Donate Now Goal amount for this year: 2500 USD, Received: 1627 USD (65%)

Page 1 of 2 12 LastLast
Results 1 to 10 of 20
Like Tree7Likes

Thread: Heating and Cooling Loads

  1. #1
    Senior Member
    Join Date
    June 14, 2011
    Location
    CT, USA
    Posts
    563
    Current Local Time
    06:40 AM

    Heating and Cooling Loads

    Finally, I'm being called upon to do heating and cooling loads and I need to find a workflow.


    In addition to Revit, I will also have Tane Trace available. I'm looking for some best practices and dos/donts from anyone else that has been doing this.

  2. #2
    Mr. Revit OpEd
    Join Date
    December 14, 2010
    Posts
    2,876
    Current Local Time
    03:40 AM
    The engineers I've worked that have put in the time and effort have told me their results with Revit are not too far off (critically different) from doing the work in Trane Trace alone. The common complaint is that Revit is more/too conservative by comparison (Autodesk will say the same).

    You'll need to make sure you understand what input values your engineers would provide to Trane Trace without using Revit and then determine how/where to provide that same information, for example via Space properties and Project Settings...as well as modelling habits (surfaces clearly interior vs exterior etc). You definitely won't get apples and apples if you just work with default values and press the button. More often than not I find that the final say is based on Trane Trace (or something other tool/Excel...) while using Revit to export data to Trane to avoid some of the tedious manual data entry.
    Last edited by Steve_Stafford; December 26th, 2018 at 04:43 PM.

  3. #3
    Senior Member
    Join Date
    June 14, 2011
    Location
    CT, USA
    Posts
    563
    Current Local Time
    06:40 AM
    Thanks Mr. Stafford.

    I've already discovered pretty much what you've said. What I am doing is to preparing spaces for load calcs in Revit and an energy model to export in gbMXL for calcs in Trace. I will be doing a comparison of the results and analyzing the time it takes for each method along with the amount of manual editing in preparation or in the reports.

    I'm finding the AKN quite useful for setting up the model and spaces for doing the calcs in Revit. It's not a step by step tutorial but I think all the relevant information is there. What I am not finding is detailed information about preparing the energy model for exporting to gbxml for importing to Trace. I don't have the license for Trace yet so I can't actually import the gbMXL file at this point.

    I was hoping to find someone who has done a similar comparison that could give me some pointers on the process.

    There aren't any HVAC guys in the office today and I am stuck at one thing while I am fine tuning the spaces in Revit and it's about ceiling cavities. I'm not sure if I should create separate spaces above the ceilings or make the room space extend to the bottom of the floor/slab above.

  4. #4
    Mr. Revit OpEd
    Join Date
    December 14, 2010
    Posts
    2,876
    Current Local Time
    03:40 AM
    Quote Originally Posted by RobDraw
    ...I'm not sure if I should create separate spaces above the ceilings or make the room space extend to the bottom of the floor/slab above...
    You don't want any undefined cavities as I believe those will end up interpreted as exterior surfaces and throw off the calculation. There is probably some disagreement on this but I believe it is necessary to put properly defined (not occupied etc.) spaces above ceilings. Extending the space boundary up to the floor above won't do it alone if ceilings are room bounding since they'll stop the space volume from going above it.

  5. #5
    Senior Member
    Join Date
    June 14, 2011
    Location
    CT, USA
    Posts
    563
    Current Local Time
    06:40 AM
    I am trying to fill in the "undefined cavities" because they will be interpreted as exterior spaces. That I get. What I am not sure about is the real value in having separate spaces above the ceiling. In thinking about it, I'm not sure that increasing the volume of the rooms would make much difference in the gains and losses for this exercise. Maybe it's a judgement call according to the type of building. This one is a small apartment building, so it's not that critical to get fine tuned calcs at the room level.

  6. #6
    Mr. Revit OpEd
    Join Date
    December 14, 2010
    Posts
    2,876
    Current Local Time
    03:40 AM
    Well you won't increase the volume of the "room" space just by increasing its height...the ceiling will stop the calculation if it/they is/are room bounding. Assuming they are in a linked file you'll need to alter their parameter there to change that. As such your own spaces above the ceiling account for the volume in a way you can control.

    Try it both ways and compare.
    cganiere likes this.

  7. #7
    Senior Member
    Join Date
    June 14, 2011
    Location
    CT, USA
    Posts
    563
    Current Local Time
    06:40 AM
    Since this is my first go at this, I've made a copy of the architect's model so that I can easily make modifications as I choose. I'm going the easy route for now and making the ceilings not room bounding so that the spaces ignore them. Next go around, I will work with a linked model without making changes to the architects model which would be more like a typical workflow. This particular model would be ideal for figuring out what needs to be done when the architect's model is incomplete or not done properly.

    On a side note, this forum seems to have become a lot less active than it was in the past.

  8. #8
    Mr. Revit OpEd
    Join Date
    December 14, 2010
    Posts
    2,876
    Current Local Time
    03:40 AM
    Quote Originally Posted by RobDraw
    ...On a side note, this forum seems to have become a lot less active than it was in the past...
    Have you noticed it is the day after Xmas?
    Necro99 likes this.

  9. #9
    Senior Member
    Join Date
    June 14, 2011
    Location
    CT, USA
    Posts
    563
    Current Local Time
    06:40 AM
    I wasn't referring to only today. If you look at the number of views of recent posts, you can see what I'm talking about.

  10. #10
    Mr. Revit OpEd
    Join Date
    December 14, 2010
    Posts
    2,876
    Current Local Time
    03:40 AM
    Well I'd expect the participation to fall off all month (December). As far as overall participation it doesn't seem that much different to me. Since forum activity is mostly problem oriented maybe people aren't having as many problems lately? People might be finding answers by searching and not creating new posts as much either, though I'm skeptical.

    AUGI seems much slower to me and the Autodesk Forums seem about the same as they've been.
    Last edited by Steve_Stafford; December 26th, 2018 at 08:42 PM.

Page 1 of 2 12 LastLast

Similar Threads

  1. Heating & Cooling Loads - First Go!
    By domsib in forum MEP - General
    Replies: 5
    Last Post: October 30th, 2017, 06:25 PM
  2. Construction Types/Heating & Cooling Loads
    By nick_h in forum MEP - General
    Replies: 0
    Last Post: October 24th, 2017, 05:22 PM
  3. Heating and Cooling Loads Tool - Peak Heating Airflow
    By fred_ex in forum MEP - General
    Replies: 8
    Last Post: March 19th, 2014, 10:55 AM
  4. Help for Level Quantity (Heating - Cooling loads)
    By kvusal in forum MEP - General
    Replies: 2
    Last Post: October 16th, 2013, 01:47 PM
  5. Heating and cooling loads warning sign
    By ahmed_hassan in forum MEP - General
    Replies: 1
    Last Post: January 19th, 2012, 01:03 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •