Room Result Variables

Load model results for each room in a building

Patrick Chopson avatar
Written by Patrick Chopson
Updated over a week ago

Room results are calculated for each room within a Zone. This is done by a parallel EnergyPlus simulation to generate the detailed load breakdowns per room. The parallel simulation uses the same inputs for all aspects of the simulation. Results are available after the model is run via the Room Results Panel. This article provides definition for every result variable available.

Room Details

  • Area [ft² (IP) | m² (SI)]: The total area of the room.

  • Number of People: The total number of occupants in the room.

  • Zone Name: The name of the thermal zone which the room is assigned to.

  • Cooling Setpoint [°F (IP) | °C (SI)]: The temperature setpoint in cooling. This is the internal temperature used to size the air flow.

  • Heating Setpoint [°F (IP) | °C (SI)]: The temperature setpoint in heating. This is the internal temperature used to size the air flow.

  • Space Type: The name of the Room Template Assigned.

  • Room Level: The floor that the selected room is located on.

Room Cooling Peak Load Details

  • Total Cooling Load [Btu/h (IP) | Watts (SI)]: Actual peak cooling load for the room taking into account the dynamic nature of internal load and external loads that make up the total.

  • Sensible Cooling Load [Btu/h (IP) | Watts (SI)]: The component of the total cooling load that is sensible.

  • Latent Cooling Load [Btu/h (IP) | Watts (SI)]: The component of the total cooling load that is latent.

  • Time of Peak: The Month, Day, and Hour at which the Total Cooling Load occurs.

  • Dry Bulb [°F (IP) | °C (SI)]: The dry bulb temperature at the time of peak load.

  • Wet Bulb [°F (IP) | °C (SI)]: The wet bulb temperature at the time of peak load.

Room Cooling Peak Load Breakdown:

Cooling peak load is divided into contributing factors to envelope gains and losses as well as internal gains.

  • Envelope Gains/Losses [Btu/h (IP) | Watts (SI)]: The portion of total cooling load that was gained or lost through building envelope.

    • External Walls: Cooling load gains and losses through external walls.

    • Ground Walls : Cooling load gains and losses through ground contact walls.

    • Roofs: Cooling load gains and losses through the roof.

    • Ground Floor: Cooling load gains and losses through the ground contact floors.

    • Exposed Floor: Cooling load gains and losses through floors exposed to outside air.

    • Glazing Conduction and Solar Radiation: Cooling load gains and losses through glazing conduction and radiation. Typically the heat gains are divided into two components, the Conduction related to the U-value and the Radiation related to the SHGC. Dividing the heat gains in this fashion is helpful because it allows key characteristics of the glazing, U-value and SHGC, to be considered in regard to their impact on cooling loads. More detail on the glazing calculations can be found here.

    • Doors: Cooling load gains and losses through the conduction heat transfer of doors.

    • Infiltration: Cooling load gains and losses through infiltration between inside and outside of the building

  • Internal Gains [Btu/h (IP) | Watts (SI)]: The portion of total cooling load that was gained through internal loads such as occupant, light, equipment and adjacent spaces.

    • Internal Walls: Internal load gains from the adjacent spaces through internal walls

    • Internal Floors: Internal load gains from the adjacent spaces through internal floors

    • Lights: Internal load gains from lights in the space

    • People: Internal load gains from the occupants.

    • Equipment: Internal load gains from the adjacent spaces through electrical equipment

    • Ventilation: Internal load gains through ventilation, note these are only reported when the Ideal Air Load system is used.

  • Latent Gains/Losses [Btu/h (IP) | Watts (SI)]: The portion of cooling load gained or lost representing the amount of energy that is necessary to dehumidify the air in a room.

    • Infiltration: Latent load gains and losses through infiltration between building and outside environment.

    • People: Latent load gains and losses caused by occupants

    • Equipment: Latent load gains and losses generated by operating equipment

  • Simulation Factors [Btu/h (IP) | Watts (SI)]:

    • Breakdown estimate: EnergyPlus calculations peak loads via the Heat Balance method. This method reports a single combined value for all gains and losses at time of peak. In order to report components EnergyPlus runs a secondary method to estimate the gain and losses from each component at that time of peak. The difference between sum of these estimates and the actual peak is reported here.

    • Safety factor represent the added value to the total load to account for the safety factor assigned on the Setting page.

Room Heating Peak Load Details

  • Total Heating Load [Btu/h (IP) | Watts (SI)]: Actual peak heating load for the room taking into account the dynamic nature of individual zone loads that make up the total.

  • Sensible Heating Load[Btu/h (IP) | Watts (SI)]: The component of the total heating load that is sensible.

  • Latent Heating Load [Btu/h (IP) | Watts (SI)]: The component of the total heating load that is latent.

  • Time of Peak: the day and hour of the year when selected room experience the peak heating load.

  • Zone Heating Peak Load Breakdown: Heating peak load is divided into contributing factors to envelope gains and losses as well as internal gains.

  • Envelope Gains/Losses [Btu/h (IP) | Watts (SI)]: The portion of total cooling load that was gained or lost through building envelope.

    • External Walls: Heating load gains and losses through external walls.

    • Ground Walls : Heating load gains and losses through ground contact walls.

    • Roofs: Heating load gains and losses through the roof

    • Ground Floor: Heating load gains and losses through the ground contact floors.

    • Exposed Floor: Heating load gains and losses through floors exposed to outside air.

    • Glazing Conduction and Solar Radiation: Heating load gains and losses through glazing conduction and radiation. Typically the heat gains are divided into two components, the Conduction related to the U-value and the Radiation related to the SHGC. Dividing the heat gains in this fashion is helpful because it allows key characteristics of the glazing, U-value and SHGC, to be considered in regard to their impact on cooling loads. More detail on the glazing calculations can be found here.

    • Doors: Heating load gains and losses through the conduction heat transfer of doors.

    • Infiltration: Heating load gains and losses through infiltration between inside and outside of the building

  • Internal Gains [Btu/h (IP) | Watts (SI)]: The portion of total heating load that was gained through internal loads such as occupant, light, equipment and adjacent spaces.

    • Internal Walls: Internal load gains from the adjacent spaces through internal walls

    • Internal Floors: Internal load gains from the adjacent spaces through internal floors

    • Ventilation: The calculated load due to outside air required for the room at peak heating. Note that the flow rate is determined during heating mode which most typically will have no occupants present, this will lead the ventilation load to reflect the area based air flow only.

  • Latent Gains/Losses [Btu/h (IP) | Watts (SI)]: The portion of heating load gained or lost representing the amount of energy that is necessary to dehumidify the air in a room.

    • Infiltration: Latent load gains and losses through infiltration between building and outside environment.

  • Simulation Factors [Btu/h (IP) | Watts (SI)]:

    • Breakdown estimate EnergyPlus calculations peak loads via the Heat Balance method. This method reports a single combined value for all gains and losses at time of peak. In order to report components EnergyPlus runs a secondary method to estimate the gain and losses from each component at that time of peak. The difference between sum of these estimates and the actual peak is reported here.

    • Safety factor represent the added value to the total load to account for the safety factor assigned on the Setting page.

Room Airflows

  • Supply Air [CFM (IP) | L/S (SI)]: Air volume supplied by the air system into the connected room.

  • Outside Air[CFM (IP) | L/S (SI)]: Air volume of the outside air brought into the room.

  • Return Air [CFM (IP) | L/S (SI)]: Air volume of the air that gets recirculated into the room.

  • Exhaust Air [CFM (IP) | L/S (SI)]: Air volume of the air that gets released into the atmosphere after circulating through the room.

Room Checks

  • Total Cooling [Btu/h/ft²(IP) | W/m² (SI)]: This check provides the total cooling load per served area for the room and is calculated by dividing total cooling peak load to the area of the room.

  • Total Cooling [ft²/ton R (IP)]: Total cooling check reported in ft²/ton of refrigeration.

  • Sensible Cooling [Btu/h/ft²(IP) | W/m² (SI)]:This check provides the sensible cooling load per served area for the room and is calculated by dividing sensible cooling peak load to the area served by the room.

  • Sensible Cooling [ft²/ton R (IP)]: Sensible cooling check reported in ft²/ton of refrigeration.

  • Heating [Btu/h/ft²(IP) | W/m² (SI)]: This check provides the heating load value per square foot area of the room.

  • Cooling [CFM/ft²(IP) | L/s/m² (SI)]: This check provides the cooling air volume flowing into the space per square foot area of the room.

  • Heating [CFM/ft²(IP) | L/s/m² (SI)]: This check provides the heating air volume flowing into the space per square foot area of the room.

  • Outside Air [CFM/ft²(IP) | L/s/m² (SI)]: This check provides the outside air volume per served area for the room and is calculated by dividing outside air flow volume to the area of the room.

Did this answer your question?