For the spaces in your model to report the correct lighting level, they must be modeled accurately. If the height of the space is short of the ceiling, the lighting fixtures will not be in the space, and thus provide no light to that space. A ceiling can be defined as a room-bounding element, which means that it will define the upper boundary of the space. If you model your spaces
so that their upper limit is higher than the ceiling heights, you can be sure that you are getting accurate volume information for the spaces. When you are placing spaces into the model, set the upper limit to the level above the current level on which you are working to ensure proper volumes. If you have a space that spans multiple ceiling heights, make sure you set the upper limit
appropriately, as shown in Figure 12.1.
Going above and Beyond
Rachel is getting some strange numbers from her lighting calculations. She checks her spaces and finds that the volumes of the rooms at the perimeter of the building are not being calculated to the ceiling, but all the way up to the next level. A quick phone call to her architect reveals that the mechanical designer has requested that the ceilings in these rooms be set so they are not room bounding. This is necessary for accurate heating and cooling load calculations.
Rachel is glad that her file is separate from the mechanical file, because all she has to do is set the upper limit of her exterior spaces to match the ceiling heights.
Space volume is important to the proper calculation of average estimated illumination within a room. The ability to calculate the volume of a space can be turned on or off to help with file performance. If you intend to use Revit MEP to analyze your lighting design, you need to ensure that this setting is turned on. Do this by clicking the Room & Area panel drop-down on
the Architect tab.
Select the Area And Volume Computations tool to access the settings for space volume computations. Choose the setting shown in Figure 12.2 when using Revit MEP for lighting analysis.
You can practice placing and manipulating spaces by doing the following:
1. Open the Ch12_Exercise.rvtfile, which can be downloaded from www.sybex.com/go/masteringrevitmep2012.
2. Link in the architectural model file Ch12_ArchModel.rvt, which can also be downloaded from the book’s website. Use the Auto – Origin To Origin positioning option for placement.
3. Set the property of the linked file to Room Bounding by selecting the link, clicking the Edit Type button in the Properties palette, and selecting the Room Bounding box.
4. Click the Space tool on the Analyze tab.
5. On the Options Bar, set Offset to 8′-0″, and place a space in the large curved room at the right side of the building.
6. Create a Building Section view, looking north through the large room.
7. Open the section view, and select the Space object. (You may have to hover your mouse pointer on the room edges.) Notice that the upper limit is below the ceiling object in the room.
8. Check the instance properties of the space, and verify that the volume is computed under the Dimensions group. If not, go back and set your model to compute volume by adjusting the Area And Volume Computations settings on the Room And Area panel of the Architect tab.
9. Once again, with the Properties palette showing the properties of the space, change the Limit Offset parameter value to 10′-0″and examine the Volume parameter value of the space. You may need to click the Apply button on the Properties palette for the change to take place.
10. Change the Limit Offset parameter value to 12′-0″, and note that the Volume parameter value stays the same. This confirms that the ceiling is acting as a room boundary.
11. Open the 1 – Lighting plan view, and click the Space button on the Analyze tab to place another space in the room located in the upper-right corner of the building. Before placing the space, on the Options Bar, set the upper limit of the space to Level 2, and set the Offset to 0′-0″. Then click in the room to create the space.
12. Create a section view of this room, and select the Space object. Notice that the space extends beyond the ceiling. This confirms that the ceiling is not set to be room bounding.
13. In the section view, select the Space object, and use the grip arrow to stretch the top of the space beyond the roof. Notice that the space fills the entire volume up to the roof.
14. Continue placing spaces in the model, and examine their properties based on the settings you choose on the Options Bar for placement.