Simulation Detailed Results

The main Display options are in the bottom left of the screen. They allow you to control the content of the Detailed data and also the Display style.

The 'Analysis' tab has detailed simulation results (displayed as a line graph by default).

See also the Analysing results in DesignBuilder’s interface and Simulation Manager and Results viewer tutorials

For more on how the output is calculated see: Calculation of DesignBuilder Output from EnergyPlus Report Variables.

Environmental/Comfort Output

• Air Temperature - the calculated average temperature of the zone air.
• Radiant Temperature  - the (area * emissivity) weighted average of the zone inside surface temperatures.
• Operative Temperature - the mean of the zone air and radiant temperatures.
• Outside Dry-Bulb Temperature.
• Relative Humidity - the calculated average relative humidity of the air.
• Fanger PMV - Fanger Predicted Mean Vote calculated according to ISO 7730.
• Pierce PMV ET - the Predicted Mean Vote (PMV) calculated using the effective temperature and the Pierce two-node thermal comfort model.                
• Pierce PMV SET - the Predicted Mean Vote (PMV) calculated using the 'Standard' effective temperature and the Pierce two-node thermal comfort model.                
• Pierce Discomfort Index (DISC) - the Discomfort index calculated using the Pierce two-node thermal comfort model.
• Pierce Thermal Sens. Index (TSENS) - the Thermal Sensation Index (PMV) calculated using the Pierce two-node thermal comfort model.
• Kansas Uni TSV - the Thermal Sensation Vote (TSV) calculated using the KSU two-node thermal comfort model.
• Discomfort hrs (summer clothing) - the time when the zone is occupied that the combination of humidity ratio and operative temperature is not in the ASHRAE 55-2004 summer clothes region.
• Discomfort hrs (winter clothing) - the time when the zone is occupied that the combination of humidity ratio and operative temperature is not in the ASHRAE 55-2004 winter clothes region.
• Discomfort hrs (all clothing)  - the time when the zone is occupied that the combination of humidity ratio and operative temperature is not in the ASHRAE 55-2004 summer or winter clothes region.

More on Comfort Analysis...

Fabric and ventilation

• Glazing  - the total heat flow to the zone from the glazing, frame and divider of exterior glazing through conduction (i.e. excluding transmitted short-wave solar radiation which is accounted for in Solar Gains Exterior Windows below).

For windows without an interior shading device this heat flow is equal to:

+ [Convective heat flow to the zone from the zone side of the glazing]

+ [Net IR heat flow to the zone from zone side of the glazing]

– [Short-wave radiation from zone transmitted back out the window]

+ [Conduction to zone from window frame and divider, if present]

Here, short-wave radiation is that from lights and diffuse interior solar radiation.

For windows with an interior shading device this heat flow is equal to:

 [Convective heat flow to the zone from the air flowing through the gap between glazing and shading device]

+ [Convective heat flow to the zone from the zone side of the shading device]

+ [Net IR heat flow to the zone from the zone side of the glazing]

+ [Net IR heat flow to the zone from the zone side of the shading device]

– [Short-wave radiation from zone transmitted back out the window]

+ [Conduction to zone from window frame and divider, if present]

Note: The Glazing conduction gain is only displayed when the Allow custom outputs option is selected, or when generating opening level outputs using the Store surface output and Store opening outputs along with the Glazing Heat Gain and Solar Transmitted opening outputs. It is not generated when Allow custom outputs is switched off.

• Walls - Sum of heat gains to the zone from external wall inner surfaces plus all heat gains through linear thermal bridges.
• Roofs - Sum of heat gains to the zone from external roof inner surfaces.
• Ceilings - Sum of heat gains to the zone from ceiling inner surfaces.
• Floors - Sum of heat gains to the zone from internal floor inner surfaces.
• Floors (ext) - Sum of heat gains to the zone from external floor inner surfaces (e.g. floor in cantilevered space, roof eaves etc, not ground floors).
• Ground floors - Sum of heat gains to the zone from ground floor inner surfaces.
• Partitions - Sum of heat gains to the zone from internal partition inner surfaces.
• Doors and Vents - Sum of heat gains to the zone from door and vent inner surfaces.
• External Infiltration - heat gain through air infiltration (non-unintentional air entry through cracks and holes in building fabric) when using Scheduled natural ventilation option.
• External Natural Vent - heat gain due to the entry of outside air through natural ventilation, as defined on the HVAC tab, when using Simple natural ventilation option.
• Internal Natural Vent - for Calculated nat vent, this output includes heat gain from other zones due to air exchange through open internal windows, doors, vents, holes and virtual partitions. For Schedule nat vent, it includes the thermal impact of any Interzone Airflow paths.
• External Mechanical Vent  - heat gain due to the entry of outside air through the air distribution system.  You can exclude mechanical ventilation from the cooling design calculations by unchecking the 'Air Distribution On' Model Data.
• External Air - heat gain due to the entry of outside air through external windows, vents, doors, holes and cracks when using Calculated natural ventilation option.
• Mixing Air - heat gain due to the entry of inside mixing air through internal windows, vents, doors and holes when using Scheduled natural ventilation option.

Note: Surface conduction data for Walls, Roofs, Ceilings, Floors, Partitions and Doors and Vents represents the heat conduction flow just below the surface of the construction and so includes all surface heat transfer mechanisms (convection, long and short-wave radiation).

Airflow

• Mech Vent + Nat Vent + Infiltration - The sum of outside air (in ac/h) flowing into the zone through:
• The HVAC air distribution system +
• Infiltration +
• Natural ventilation +
• Airflow through earth tubes (mechanically or naturally driven)

Note: You will usually see a small difference in air changes per hour (ac/h) between the sum of mechanical and natural ventilation and infiltration values you entered on in model data and the values reported in simulation results. This is caused by the method used to calculate and report ac/h in EnergyPlus. ac/h is reported including consideration of the air density and the exact values displayed will depend on the density of the outside air being introduced into the building relative to the density of the zone air. Cooler air is of course more dense than warmer air. More specifically, the design volume flow rate entered in ac/h is converted to mass flow (kg/s) during the simulation using the current outdoor air density. The simulated mass flow rate is then reported back out in indoor air density (for infiltration and natural ventilation) or EnergyPlus standard air density for HVAC system outside air, neither of which will ever (or extremely rarely) match the outdoor air density. So, the ac/h outputs will never exactly match the inputs. The difference between input and reported ac/h will normally be less than +/- 10%. At times when the outside air is cooler than inside there will be an underestimate of ac/h and when it is warmer there will be an overestimate. The difference between input and output values is in proportion to the difference in inside and outside air temperature.

Internal Gains

• Task Lighting - heat gain due to task lighting.
• General Lighting - heat gain due to general lighting.
• Miscellaneous - heat gain due to miscellaneous equipment.
• Process - heat gain due to process equipment.
• Catering - heat gain due to cooking.
• Computer and Equipment - heat gain due to computer and other IT-related equipment.
• Occupancy - sensible gain due to occupants.  Please note that this can vary depending on the internal conditions.  With very high temperatures the sensible gain can drop to zero with all cooling effects taking place through latent heat transfer.
• Solar Gains Exterior Windows -  Short-wave solar radiation transmission through all external windows. For a bare window, this transmitted radiation consists of solar radiation passing through the glass and diffuse radiation from solar reflected from the outside window reveal, if present. For windows with a shade, this transmitted radiation is totally diffuse (shades are assumed to be perfect diffusers). For windows with a blind, this transmitted radiation consists of beam + diffuse short-wave radiation that passes between the slats and diffuse radiation from beam-to-diffuse reflection from the slats. The heating effect of solar radiation on opaque roofs and walls is accounted for in the Roofs and Walls fabric heat conduction data. Any solar radiation re-reflected back out of the external window or transmitted through interior windows is not subtracted.
• Solar Gains Interior Windows -  Total beam + diffuse solar radiation transmission through interior windows. Requires the 3-Full interior and exterior solar model option to be set.
• Zone Sensible Cooling - is the overall sensible cooling effect on the zone of any air introduced into the zone through the HVAC system. It includes any 'free cooling' due to introduction of relatively cool outside air and the heating effect of any fans present. Cooling always shows as a negative heat gain in the results. It is therefore not the same as a cooling coil energy delivery when mechanical ventilation is involved. It is best thought of as the overall HVAC cooling contribution to the zone heat balance.More on this below.
• Zone Sensible Heating - is the overall sensible heating effect of any air introduced into the zone through the HVAC system including any 'free heating' due to introduction of relatively warm outside air and the heating effects of fans. It is therefore not the same as a heating coil energy delivery when mechanical ventilation is involved. It is best thought of as the overall HVAC heating contribution to the zone heat balance. More on this below.

Surface heat gain data refers to heat transfer from the inside surface of the building elements to the zone.

Note: taken together the Internal gains and the Fabric and ventilation data above give an approximate Zone Heat Balance, i.e. the data represents all of the heat flows into and out of the zone.

Heat Balance Technical Note

 

It is important to understand when looking at the Zone heat balance data that the values do not necessarily add to exactly to zero. Factors which have a bearing on this are:

 

1. Solar radiation values reported by EnergyPlus are gross values and do not account for the radiation re-reflected back out of internal and external windows. EnergyPlus tracks solar radiation in full detail but does not report all of the calculated values.

2. Also bear in mind that solar and some internal gains are mostly radiative gains and find their way into the fabric whereas the cooling is to the air. In thermal modelling terms it is not possible to make a simple heat balance of heat which is added to different parts of the thermal network. More specifically, heat transfer gains between the zone and the surfaces cannot be added directly to ventilation gains because they are to different 'points' in the zone heat balance (surface heat transfer is to the 'rad-air' point and ventilation is to the 'air' point).

3. Minor EnergyPlus inaccuracy in reporting of conduction through window frames causes a minor error (~1%) in Glazing heat gain reported values. This does not affect the rest of the simulation, it is just in the Glazing heat gain report.

4. There are issues such as heat conduction through walls, floors, roofs etc and diurnal storage of heat in thermal mass, especially in thermally massive buildings to take into account. When doing heat balances make sure to view data over a reasonable period (> week) to avoid such thermal storage issues.

System Heat Flows

These heat flows are plotted on the System Energy axes:

• Zone Heating - energy supplied by local room heaters and reheat coils to maintain room internal heating temperature setpoint temperature when using Detailed HVAC data.
• Radiant + Convective Heating - energy provided by heated floors to the floor construction. Check the Ground Floors and Internal Floors zone heat balance outputs to see the heat transfer from the floor to the zone itself.
• Total Cooling is the rate at which total energy (sensible and latent) is removed from the mixed outside and return air stream in order to bring the mixed air stream to the specified temperature and humidity ratio of the supply air stream. Total Cooling also includes any cooling energy provided by radiant cooling systems.
• Sensible Cooling is the rate at which sensible energy is removed from the mixed outside and return air stream in order to lower its temperature to the specified temperature of the supply air stream. Any energy needed for moisture addition or removal is ignored.

What is the difference between Zone Sensible Heating/Cooling (on the Heat Balance graph) and Zone Heating, Sensible/Total Cooling (on the System Energy graph)?

 

The Zone Sensible Heating is the heating effect of the HVAC system action on the zone heat balance, or in other words, the heating effect of introducing air that is warmer than the zone air. Likewise Zone Sensible Cooling is the cooling effect of the HVAC system on the zone. Note that these are not always directly related to heating and cooling coil energy delivery, especially because of the effect of free cooling from outside air. So for example even if there is no cooling coil operational at a particular time, the Zone Sensible Cooling output on the Heat Balance graph can be high due to introduction of relatively cooler outside air into the space through mechanical ventilation. These Zone Sensible Heating/Cooling outputs will also include a component due to fans (if operational) which will tend to warm air that moves through it. The Zone Heating data in the System energy graph is the energy provided by zone heating equipment such as reheat coils and radiators/baseboard units. Likewise Sensible and Total Cooling report the sensible and total energy transferred by cooling coils to the air stream.

• Preheat - energy supplied by preheat coils to temper the outside air before it enters the outside air mixing box when using Detailed HVAC data.
• AHU Heating - energy supplied by the AHU heating coil when using Detailed HVAC data.
• Chiller Load - cooling energy supplied by the chiller.
• Total Cooling - at building level: sensible + latent cooling transfer to the supply air from the AHU cooling coil + any single zone unitary and fan coil units in the building. At zone level: sensible + latent cooling transfer to the supply air from a single zone unitary or fan coil unit. Note that any differences between Total Cooling and Chiller Load outputs are typically caused by the thermal inertia of the water in the chilled water loops. These differences will be most noticeable for data at hourly and sub-hourly intervals.
• Sensible Cooling - sensible only cooling transfer from the cooling coil to the supply air. Latent coil heat can be calculated as the difference: Total Cooling - Sensible Cooling.
• Heat Recovery Sensible Cooling - the sensible cooling rate of the supply air by the heat exchanger. This rate is determined using the supply air mass flow rate through the heat exchanger unit, the supply air inlet and outlet conditions, and the specific heat of the inlet supply air. A positive value is reported if the supply air is cooled by the heat exchanger, else the rate is set to zero.
• Heat Recovery Total Cooling - the total cooling rate of the supply air by the heat exchanger. This rate is determined using the supply air mass flow rate through the heat exchanger unit, and the enthalpy of the supply air entering and leaving the unit. A positive value is reported if the enthalpy of the supply air is decreased by the heat exchanger, else the rate is set to zero.
• Heat Recovery Sensible Heating - the sensible heating rate of the supply air by the heat exchanger. This rate is determined using the supply air mass flow rate through the heat exchanger unit, the supply air inlet and outlet conditions, and the specific heat of the inlet supply air. A positive value is reported if the supply air is heated by the heat exchanger, else the rate is set to zero.
• Heat Recovery Total Heating - the total heating energy added to the supply air by the heat exchanger.

Building Level Only

Fuel breakdown

The data for fuel consumption for building level broken down by end-use:

• Heating - total fuel consumption due to operation of heat generators such as boilers and heat pumps.
• Cooling- total chiller fuel consumption plus any fuel consumption due to DX cooling coils, air-cooled chiller condenser fans and evaporative coolers.

• Heat rejection - cooling tower fan electric consumption.

• Fans - total electrical energy consumed by HVAC fans (only available in Simple HVAC when using the Separate fans and pumps model option).
• Pumps - total electrical energy consumed by HVAC pumps (only available in Simple HVAC when using the Separate fans and pumps model option).
• Auxiliary Energy - total electrical energy consumed by HVAC fans and pumps (Simple HVAC only and only when using the NCM model option).
• Preheat - heating energy transferred from main plant preheat coils to HVAC system air when using Detailed HVAC data.
• Lighting - electricity consumed by general and task/display lights.
• Room Electricity - electricity consumed by room equipment other than lights (computers, equipment, process etc).
• Room Gas - gas consumed by room equipment (miscellaneous, process and catering)
• Room Oil - oil consumed by room equipment (miscellaneous, process and catering)
• Room Solid - solid fuel (such as coal) consumed by room equipment (miscellaneous, process and catering)
• Room Bottled gas - bottled gas (propane) consumed by room equipment (miscellaneous, process and catering)
• Room Other - other fuel consumed by room equipment (miscellaneous, process and catering)

Fuel totals

Total fuel consumption for building, data available at building level only:

• Electricity  - total building electricity consumption.
• Gas - fuel consumption total building gas consumption.
• Oil - total building or oil consumption.
• Solid - total building solid fuel consumption.
• Bottled gas - total building gas consumption.
• Other fuel consumption - total consumption of all other fuels.

CO2 emissions

Total carbon dioxide emission for building, data available at building level only:

• CO2 emissions - total CO2 emissions mass. This is calculated from fuel consumption totals (above) and the fuel emission factors for the region.

Site Weather data

Weather data stored at the site level and derived from the hourly weather file:

• Outside Dry-Bulb Temperature
• Outside Dew-Point Temperature
• Direct Normal Solar
• Diffuse Horizontal Solar
• Wind Speed
• Wind Direction
• Atmospheric Pressure
• Solar Altitude
• Solar Azimuth

Note: Although Site weather data is stored at the Site level, it can be displayed at Building, Block, Zone, Surface and Opening levels too. When at Building level or lower the site weather reported by EnergyPlus is displayed, but at site level, the data stored in the epw file itself is displayed. You will therefore notice small differences in site weather data when viewing at site level compared with other levels.

Note: If the data in the hourly weather file itself is changed then the corresponding simulation site weather within DesignBuilder must be manually updated for correct display at site level. You can do this at site level by pressing the Update button or by pressing <Ctr>l-U.

Surface and Opening Levels

• Inside Surface Temperature - temperature at the inside surface of the surface or opening.
• Outside Surface Temperature - temperature at the outside surface of the surface or opening.
• Surface Heat Gain - heat gain from the inside surface of the main opaque part of the surface into the zone, excluding any effects from openings.
• Glazing Heat Gain - total conductive heat gain into the zone, minus any solar gains for openings.
• Solar Incident - total long-wave and short-wave incident solar gain received on the outside surface of a surface or opening.
• Solar Transmitted - total long-wave and short-wave solar gain transmitted through a window opening.
• External Sunlit Fraction - The average fraction of a surface or opening that receives direct solar gain.
• Internal Convective Heat Transfer Coefficient - the average internal convective heat transfer coefficient over the interval for surfaces and openings.
• External Convective Heat Transfer Coefficient - the average external convective heat transfer coefficient over the interval for surfaces and openings.
• Airflow - data is available at both surface and opening level. At surface level the data includes only infiltration through the opaque part of the parent surface and does any flow through the openings contained on the surface. At opening level the flow includes both natural ventilation through the main opening and also infiltration through gaps. Window infiltration is defined by the selected crack template. Positive flow is flow into the zone and negative airflow is flow out. This is true for both red and blue Airflow data.

Hourly and Sub-Hourly Results Times

The times on the x-axis for hourly and sub-hourly results refer to the time at the end of the period. So for example hourly results data for 10am refers to the period 9am to 10am.

Note also that the x-axis times in the results refer to "standard" time without any daylight saving correction applied and not the "clock" time used in schedules. This means that when viewing gains results (for example) in the summer periods with an hour of daylight saving time applied you will see the gains starting an hour earlier than in the winter.

Time values that appear in schedules refer to clock time and, while the gains would be simulated as starting at the same (clock) times as defined in the schedules in summer and winter, you may see what at first sight seem like discrepancies between scheduled start/end times and outputs until you consider the points above.