Spaces and Lighting

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 recognized as being in the space and thus no lighting data will be seen or be detectable by Revit for that space. The room calculation point feature available in lighting fixture families allows you to associate a fixture with a space even though the fixture is not within the bounds of the space. See Chapter 20 for more information on this feature.

A ceiling can be defined as a room-bounding element, which means that it can define the upper boundary of a 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 (or floors), make sure you set the upper limit appropriately, as shown in Figure 12.1.

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 Architecture tab, shown in Figure 12.2.

Select the Area And Volume Computations tool to access the settings for space volume computations. Choose the setting shown in Figure 12.3 when using Revit MEP for lighting analysis.

You can practice placing and manipulating spaces by completing the following exercise:

1. From www.sybex.com/go/masteringrevitmep2016 download the following files:
   • RMEP2016_Ch12_Dataset.rvt
   • RMEP2016_Sample_Architecture.rvt
2. Open RMEP2016_Ch12_Dataset.rvt. The sample architecture file is linked using the methods described in Chapter 4, “Project Collaboration,” which also describes what to do if the link file does not display.
3. From the Electrical Discipline of the Project Browser, open the floor plan LIGHTING First Floor.
4. Check that the property of the linked file is set to Room Bounding by selecting the link, clicking the Edit Type button in the Properties palette, and selecting the Room Bounding box.
5. Click the Space tool on the Analyze tab.
6. On the Options Bar, set Upper Limit to Second Floor and Offset to 0′-0″ (0 mm), and place a space in the large curved room at the right side of the building.
7. Create a Building Section view looking north through the large room.
8. 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.
9. 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 & Area panel of the Architecture tab, as previously indicated in Figure 12.3.
10. Once again, with the Properties palette showing the properties of the space, change the Limit Offset parameter value to 4′-0″ (1200 mm) 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.
11. Change the Limit Offset parameter value to 6′-0″ (1800 mm), and note that the Volume parameter value stays the same. This confirms that the ceiling is acting as a room boundary.
12. Open the LIGHTING First Floor 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″ (0 mm). Then click in the room to create the space.
13. 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.
14. In the section view, select the Space object, and use the grip arrow to stretch the top of the space beyond the Second Floor. Notice that the space does not come past the Second Floor Slab, indicating that the floor is correctly designated as room bounding.
15. Continue placing spaces in the model, and examine their properties based on the settings you choose on the Options Bar for placement.

The Reflected Ceiling Plan

The first step in creating a well-coordinated lighting plan is to ensure that your reflected ceiling plan is properly set up to display the model in a way that allows you to see all the items necessary to coordinate as you design. Adjust the view range settings of your view so that all ceilings are clearly visible, and turn on any worksets or component categories from other disciplines that may contain items in the ceiling. You can set the categories from other disciplines to halftone to see your lighting layout more clearly. If you are linking in files from MEP consultants, use the visibility control options for linked files to achieve the desired result.

If you intend to display the ceiling grids on your lighting construction documents, you have to make visibility adjustments to ensure that the building model is displayed correctly. Remember that with a reflected ceiling plan, you are looking up at the model, so certain elements, such as plumbing fixtures or windows, may not appear as desired until you adjust the view range and the Visibility/Graphic Overrides. Stairs also display differently in reflected ceiling views than they do in normal plan views. Also, consider that the order of objects is different than in a plan view. A fixture shown below an object in a plan view appears to be above the object in a reflected ceiling plan view. This may have an adverse effect on your construction documents.

Another method for displaying ceiling grids on the construction documents of your project is to create a reflected ceiling plan view that shows only the ceiling objects. This view can be placed on a sheet in the same location as the lighting floor plan view. When placed onto a sheet, the view can be snapped to the same location as the floor plan view so you can be sure of the alignment. This allows you to display the model correctly as a plan view and still be able to see the ceiling grids or surfaces. For best results, you should place the ceiling plan view on the sheet first and then the lighting plan view on top of it.

There is often debate between architects and electrical designers as to whose model should contain the ceilings. Ceilings are not always required in early project submittals, so the architect may not get around to modeling them when the electrical designer needs them. This may prompt the electrical designer to create ceilings in their model in order to begin the lighting design, which can cause coordination issues after the architect begins designing the ceilings in their model. Having duplicate information in multiple models can be a recipe for error. The electrical designer would have to keep the ceilings in the electrical model coordinated with the architect's ceilings and would have to ensure that all model views were displaying the proper ceilings. This extra effort defeats the purpose of using a BIM solution such as Revit MEP and hampers the effort to achieve a coordinated project delivery because it adds another level of manual coordination that creates more opportunities for error.

You may use the option of creating reference planes in your model to host your lighting fixtures temporarily. When the ceilings are placed in the architectural model, you could then re-host your fixtures to them. Another option is to use nonhosted families in your project. Because you cannot replace a nonhosted family with a hosted one, you have to make the decision to use hosted or nonhosted.

Lighting fixtures that are modeled in the architectural model are another thing to consider. Many architects like to create lighting layouts for their design to get a feel for how the rooms will look with lighting fixtures in the ceiling or to create renderings. If the architect uses 3D families to represent the lighting fixtures, this can cause problems for the electrical designer when it comes to using the linked model for hosting. Lighting fixtures in the architectural model will most likely cut a hole in the ceiling where they are placed. An electrical designer who attempts to put a light fixture in the same location as the fixture in the linked file may not be able to do so because there won't actually be a ceiling there. There is also the chance that a face of the fixture in the link hosts the fixture in the MEP file. So if the architect deletes the fixture in their file, the fixture in the MEP file will not have a host and will not respond to changes.

Early in the project, the architect and electrical designer should agree on who will model the ceilings and in which model they will reside. They should also coordinate which types of families will be used if the architect intends to place lighting fixtures in the architectural model. If they need to be modeled in one file initially, they can be copied and pasted into another file if necessary. Another option is to use the Copy/Monitor tool to copy the lighting fixtures from the architectural model. The ultimate goal is to have one ceiling design that all disciplines can use for layout and coordination.

Lighting Worksets

When you're working in a model file with other MEP disciplines, it is best to create a lighting workset to distinguish model elements that would belong to that design system. It may even be necessary to create multiple worksets for lighting systems. Doing so will allow you to divide your lighting design into separate systems (such as interior and exterior) or by floor levels.

This can aid you in controlling the visibility of groups of model elements and can also help multiple users work on different sections of the lighting model at the same time without interfering with each other's designs.

Lighting Fixtures in a Ceiling

Face-hosted lighting fixture families are most commonly used because they can be attached to ceilings in your model or ceilings within a linked file in your model. You can use face-hosted fixtures to represent recessed, surface-mounted, and pendant lights.

The default hosting for a face-hosted family is to a vertical face. To place lighting fixtures onto a ceiling, you need to select the Place On Face option, located on the Placement panel of the contextual tab that appears when placing a lighting fixture family. Lighting fixture families for ceiling-mounted lights should have an insertion point at one corner of the fixture. This lets you align the fixture to the ceiling grid on placement. If the family you are using does not have an insertion point at a corner, place the fixture on the ceiling and use the Move or Align tool to line it up with the grid.

Using the Align tool is great for lining up your fixtures with ceiling grid lines, but it is important that you do not lock the alignment. Face-hosted families do not move with the grid lines when changes are made to the ceiling. Locking the alignment causes constraint errors when the link is updated after the grid has moved. Either way, the lighting fixture stays attached to the ceiling if its elevation changes.

Once you have placed lighting fixtures onto a ceiling, you can copy them where needed. It is important to copy only the fixtures within the ceiling by which they are hosted. If you attempt to copy a face-hosted fixture from one ceiling to another that has a different elevation, you may receive a warning that the new instance of the fixture lies outside its host or that the fixture will remain at the elevation of the original. This will cause the fixture to be in the model without a host or to be above or below the ceiling, which can result in an inaccurate model. If the fixture is not hosted by the ceiling, it will not react to any changes in the ceiling elevation. If the fixture is above the ceiling, lighting calculations will be inaccurate because it will not be inside the space.

The Create Similar command is an easy way to use the same type of fixture family from one ceiling to another. Use this command instead of Copy to duplicate a fixture family in another location. When you use this method, you have to set the hosting option to Place On Face before picking the location of the new fixture. Use the Pick New tool on the Work Plane panel of the Modify | Lighting Fixtures contextual tab to move a lighting fixture from one ceiling to another.

Face-hosted lighting fixture families can be used in areas where a ceiling does not exist. Another choice for placement is to use the Place On Work Plane option. This associates your fixture to a defined plane in the model. Because of the mounting behavior of face-hosted families, it is important to draw your reference planes in the correct direction. Drawing a reference plane from right to left orients the plane properly for overhead lighting fixtures. Drawing from left to right causes your lighting fixture families to be upside down in the model, as shown in Figure 12.11. Based on this, it is my experience that creating your own ceilings for hosting gives the best results. The only thing you need to remember when coordinating is to leave them turned off!

Lighting Fixtures in Sloped Ceilings

Sloped ceilings can of course host lighting fixtures (and anything else that is face hosted, for that matter). Although this is an important feature of Revit MEP, there are some consequences. When the fixture is sloped, the symbolic line representation is no longer visible in a plan view. Figure 12.12 shows the same kind of lighting fixture hosted by a sloped ceiling and another by a flat ceiling. The section view indicates that the fixture is hosted correctly, but the plan view displays the fixture differently.

The fixture that is attached to the sloped ceiling displays the actual fixture geometry at an angle, whereas the fixture on the level surface shows the symbolic lines used to represent the fixture. This is because symbolic lines can be displayed only in a view that is parallel to the plane in which they are created. There is no way to display these symbolic lines when the fixture is sloped. You would need to either add a note to your documents that identifies the sloped fixtures or add the sloped-fixture representation to your symbol legend.

Another option is to use model lines in your lighting fixture family instead of symbolic lines. Model lines display in plan views if the fixture is in a sloped ceiling. When using this method, consider defining subcategories in the lighting family for the fitting body and sloping symbol. This gives you greater control over the look of your family. You wouldn't, after all, want the symbolic model lines showing up in any sections.

Ceiling Changes

Changes to ceilings may require some management of the lighting fixtures in your model. Face-hosted lighting fixtures maintain their association with the ceiling when there is a change in elevation, but you should also be concerned with any lateral movement, especially with grid ceilings.

Lateral movement can have different effects on your lighting fixtures depending on how the grid was placed into the model. Grids that are placed by automatically locating the boundaries of a room do not affect your light fixtures when they are moved laterally. This is true as long as the movement does not cause your fixtures (which won't move laterally with the ceiling) to be located outside the boundaries of the ceiling. If the architect deletes a ceiling and then replaces it, your fixtures will become orphaned when you get the updated architectural file, and they will remain at the elevation of the original ceiling and will no longer respond to changes in the elevation of the new ceiling. You will have to use the Pick New tool to associate the fixtures with the new ceiling.

Ceilings that are created by sketching the shape of the ceiling have a different effect on your fixtures when moved laterally. If the entire ceiling is moved, your light fixtures will remain in their location relative to the ceiling. If a boundary of the ceiling is edited by dragging it to a new location while in sketch mode, your fixtures will remain where they are located; however, any attempts to place new fixtures into the ceiling may cause them to appear outside the host, and you will receive a warning indicating that the fixture has no host. You can use the Pick New tool then to place the fixture into the ceiling.

Because ceilings tend to move around quite a bit in the early stages of a design, you may want to initially consider hosting your lighting fixtures to a reference plane until the major changes have settled down. At that point, you could move your fixtures into the ceilings by using the Pick New tool. In the meantime, encourage the architects you work with to avoid deleting ceilings and simply alter the ones that exist, when possible. Although people do use this option successfully, there are problems with this workflow, which you saw in Figure 12.11.

Overhead Fixtures in Spaces with No Ceiling

Not every building area for which you need to provide lighting will have a ceiling. Having a space with no ceiling does not mean that you cannot use a face-hosted fixture family. Pendant fixtures can be face-hosted to the floor or structure above, as shown in Figure 12.13.

You can also use lighting fixture families that do not require a host object. You have to set and manage their elevations manually. These types of fixtures should have a parameter that lets you define the mounting height, or you can use the Offset parameter.

Wall-mounted Lights

Lighting fixtures can be mounted to walls as well as ceilings. In fact, you can place a face-hosted lighting fixture family on practically any surface. However, you should note that any model element categorized as a lighting fixture does not have the ability to maintain its annotation orientation. This means that you cannot use an annotation symbol nested directly in the family to represent the lighting fixture in a plan view when the fixture is mounted to a vertical face. See Chapter 20 for information on nesting an annotation into lighting fixture families that are mounted on vertical surfaces.

One option to work around this shortcoming is to categorize your wall-mounted lighting fixture families as lighting devices instead of lighting fixtures. This gives you the ability to use a symbol, but it could also result in additional effort to control visibility and to schedule these devices along with all your other lighting fixtures.

Your best option, if you want to use face-hosted families and represent wall-mounted lights with symbols, is to create linework in the family that represents the fixture. Then set the visibility of the linework so that it appears only in front and back views. This is necessary because, with the face-hosted family placed on a vertical face, the fixture is seen from within the plan view from the back. The linework must be done with model lines; therefore, they do not react to changes in view scale. This technique is discussed in further detail in Chapter 20, but as shown in Figure 12.14, it is quite achievable.

The use of nonhosted families for wall lighting is perfectly acceptable. This requires that you manually maintain the association of the fixtures with the walls because you cannot lock the family to the linked wall. With a nonhosted family, you can use an annotation symbol to represent the lighting fixture in a plan view. This works well for exit lights because the actual fixture is typically not shown; rather, a symbol is shown.

Switches

Using face-hosted lighting switch families keeps your switches coordinated with the locations of their host walls. This does not mean that the movement of doors does not affect the hosting of your switches. Because you cannot constrain your switches to a distance from a door in a linked file, if the door moves so that the switch is in the door opening, you will see the warning shown in Figure 12.15 that the switch has lost its association with the host.

You can associate your switches with the lighting fixtures that they operate, provided that the switch family Part Type parameter is set to Switch, as shown in Figure 12.16.

To create a switch system, do the following:

1. Select a lighting fixture, and click the Switch button on the Create Systems panel of the Modify | Lighting Fixtures contextual tab. This changes the ribbon to the Modify | Switch System contextual tab.

   On the System Tools panel of this tab, you have options to select the switch to be used for the system and to edit the system. Editing the system allows you to add or remove elements and view the properties of the switch system. Click the Select Switch button, and select the desired switch in the drawing area.

2. After selecting a switch, you can select additional lighting fixtures to be included in the system by clicking the Edit Switch System button. Click the Finish Editing System button once you have selected all of the fixtures for the system.
3. To view the system, place your mouse pointer over any item that is part of the system and press the Tab key until dashed lines are shown connecting the fixture(s) back to the switch. This highlights the system elements and indicates their connectivity.
4. With the dashed lines highlighted, click to select the system.

A switch system can contain only one switch, so for lighting fixtures controlled by multiple switches, such as three-way switches, you can select only one switch for the system. In the example shown in Figure 12.17, the three-way switch at the top end of the room—marked [1]—would also control the lighting fixtures but cannot be added as part of the switch system highlighted and indicated with dashed lines—marked [2].

Switches can be assigned an ID by using the Switch ID parameter, which helps identify their relationship with lighting fixtures. This parameter exists in families that are categorized as lighting devices. When you select a lighting fixture and access the Switch Systems tab, you see the ID of the switch associated with that light fixture in parentheses, in the System Selector drop-down on the System Tools panel of the tab.

Creating switch systems is independent of any circuiting of the lighting fixtures and switches. You still need to include the switches in the power circuit for the lighting fixtures if you want to remove them from the Unassigned category in the System Browser. Having as many elements as possible assigned to systems helps improve the overall performance of your model.

The Site Plan

If you are working with a civil engineering consultant, it is likely that the engineer is developing the site plan with some sort of CAD software. When the engineer uses a BIM solution, the 3D information (such as elevation points and contours) can be shared with Revit. This is necessary only if you are interested in creating topography within Revit to match the information in the site file. Otherwise, what you require from your civil engineering consultant is just linework that represents the layout of the site. Knowing the layout of parking lots, sidewalks, and major site elements should be enough for you to generate a site lighting design. In one sense, you are working with the site plan in the same manner that you would if you were using a typical 2D CAD system for your design. The difference is that, with Revit MEP, you can use the data within your design to help make decisions and to coordinate with other disciplines and project systems. Ask your consultant for a flat CAD file that you can use throughout the project—in other words, a file that the consultant will update as changes are made to the project site.

The civil engineering and architectural consultants on your project may be sharing files also. At a minimum, the architect would share the building model so that the civil consultant could properly locate the building on the site. Your architect may choose to use the 3D data from the site file to generate a site plan within Revit. If so, you can use this information to create your site lighting layout. Although the architectural site model would give you topographical information, it also is only as up to date and accurate as the architect keeps it.

To get started, do the following:

1. Create a view associated with the ground level of your project. Because this is a site plan, the view does not have to contain only lighting system elements, so categorize your view in a manner that makes the most sense for your Project Browser organization. It may be best to create a subdiscipline under Electrical called Site to keep all your site-related views properly organized.
2. Set the View Range settings to display the building model properly—that is, as it would appear in a site plan. You can set the Top setting of your view and the Cut Plane setting to an elevation higher than the building so that it appears as seen from high above.

   It should not be necessary to use a plan region unless you require the cut plane to be lower in a specific area of the site. If the building is represented in the linked site file, you may choose to not show the linked building model in your view. However, this workflow would mean that you are relying on the civil engineering consultant for an accurate representation of the building outline instead of getting that information from the architectural model.

3. Link the CAD file from your consultant into this view. Consider the option for linking the file into this view only, if it is the only place that the site CAD file needs to appear. You could also create a workset for the linked site file so that you can easily control whether it is loaded when your file is opened.

   Whatever you decide, be sure to link the file; do not import it. An imported site file can wreak havoc on your model, and you will not be able to update the file automatically when it changes.

4. Depending on the origin of the site file and your Revit file, you may have to place the site drawing manually into your view. The site file should contain an outline of the building so you can align it with your linked Revit architectural model. If not, it may be necessary to open the site CAD file and create an alignment-point indicator used to match up with your file.

Site Lighting Layout

With your site plan in place and a view that represents the building in relation to the site, you can now begin to place site lighting fixtures in your model. If you have enabled worksharing in your project, it is best to create a workset for the site lighting plan, or at least for site elements in general. Lighting fixtures that are mounted to the exterior of the building should be included in this workset if they are to be displayed in the site plan view.

A limited number of site lighting fixtures come with Revit MEP, so you likely will have to get your site lighting families from manufacturers' websites or create them yourself. The chapters on content creation in Part 5 of this book will equip you with the skills necessary to create any lighting fixture that your project requires.

The topographic surface from a linked Revit site model does not provide you with a face on which to host your fixtures. You can use the option to place your fixtures on a work plane and associate them with the ground level defined by the building. This works fine for a 2D plan view representation of the site, but if you need to show the site plan in section, elevation, or 3D, you have to adjust your lighting fixtures to match the topographic elevation of their location.

You cannot adjust the Elevation parameter of your lighting fixture families that are hosted by a work plane or level, so you can either use nonhosted families for site lighting or use this little trick: Tab-select the topo surface in the Architectural link file and copy it to the clipboard and then paste Aligned to the same place. Now you can place your external light fittings on the surface of the topo. Either delete it when you have done (the external lights just stay where you put them), or hide the topo from the view. Notice in Figure 12.18 that the elevation of the lighting fixtures is set to match the topography. Even though these families are plane based, they still pick up the topo surface as a host! Face-hosted fixture families were used in this example, since the 3D view is used only for reference.

Site Lighting Analysis

Revit MEP can calculate the average estimated illumination of a Space object by using the data from the photometric web file associated with a lighting fixture, but only because the Space object has a volume. Exterior lighting levels cannot be calculated. Most exterior lighting calculation applications are able to import CAD data, so you could export your model to CAD and use the file in your analysis software.

You can, however, use Revit MEP for visual analysis of your site lighting layout. Lighting fixtures that contain photometric web files can display the pattern of light emitted from the fixture in renderings. Creating exterior renderings of your project will give you an idea of the coverage of your lighting fixtures on the site. This can help you determine whether you are using the right type of fixture or whether you need to adjust the number of fixtures used or the spacing of fixtures.

To see the exterior lighting in a rendered 3D view, you need two things. You need to have a surface upon which the light shines, and you need fixtures that contain a light source. If you are using a 2D CAD file for your site plan, you can place a dummy surface at ground level to act as your site surface. Your 3D view should be set with a nighttime sun position so that the sun does not interfere with your lighting. You can display the sun position by using the Sun Settings options on the View Control Bar, as shown in Figure 12.19.

When you turn on the sun path, you may see a dialog box with options for displaying the sun path based on the sun settings defined in the Graphic Display Options settings of the view, as shown in Figure 12.20.

If you choose the option of using project location and date, the sun path appears in the view, as shown in Figure 12.21. You can adjust the position of the sun by dragging it along the path, or you can click the time shown and edit it manually. The date can also be edited by clicking the text.

To render your site lighting, do the following:

1. Click the Show Rendering Dialog button on the View Control Bar of your 3D view. First choose your rendering engine. This is a new feature in Revit MEP 2016 that provides you with the options of NVIDIA mental ray® or Autodesk® Raytracer. Either will give you a photorealistic rendered image and it becomes a matter of preference which you choose.
2. Set the lighting scheme as shown in Figure 12.22. It is best practice to try out your renderings in draft mode when you are testing your design because of the amount of time it takes to render a view. Choose the Exterior: Artificial Only lighting scheme.

   

3. You can group lights together and choose which groups to render. This decreases your rendering times because Revit takes into account only the lights within the selected group. To create a light group, simply select a fixture and use the Light Group tool on the Options Bar, as shown in Figure 12.23.

   

4. Click the Artificial Lights button in the Rendering dialog box to determine which groups of lights will be rendered (see Figure 12.24). You can turn on or turn off entire groups of lights or individual fixtures to decrease rendering times.

   

5. Click the Render button at the top of the Rendering dialog box to generate a rendering of the view.

Once the rendering is finished, you will be able to see the lighting from your fixtures and how the light appears on the site. You can click the Adjust Exposure button to lighten or darken the image for more detail. The rendered view is a useful tool for the visual analysis of your lighting model. If you want to use the rendered view for presentation purposes, you can render the view at a higher level of detail. Figure 12.25 is an example of a rendering showing bollard lighting on a sidewalk with different rendering settings shown inset.