Tuesday, May 29, 2018

Notes from the Support System – Revit Lighting Analysis

Autodesk continues to expand its analysis capabilities, with the addition and improvement of the Insight 360 tools, heating and cooling load analysis, lighting analysis and solar analysis. I’ve been seeing more trends of users taking advantage of these tools, but encountering errors that at first glance seem un-explainable. The lighting analysis tools have had a rush of support questions lately, so let’s clear up the air on this tool, and help you get it working for you.

First, refer to this document that was provided by Autodesk in October, 2017 by Krishnan Gowri, Ph.D. FASHRAE, LEED AP, Principal Engineer, Generative Design Group:

Here are my tips to help you get the best results:

The lighting analysis should be conducted early in the design process, prior to a lot of heavy modeling that adds content such as furniture, equipment, structure, MEP systems and more. The more complex geometry can cause the model to fail, especially with the addition of highly detailed components containing small surfaces. This includes content modeled to LOD 350 and above. If you want to include it, keep it in separate models that can be easily removed, or in worksets that can be turned off.

Make sure your model includes all of the bounding elements, including floors, ceilings, and roofs, in addition to walls and openings (including doors and windows). Keep the detail level at a minimum – for example, if you are placing curtain walls, avoid panels and mullions that include complex shapes, such a louvers, or frames that include the caulking (yes – this has happened. Great for detail but lousy for analysis). Avoid using extra surfaces like wall sweeps – these can cause a known issue with the lighting analysis tool. One additional tool – don’t make items like column enclosures room bounding – at least not during the early stages of design, where you’re using this tool. The few the surfaces, the more like the tool is to work.

Assign materials from the material library to the bounding elements that include surface settings for color, reflectance and more. As with the bounding elements, keep this simple. You’re trying to gain a general knowledge of the lighting conditions for illuminance and LEED credits, and how altering these materials can affect the overall energy and lighting performance of the building. but not drill down to  the specific foot-candle levels at 2” intervals.

Rooms. Rooms. Rooms. You have to model these and do it correctly. Every area of building that is going to be analyzed must have a room object, with Height assigned. I recommend at a minimum to set the room upper limit to the next bounding floor level above. When a ceiling is placed and set to be room bounding, it will automatically cap the room to that level. It will pick up the materials assigned to the ceiling, and as the ceiling is moved, the room height will automatically update. Take the time to assign the room name and number, even if it’s preliminary. You’ll need this for the schedules the tool produces, since the analysis is primarily based on room properties.

Fix your errors – avoid overlapping elements such as walls, deleted unplaced rooms, and find/fix  voids. For example, don’t model your interior walls 8’ tall, if they should extend 6” above that 10’ ceiling you just placed. If you build a crappy, half finished model, you’re going to get failures every time – and this includes all of the other analysis tools too. You can find your list of model errors on the Manage Tab, Inquiry panel – click Warnings, and you will get a list you can export and review.

Speaking of levels – make sure you’re using these correctly as well. Floor datum levels should not be used to define the height of a countertop – use a workplane instead, or use a level that does not defined a story. This can affect your upper limits on the rooms if you’re setting them to be bound at the next level – you don’t want 42” tall rooms that match the level you added for the countertops.

Leverage the Insight energy model first. This tool is great for checking your model and making sure it’s well defined for analysis. The heating and cooling load tool also includes tools for reviewing the room and space volumes, as well as each analytical surface for walls, doors, windows, floors, etc. You can review this first before perform any analysis, and get a good idea of how well formed your model is defined.

Make sure you have all of the available updates for Revit installed, and the latest build of Insight installed. There have been a lot of updates that fix earlier issues, so don’t stick around on Revit 2016 and try to do this – get on 2018.3.1 (the latest build as of this article date for 2018) or 2019, and you should reduce the number of potential errors.

Worse case – you do all of this, and still don’t get the results you need – start a support case at support.autodesk.com, and make sure you include this information – your version of Revit, a link to the Revit model and any linked files.

Thanks – David B.

UPDATE - Autodesk is hosting a series of online classes all about Insight 360 - for more details, follow this link - the sessions are offered on June 14, 2018"


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