What is ENVI-met?

ENVI-met is a holistic microclimate model, in which all the different elements of an urban or landscape setting interact which each other.

The model’s calculation modules span over a wide range of different scientific disciplines -from fluid dynamics and thermodynamics, to plant physiology and soil science.

It is the guiding principle of ENVI-met philosophy to integrate all of these different approaches into a single model, so that all elements can interact with each other and reproduce the synergies we observe in reality. This holistic approach makes ENVI-met different to other modelling platforms for environmental simulation purposes. There are many models which calculate the air flow between buildings or the solar input on facades, but there are very few that see the whole environment as a single system and consider the multitude of processes that take place between elements.

 

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.

 

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.

What is BIO-met?

BIO-met is a post-processing tool to calculate human thermal comfort indices based on simulation data. It directly interacts with the ENVI-met output and lets users set the physical parameters of a person within the model domain to determine the Thermal Comfort Index and a range of other calculations.

It is important to understand that a proper Thermal Comfort Index can only be calculated if the microclimate data it is based on is correct. First a valid ENVI-met simulation output is needed, followed by the calculation of Thermal Comfort.

A brief introduction and guide on how to use BIO-met can be found here: BIO-met Quick-Start.

 

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).

 

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.

Licenses and fees

 

 

Which extra charges do I have to expect in addition to the license fee, eg. for updates and support?

There will be no additional costs except the annual license fee. All updates and technical support are included during the runtime of your software license.

 

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.

 

What is the difference between the Student and Science License?

The ENVI-met Science license offers universities and research institutions the advanced full-size model with all the features, intended only for research and education purposes. It cannot be used for any projects with external funding aiming to generate financial gain or based on funding generally available to the free commercial market.

The Student license reflects our commitment to education and allows individuals to install ENVI-met on up to 2 computers, does not include parallel computing. The maximum usage is one year and cannot be renewed. In order to buy the Student license, a proof of enrolment needs to be sent to license@envi-met.com.

Annual or perpetual license? Can I buy for more than one year?

An ENVI-met license lasts for a duration of 12 months, purchasing for a shorter time period is not available. A discounted price can be applied to multi-year license purchases, beginning with the 2nd year, with the possibility of up to 5 years. Please contact license@envi-met.com for additional information.

After purchasing ENVI-met – which technical support will be offered?

Business License:

  • For support, customers can reach us via email (Mon-Thu 8-6 p.m./Fr 8-3 p.m. CET) – our team will provide technical services in a timely and efficient fashion.
  • Access to a comprehensive, constantly growing knowledge database

Science/Student License:

 

After purchasing ENVI-met – how do I get started?

You will receive a download guide and electronic license key that allows you immediate use of the software within the next 2 workdays.

Windows OS and Computer Specific Questions

 

 

What are the minimum system requirements to run ENVI-met?

The performance mainly depends on the CPU clock speed and the number of CPU cores. Small RAM capacity (less than 4GB) increases the simulation time of larger model areas (larger than 200 x 200 x 30 grids), so a 64bit CPU and operating system is required. The performance of the simulation does not depend on the graphics card since all calculations are performed by the CPU.

Minimum system requirements:
CPU: Intel Pentium D or AMD Athlon 64 X2
RAM: 4 GB
OS: Windows 7 / Windows 8 / Windows 10
VIDEO CARD: no specific requirements
FREE DISK SPACE: more than 5 GB

Recommended system requirements:
CPU: modern 6 or 8 core CPU, Intel i5-8400 –
Ryzen 5 1600X or better
RAM: 16 GB
OS: Windows 7 / Windows 8 / Windows 10 (64bit)
VIDEO CARD: no specific requirements
FREE DISK SPACE: more than 30 GB

High end setup:
CPU: modern 16 or more core CPU,
Intel i9-7960 – Ryzen Threadipper 2990WX or better
RAM: 64 GB
OS: Windows 10 (64bit)
VIDEO CARD: no specific requirements
FREE DISK SPACE: more than 100 GB

 

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 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. Also, ENVI-met constantly reads from and writes to the memory.

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.

 

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.

 

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.

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.

A few tips to promote a successful simulation are:

  • Move complex buildings away from the model border.
  • 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.