Placing light families with accurate photometric values along with manufacturer-specific IES files, allows Revit to calculate average estimated illumination without the use of third party software.

This post shows how to develop comprehensive Revit Lighting Fixture Type Catalogs for manufacturer-specific fixtures. Various photometric definitions are explained and how Revit uses these definitions to accurately calculate Photometric Parameters.

Lighting Fixture Family Category

There are two basic types of light fixture families. Those that have a Light Source and those that do not. For the purposed of this article, we will need to make sure that the Light Source box is checked. This will grant is access to all the powerful parametric capabilities Light Sources offer, allowing us to develop Revit Lighting Fixture Type Catalogs for manufacturer-specific catalog numbers lamping.

Initial Intensity Parameters

First, let’s look at the photometric parameter in Revit named Initial Intensity. Initial intensity includes settings for Wattage and Efficacy which are the parameters that determine values for Luminus Flux, Luminous Intensity, and Illuminance. Here is an HTML version of the same calculator that runs in Revit.

Luminous Flux

Luminous flux, or luminous power, is the measure of the perceived power of light and must be factored by the sensitivity of the human eye to establish luminous flux in lumens (symbol: lm). Think of luminous flux as an abstract way of measuring human sensitivity to various wavelengths of light.

Luminous Flux = Wattage ÷ Efficacy
Illuminance = Luminous Intensity ÷ 9.29 (1 square which is equal to approximately 9.29 square metres)
Luminous Intensity = Luminous Flux ÷ 12.5663706 (Solid angle of a complete sphere or 4π steradian which is approximately 12.5663706)

Revit Lighting Parameters

Wattage##ELECTRICAL_WATTAGE##WATTS

Efficacy##ELECTRICAL_EFFICACY##LUMENS_PER_WATT

Luminous Flux##ELECTRICAL_LUMINOUS_FLUX##LUMENS

Luminous Intensity##ELECTRICAL_LUMINOUS_INTENSITY##CANDELAS

Illuminance##ELECTRICAL_ILLUMINANCE##LUX

Using simple math and something called concatenation one can easily add many lamping options to lighting fixture type catalogs.