Perform conceptual lighting analysis

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In this video, we will cover reviewing space illumination parameters and reviewing lighting fixture light sources.

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Revit has several built in parameters that can help you analyze the lighting layouts in your building model.

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Let's take a look at how this works.

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Currently, there are not any lighting fixtures placed in this model.

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When you select a space, you can see that there are several electrical lighting parameters in the properties palette.

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Some of these parameters will populate when lighting fixtures are added to the space.

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For example, the average estimated illumination is calculated by determining the lumens contributed by each fixture,

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at the lighting calculation work plane and then dividing it by the spaces area.

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If you scroll down on the properties palette, you can see the area perimeter, unbounded height, volume and computational height of the space.

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And so some of these parameters are used in calculating some of the lighting parameters.

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Another quick note is that the room cavity ratio will also populate when lighting fixtures are added.

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The room cavity ratio is calculated by a formula that is 2.5 times the room cavity height, times the perimeter divided by the area,

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and the room cavity height is the lighting calculation Luminaire Plane minus the lighting calculation work plane.

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And so instead of throwing out a bunch of these formulas, let's take a look at adding lighting fixtures and seeing how these populate.

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On the systems ribbon in the electrical panel, click Lighting Fixture and then expand the type selector.

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And let's select the 2 by 4 120 type.

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And then in the contextual ribbon we'll select place on face and we'll place two of the 2 by 4s in this first exam room.

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And then let's switch to the 2 by 2 120 type and let's place four in the next exam room.

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And then let's select the 1 by 4 120 type and we'll place three in the next exam room and then click Modify to end the command.

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Now when you select a space you can see that some of these parameters are populating,

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and once again these, the average estimated illumination is based off of the amount of light from each light fixture.

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And then as we saw a minute ago in those formulas that I was stating,

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the lighting calculation, work plane affects that along with the reflectance values.

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And so right now our lighting calculation work plane is at 2 feet 6 inches.

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If I change that to 3 feet, you can see that the average estimated illumination increases,

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because as our lighting calculation, work plane gets closer to the lighting fixtures, then you can see that we get more light at that work plane.

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I'll change it back to three.

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There are also reflectance values for the ceiling, the wall and the floor.

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So let's say there were tile floors and I changed the floor reflectance to let's say 50%.

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And you can see that the average estimated illumination increases, if I decrease the reflectiveness then the illumination is decreased as well.

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And so once again these parameters are all affecting the average estimated illumination.

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And so you can take a look at different lighting fixtures and see how it's affecting the space.

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So if we select the next space, we can see the average estimated illumination from the 2 by 2s.

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And then similarly, if we select the next space, we can see the average estimated illumination from the 1 by 4 lighting fixtures.

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Now the lumens at the work plane, there's also a calculation that goes into that,

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and that is the initial intensity multiplied by the light loss factor, multiplied by the coefficient of utilization.

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Now, the first two parameters that I mentioned, they are controlled by the lighting fixture type.

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So, if I look at the type properties of the of the 2 by 4 light fixture,

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you can see that there is a light loss factor parameter and an initial intensity parameter.

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The coefficient of utilization that is computed based on those reflected its properties that we looked at as well as the room cavity ratio.

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And so now, hopefully you can see how all those parameters are working together to determine the average estimated illumination.

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All right.

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So, just to summarize here, when you look at a space,

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the average estimated illumination is populating based on the amount of lumens at the lighting calculation work plane.

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And you can adjust that work plane in order to see the amount of light at that work plane.

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So let's say if you're working in a school and you want to see the amount of light at the desk level,

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you'd want to make sure you set that work plane to the desk level or in an office.

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Maybe you want to set it at the at the desk level or the conference room level or whatever it may be.

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And so you can see how all those parameters work together.

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It's also critical that the lighting fixtures are placed at the correct height.

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Here's the lighting calculation Luminaire Plane that is the height of the lighting fixtures in the space.

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And so in this case we have the lighting fixtures at 9 feet.

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And so that is the lighting calculation Luminaire Plane.

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If I select a light fixture and I flip the work plane and then select the space again.

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You can see that the average estimated illumination changes and that's because the light fixture is now it's flipped.

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It's facing the wrong direction.

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You may also have light fixtures that are unhosted and maybe they are place slightly above the space.

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And so all those things can go into account and in having your average estimation average estimated illumination being incorrect.

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And so you want to make sure that they are placed correctly and that they are in the space.

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Another thing is we want to make sure that the light source is enabled.

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So I'm going to click Edit Family to take a look at this lighting fixture,

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and you can see that this yellow component here is the light source and the light source can be controlled right here in the properties palette.

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So for example, if I deselect light source and then load the family back into the project.

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You now see that there is there is not any light being calculated in the space because we're missing the light source.

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Another thing that you can use, I'm going to turn the light source back on and it's changed now because I modified it.

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But the if this is really important, if you're working with non-hosted light fixtures and the space may not be seeing it,

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you can use the room calculation point and when I enable the room calculation point,

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you can then use this point to control where essentially where Revit is going to be looking for that in the space.

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And so if you're light fixture maybe slightly above the space, you can enable the room calculation point and have it be found inside the space.

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So once again, place light fixtures in the space Revit will calculate the electrical lighting parameters,

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and it's important that your light source is enabled and is defined correctly and that your light fixtures are placed appropriately.