Is ENVI-met different from other Windows programs? Is it easy to install? Does it work right out of the box?

Yes and No. On one hand, ENVI-met is a typical Windows program, on the other hand, it has system requirements that other programs do not have. Users may experience trouble that may not come up with other programs due to bad resource management. Also, ENVI-met constantly reads from and writes to the memory. A single incorrect value (e.g. a temperature of -9999 degrees) can crash the whole simulation.

ENVI-met will utilize all the CPU power it can get, but it does not force Windows to allocate all of the CPU power away from other programs meaning a user can switch to other applications – if there is enough memory. ENVI-met may appear to be frozen or “Not Responding” but it is fine and actively working in the background.

 

Can I run ENVI-met in a virtualized environment under Mac OS X or Linux?

Theoretically yes, but it will probably run much slower compared to a generic PC (although a lot of progress can be made in virtualization in the latest update). It is better to partition the hard drive on a Mac if the plan is to run ENVI-met on that machine. For more robust simulation processing, Cloud Computing is another option.

 

Can I stop a model run and continue later ?

This feature is not implemented at the moment, if a simulation is cancelled, it must be restarted from the beginning.

 

Can I use more than one CPU (core) to simulate with ENVI-met?

Starting with Version 4.3 (Winter 2017/ 18 Release) the SCIENCE and BUSINESS versions are able to run parallel code on many CPUs.

Is it possible to simulate a whole city in ENVI-met?

Users will need to pick more discrete or typical areas and simulate those sites as a case studies. Starting with V4.3, it is possible to simulate much larger areas, but a strong computer and lot of memory is needed.

 

I have seen ENVI-met simulations covering a large domain with topography and with a coarse resolution. Does this work?

ENVI-met is a pure physical model. It was designed for high-resolution simulations, but the model physics will also work for much larger spaces and coarser grid resolutions. Hence, ENVI-met might also be used for mesoscale applications if the features of the domain can be represented within the digital domain concept used in ENVI-met (e.g. there are no mixed landuse options in ENVI-met).

 

I am working in a consulting company/ architectural office. Can I use ENVI-met?

In a commercial environment (that is any environment that aims to earn money, public or private) you need the BUSINESS license of ENVI-met to work.

 

I would like to use ENVI-met commercially. How can I get/buy a license?

The price list and the feature of the different versions are listed on our website. If you are interested, please drop us a mail under license@envi-met.com.

 

How do I get support?

There are a large number of documents and video tutorials on our webpage, which are constantly being updated. In addition, there is our online forum, which is intended as a place to exchange ideas with other users.

Simulation Trouble Shooting

 

 

If ENVI-met crashes, what can I do? I get a “floating point error” or a “Division by zero” error – is this due to a bug in the programming?

If this issue arises, it is most likely due to a numerical instability that causes these problems. There are billions of operations executed in ENVI-met each minute and yet every user (including us) wishes for even greater complexity.

Almost any of the variables calculated within the simulation depend on other spatial and temporal factors, which may give rise to a rogue variable that contains unrealistic values. This may be corrected internally by some other system dynamic, but it may also be the case that the variable unexpectedly went to a value such as zero before it is used for a division in the next operationm, which triggers an error.

This does not arise as a function of a programming error, but instead that the dataset was broken during calculations. Checking the validity of the data before every operation is not possible as that would increase the calculation time dramatically. An immense number of “intelligent” routines have been introduced into ENVI-met to auto-correct the most common problems. Ultimately, it is a sophisticated numerical tool and these routine errors are inherent in numerical modeling.

You might also want to check our forum, where many individual cases asre answered.

How can I improve the stability or solve stability problems?

There is no general cause of for why a model may not run correctly. In most cases you have to try different things to get a stable simulation, if errors are occurring. However, if your configuration does not work, here are a few things to check:

If ENVI-met crashes at the beginning, check the simulation log output present on the screen. Use the “Check Model” option to generate a review of the output. Check to see if the input files and database files are ok and contain realistic values.

Is Windows working properly? ENVI-met allocates huge amounts of memory for data storing. If a program crashes or Windows has serious issues either before or during the model run, stored data may be lost. Do not run ENVI-met if there is little remaining memory, make sure that the simulation is run in your physical memory, NOT in the virtual memory.

ENVI-met may fail in producing a solution, which may be a possibility with such a complex numerical tool. A lot of time has been invested to increase the internal intelligence of ENVI-met, with recent versions being able to handle more complicated trouble shooting and finding solutions to ensure a proper model run. A few tips to promote a successful simulation are:

  • Move complex buildings away from the model border.
  • Clean up the model and only keep important structures. These structure must make sense though. For example, A narrow path between buildings may be close to the resolution of the model, it is key to decide whether its presence is significant and warrants keeping.
  • Increase the vertical extents of the model.
  • Decrease the time step if the model gets unstable in the normal calculation loop.
  • Simplify your model, complex geometries of certain buildings can be adjusted to a more simple configuration.

Windows OS and Computer Specific Questions

 

 

When the ENVI-met window was hidden by another window, it remains white and is only in areas redrawn when new outputs are posted….Why?

Although this may look messy, it is correct. ENVI-met does not react to Windows messages such as “Redraw yourself” during the simulation in order to save processing time. It will update the simulation window from time to time. Updates from Summer 19 onwards will react much more direct on user interactions.

 

When I look at the CPU load, ENVI-met uses only 50% (25%,…) of my computer. Why?

ENVI-met up to and including version 4.2 only use one thread for the simulation (see next two FAQs). If your system has more than one CPU core, ENVI-met still only uses one of the CPU cores. Although this single core is used a 100%, the overall usage is only 25% (if the system has four cores) if the other cores are without tasks.

ENVI-met 4.3 and newer support parallel computing with the BUSINESS and SCIENCE licenses.

 

Can I run more than one ENVI-met simulation at the same time?

Yes, if the system has enough memory and CPU cores free. If ENVI-met is used in parallel mode, the CPU loading may need to be adjusted (see documentation for V4.3). As an example, if a system has four cores, theoretically three ENVI-met simulations can be run in single-core mode.

Allow each ENVI-met simulation a free memory of 3 GB. This will leave one core free for the operating system and other software devices.

 

Can I distribute my ENVI-met run over several PCs?

Not at the moment.

 

Is there a 64-bit version of ENVI-met?

Version 4.3 comes as a hybrid system for both 32-bit and 64-bit systems. On a 64-bit Windows installation, the 64-bit versions of ENVI-met and Leonardo will be started. The other applications are still 32-bit. In the near future (this is Winter 19/20), all of the ENVI-met software will be developed for 64-bit Windows only