Thursday, November 21, 2013

Room Area Net vs Gross

When it comes to documenting room area we have one global setting called Room Area Computation, found in the Area and Volume Calculations dialog.

We get to choose from four options that affect the entire project's room area calculations: Wall Finish, Wall Center, Wall core Layer and Wall Core Center. Wall Finish tends to work for net area calculations while Wall Center works better for gross area.

When we need to be able to show both net and gross one approach we can take is to use Area elements and Area plans. Unfortunately area and room objects are totally ignorant of one another. That means an area plan using area elements is NOT a room so we've got a lot of redundant data entry to deal with. Another way to deal with it is to print sheets with the Room Area Computation set for one condition and then switch to the other setting for other sheets intended for that condition. We'll need some "redundant" views with tags etc. but perhaps it will provide the necessary differences required.

Another possibility if we are using Revit, the version that includes all the disciplines tools, is to take advantage of MEP Spaces. They ignore the Room Area Computation setting, they only reference Wall Finish. This means I can create a space for each room, yes some redundancy. I can use the Space Naming Utility (subscription extension) to pass the name and number of the related room to the space name and number parameters so I don't have to enter the redundant information. The end result could look something like this, where I use a plan focused on spaces and another focused on rooms to show both net and gross area calculations.

This nexst image is Gross Area using Wall Centerline as the Room Area Computation settings.

This image is the Net Area using Spaces instead, leaving the Room Area Computation the same as for the above.

This is using Area elements instead matching names and numbers manually. The API might be able to be harness to resolve this to some degree.

Something to consider.


Luke Johnson said...

The other cool thing about Spaces is that you can "graphically" group them using Zones... mentioned here

Anonymous said...

When I first read this I thought it would cause problems in the MEP model - I tried ElumTools and Revit's Energy Simulation and did not see any issues.

The MEP folks would need to be aware of Spaces in an Arch model if they are creating schedules (with include linked data checked).

Rather than using the Space Renaming utility, the space tag can be edited to show room name and room number (which is based on a space occupying the same area as a room).

One more thing users need to be aware of: gross area is missing half of all the exterior walls.

Dan Stine