Calculation Points - Concepts

Calculation points are positioned  in the environment, to represent light meters. You may quantify numerous types of metrics depending on the grid type and analysis option that you select. Metrics available in AGi32 include:

Illuminance - incident light

The Illuminance metric measures the light incident on a surface or workplane -  measured in Footcandles or Lux. Illuminance measurements may be made in Full Calculation mode or Direct Calculation mode. Depending on the calculation mode selected and model, Illuminance measurements may reflect direct and interreflected contributions. The following Calculation types measure Illuminance (some in conjunction with other metrics):

Exitance - reflected light

The Exitance metric measures the light reflected off a surface - measured in lumens per square foot or lumens per square meter. Exitance measurements are only available in Full Calculation mode. The Exitance measurements may reflect direct and interreflected contributions depending on the model. Exitance may be measured by using the Automatic Placement Calculation type and selecting a real, reflective surface.

Luminance - reflected light

The diffuse Luminance metric measures the light reflected off a surface - contained within a volumetric cone with the volume PI. It is measured in candelas per square meter. Diffuse Luminance measurements are only available in Full Calculation mode. The Luminance measurements may include both direct and interreflected contributions incident on the measured surface depending on the model. Diffuse Luminance may be measured by using the Automatic Placement Calculation type and selecting a real, reflective surface.

Daylight Factor

The Daylight Factor metric (DF) measures the ratio of illuminance on a plane in the environment (usually the horizontal working plane) as it compares  to the measured illuminance produced by an unobstructed sky. The result is given as a percentage value (e.g. 75%  of the daylight is reaching this point)  Daylight Factor measurements are only available in Full Calculation mode. These measurements may reflect direct contribution from the sky and interreflected contributions from the model.

UGR - Unified Glare Rating - Discomfort Glare measurement for electric lighting

The Unified Glare Rating metric (UGR) measures discomfort glare from electric lighting in an interior environment. The calculation considers the ratio of luminaire luminance and position compared to the background luminance of the environment. The result in given as a UGR value between 10 and 30, where a high value indicates significant discomfort glare and a low value indicates little discomfort glare. UGR measurements are calculated according to CIE 117-1995 and are only available with the Full Radiosity calculation method.

Roadway Metrics - Pavement Luminance, Illuminance, Veiling Luminance and STV

The Roadway Luminance metrics allow you to create a linear stretch of roadway on which to measure a variety of calculation types. The calculations are performed in accordance with IESNA, British, Brazilian, Australian, New Zealand, or CIE guidelines, whichever the user specifies. Roadway Luminance measurements are available in Full Radiosity and Direct Only calculation methods. The following metrics are available, depending on the roadway standard selected:

The Roadway Luminance metric also allows you to create a linear stretch of roadway to be used in conjunction with an interior environment or other contributing surfaces.

Glare Rating - Disability Glare measurement for electric lighting (direct component only)

The Glare Rating metric (GR) measures disability glare from electric lighting in an exterior environment. The calculation considers the effect of veiling luminance produced by the luminaires as compared to the background luminance of a specified ground plane for an observer within the illuminated plane. The result in given as a GR value between 10 and 90, where a high value indicates significant disability glare and a low value indicates little disability glare. GR measurements are available in Full Calculation or Direct Calculation mode.

Dialog Defaults

The individual parameters available in all Calculation Point dialogs are automatically saved and restored in the Calculation Point dialogs. There are two types of defaults present in all of the dialogs: Global and Local. Global defaults occur in every Calculation Point dialog and carry over to other Calculation Point dialogs as well. Local defaults only occur in specific dialogs. The following defaults are global for all Calculation Point commands.

Reset Defaults - Selecting this button will reset all Global dialog parameters to the factory defined specifications.

Modifying Calculation points

Once placed in the environment you can modify calculation points in many ways. Here are the available options:

Other analysis options