Revit Tip – Need length parameter in a MEP Multi-Category Schedule?

by Dennis Collin

One of the many benefits of Revit is the ability to create and produce coordinated schedules of building components whether they are plumbing fixtures, pipework, fittings, ductwork, or electrical fittings.

A schedule is just another view type from a plan with a tabular listing of components and associated parameters. This will update with any model changes within the project. Schedules are available in several forms. Category Specific schedules and Multi Category (MC) which are more comprehensive in what categories are listed.

When creating a Duct Schedule for example, Revit will list relevant data for the ductwork, listing such properties as length, elevation of ductwork, system type, flow, friction and velocity etc.

Fig 1. Category specific pipe, duct, cable tray and conduit schedules can display length properties.

These categories can be transferred into schedule header positions and quantities viewed, totalled and filtered etc. The schedule can be exported to MS Excel or placed on a sheet for plotting, printing, or publishing to a digital print format like PDF.

Fig 2. Multi Category Schedules lack the ability to read the OOTB length parameter for MEP services!

At times however, it is required to have a schedule listing multiple categories such as ductwork, fittings, accessories and air terminals. Whilst different views can be placed adjacent on a sheet, it may be required to list them into a single schedule. This is where multi-category schedules are useful. However, due to its more generic nature the multi-category (MC) schedule does not have specific parameters like length or invert level which may be specific to just one category. Instead, it lists common parameters like family name, category and type comments. However, fittings may also have a length parameter to be shown along with the relevant ductwork, so what can a user do to remedy the situation?

Fig 3. Dynamo scripting will be used to extract length values and push the data to the “Actual Length’ property.

If the desired fittings have shared parameters defined, they will appear in the multi-category schedule BUT the out of the box (OOTB) length parameter for the duct/pipe/tray system family will not. Therefore, to bring the length parameter of the example ductwork into the ‘MC’ schedule a Dynamo script needs to be used to pull the different parameters together.

The Dynamo editing environment can be accessed from the manage tab on Revit’s Ribbon menu. Within Dynamo each of the categories needs to be selected and have their ‘length’ parameters harvested into a list of lengths. This list can then be ‘pushed’ to a new user defined length parameter that contains not just duct/pipe/cable tray length but also fittings and accessory length values too!

Fig 4. Simple Dynamo Script to merge all length parameters into a single length data column!

This can be achieved via the Category Selection, Select all elements and the GetParameterByName nodes. This will form our length listings from Fittings, Accessories and Ductwork. These lists can then be ‘pushed’ using the SetParameterByName node to a custom Shared or Project parameter ‘ Actual Length’ resulting in a schedule result displayed in Fig 5.

Fig 5. Ductwork and Fittings Actual Length value populated by a mix of OOTB and custom parameters!

The MEP disciplines are not alone in these kinds of challenges. A similar approach can be used within Structures to combine columns and frames into a singular table, or have Door and Window elements combined into a single schedule. I will post about these separately.

Revit Tips and tricks, advanced scheduling, Revit parameter types and keyboard shortcuts etc are just some of the topics that we offer on our training and webinar sessions. Visit our Arkance UK site to get an overview of the courses on offer and talk to one of the team for dates and availability or if you have more bespoke requirements please get in touch, we’re here to help!