 

NB The subtraction of solar from glazing heat gain is done as a post process on the output results and does not affect the simulation itself.

Walls, Roofs, Ceilings (int), Floors (int), Floors (ext), Ground floors, Partitions (int), Doors and vents

Opaque Surface Inside Face Conduction [W]

SurfaceId

 

External infiltration

Zone Infiltration Sensible Heat Loss [J] + Zone Infiltration Sensible Heat Gain [J]

ZoneId

Scheduled Natural ventilation only

 

External natural ventilation

Zone Ventilation Sensible Heat Gain [J] + Zone Ventilation Sensible Heat Loss [J]

ZoneId

Scheduled Natural ventilation only

External mechanical ventilation

Zone Ventilation Sensible Heat Gain [J] + Zone Ventilation Sensible Heat Loss [J]

ZoneId

Scheduled Natural ventilation only and only when the Mechanical ventilation method model option is set to 1-Room ventilation

 

Internal Air

AirflowNetwork Mixing Sensible Loss Rate [W] + AirflowNetwork Mixing Sensible Gain Rate [W]

ZoneId

Calculated Natural ventilation only

External Air

AirflowNetwork Infiltration Sensible Loss Rate [W]+ AirflowNetwork Infiltration Sensible Gain Rate [W]

ZoneId

Calculated Natural ventilation only

Airflow

Mech Vent + Nat Vent + Infiltration

 

Calculated as the sum of the 3 EnergyPlus reports in the next column

Zone Mechanical Ventilation Air Change Rate [ach]

ZoneId

Summed across blocks and building using volume-weighted average

Zone Ventilation Air Change Rate [ach]

ZoneId

Summed across blocks and building using volume-weighted average

Zone Infiltration Air Change Rate [ach]

ZoneId

Summed across blocks and building using volume-weighted average

Internal Gains

Task lighting gains

ELECTRIC EQUIPMENT#ZoneId#TaskLights* [J]

-

 

General lighting gains

ELECTRIC EQUIPMENT#ZoneId#GeneralLights* [J]

-

The 'GeneralLights' ELECTRIC EQUIPMENT EnergyPlus output is a lighting fuel consumption and is summed to give the Lighting fuel consumption (below). The gain to the zone is calculated from this in each zone by multiplying by (1 - Return air fraction).

Miscellaneous gains

ELECTRIC EQUIPMENT#ZoneId#02:InteriorEquipment* [J]

-

The '02' ELECTRIC EQUIPMENT EnergyPlus output is the miscellaneous internal gains fuel consumption and is summed to give the Room fuel consumption (below). The gain to the zone is calculated from this in each zone by multiplying by (1 - Fraction lost).

Process gains

ELECTRIC EQUIPMENT#ZoneId#03:InteriorEquipment* [J]

-

The '03' ELECTRIC EQUIPMENT EnergyPlus output is the process internal gains fuel consumption and is summed to give the Room fuel consumption (below). The gain to the zone is calculated from this in each zone by multiplying by (1 - Fraction lost).

Catering gains

ELECTRIC EQUIPMENT#ZoneId#04:InteriorEquipment* [J]

-

The '04' ELECTRIC EQUIPMENT EnergyPlus output is the catering internal gains fuel consumption and is summed to give the Room fuel consumption (below). The gain to the zone is calculated from this in each zone by multiplying by (1 - Fraction lost).

Computer and equipment gains

ELECTRIC EQUIPMENT#ZoneId#05:InteriorEquipment* [J]

-

 

Occupancy gains

Zone People Sensible Heat Gain [J]

ZoneId

 

Solar Gains Exterior Windows

Zone Transmitted Solar [W]

ZoneId

 

Solar Gains Interior Windows

Zone Diff Solar from Interior Windows [W] + Zone Beam Solar from Interior Windows [W]

ZoneId

 

Zone Sensible Cooling

Zone/Sys Sensible Cooling Rate [W]

ZoneId

Overall sensible cooling energy to the zone from the HVAC system (not energy consumption)

Zone Sensible Heating

Zone/Sys Sensible Heating Rate [W]

ZoneId

Overall sensible heating energy to the zone from the HVAC system (not energy consumption)

System Heat Flows

Zone Heating Ideal Loads Sensible Heating Rate [W] ZoneId Ideal Loads Air Simple HVAC convective

Zone Heating

Total Water Heating Coil Rate [W]

ZoneId REHEAT COIL

VAV/CAV Hot water reheat coils

Zone Heating

Heating Coil Rate [W]

ZoneId REHEAT COIL

VAV/CAV Electric reheat coils

Zone Heating

Heating Coil Rate [W]

ZoneId AHU HEATING COIL

Unitary single zone

Zone Heating

Total Water Heating Coil Rate [W]

ZoneId HEATING COIL

Fan coil

Preheat

Heating Coil Rate [W]

AHU PREHEAT COIL

VAV/CAV Gas/Electric preheat coils

AHU Heating

Total Water Heating Coil Rate [W]

AHU HEATING COIL

VAV/CAV Hot water coils

AHU Heating

Heating Coil Rate [W]

AHU HEATING COIL

VAV/CAV with Gas/Electric AHU heating coils and Unitary multizone

Total Cooling

Ideal Loads Total Cooling Rate [W]

ZoneId Ideal Loads Air

Simple HVAC convective and ASHRAE Cooling design

Total Cooling

Total Water Cooling Coil Rate [W]

AHU COOLING COIL

VAV/CAV with Chilled water coils

Total Cooling

DX Coil Total Cooling Rate [W]

AHU COOLING COIL

Unitary Multizone

Total Cooling

DX Coil Total Cooling Rate [W]

ZoneId AHU COOLING COIL

Unitary single zone

Total Cooling

Total Water Cooling Coil Rate [W]

ZoneId COOLING COIL

Fan coil

Sensible Cooling

Ideal Loads Sensible Cooling Rate [W]

ZoneId Ideal Loads Air

Simple HVAC convective and ASHRAE Cooling design

Sensible Cooling

Sensible Water Cooling Coil Rate [W]

AHU COOLING COIL

VAV/CAV with Chiller water

Sensible Cooling

DX Coil Sensible Cooling Rate [W]

AHU COOLING COIL

Unitary multizone

Sensible Cooling

DX Coil Sensible Cooling Rate [W]

ZoneId AHU COOLING COIL

Unitary single zone

Sensible Cooling

Sensible Water Cooling Coil Rate [W]

ZoneId COOLING COIL

Fan coil

Fuel breakdown (building level)

Heat Generator

Boiler {Electric/Gas etc} Consumption Rate +

BaseBoard Electric Consumption +

DX Heating Coil Electric Consumption +

DX Heating Coil Electric Defrost Consumption +

DX Heating Coil Crankcase Heater Consumption +

Heating Coil Electric Consumption +

Heating Coil Gas Consumption +

Heating Coil Rate (electric)

 

Compact and Detailed HVAC

Note: CoP for direct gas coils is assumed to be 0.8 and direct electric coils 1.0.

Heat Generator

 

Simple HVAC

Heat generator fuel = Heating load / Heating system CoP

 

Note: the Heating system CoP is defined separately for each zone.

Chiller

Chiller Electric Power +

DX Cooling Coil Electric Consumption +

Chiller Cond Fan Electric Consumption +

Evap Cooler Electric Power

 

Compact and Detailed HVAC

 

Chiller

 

Simple HVAC

Chiller fuel = Cooling load / Cooling system CoP

 

Note: the Cooling system CoP is defined separately for each zone.

System Fans

Fan Electric Consumption [J]

AHU SUPPLY FAN

VAV/CAV with Chiller water, Unitary multizone

System Fans

Fan Electric Consumption [J]

ZoneId AHU SUPPLY FAN

Unitary single zone

System Fans

Fan Electric Consumption [J]

ZoneId SUPPLY FAN

Fan coil

System Pumps

Pump Electric Consumption [J]

HOT WATER LOOP HW SUPPLY PUMP + CHILLED WATER LOOP CHW SUPPLY PUMP + CHILLED WATER LOOP CNDW SUPPLY PUMP

 

System Fans

Fan Electric Consumption [J]

Simple HVAC with 2-Separate fans and pumps Auxiliary option

 

System Pumps

ELECTRIC EQUIPMENT#ZoneId#07:InteriorEquipment

Simple HVAC with 2-Separate fans and pumps Auxiliary option

 

Auxiliary Energy

ELECTRIC EQUIPMENT#ZoneId#07:InteriorEquipment

Simple HVAC with 1-NCM Auxiliary option

Auxiliary Energy = Auxiliary energy (kWh/m2) x Floor area (m2)

DHW

Domestic Hot Water Consumption [m3]

ZoneId DHW 1

DHW energy (kWh) = 1000 (kg/m3) x 4.187 (KJ/kg-K) x (Domestic Hot Water Consumption [m3]) x (Delivery water temperature - Mains water temperature) / DHW CoP

 

Where:

 

DHW CoP is Heat generator CoP when using 1-Central heating boiler DHW type.

Preheat Energy

 

 

(Preheat Heating Coil Rate + Distr loss if appropriate) / Preheat CoP

Lighting

 

 

Sum of lighting electricity consumption for all zones.

Room Electricity

 

 

Sum of Computer and equipment, Miscellaneous, Process, Catering electricity consumption for all zones.

Room Gas

 

 

Sum of Computer and equipment, Miscellaneous, Process, Catering gas consumption for all zones.

Room Oil

 

 

Sum of Computer and equipment, Miscellaneous, Process, Catering oil consumption for all zones.

Room Solid

 

 

Sum of Computer and equipment, Miscellaneous, Process, Catering solid fuel consumption for all zones.

Room Bottled gas

 

 

Sum of Computer and equipment, Miscellaneous, Process, Catering bottled gas consumption for all zones.

Room Other

 

 

Sum of Computer and equipment, Miscellaneous, Process, Catering "other" fuel consumption for all zones.

Fuel totals (building level)

Electricity

 

 

1-Electricity from grid

Gas

 

 

2-Natural gas

Oil

 

 

3-Oil

Solid

 

 

4-Coal + 7-Anthracite + 8-Smokeless fuel (including coke)

Bottled gas

 

 

5-LPG + 6-Biogas

Other fuel consumption

 

 

9-Dual fuel appliances (mineral + wood) + 10-Biomass + 11-Waste heat

CO2 production (building level)

CO2

 

 

Calculated from Fuel totals above using locally published CO2 emission factors from the Emissions tab on the Legislative regions dialog accessed from the Site level on the Regions model data tab.

Site Weather data

Outside dry-bulb temperature

Outdoor Dry Bulb

Simulation: Direct from EPW - spot value,

 

Cooling design: Outdoor Dry Bulb - spot value.

For Cooling design, value is initialised from user input before calculation is run but is updated with E+ value after the calculation.

Outside dew-point temperature

Outdoor Dew Point

Simulation: Direct from EPW - spot value,

 

Cooling design: Outdoor Dew Point - spot value.

Direct normal solar

Direct Solar

Simulation:

Direct from EPW - preceding hour,

 

Cooling design: Direct Solar - preceding hour.

 

Diffuse horizontal solar

Diffuse Solar

Simulation: Direct from EPW - preceding hour,

 

Cooling design: Diffuse Solar - preceding hour.

 

Wind speed

Wind Speed

Simulation: Direct from EPW - spot value,

 

Cooling design: Wind Speed - preceding hour.

 

 

Wind direction

Wind Direction

Simulation: Direct from EPW - spot value,

 

Cooling design: Assumed wind is from North.

 

 

Atmospheric pressure

Outdoor Barometric Pressure

Simulation: Direct from EPW - spot value,

 

Cooling design:Outdoor Barometric Pressure - preceding hour.

Estimated from elevation before cooling design calc is run but E+ value used after calculation.

Solar altitude

Solar Altitude Angle

Simulation: Calculated - spot value,

 

Cooling design:Solar Altitude Angle - preceding hour.

For Cooling design, solar positions are initialised with calculated values before calculation is run but are updated with E+ values after the calculation.

Calculated simulation data is based on 'spot values' on the hour so in this case the value for 12:00 is the value exactly at midday.

Solar azimuth

Solar Azimuth Angle

Simulation: Calculated - spot value,

 

Cooling design:Solar Azimuth Angle - preceding hour.

 

* Variables shown in green represent EnergyPlus output.

'Direct from EPW' means that the values in the hourly weather file itself are displayed.

EnergyPlus hourly output always represents totals and averages over the preceding hour so data for 12:00 is for the period 11:01 to 12:00.

 

See also: When DesignBuilder output is different from unprocessed EnergyPlus Output