Practice Exercise: HVAC Systems
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Practice Exercise: HVAC Systems

Focus / Design Goal

The focus of this exercise is to explore how mechanical systems can be designed to meet their functional requirements without compromising the aesthetics and spatial feeling of a proposed building design.

Download these two Revit models as the starting point for this exercise:

This early version of the mechanical model includes:

  • Spaces and zones
  • Mechanical room (Room 15) on Level 0
  • Heating and Cooling Load Report

Model the supply ducts for an Air Transport HVAC system to deliver heating and cooling from the mechanical room to each of the spaces.

Design Tasks

  1. Start by exploring the space available for your ducts and thinking about the layout you will use for routing the ducts from the mechanical room to the supply diffusers in the spaces. Consider:
    1. How much space is available overhead given the floor-to-floor height of the building and the structural beams that will support the floor?
    2. What routing will create the most efficient duct layout and not compromise the aesthetic goals for the project?
  2. Next, analyze the mechanical model. Check:
  3. Are the Spaces defined appropriately?
    1. Are they fully enclosed (have the right Upper Limit)?
    2. Are they set to the appropriate Space Type and Condition Type?
  4. How many Zones are defined in model? Is the zoning appropriate for the level of thermal control that you’d like to offer the building’s users?
  5. Review the Heating and Cooling Loads Report and the Space Schedule. Do you notice anything unusual or unexpected?
  6. After completing your analysis, refine the model of the HVAC design to add the supply diffusers and route the supply ducts that will supply air from an air handler located in mechanical room.
    1. Add supply diffusers to each space based on the Calculated Supply Airflow reported in the Space Schedule. As you place the diffusers, think about:
      1. What height will you place the supply diffusers above the floor level?
      2. How many diffusers are needed in each space if a single diffuser can provide up to 500 CFM?
      3. Can you reset the flow for some diffusers to a lower number in spaces where less airflow is needed?
    2. Check the Space Schedule to verify that the Actual Supply Airflow (based on the diffusers that you have placed) exceeds the Calculated Supply Airflow in each space.
    3. Place ducts to connect your supply diffusers to an air handler that will be located in mechanical room. As you place the ducts, think about:
      1. What height you will place the ducts above the floor level? You’d like them as high as possible (to minimize their visual impact), but low enough to clear the structural beams that support the floor above?
      2. What shape should the ducts be? Round? Rectangular?
      3. What size should the ducts be? The Duct Sizing tool will help compute the needed duct sizes, but you should have an initial size in mind as you place them in the model -- say 12x12 or 12x18.
      4. Your duct routing should match the zones that have been set up in the model.
        1. There should be separate branches in the duct system to supply spaces in the West zone versus the East zone.
        2. You’ll probably want separate branches on each floor level.
        3. If you implement both suggestions, you’ll have 4 supply branches that route independently back to the mechanical room.Note: For this exercise, you DO NOT need to model the air handler unit in the mechanical room or VAV zone controllers on the duct branches. Just route the ducts from the diffusers to the mechanical room location, where the air handler will be modeled later.
  7. Optional (Not Required -- Extra Practice): Use the Duct Sizing tool to calculate the needed duct sizes in each branch of your supply duct system.
    1. Select each branch separately and run the Duct Sizing tool on each independently to make it easier to isolate any problems.
    2. Think about whether to restrict the maximum duct heights (to preserve headroom) or allow them to resize in both height and width.
  8. Upload your proposed HVAC model to your Autodesk Construction Cloud project folder, and then copy it to your Coordination Space folder. Then, merge it with the architectural model and structural models (already uploaded to Model Coordination) from the practice exercise in the Structural Systems module.
  9. Capture a screenshot of an interior view showing the merged model similar to the image below.
image

As you review the merged model view, consider:

  1. Did you accidentally cover any floor openings (elevator, stairs, atrium)?
  2. Are there any obvious conflicts between your structural system and your mechanical systems? (for example, ducts and beams that intersect)
  3. Would you place a ceiling to conceal the structural and mechanical systems or leave the systems exposed? What height would the ceiling be above the floor level? And would that height meet your aesthetic and use goals for the project?

Then, post your Practice Exercise results below.

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Click the + New Button and add a card for your plumbing system design to this gallery. Tips for Editing: - If you don’t see the + New button, click the Edit button in the toolbar at the top of this page. - If you can’t edit your new page, click the “Open as page” link at the top of the page.

Be sure to include:

  • The screenshot of an interior view of your merged view from Model Coordination tool showing the HVAC elements.
  • A brief paragraph discussing:
    • any challenges that you encountered in this supply duct routing exercise
    • whether your proposed design meets the project’s spatial design goals
    • any recommendations to make the design more sustainable (and lower the heating and cooling loads)

HVAC System Practice Exercise / Recommendations