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Point-by-Point Photometrics

This section describes how to calculate and display indoor, outdoor, and egress point-by-point photometrics.

Training Videos

Photometrics Overview

Common Photometric Boundary Information​

The values that can be specified for a photometric boundary are listed below.

  •  ☐ Override Schedule Title Whether the schedule title for the current calculation area is to be changed from the default calculation schedule title.

  •  Schedule Title: The title to be used in the calculation schedule for the calculation area. This field can be modified if the ☐ Override Schedule Title box is checked.

  •  Grid/Illuminance Level Spacing: The distance between points where illuminance levels will be calculated. See the Distance Input Format section for more information about specifying this distance.

  •  Calculation Elevation: The elevation of the floor within the calculation area. See the Distance Input Format section for more information about specifying this elevation.

  •  Top Elevation: This is the elevation at the top of the slope. See the Distance Input Format section for more information about specifying this elevation.

  •  Bottom Elevation: This is the elevation at the bottom of the slope. See the Distance Input Format section for more information about specifying this elevation.

  •  🔘 Boundary Obstructions Whether the area has a ceiling and walls.

    •  None The area has no ceiling or walls.
    •  Ceiling The area has a ceiling.
    •  Ceiling and Walls The area has a ceiling and walls. This setting prevents light generated from light fixtures outside the boundary from affecting the photometric calculations.

  •  Ceiling Height: The height of the boundary ceiling. This setting is available if 🔘 Boundary Obstructions is set to Ceiling or Ceiling and Walls. See the Distance Input Format section for more information about specifying this height.

  •  Surface Reflectance: The percentage of light reflected by the boundary. This setting is available if 🔘 Boundary Obstructions is set to Ceiling or Ceiling and Walls, and is only used if reflections are enabled in the calculation.

  •  ☐ Calculate Vertical Illuminance Levels (At Area Boundary) Whether vertical illuminance levels are to be calculated along a calculation line or at the edges of a calculation area.

  •  Vertical Calculation Spacing: The distance between points where vertical illuminance levels will be calculated.See the Distance Input Format section for more information about specifying this distance.

  •  Vertical Display Spacing: The distance between vertical calculation points as they are displayed on the drawing.See the Distance Input Format section for more information about specifying this distance.

  •  Ending Vertical Calculation Elevation (Above Slope): The maximum height at which vertical illuminance levels will be calculated. See the Distance Input Format section for more information about specifying this elevation.

    If the calculation area is sloped, the Ending Vertical Calculation Elevation Above Slope specifies the maximum vertical distance above each point along the slope. For example, an area with a Top Elevation of 30 and an Ending Vertical Calculation Elevation Above Slope of 10 will calculate illuminance levels from 30' to 40' at the top of the slope.

Common Photometric Solid Information​

The values that can be specified for a photometric solid are listed below.

  •  Starting Elevation: The elevation at which the photometric solid starts. See the Distance Input Format section for more information about specifying this elevation.

    If this is 0 and the object is a closed area, no values inside the object will be calculated or displayed.

    If this is greater than 0, the light levels underneath the object will be calculated. This setting can be used to model overhangs.

  •  Ending Elevation: The elevation at which the photometric solid ends. See the Distance Input Format section for more information about specifying this elevation.

    If this elevation is lower than the elevation of a light fixture, some light will pass over the object.

  •  Reflectance: The percentage of light reflected by the photometric solid. It is only used if reflections are enabled in the calculation.

Point-by-Point Photometrics Calculations​

There are two types of point-by-point photometric calculations available: general and egress. Each calculation uses separate fixtures, separate fixture lumens, and separate layers.

General vs. Egress Light Fixtures, Lumens, and Layers​

Each calculation uses a separate set of light fixtures. Each light fixture on the drawing can be marked as being included in the general lighting calculation, egress lighting calculation, both calculations, or neither calculation. This is important for egress calculations, as only certain light fixtures will be on during an emergency situation. See the Insert Light Fixture section for more information about specifying whether a light fixture is used for general or egress calculations.

In the light fixture schedule, the total lumens for the fixture can be set differently for the general calculation and egress calculation. This is important for egress calculations for fixtures, as only certain lamps will be on in an emergency situation. See the Common Light Fixture Information section for more information about lumens settings.

Light fixtures included in the egress calculation can be inserted on a separate layer from other light fixtures. The separate layer allows you to create a view of the drawing with only general or egress light fixtures included. See the Layers section for more information.

Multiple Calculation Areas and Lines​

Multiple general and egress calculation areas and lines can be defined on a single drawing. The general boundaries include the light from all general lights on the drawing. The egress boundaries include the light from all egress lights on the drawing.

Reflections​

Reflections from buildings and walls can be included in the calculation. The walls for each boundary have a reflectance value that is used to calculate the amount of light that they reflect. For outdoor photometrics, this reflection results in slightly higher values near buildings. For indoor photometrics, wall reflections are an important component of the calculation.

Reflections from the ceiling can also be included in the calculation. The ceiling height and reflectance values are set when an area is first inserted and can be modified using the Query Calculation Area or Solid command.

IES Files​

The illuminance level at each point within a defined boundary is calculated using the IES file for each light fixture. See the Common Light Fixture Information section for more information about light fixture IES files.