Can anyone explain the difference in room/space area in the attached screenshot from Revit 2013? One is a room schedule and the other is a space schedule with an embedded room schedule. The rooms are in a linked file that has the architectural room area computation set to at wall center. The spaces also have room area computation set to at wall center. There is no option to schedule the room area parameter in the space schedule. So why would the room area in the room schedule be larger than the space area in the space schedule in the same model? In this day and age of LEED certification, there is such an emphasis on the entire design team reporting the same building area that this is pretty important stuff and Revit should be a good tool to achieve consistency.
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Obviously, it's not a rounding issue as the discrepancies are quite significant...............I vaguely remember running a ccross this awhile back.............let me do some mental digging........
Room Schedules use the face of the wall to calculate area, while area plans will use wall centerlines, exterior wall faces of exterior walls, glazing lines of windows, etc.
They use a different set of rules to calculate area.
Scott,he was comparing Rooms to Spaces........Not area plans, which would be different, correct?
oops, yeah, you are right. Sorry, i read "Areas" vs Rooms, when the question was clearly about "Spaces" v Rooms.
The setting for Room Area Computation only affects Rooms. For scheduling and display in the view, it will always show that space area value calculation to wall finish.
There is an article written in this regard here: http://cadshack.blogspot.com/2011/12/revit-rooms-v
The article refers to the documentation in Revit found below: http://wikihelp.autodesk.com/Revit/enu/2013/Help/0
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Hmmm. The USGBC definition for floor area is based on the ASHRAE 90.1 energy standard definition and is as follows:
Gross Floor Area: (based on ASHRAE definition) Sum of the floor areas of the spaces within the building, including basements, mezzanine and intermediate‐floored tiers, and penthouses with headroom height of 7.5 ft (2.2 meters) or greater. Measurements must be taken from the exterior faces of exterior walls OR from the centerline of walls separating buildings, OR (for LEED CI certifying spaces) from the centerline of walls separating spaces. Excludes non‐enclosed (or non‐enclosable) roofed‐over areas such as exterior covered walkways, porches, terraces or steps, roof overhangs, and similar features. Excludes air shafts, pipe trenches, and chimneys.
We take this to mean that center-to-center space areas should be used for all load calculations and energy modeling. Interestingly, ASHRAE 62.1 for ventilation uses a definition based on inside surfaces of walls. We use the energy standard definition for all of our calculations for consistency and because it results in more stringent requirements for ventilation.
The space size information exported in a gbxml file from Revit MEP is less than required by these definitions. I will point this out to the development group.
Our industry should standardize these definitions. Does anyone have a contact at ASHRAE who could help move this issue forward?