In this lesson we're going to model parametric runs using global parameters. More specifically, we're going to evaluate the most common thing-- lights. We first need to create a global parameter. To do this we need to be in any of the modules, and we need to be in detailed mode. If we right click on the project, we can create a global parameter. We have to give it a name and we're going to call this “LPD.” It's always a good idea to give it a name of what it is going to be because you could have multiple global parameters. The type is going to be numeric, and the parameter value is going to be 1.2 watts per square foot. Leave the label out of it for now since this is just a numeric value. Once we click OK it's going to list the global parameter added to our current list of global parameters.