Under water simulation

Replies to This Discussion

Permalink Reply by Chris Mackey on February 5, 2015 at 5:56pm

Tasos,

This is certainly an interesting question.  As far as I know, EnergyPlus doesn't have any specific objects for modeling something submerged in water.  The best that I could recommend is continuing with your underground strategy and use the IDFEditor to change your ground temperatures to be what the water temperature would be (as opposed to the usual ground).

Here's an image showing how you could plug in your own ground temperatures with the IDFEditior and the IDF that Honeybee writes:

Also, since you building is on the water, make sure that you change your terrain to "Ocean" or at least "country" with the EnergySimulationPar component.

-Chris

Permalink Reply by Mostapha Sadeghipour Roudsari on February 7, 2015 at 9:03pm

Hi Anastasios,

What Chris suggested is the first thing that also came to my mind but I suggest you to send this question to EnergyPlus mailing list or unmethours website (https://unmethours.com/) and let us know if you got any better solution. I think being able to overwrite the the boundary condition of a surface is something that is worth to apply to honeybee in general. I'm not sure if you can do that in EnergyPlus though.

Mostapha

Permalink Reply by Anastasios Kokkos on February 12, 2015 at 10:13am

Hi Chris, Mostapha,

Thanks a lot for your replies. I couldn't check earlier this week but I did today. I am not sure though after I change the temperatures in the IDF editor what happens (should I save as new object?) cause I simulated again and didn't find differences in the results. Indeed is interesting to see how we could do this overwrite through Honeybee. One issue regarding water temperatures throughout the year is that the available data are limited and differ from place to place even within a region. Another interesting point, since the area that is enclosed under water will be a living space is to see how we could simulate the heat gains from the direct sun on the underwater surface, if any, and how we could simulate also the heat exchange between the space and the water body. Would this follow the sae behaviour as the heat exchange between inside and outside air?

Thanks again!

Tasos

Permalink Reply by Mostapha Sadeghipour Roudsari on February 12, 2015 at 9:31pm

You should see a difference unless the R-Value of your walls is pretty high and conduction is very minimal. We can have a component to overwrite ground temperature but looks like you need to overwrite the values for every single hour?

Another interesting point, since the area that is enclosed under water will be a living space is to see how we could simulate the heat gains from the direct sun on the underwater surface, if any, and how we could simulate also the heat exchange between the space and the water body. Would this follow the sae behaviour as the heat exchange between inside and outside air?

Sounds like some interesting multi-phase CFD studies unless someone has already come up with an equation to model this. I can tell you that this is not something that you want EnergyPlus to do. The only energy simulation software that might be capable of modeling this to some extent might be transys but I know very little about Transys to make a comment. There are others on the group who can answer to this question.

Mostapha

Permalink Reply by Chris Mackey on February 13, 2015 at 6:32am

Anastasios ,
To be clear about my initial suggestion, you need to create the new ground temperature object, set monthly values for ground temperature, save the new IDF, and then open it in EPLaunch and simulate it. Only then can you bring in the CSV file to GH with the read EP result component.
Re - running the Run Energy Simulation component in GH will overwrite an IDF that you save with the IDF Editor.

I should emphasize that this is only a rough approximation and it is how I would begin to assess the effect of submerging a building partially in water. It is also probably all that I would get to do within the scope of a built project unless the building was completely submerged and I knew the accuracy would affect the results a lot. If this is the case or it is for a research paper on the topic that demands a really high accuracy result and factors all of the criteria that you mention like possible solar gains through the water, you would probably have to edit the energy modeling engine since this seems to be an uncommon situation. The two types of software I know where you can edit the engine would be trynsys, as Mostapha mentioned, or you could edit the EnergyPlus source code and recompile it into your own version. Both are big feats of research that will probably take a few months so be warned. Before embarking on such a quest, definitelt post the question on the unmet hours site and check if there are not other EnergyPlus objects for modeling this.

-Chris

Permalink Reply by Anastasios Kokkos on February 13, 2015 at 12:29pm

Chris, Mostapha,

Thank you again for your replies. I indeed overwrote the idf file and imported it to HB. I got slight higher consumptions especially during winter time since I changed the boundary ground/water conditions to be on average 7-10 degrees during winter time. I will not go further since the project I am working on is a floating neighbourhood that will be developed in Amsterdam and not a scientific research, as such the accuracy is adequate for now. I would like to investigate further though since in our region floating houses are being built quite often and submerged volumes are a good solution to the height restrictions there are due to local regulations and structural behaviour of such units. I am using both HB and LB for the overall analysis of the project and I would like to upload chunks of the work once is completed. The new releases are really helpful!  

Thanks again for your input! 

Tasos