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Heating and cooling load calculations in Revit MEP

60 REPLIES 60
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Message 1 of 61
Mehdi.Kardehi
27391 Views, 60 Replies

Heating and cooling load calculations in Revit MEP

Hi All,

 

Couple of questions with this?

 

- Do you trust Revit heating and cooling calculations? I mean after you modify all the building materials and weather information do you do your calcs with Revit or a third party laod calculation software?

- How about duct and pipe sizing? Most of consultants do those with other tools.

- I have been exporting revit spaces as gbXml to E-20 to do the load cals but I need to mannually input all those calcs back into Revit. Is there a faster way of doings that?

- And lastly most of the clients don't like the way Revit shows the calculations Report. Is there a way to customise those outputs and get them shown in the way I want?

 

Cheers,

Mehdi

60 REPLIES 60
Message 41 of 61
gbs_subsuser1
in reply to: russellvee

The heating and cooling load calculations in Revit uses the RTS method published in ASHRAE Handbook of Fundamentals (2005 edition).  This approach calculates the radiant components for people, lighting and internal loads for twenty four hours prior for each hour of the design day.  Occupancy fraction as specified by the schedule is used along with the convective and radiant components.  This will almost always result in sensible cooling load for people and lighting below the typical sensible load based on activity type.  A brief summary of the calculation method can be found at:

 

https://knowledge.autodesk.com/support/revit-products/learn-explore/caas/CloudHelp/cloudhelp/2017/EN...

Message 42 of 61
Nick_Noe
in reply to: gbs_subsuser1

New HVAC designer here trying to learn how to use revit for calculations. is the 2018 version still not working? It seems that everything is always undersized or wayyyyy oversized.

 

Thanks

Message 43 of 61
mmcglone
in reply to: Nick_Noe

As far as I am aware there has been little to no progress on the HVAC load calculations with-in Revit.
Message 44 of 61
safakgunes
in reply to: mmcglone

I am going to test a small example project this week. I will compare HAP results with Revit calculations in different versions like 17, 18 and 19. I'll post the results when i finish it.

Message 45 of 61
Nick_Noe
in reply to: safakgunes

So far with what I have been finding if you are very very careful about what data you are putting in then you are able to get similar results to hand calcs.

Message 46 of 61
Nick_Noe
in reply to: Nick_Noe

So a few questions when getting this back. Why do the level summarys not add up to the whole building loads, when looking at the peak loads should I use the space peak load or the zone peak load?

 

Thanks

Message 47 of 61

Do you get change the U factor from default values!?


@mohammedjazim25 wrote:

Is it possible to edit the u values of components in revit ???

2017-02-27_10h28_36.png


 

Message 48 of 61

Hello,

 

I can't understand why the revit doesn't show the load from partitions. If I create spaces unconditioned the load from internal walls (partition) didn't appear in the results. Do you guys know why!?

 

It's work if create a special zone and change the set point to higher temperature, but it's fraudulently way. 

Message 49 of 61
safakgunes
in reply to: paulo.celarius

Yes, you need to create new walls with your desired details.

Message 50 of 61
safakgunes
in reply to: paulo.celarius

Also, you cannot see heat transfer from ground. It means more work. 😕

Message 51 of 61
paulo.celarius
in reply to: safakgunes

In this case you are considering a method of conceptual mass, right? but i'd like to use just the construction elements for load calculation. 

 

Is it possible create new speficications for construction elements?

 

 

 

Message 52 of 61
safakgunes
in reply to: paulo.celarius

Yes, you can add whatever you want. 

Message 53 of 61
infoC8RYK
in reply to: mmcglone

Hi @all,

I am currently working on an exemplary investigation of thermal load simulation with Revit. Took me already several months and will be published in a german version in 03/2019. I think I will translate it, but it should take me some time. This means a load of non-profit work for me and I will only start if there is some serious interest or support.

I figured out the precise problems (also some wrong calculations done by Revit in simple One-Dimensional Steady-State Conduction or at least simply wrong declaration of important parameters leading the user to a false track) and have several suggestions for Autodesk how to fix the "load" of problems and also how to make Revit MEP more interesting for use in HVAC-eigineering. Without third party software, means no extra costs for another license ...

For sure only if Autodesk Inc. is interested in solving their problems and establishing Revit not only as half-useable BIM Software. Still a long way to go, but I think it is worth it. Getting one step closer to integrated planning process.

Feedback welcome!

Greetings from Germany,

Fabian

Message 54 of 61
vitaliy5151
in reply to: infoC8RYK

It is a pity, but in the 2019 version the problem has not been fixed. But in the calculation you need to add only two variables! Is it so hard to implement, Autodesk?

Message 55 of 61
hcemucar
in reply to: infoC8RYK

Thats great to hear that, hope to meet with you and your article asap

because (for someone who wants to summarize all the works digitally by end-to-end consept) from design to operations these calculations are extremly valuable

 

bests from İstanbul/Turkey

Message 56 of 61
kisiel1mk
in reply to: hcemucar

Any progress in this subject from Autodesk in the latest version of Revit?

Please use *Mark Solutions!* Accept as Solution and Give *Kudos* as appropriate to further enhance these forums. Thank you!
Message 57 of 61
RobDraw
in reply to: kisiel1mk

Have you checked the new features list?


Rob

Drafting is a breeze and Revit doesn't always work the way you think it should.
Message 58 of 61
vitaliy5151
in reply to: kisiel1mk

nope

Message 59 of 61
vitaliy5151
in reply to: Mehdi.Kardehi

We are still here 😂

Message 60 of 61
russellvee
in reply to: vitaliy5151

Wow 10 years went by so fast! Too bad they still haven't fixed the software that we pay thousands of dollars per seat for. Maybe next year!

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