Let’s get straight to the point. If you are reading this, you have several renovation projects that someone wants done in Revit. And, more than likely, you are hesitant or flat out do not want to do them in Revit. So you are looking for how this should work. You may not want to, and you probably feel like you are forced to.
So let me begin by saying I completely understand. I’ve been there. I’ve felt the same thing. But now looking back, I’m glad I took the time to dig in and understand.
Was it easy for me? Absolutely not! I hope I can save you some trouble, though. I have done several renovation projects in Revit–from minor build-outs to hundreds of thousands of square feet of renovation with new construction added on. I’ve learned a lot of lessons along the way, and I hope I can pass some along to you.
The majority of this article will be an actual guide to how renovation projects work in Revit. For those of you that are skeptical, I’ll start by giving you some reasons why you should create an actual building model for renovation projects. Then the majority of the article will focus on how to use phases in Revit to progress through a renovation. Lastly, I’ll throw in some tips and tricks to help speed some things up. I hope you find the content here beneficial.
Why Model in Revit
There are really several benefits that are available when creating a building model. In my opinion, energy analysis is a major factor in influencing owners and winning projects. While pretty pictures and walkthroughs are great and can help, showing an owner that they can save cash money speaks volumes. You can also create amazing renderings these days that can only help. Whether you are trying to win a project, convince an owner/organization to renovate, or show design options, energy models and renderings can dramatically help. And having a building model helps you create energy models and renderings.
Additionally, there are numerous benefits to the design team. With Revit, you can create a parametric building model that contains all of your design information. You can also use tools like Dynamo to dramatically speed up certain portions of the design. Once you have a building information model, you can query information from it, document it on sheets, use it for construction, and so on. Using models for construction allows for more coordination and can speed up fabrication.
Energy simulations are best performed early in the design stage. Once you have a project identified, you need to get some information about the existing building. For starters, you need to get measurements for the building envelope and basic information about what’s in the building, such as HVAC systems, lighting systems, equipment and space usage. Best case scenario is to get as-built drawings. Then, you can simply trace over the exterior walls to create the exterior walls of the building model.
If all else fails, use an online map application. You can import an image into Revit. You just have to make sure the scale is correct. If needed, you can visit the site for some quick spot measurements to aid in getting the scale set for the map image. To start the process, you really just need the building envelope.
Along with exterior walls, you also need exterior fenestration. Once again, if you do not have as- built drawings, you can use a map application to look at a street view of the building. You may be surprised how much information you can actually get from this. And again, a quick site visit and photos of the exterior always helps too.
Once you have the building envelope modeled, you should also model some interior spaces. You do not have to model every single space. However, having some zoning can help with the analysis. I would recommend at a minimum to create a space for each exterior exposure, beginning at the exterior wall and extending 12 feet towards the interior. Then you can create a single interior space for each floor, or divide it up by functional areas. For example, offices, break room, lobby, etc. The point is to have a little more definition to the areas than just one space for each floor.
Once you have a primitive building model, you can export a gbXML file to perform an energy analysis in a third-party program, or you can use the integrated energy simulation tool in Revit. Or, even better, you can use Insight 360 to generate some initial insights to help map out the design.
Insight 360 is great in helping to understand what factors will influence the energy consumption the most, as well as how the various design options affect the energy usage. When using the energy analysis tools or Insight 360, make sure you specify the Energy Settings and space settings in Revit. While you can use rooms, spaces provide more parameters that affect energy analysis.
Insight 360 is a great place to start, but you may want to create more in-depth energy models, depending on your needs. If this is the case, you can use the energy simulation tool in Revit, or use a third-party analysis tool. When importing a gbXML file into a third-party program, the biggest thing is to check the analytical model that was imported. Ensure that everything was imported properly, and then specify the appropriate settings.
For these types of energy models, you want to focus on design options. For example, which HVAC system will work the best? What are the best lights to use? What is the maximum amount of insulation needed in the roof before the cost outweighs the savings? A quick analytical model based on the building envelope will help you answer some of these questions. Then as the design progresses, you can create more in-depth energy studies, if needed.
Understanding Phases in Revit
With renovation projects, there is an existing structure. Therefore, the existing conditions need to be modeled along with the new or renovated work that is to take place. Phases allow you to model existing conditions and then show the new work that is to be performed – including elements that need to be removed or temporally added for construction. Phases in Revit essentially allow model elements in the project to be aware of time.
Each phase represents a distinct time period in the life of the project. By including time as a parametric relationship within the Revit model, creating phases is much easier than in a 2D CAD environment. Phases in Revit enable you to develop complex, phased projects within a single building model, even if those phases involve complex renovations to existing buildings.
When working with phases, you will need to understand 4 concepts:
Phase of the view
Phase status of a model element
Phase filter assigned to the view
Graphic overrides that have been assigned through the phase filter
By default, there are 2 phases in a Revit project: Existing and New Construction. However, you can create additional phases in a project as needed. Phases are controlled in the Phasing dialog.
Each view has a Phase parameter, and elements created in the view will have the same phase as the view. The Phase can be set to any phase created in the project. By default, when you start a new project, each view has the Phase set to New Construction. If you are working on a renovation project, it is useful to have views with the Phase set to Existing, so that elements created in that view will have the correct phase; in other words, they will be the existing building elements before renovation begins.
Each element in a project has 2 phase parameters: the phase in which the element was created (Phase Created), and the phase in which the element was demolished (Phase Demolished). The combination of these properties results in 4 possible phase statuses: existing, new, demolished, and temporary.
An existing element is an element that was created in an earlier phase and continues to exist in the current phase. A new element is one that was created in the current phase of the view. A demolished element was created in an earlier phase and demolished in the current phase. And a temporary element was created and demolished during the current phase.
For example, based just on the 2 default phases, Existing and New Construction, if an element is created in the Existing phase and the element is not demolished, it is an existing element.
If an element is created in the Existing phase and is then demolished during the New Construction phase, the element is demolished.
If an element is added in the New Construction phase, the element is new.
And if an element is added in the New Construction phase and demolished in New Construction, the element is temporary.
If you are having difficulty grasping this concept, just think of it as you would if you were going onto the job site of a renovation project. All of the elements that are present before you begin work are existing, so they were created with their Phase parameter set to Existing. Once the contractors get to work, which would be the new construction phase, elements to be removed would be demolished. Any elements that are added as part of the new construction would obviously be new construction. And any elements that are added as part of the new construction, but are then demolished during that new construction, such as a dust partition that is built to separate an occupied area from the construction zone, would be temporary. Of course, in more complex projects, you can add more phases.
Each view also has a Phase Filter parameter that lets you control the display of elements in a view. Think of a Phase Filter as a rule that you apply to a view to control the display of elements based on their status: new, existing, demolished, or temporary. Each view can show one or more phases of construction. The phase filter enables you to control which phases appear in the view, as well as the graphics applied to those elements.
There are several default phase filters, and you can create custom phase filters as needed. They are also controlled in the Phasing dialog. Phase filters show elements in a view based on their phase status. The elements can either display By Category, be Overridden, or be Not Displayed at all. The appearance of elements with a phase status set to Overridden is controlled on the Graphic Overrides tab of the Phasing dialog.
In short, views have a phase parameter and elements have a phase status based on the phases in the project. You can then control how the elements are displayed with phase filters. Being able to incorporate the aspect of time into your projects can be extremely powerful once you understand how to use it properly.
Jason Boehning is the building content manager at 4D Technologies and authors Revit and Dynamo courses for AEC design professionals. Jason has a degree in Mechanical Engineering and helped a design firm in Houston, TX implement Revit to increase productivity for sustainable design and energy modeling. In 2012, Jason decided to make a career of teaching building professionals how to use building design tools. He joined 4D Technologies in development of their CADLearning products, helping create affordable training for Autodesk software. Jason is also a contributing author to several CADLearning eBooks. He also serves as an Autodesk Revit Mentor All-Star to help people get started using Revit, and he is a repeat speaker at RTC North America and Autodesk University. Jason is a Certified Professional for Revit Architecture, Revit Structure, Revit MEP Mechanical, and Revit MEP Electrical.