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 Simulation Results Tutorial

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

Environmental/Comfort Output

 

More on Comfort Analysis...

Fabric and ventilation

 

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: 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

Internal Gains

 

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.

 

ClosedTechnical 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. It is not currently possible to generate net solar radiation gains from EnergyPlus.
  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:

 

A common question from new users

"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.

Building Level Only

Fuel breakdown

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

 

Fuel totals

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

 

CO2 emissions

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

 

Site Weather data

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

 

Note: Although Site weather data is stored at the Site level, it can be displayed at Building, Block, Zone, Surface and Opening levels too.

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.