Cooling Design Detailed Results

The 'Analysis' tab has detailed half-hourly cooling design results (displayed as a line graph by default).

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

• Air Temperature - the calculated average temperature of the air.
• Radiant Temperature  - the (area * emissivity) weighted average of the zone inside surface temperatures.
• Operative Temperature - The mean of the mean internal air and mean radiant temperatures.
• Outside Dry-Bulb Temperature.

• Glazing - the total heat flow to the zone from the glazing, frame and divider of exterior glazing 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]

• Walls - heat gain due to conduction through all external walls, including the effect of solar radiation and longwave radiation to the sky.
• Roofs - heat gain due to conduction through all external roofs, including the effect of solar radiation and longwave radiation to the sky.
• Ceilings (int) - heat conduction gain through internal ceilings (e.g. zone above is colder).
• Floors (int) - heat conduction gain through internal floors (e.g. zone below is colder).
• Floors (ext) - heat conduction gain through external floors (not ground floor, e.g. floor in cantilevered space, roof eaves etc).
• Ground floors - heat conduction gain through ground floors.
• Partitions (int) - heat conduction gain due to heat conduction through all internal partitions from adjacent zones at different temperatures.
• Doors and vents - conduction heat gain through doors and vents.

• External Infiltration - heat gain through air infiltration (non-unintentional air entry through cracks and holes in building fabric).
• External Vent - heat gain due to the entry of outside air through natural and mechanical ventilation (as defined on the HVAC tab). You can exclude mechanical ventilation from the cooling design calculations by unchecking the 'Mechanical ventilation On' Model data.
• Internal Natural Ventilation - heat gain from other zones due to air exchange through open internal windows, doors, vents, holes and virtual partitions.
• 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 -  (used to be called 'Transmitted solar gains'). Short-wave solar radiation transmission through 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 radiation that passes between the slats and diffuse radiation from beam-to-diffuse reflection from the slats. Solar re-reflected back out of the external window and 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 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. Cooling always shows as a negative heat gain in the results. It is best thought of as part of the zone heat balance.

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

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.
• Total Cooling - depending on the Sizing method:
• for the default ASHRAE sizing method 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.
• for the 2-Unitary DX Sizing method - 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.
• Sensible Cooling - depending on the Sizing method:
• for the default ASHRAE sizing method 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.
• for the 2-Unitary DX Sizing method Sensible Cooling is sensible only cooling heat transfer from the cooling coil to the supply air. Latent coil heat can be calculated as the difference: Total Cooling - Sensible Cooling.

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

You can also customise the data and the way it is displayed using the Display Options panel.