blog section, code


PVF logo facteur forme

Dans la continuité des stages de Marc ALECIAN (2021), puis Mina CHAPON (2021), un outil Python a été développé pour calculer les facteurs de formes de rayonnement entre « facettes » planes.

Incontournables dans la détermination de la température moyenne radiante, les facteurs de formes sont un paramètre de première importance dans la détermination du confort thermique, notamment pour le rayonnement CLO & GLO (Courtes Longueurs d’Ondes and Grandes Longueurs d’Ondes – plus d’explications sur la page dédiée : Calcul de la MRT).

Après avoir été présenté à la conférence IBPSA France 2022, le code est désormais disponible sur Gitlab : et sur PyPi avec un simple pip install pyviewfactor !

La documentation complète de la librairie est accessible here.

blog section, Publication

IBPSA France 2022

AREP L'hypercube attended the IBPSA France 2022 conference (at Châlons-en-Champagne, may 19th-20th), to present a paper entitled " Computation of View Factors between polygons - Application to urban thermal and comfort studies« .

Des travaux sont en cours pour rendre ces codes open-source, sous forme de librairie Python : pyViewFactor

Abacus of VF between a wall and an individual (cylinder)

Comparison of surface temperatures with and without taking into account the exact view factors

MRT computation with view factors

blog section, Projects

National Grand Prize for Engineering - Syntec

L'hypercube is proud to have contributed to the Grand Prix National de l'Ingénierie 2021, won by AREP teams, for the transformation project of the Saint-Michel Notre-Dame station (RER C).

For the hypercube, it is the recognition of the Air Quality expertise, born during this project in 2017.
After preliminary study phases that were marked by the development of predictive models of air quality in train stations and a fruitful collaboration with the CSTB allowed us to develop a simulation framework to estimate the ventilation induced by train passages ("piston" effect),the main driving force of the air quality improvement on this project.

Subsequently, we had to deal with other site constraints, such as acoustics and flood control. It is precisely this collective and iterative work of the different engineering departments that was rewarded by the GPNI!

Below is a video presentation of the main challenges of the project:


Melun train station

An annual wind comfort study, in and around a new passenger building, as well as on the platforms.

  • "CSTB" wind comfort criteria,
  • 12 CFD simulations,
  • Local phenomena characterisation,
  • Mapping the wind comfort criteria : the probability of exceedance of a given threshold over a complete year, indoor as well as indoor.


Non classé

World UTCI and MRT

A "new" database has been made available by the EU, from the Copernicus project (free access, login required).

UTCI and T_{MRT} , August 31st, 2018


This dataset provides a complete historical reconstruction of the UTCI (Universal Thermal Confort Index, a thermal comfort index as well as the MRT (Mean Radiant Temperature, essential for the thermal comfort) depuis 1979 jusqu’à aujourd’hui. Ces paramètres sont calculés par le modèle ERA5-HEAT (Human thErmAl comforT). Il s’appuie sur des réanalyses d’observations planétaires  qui permettent d’avoir une description cohérente et complète du climat à la surface de la terre, ainsi que de son évolution.


Technical data:

Data typeGridded
Horizontal coverageGlobal except for Antarctica (90N-60S, 180W-180E)
Horizontal resolution0.25° x 0.25°
Vertical resolutionSurface level
Temporal coverage1979-01-01 to near real time for the most recent version.
Temporal resolutionHourly data
File formatNetCDF
ConventionsClimate and Forecast (CF) Metadata Convention v1.6
VersionsUTCI v1.0
Update frequencyIntermediate dataset updated daily in near real time, Consolidated dataset monthly updates with 2-3 month delay behind real time.


Non classé

160 Cores dedicated to building physics

Since 2017, The Hypercube has been performing detailed airflow simulations and implementing numerical optimization procedures. These methods require significant computing power, which until now has been provided by "virtual machines" in Microsoft's Azure cloud. The team thus had 24 bodybuilt "machines" (8 ultra-clocked logic cores and 56 to 112 GB of RAM), switched on on demand and allowing a high reactivity.

This solution, which has been in use for 2 years, limited us in terms of reactivity (IT maintenance) and connectivity (data transfer speed) with a non-negligible associated cost.

The question then arose, with the AREP IT team, of an opportunity to invest in an "on-premises" calculation server... It is now done! It has just been delivered, in kit form.

It is therefore a computing rack with 4 processors, 20 cores each capable of hyperthreading (virtualization of a second core), in other words, 160 cores dedicated to simulating building physics phenomena! This represents the equivalent of more than 25 high-performance computers (for example for 3D visualization).

160 cores in action !

Today, this "beast", with 256 GB of RAM memory, extensible up to 3TB, runs on the open source Linux operating system (Debian 9).

Many thanks to AREP IT Services for their advice, support and energy!


Nice Saint-Roch – New maintenance and storage facility

Feasibility of cooling by natural ventilation for the administrative premises as part of the "AZUR Technicentre" project in Nice Saint Roch:

  • Calculation of pressure coefficients on façades over a full year using CFD,
  • Simulation Thermique du Bâtiment enrichie des résultats CFD,
  • Comfort assesment (number of hours above 28°C) for a typical year (2018)
  • Comfort Assesment for a 2050 climatic scenario : HadOM3 & HadAM3 models + RCP scenrios from IPCC (Intergovernmental Panel on Climate Change)