Efficient and Consistent MEP Engineering Calculations Directly Inside Revit (BES500048) - follow up

[toon_demuynck]

Hi All,

We will use this forum post to follow up on any questions regarding our session on AU2021 "Efficient and Consistent MEP Engineering Calculations Directly Inside Revit (BES500048)".

We will post the answers to questions asked during the session here, as well as answer questions that might still arise after the live Q&A session.

Thanks to @panda_arcadis for supporting me here :-).

[rob.harmer]

Hi Toon,  could you please explain again how to select the different sections of pipe or duct by choosing the start and end points that you mentioned? 

[toon_demuynck · Accepted solution]

Hi Rob,

Select your start point, place your mouse over the end point (do not click yet at this time), press tab (everything between your start and endpoint should highlight now), and now click on the end point. This should select everything between start and end point.

Best regards,
Toon

[toon_demuynck]

We will be adding answers to all your questions right here on the forum. We will start with the ones that did not get answered during the live session. The ones that got an answer during the live session will follow later.

[rob.harmer]

Thanks that's useful

[toon_demuynck]

Here we go with some answers to the questions (feel free to reply for more information, or send me a message, always happy to discuss):

• Q: can you send a link for certification courses? - A: Unfortunately, we can not send such a link. I'm not quite sure what you are requesting 🙂
• Q: You mentioned that you use the "same Revit model" for all your calculations when the model is "workable" from the architect. What specifically do you look for when you are determining whether their model is suitable to use for energy modelling? When not usable, do you "re-model" their model in a rather simplified way? Just walls, windows, doors, roofs and floors? - A: We load the AR model, and first do a visual check, look at some sections etc. Next step is to assign U-values, either via materials (and associated thermal properties), or via schematic types (which are stored in the constructions.xml file residing in your revit installation folder). Then we just try to create an energy analysis model, and check the quality of that model: are all spaces and surfaces regocnized and classified correctly. You have several views and filters available to check that. When we realize the model is not usable, we indeed model the buliding ourselves in a simplified way, leaving out railings, furniture etc. We model with enough detail to suit our needs: heating/cooling load calculation, lighting calculation and spatial coordination (althoufh for that last purpose we tend to use the model from the architect during the complete process).
• Q: Is there a good add on that you recommend for the mechanical loads in the United States? is there an add on that you would recommend for HVAC calculations in the US - A: Our project are mostly EU based. I can recommend watching the activity of Sean Fruin, from Sigma AEC.
• Q: Can Revit MEP cover electrical panel short circuit calculations? - A: I am not aware that revit supports this type of calculation at the time. There could be some external add-ins that might do this in revit, of be able to link with a revit model, but we have not investigated this yet.
• Q: Are you thinking of using Inventor models inside Revit models, now that you can link Inventor into Revit and vice versa - A: This it not a topic currently on our backlog, since we have very few projects using inventor together with Revit. But I'm quite sure interesting relations can be established between those models, and information from inventor models could be used in revit. It's certainly worth investigating if the revit API supports this currently. I typically use this resource to check the API: https://www.revitapidocs.com/2022/, but I can't find much on inventor here.
• Q: How about pump curves? How do I apply fixtures for calcs? - A: Pump curves are currently not included in our families and calculations. Applying fixtures for calculations comes down to making sure the families you use contain the correct values in the parameters for WFU (for wast water), HWFU (for hot water) and CWFU (for cold water). Those parameters are added up automatically by revit in the piping system connecting all the families (similiar to the flow in heating/cooling systems that is also just added up)
• Q: Stainless Steel and HDPE already with fixture units in Add ins by any chance? - A: Fixture units are not assigned to the pipes, but to the plumbing fixtures/mechanical equipment. Stainless steel and HDPE would be pipe types in revit, each with their own set of properties (roughness, available diameters etc).
• Q: One of the issues with calculations is matching the units. Are you using the actual units associated with the parameter, or converting calculations into integers or numbers? - A: When sizing pipes and ducts with standard revit functions, the units correspond to your revit settings. When you want to apply the sizing in the schedules with calculated parameters, you indeed have to manage units carefully. We are actually using unit-less numbers for our calculations, since managing the units in formulas in revit is not always a smooth process :-

[toon_demuynck]

Some more questions and related answers:

• Q: What is the maximum temperature for air? - A: I'm not aware of any temperature limits for Air temperature in Revit, but you should check that air properties are defined properly for the temperatures you want/need to use.
• Q: Any ticks and trips for electrical guys this hour? - A: We do have a tool in dynamo that calculates cable lenghts routed over available cable trays. This is just an implementation of the dijkstra algorithm, and you can find information about this script via google search, and I think this is where we got our inspiration: https://forum.dynamobim.com/t/shortest-route/16360/12. Other than that, we also have space types defined in revit, that help us set up early power (and cost) estimations. We just place spaces, select the correct type for each space (can also be just a few spaces per floor in concept design, to indicate the correct surface area for each type) and we basically have our power and cost estimation
• Q: Do you have any plans to move your custom tools to BIM360 using Forge? - A: As a matter of fact, we allready have some forge-based tools, but they reside in another business line with the company dealing with infrastructure. We have a forge-based application that we use to generate the largest assets in water clarification plants. Currently we are not looking to migrate the the tools for buildings to Forge, but it is in the back of our minds.
• Q: Using the revit Internal Revit calculation workflow what is the percentage of working hours savings ?- A: This offcourse depends heavily on the size of the project, but I'l give you some ballpark figures. It's mainly engineering hours that are reduces, as typically the engineer calculates based on a sketch in combination with an excel sheet or external calculation software. This engineering time is almost completely erased, since our modelers take over the sizing task together with the modeling task. So if an engineer would have to do 2 days less work, the modeler might have to do one day extra work. But we are also a big fan of the other advantages that these methods bring us: quality, consistency etc...
• Q: With ElumTools, using a linked arch model, do you need to set reflectance and textures of surfaces each time you run a calculation? - A: I'm actually not an expert on elumtools myself, but if I remember correctly you only have to set these values once, not again for every calculation run.
• Q: When sizing pipe, does revit take into account the pipe material and available pipe sizes in that material when doing calculations. For instance if the water piping is CPVC cts sdr 11? - A: when using the standard revit pipe sizing, revit only takes into account the sizes of the pipe that are defined in the project/template. So if you need that specific type of pipes, make sure these are defined in your template, and set up roughness values correctly. You also have the possibility to exclude certain pipe sizes from the sizing procedure
• Q: Do you rely on the System Browser to track calculations???? - A: We mainly use the system browser to check our systems as such, since a correctly connected and designed system really is crucial to perform any calculations in revit. We do not use it to track actual calculations

[toon_demuynck]

And yet some more answers:

• Q: is it possible to define custom calculation parameters? - A: what custom calculation parameters are you referring to please?
• Q: During the energy analysis revit 2022 it takes sometimes really long time to calculate at background even can not calculated error appears infrequently. Why is that so? thank you. - A: Unfortunately I'm not able to answer this question with this limited amount of information. I suggest you contact the autodesk helpdesk, they usually respond quite fast in my experience.
• Q: How trust worthy are the built in Revit calculators? I have had different ASHRAE fitting numbers assigned to the same fitting family just in different parts of a duct system. Is this a common error on my part or a Revit issue? - A: When sizing pipes and ducts, fittings are not taken into account. Revit just takes the pressure drop per meter length, but does not look at pressure in fittings in this process. I'm not sure what you mean with "fitting numbers" assigned to families, can you elaborate please? We have had no issues with sizind pipes on pressure drop and ducts on velocity, all our results where very realistic and have been cross-checked on quite some occasions
• Q: what time is it/day? can you check your # AU2019 & EN-12831 - A: answered via chat, link to be provided: https://www.autodesk.com/autodesk-university/class/Revit-Systems-Analysis-Features-and-Framework-Int...
• Q: what is the difference between loss methods? - A: Not sure what different loss methods you are referring to here, if you could provide more information on that we would be happy to get back to this
• Q: what are the different loss methods for example duct have ashrae, smacna and acca but sometimes a fitting must be guestimated as it is not regulater and unable to even draw in revit. similar there are certain valves (butterfly and control) that is harder to find the pressure drop - A: When sizing pipes/ducts on pressure drop, we typically only look at the pressure drops in the straight sections. So fittings are not taken into account in this stage. Off course when sizing is done, and you would want to calculate the actual pressure drop in your systems, you also need pressure drops in fittings and accesories. This is more complicated, and not used by us currently inside revit.
• Q: When it comes to loss method calculation for elbows, fittings, etc. How have you dealt with the issue with Revit not being to determine the type from the ASHRAE Tables? - A: When sizing pipes and ducts, fittings are not taken into account. Revit just takes the pressure drop per meter length, but does not look at pressure in fittings in this process. I think you are referring to the pipe pressure loss report? We have looked into that briefly in the past, but decided to not use it at that time. So unfortunately I can not help you out with this one (at this moment in time that is).