Reliability Revit calculations

[Anonymous]

Hi,

With this post I would like to demand for more information about the reliability of Autodesk Revit calculations ( Heating and cooling loads).

Currently, I am researching the reliability of energy calculations in Autodesk Revit. The goal of this project is to compare multiple energy simulation programs used in engineering to determine the differences in calculation outcomes among them. At the moment I use another software package for the simulations of energy calculations, but I am planning to switch and use Revit only in the near future.

My questions are:

1. How can I be sure that the Revit calculations are reliable?
2. Different energy simulation programs are validated by the building energy simulations test (BESTEST). Has this test been used by Autodesk for validation of results?

I am looking forward to your reply, many thanks for answering my questions.

[HermanSolomon]

You will find 50% of people in the pro-Revit H&C calc camp, and the other 50% of people trhowing rocks at the first camp. The best way to verify whether Revit's calculation methods are correct, is to test it yourself. The key to accurate H&C load calculations is an accurately set up model. Quite a few of my clients have spent a few months verifying theRevit calc results to HAP's results, and most of them are satisfied. Yet again, it depends on the accuracy of the modeled building itself, it's location, positions, physical and thermal material properties, etc. etc.

You are more than welcome to have a look at the following links:

* Heating and Cooling Load Analysis

* Performing a Heating and Cooling Load Analysis

* Heating and Cooling Reference

* Calculation Reference for Heating and Cooling Loads

If you are still not satisfied/comfortable with the results, you can export the model to a gbxml format, and import the file into the H&C calc software package of your choice

[Anonymous]

When I make a calculation, I see something that surprised me.

Is it true that there is no heat transfer through the floors?

And is it true that the coefficient of heat transfer resistance (R) is incorrect? Because there is no R_inside and R_outside. There is only the thermal resistance of the wall.

[heimo.l]

hello,

according to this technical information for Rveit 2013 from Autodesk Germany you have to add the R_in and R_out to the calculated U-Value 

http://www.autodesk.de/adsk/servlet/pc/item?siteID=403786&id=20378691

but it doesn't say, where you can add this, so that the correct U-Value will be used. 

in this thread there is a description of a workaround and some furher information

http://forums.autodesk.com/t5/revit-mep/heating-and-cooling-load-calculations-in-revit-mep/td-p/4836...

[arghavan.A]

@Anonymous

Hello,

I was wondering if you found out whether AutoDesk has used BESTEST cases for verification? Because I am using BESTEST cases in my thesis for energy analysis, and BIM2BEM, and I really appreciate if you answer me.

Also, about the second question you asked, I had heard about the incorrect R-values as well!