1. Learn how to generally set up a project in Sefaira Systems
  2. Learn how to specifically compare multiple HVAC systems to justify your decisions

Early comparison of systems provides engineers with information that can help unlock and justify decisions. Differences in loads and energy use between different HVAC systems can show the impact of key decisions during design discussions and client presentations.


If you prefer watching a video – you can view a 6-minute demonstration of the product set up and some short analysis examples here.

How to generate a
Systems Comparison Matrix

Setting Up a Project

Open your model and select the Sefaira Add-in (Revit) or Extension (Sketchup). Uploading to Sefaira Systems is an easy, two click process. Note that if you don’t have one of the plugins installed yet, Chapter 3 has all the information you need to get started. If you don’t have a model handy but want to try using Sefaira Systems, you can use one of our sample models for SketchUp or Revit.

SketchUp Plugin

Revit Plugin

Additional options may show if you are a Sefaira Architecture and Systems license holder.

When you upload a model to start a new project, select Sefaira Systems to create a new project. If you are adding a model to an existing Sefaira Systems project, choose that option in the interface.

As a next step, name your project and select the location and the main building type.

Now you are ready to get your initial results and start your analysis! These results are based on a standard HVAC system. This process can take up to a few minutes depending on your model complexity.

If at any time in the process you run into trouble, please visit our Knowledgebase or email support@sefaira.com with your questions.

Setting up your analysis

Your project will have returned some initial results and you can now go ahead and modify the envelope properties and internal conditions to reflect realistic values for your project. You can also change the system type for your baseline.

Select envelope variables appropriate for your baseline.

Select your space use and adjust any associated load densities in the building.

Select the initial system.

Setting up a Comparison Matrix

In our example we will start with the system type “Heating and Ventilation” and compare the heating, cooling, design airflow and EUI of this system type with results from a “Fan Coil Units and Chilled Beams” system in the same building.

Using the ‘Clone’ button (1), we create a second row to create a simple comparison matrix. This row will at first have the same values for envelope, conditions and system type. We can select the ‘HVAC System Type’ (2) dropdown menu to change the system type to FCUs and wait for the analysis to update and show us how these two different system types compare for the same building with the same envelope properties and internal conditions. Double clicking on the name beside the thumbnail image allows us to name each row for ease of comparison.We can then repeat this cloning process and choosing additional system types to complete the initial comparison (3).

The matrix will generate a number of different results, namely AHU design airflow, peak cooling loads, peak heating loads and EUI. However, by selecting the title dropdown, you can view additional results.

Analysis Interpretation

As an example, focusing on the Heating Equipment Peak Design Capacity, we can now understand the impact that the three different HVAC system types we selected would have on our options for a heating system for this building. This analysis will also allow us to consider all the consequent space and programme differences that exist between the three systems we compared and we are at a point where, all else equal, we can recommend the best system type for this building. Sefaira outputs can be downloaded as .csv or .idf files.

However, our systems comparison matrix also allows us to run a number of other analyses that we might want to look into:

  1. We could edit the Internal Conditions to see whether density changes in the space or the use of different lights might improve the performance of a particular HVAC system.
  2. We could edit the values associated with our chosen system under the Air-Side and Water-Side input tabs to see how heat recovery or different supply temperatures affect the loads.
  3. Or we could add a changed geometry massing to our project and compare the impact of, for example, larger windows on peak plant sizing.


  • Sefaira Systems can very quickly create an initial analysis off 3D models
  • A comparison matrix can be used to compare different system types
  • Sefaira Systems allows you to modify and compare all aspects of the building