How much detail should you include about wall, floor and roof composition at different stages?
◦ Conceptual design
Very little detail; the whole purpose of conceptual design is to generate a broad outline of the project (conceptual massses) and ensure it meets all of the client’s requirements. At this stage of the project, only high-level details (i.e. overall thicknesses, geometries, dimensions, etc.) are required for the different assemblies.
◦ Preliminary design
During the preliminary design stage, slightly more detail about the wall, floor, and roof composition should be included, such as the different layers, type of material used, and thicknesses of each material.
◦ Design development
During the design development phase, more detail should be included about the different assemblies compared to the preliminary design phase. This includes detailed drawings of the different layers in each of the assemblies, support structures, the exact type/brand of materials, and thermal metrics (R-value, U-value, SHGC, VLT, etc.)
◦ Construction documentation
For construction documentation, significant detail should be included, so that the contractors know how to build the different assemblies. Construction documentation needs to show everything that went into building each assembly.
Many manufacturers provide Revit families for their products.
◦ What is the advantage to the manufacturer of giving them away?
One advantage to manufacturer of giving them away is that it allows engineers, architects, and the rest of the design team to select and test actual manufactured products in the modelling phase of the project. This makes it more likely for the design team to select a manufacturer’s product if it’s provided in Revit versus having to use generic library families and then switching to an actual product during the construction phase (substitution of products can alter the results of the design analyses, meaning that what was shown in the design phase may not be aligned with the final constructed product).
◦ What is the benefit to you of using them over the generic library families?
The benefit of using actual product specifications from manufacturers is that it Revit to run more accurate analyses that will be more representative of the actual building (i.e. analyses will be closer to the actual operational and embodied carbon emissions once the building is built). This allows the design team to make more informed decisions regarding the specific products that should be selected during construction compared to using the generic library families.
◦ At what point does it become appropriate to switch from generic to manufacturer specific?
Once the design enters the design development phase, it is appropriate to switch from generic to manufacturer specific families.
Your Carbon Insight Analysis result in Revit did not match your Carbon Analysis in Forma Building Design.
◦ What accounts for the difference?
The Carbon Insight Analysis in Revit didn’t match the Carbon Analysis in Forma Building Design because of the different assumptions that went into each analysis. The Forma Building Design was a rough, very high-level overview of the potential carbon emissions, however, these were based on general assumptions made for the entire building. On the other hand, the Carbon Insight Analysis combined metrics from the more detailed wall, roof, and floor assemblies created in Revit, and allowed for the usage of multiple exterior wall assemblies and floors, which is more representative of an actual building. Another major difference in the analysis results was the re-design of the building from six stories above the concrete podium to five stories above the concrete podium. This was to align with more typical mid-rise building heights for this type of construction. Thus, the Revit model has a slightly smaller gross square footage than the Module 3 Forma model, which would have impacted the carbon analysis results.
◦ Which number would you show a client, and how would you explain the gap?
I would show a client the Carbon Insight Analysis result in Revit, as it’s more aligned with the assemblies that will actually be used in the project. The gap between the two different analysis is a result of the assumptions used in running each analysis; since the Forma assemblies used general, high-level assumptions (more generalized), the values from this analysis are not as accurate as those from the one run in Revit.
◦ Does a more detailed model automatically produce a more trustworthy prediction?
Not necessarily. Due to the level of detail in a detailed model, this can increase the chances of simulation error and add in potential noise to the analysis results. Overfitting of parameters and structural/architectural details means nothing if the model isn’t calibrated with the correct thermal characteristics and climate data. Additionally, if the baseline/underlying measurements are incorrect, a more detailed 3D model will just produce even more inaccurate results (garbage in garbage out).