CFD study of the Paleontology Gallery – MNHN
CFD study of the Paleontology Gallery - MNHN
Year
2025
Customer
Paris Natural History Museum
Location
Paris
Typology
HVAC
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The mission carried out by EOLIOS ingénierie: expertise in CFD simulation and aeraulic comfort in heritage buildings
EOLIOS engineers are experts in thermo-aerodynamic comfort in large heritage buildings
EOLIOS ‘ expertise in CFD(Computational Fluid Dynamics) simulation and optimization of indoor environments played a key role in the analysis and improvement of aeraulic comfort in the Galerie de Paléontologie at the Muséum National d’Histoire Naturelle. Our expertise enabled us to characterize the thermo-aerodynamic behavior of this exceptional heritage building, and to propose concrete optimization solutions that reconcile the comfort of occupants, the conservation of collections and respect for architectural constraints.
EOLIOS is a leading player in CFD simulation applied to heritage buildings and major cultural facilities. Our studies are based on feedback from measurement campaigns in real-life conditions, and our recognized expertise in modeling complex volumes with high thermal challenges.
MNHN Paleontology Gallery: the challenges of thermal comfort in a heritage building
Large volumes, listed facades, visitors and collections: why air-conditioning comfort is an engineering challenge in its own right
Cultural and heritage buildings present a particular challenge in terms of airflow comfort. The Galerie de Paléontologie at the Muséum National d’Histoire Naturelle is a perfect illustration of this reality, with its high ceilings, open volumes spanning several levels and large glazed surfaces.
These characteristics generate phenomena that are amplified in comparison with standard buildings, notably a marked thermal stratification where hot air accumulates high up, creating vertical variations of several degrees. Added to this are strong heritage constraints, since the listed facades limit possible interventions on the envelope, as well as dual and variable occupancy between fluctuating public and permanent staff with differing requirements.
In addition to human comfort, collection conservation requirements call for stable ambient conditions. These particularities make aeraulic comfort in this type of building a complex engineering problem where empirical approaches quickly show their limits.
CFD in museums: visualizing and controlling air flows where conventional methods reach their limits
Given this complexity, CFD(Computational Fluid Dynamics) appears to be the most appropriate tool for several complementary reasons. Unlike simplified methods that calculate global flow rates without representing local physical reality, CFD offers a complete three-dimensional view, enabling precise visualization of the trajectory of air veins, recirculation zones and temperature gradients, thus identifying critical points of discomfort that escape global approaches.
It also enables the virtual testing of multiple scenarios – existing/projected comparison, modification of geometry, variation of control parameters – without any material cost or disruption to operation, avoiding costly design errors to be corrected after the fact. CFD also natively integrates thermal couplings between solar radiation, conduction and convection, essential for assessing the actual thermal comfort experienced by occupants.
Finally, the colored visualizations it produces are an effective communication tool between project participants, facilitating shared understanding of problems and technical justification of choices. In the context of this DCE phase, it is therefore an essential prerequisite for any intervention on the ventilation system.
CFD simulation does more than simply analyze existing air flows: it is first and foremost a tool for optimizing comfort. By accurately modeling the conditions experienced by occupants – air velocity, ambient temperature, thermal stratification – it canidentify areas of discomfort and test corrective solutions before any work is undertaken. In public spaces such as the Galerie de Paléontologie, where occasional visitors and permanent staff cohabit, this ability to anticipate and refine ambient conditions is a decisive asset in guiding design choices towards solutions that are both efficient and sustainable.
Understanding, analyzing, optimizing: the three axes of CFD thermo-aerodynamic research at MNHN
The CFD study carried out by EOLIOS on the Paleontology Gallery has three complementary objectives.
The first aims to understand thermo-aerodynamic phenomena by acquiring detailed knowledge of air behavior both in the existing configuration and in the projected configuration after construction: characterize velocity fields and temperature distributions, identify dominant transfer mechanisms according to zones, and highlight interactions between different levels of the building.
The second objective is to analyze the efficiency of the ventilation system by assessing its technical performance: checking the balance between supply and return air flows and the absence of short-circuits, quantifying actual air exchange rates in relation to theoretical values, detecting any malfunctions, and comparing theenergy efficiency of the different simulated configurations.
The third objective is toidentify the risks of discomfort in order to provide concrete elements for the well-being of occupants: map critical zones where velocities exceed 0.4 m/s or temperatures fall outside the 18-25°C range, assess overall thermal comfort, formulate targeted technical recommendations and prioritize interventions according to expected impact and feasibility.
These three axes structure all the work presented in this summary, and reflect the desire to provide the project owner with a clear, well-founded and operational vision of the Gallery’s aeraulic challenges.
The EOLIOS method: from field to simulation, an approach rooted in reality
In-situ measurements and smoke tests: the field audit as an indispensable foundation
An in-depth audit was carried out directly in the Galerie de Paléontologie in order to precisely characterize thermo-aerodynamic phenomena under actual operating conditions. Measurement campaigns were carried out on all levels to quantify air velocities, temperatures and flow rates at the terminals of the ventilation systems, providing a reliable and representative initial state of the installation’s operation. Qualitative visualizations of airflow trajectories were also carried out to identify recirculation zones, parasitic currents and malfunctions in existing diffusion devices.
Over and above data collection, this on-site audit is a key stage in understanding the actual behavior of the building in its often complex and constrained heritage environment. It enables us to compare theoretical diagrams and existing HVAC plans with the reality on site, and to integrate the effects of operating practices, architectural constraints, weather conditions and actual use of spaces, all elements rarely fully documented in technical files. This detailed knowledge of the site is essential to avoid simplifying modeling hypotheses or those that are far removed from actual operation.
The field observations resulting from the audit formed an essential basis for feeding, calibrating and validating the CFD numerical model. They guarantee consistency between simulation and actual system behavior, reinforcing the reliability of results and the relevance of proposed solutions. The audit is therefore an essential prerequisite for any sustainable analysis and optimization of ventilation comfort issues in this exceptional building.
50 million fluid elements: a high-fidelity 3D CFD model of the Paleontology Gallery
The 3D CFD modeling developed by EOLIOS is based on a rigorous geometrical foundation, drawn up from existing construction drawings, supplemented by the surveys and observations made during theon-site audit. The quality and representativeness of the model directly determine the relevance of the results obtained.
Based on the data collected, EOLIOS developed a detailed model integrating the complete geometry of the Galerie de Paléontologie on all its levels – from garden level to roof – as well as all the equipment influencing the site’s aeraulics: air handling units and their distribution network, supply and return air grilles, internal and solar heat sources, as well as all architectural elements guiding the flows, such as exhibition showcases, partitions and corridor railings.
The level of geometric detail is carefully chosen to faithfully represent elements with a significant influence on velocity and temperature fields, while streamlining secondary details. With a mesh of around 50 million fluid elements, this balance between precision and simplification guarantees the numerical robustness of simulations and results that can be used directly foranalysis and decision support.
Digital calibration: when simulation meets building reality
In practice, the CFD approach involves an iterative process structured in several successive stages: construction of the geometric model, definition of boundary conditions and thermo-physical properties, numerical resolution, thendetailed analysis of flow and temperature fields. This cycle is completed by a calibration phase based on field measurements, before iterations dedicated to the study of improvement configurations.
The calibration phase is a key step in the CFD process: it guarantees consistency between simulation results and actual system behavior. In concrete terms, it involves adjusting the boundary conditions and modeling assumptions – supply and return airflows, wall and window surface temperatures, weather conditions, solar gain, internal heat sources linked to occupancy and equipment – in order to obtain a satisfactory match between the calculated quantities and the measurements taken in situ during the audit.
Once the model has been calibrated and validated, with calculation convergence attested by a residual criterion of less than 10-⁴, it becomes a reliable predictive tool for studying the impact of various modifications – changes in flow rates, diffuser geometry, ventilation system configuration – and analyzing new flow and thermal distribution dynamics in support of technical decision-making.
CFD results: mapping air flows and temperatures under winter and summer conditions
Summer, winter, heatwave: simulating critical scenarios to anticipate visitor comfort
CFD digital simulation enables us to virtually reproduce the behavior of the air inside the Galerie de Paléontologie under realistic conditions, without having to wait for the relevant seasons or carry out costly and time-consuming in situ measurements. By defining representative boundary conditions based on meteorological data from the nearest station – outside temperatures, sunshine, operation of ventilation systems – it is possible to explore the behavior of the building in situations as varied as summer heatwaves or extreme winter cold.
Two critical scenarios were studied to define the gallery’s actual operating range:
- The winter scenario, corresponding to the coldest outdoor conditions, is used to check that the fan-assisted heating system is able to maintain a comfortable environment for visitors and staff, while limiting energy wastage due to excessive stratification of warm air at height.
- The summer scenario, representative of periods of high heat, aims to assess the cooling system ‘s ability to combine the high solar gains penetrating through the glass roofs and windows, and to guarantee bearable conditions despite the high thermal load.
This two-pronged approach gives the client a complete picture of the plant’s expected performance, highlighting not only average performance, but also potentially unfavorable situations that need to be addressed as a matter of priority.
Isosurfaces, sectional drawings, discomfort zones: reading CFD results to make better decisions
The simulations produce three-dimensional maps of the physical quantities studied – air velocity, temperature – which make it possible to visually locate compliant zones and those presenting risks of discomfort. These representations, in the form ofcolored isosurfaces or sectional drawings, are a direct communication tool between engineers and decision-makers.
Analysis of the velocity fields reveals a heterogeneous flow pattern at different levels and in different zones. Overall, low velocities can be observed in the large volumes of the gallery, conducive to a calm and stable atmosphere, but there are a few singular zones where theacceleration of the air creates the risk of perceptible air currents.
In summer, a particular dynamic appears:cold air injected at floor level tends to spread out in a sheet before rising along the walls, creating ascending currents that can sometimes be a nuisance when passing through the supply grilles. This phenomenon, typical of low-ventilation air-conditioning units, contrasts with winter conditions, when warm air rises naturally and more evenly.
In winter, thermal stratification works in favor of comfort: warm air accumulates in the upper part (under the vault and roof), while the occupied zone remains in a temperate environment. The planned configuration reduces this vertical gap with the existing state, improvingenergy efficiency andcomfort uniformity.
A comparison of the two scenarios reveals an overall positive assessment of the configuration: while winter operation appears satisfactory, with comfort conditions well under control on all levels, the summer scenario reveals certain limitations linked to the building’sthermal inertia and the size of its glazed surfaces. These observations, objectively highlighted by the simulation, justify the additional optimization proposals set out in the following section.
Optimization options: directional nozzles, occupancy-based control and flow redistribution
The simulations enabled us to identify a number of concrete optimization levers to improve the thermo-aerodynamic comfort of the Paleontology Gallery.
The use ofintermediate diffusion elements ensures a more even distribution of air flows before they reach occupied spaces, limiting discomfort zones caused by excessive air velocities.
Replacing existing diffusion equipment with adjustable orientation models provides seasonal flexibility, enabling air distribution to be finely tuned to outdoor conditions.
The high ceilings and communication between the gallery levels led to the recommendation of controlled sweeping of the upper parts of the volumes. This principle, which promotes the mixing of air layers without disturbing the occupied zone, proves particularly effective in the interim period, when assisted natural ventilation may be sufficient to maintain satisfactory comfort conditions.
Finally, by regulating ventilation rates in line with actual museum attendance, we can optimize the ratio between comfort and energy consumption, avoiding both undersizing and over-ventilation, which can generate unwanted draughts.
Replacing existing diffusion equipment with models with adjustable orientation would also offer flexibility of use according to the season.
Field audit and digital simulation: CFD as a decision-making tool for renovation without alteration
The CFD study carried out by EOLIOS on the MNHN Paleontology Gallery used digital simulation to objectivize the thermo-aerodynamic behavior of a complex heritage building. Combining an in-depth field audit with high-fidelity modeling, the analysis highlighted the building’s characteristic airflow dynamics and thermal distributions, in both winter andsummer configurations.
The results obtained provide input for the project owner, identifying areas requiring particular attention and suggesting possible directions for improvement, and illustrate the contribution of simulation as a decision-making tool: it offers an anticipated vision of the operation of the planned plant, helping to secure design choices and clarify trade-offs between performance, assets and investment.
EOLIOS ingénierie's expertise in solving thermal-air problems in heritage buildings
Recommendations tailored to each project
Drawing on its expertise in numerical simulation applied to large-scale heritage buildings, EOLIOS was able to propose several concrete, prioritized optimization solutions to improve the thermo-aerodynamic comfort of the MNHN Paleontology Gallery. Directly actionable levers were identified, such as the installation ofintermediate diffusion elements, the replacement of existing equipment by models with adjustable orientation, or flow regulation indexed to actual attendance. Additional measures, such as controlled sweeping of the upper parts of the volumes, were also studied for intermediate periods.
The solutions selected were rigorously simulated and evaluated, enabling us to precisely quantify their impact on visitor and staff comfort, as well as on the facility’s energy consumption. This iterative approach, combining field audit and high-fidelity modeling, guarantees recommendations that are anchored in the building’s reality and directly usable for the DCE phase.
Thanks to this study, EOLIOS was able to objectivize the Gallery’s aeraulic challenges and clarify the trade-offs between performance, assets and investment. This approach helps to secure design choices, while providing the client with an anticipated and reliable vision of the operation of the planned installation, in the service of an exceptional heritage open to all.
Video summary of the study
Summary of the study
The study carried out by EOLIOS ingénierie focuses on thethermo-aerodynamic optimization of the Muséum National d’Histoire Naturelle’s Galerie de Paléontologie, using CFD(Computational Fluid Dynamics) simulations. This approach makes it possible to visualize and analyze air distribution and temperature fields within this exceptional heritage volume, spread over several levels from the garden level to the roof. The video immerses viewers in a high-fidelity 3D model of the gallery, through which the temperature isosurfaces characteristic of the different simulated scenarios – winter and summer – are presented, revealing the dynamics of thermal stratification and the discomfort zones identified. EOLIOS combined an in-depth field audit, including in situ measurement campaigns and smoke tests, with calibrated numerical modelling involving almost 50 million fluid elements, guaranteeing a faithful representation of real phenomena. This approach made it possible to identify a number of concrete optimization levers – intermediate diffusion elements, adjustable orientation equipment, attendance-based regulation – to enhance the comfort of visitors and staff, while respecting the heritage constraints of this listed building. This study demonstrates the decisive contribution of CFD simulation as a decision-making tool for the renovation and optimization of major cultural heritage facilities.
Video summary of the mission
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