Trial / Demo
EECO2 leverages IESVE's CFD application, MicroFlo-CFD, to demonstrate the potential for using lower air change rates as part of a dynamic ventilation control approach, thereby reducing the energy use and carbon impact of cleanroom facilities.
Pharmaceutical cleanrooms pose particular challenges when it comes to implementing building energy and carbon reduction strategies. Strict air cleanliness requirements are in place to maintain product quality, stipulating tight control of air flow rates, air direction, temperature, humidity, and filtration. As a result, the necessary heating, ventilation, and air conditioning (HVAC) systems can create substantial energy demand and carbon emissions.
Strict compliance requirements have typically resulted in a conservative control approach with high fixed air change rates. However, with some cleanrooms consuming up to 25 times more energy than other standard room types, EECO2 - a global leader of sustainability solutions for the pharma and life sciences sectors - have developed a dynamic, demand-based control approach that uses lower air change rates to minimise energy consumption and carbon emissions.
Dynamic demand-based HVAC control is a promising energy saving alternative to existing cleanroom control, and a technology solution is available in EECO2’s patented Intelligent Cleanroom Control System (ICCS). However, for the industry to fully embrace this carbon reduction opportunity, a better understanding of ventilation patterns and clear evidence of successful ventilation control is beneficial.
As existing IESVE users, already using the energy simulation capabilities within the software, EECO2 decided to explore how the CFD application, MicroFlo-CFD, could help to evidence ventilation performance of different ventilation scenarios.
This real-world project, undertaken by Muhammad Yasir, an Energy and Products Engineer at EECO2, was supervised by Dr Sanober Khattak as part of Yasir’s MSc program at De Montfort University, earning the 'Best Thesis Award'. Central to the study was the use of IES software and the rigorous validation of Computational Fluid Dynamics (CFD) models through experimental data. This robust validation process greatly enhanced the confidence in the accuracy of the study’s findings, providing reliable and actionable insights.
To conduct the initial proof of concept study, EECO2 selected one room at their cleanroom testbed - a Grade C facility based in Macclesfield, UK. Using MicroFlo-CFD, they were able to conduct a CFD study exploring the ventilation performance of different air change rates within the facility, using measured boundary conditions and validation through a temperature grid.
The main risks of operating cleanroom ventilation systems at lower air change rates are poor air mixing and clean air not reaching critical locations, which can affect particle concentrations. This is where CFD analysis can provide valuable insights that help to understand and mitigate these risks.
The air supply at this particular facility is provided through 3 swirl diffusers in the ceiling and two extracts near the floor on opposite walls. To gather the necessary data for their analysis, EECO2 assigned a flow rate of 18 Air Changes per Hour (ACH) via the cleanroom’s building management system (BMS), as the base case scenario. Once the flow had stabilised, they used a balometer to measure the flow rate through each swirl diffuser, anemometers to measure air velocity to calculate the air flow rate through extracts, as well as exfiltration and infiltration beneath doors. The process was then repeated for lower ventilation rates of 13 ACH, 8 ACH and 3.5 ACH respectively.
As temperature also plays a crucial role in terms of contamination control, air distribution patterns and overall environmental conditions, the team also implemented a 3D grid arrangement of data loggers within the cleanroom, at three different heights, for measurement of air and surface temperatures. This enabled the subsequent comparison of modelled vs. measured data, to validate the accuracy of the CFD model and outputs.
EECO2 used ModelIT to create the model geometry, using construction drawings of the facility and assigning construction materials based on available information and assumptions. A dynamic annual energy simulation was then run in ApacheSim, using regional weather data, with the results imported to MicroFlo-CFD to enable the CFD analysis for each of the four ventilation rate scenarios.
The model was validated by comparing the simulated and measured data from the cleanroom, to ensure confidence in the CFD simulation’s accuracy in replicating real-world conditions. The model was found to achieve a close match to the measured temperature data. Values for the Root Mean Square Error (RMSE) – a performance metric used to quantify the difference between simulated and actual values – ranged between 0.98% and 1.37%. Convergence criteria from the CFD analysis were also evaluated to further validate and provide confidence in the model.
CFD simulations were then run in MicroFlo-CFD to assess the ventilation effectiveness of each ventilation rate scenario, considering the key metrics of Air Change Effectiveness (ACE), local mean age of air (LMA), and air flow patterns. The resulting model outputs enabled EECO2 to identify any areas of poor performance, helping to inform particle counter placement for dynamic cleanroom control, as well as calculate the energy savings potential.
Through this project, EECO2 succeeded in demonstrating that more cost-effective and sustainable cleanroom operation can be achieved by reducing the air change rate, without compromising the required ventilation standards. By reducing the air change rate from the baseline 18 ACH to a minimum 3.5 ACH, energy savings of approximately 65% were identified, facilitating significant reduction of carbon emissions.
The model results showed that some eddies formed as the air flow rates were reduced, resulting in an increase in LMA at certain locations within the room. This analysis enabled EECO2 to determine the most appropriate locations to place particle counters that feed data into the demand-based control, giving further confidence for successful implementation of the dynamic cleanroom control through ICCS® technology.
This project represents an important step forward for the pharmaceutical industry in reducing its climate impact and enabling progress towards zero-carbon cleanrooms. Following the success of this initial proof of concept for CFD enabled ventilation design, EECO2 are extending the approach to their consultancy projects, to further enhance design and implementation of dynamic cleanroom control to achieve energy, carbon and cost saving potential through ICCS®.
“Pharma companies are keen to implement energy saving technology but need to be sure that they are compatible with the quality requirements, so we always look at ways to reassure them that the strategies we propose will work.
It's a very energy intensive sector, so we were already using IESVE to provide building energy simulation to support our consultancy service in advising pharma companies in terms of energy efficiency and sustainability. Now that we've also got that CFD expertise in house, it's really helpful to be able to build that in.
Currently we've got a couple of new projects that are all linked to the installation of our patented system, ICCS, which is an intelligent cleanroom control system. Wherever we propose to install this, we hope to use this approach to demonstrate and visualise the impact.” - Dr Birgit Painter, Products Manager at EECO2
“The key thing for us was to be able to provide confidence that, even at lower air change rates, we could maintain the age of air and air change effectiveness within the required limits at our cleanroom facilities.
While we also conducted experiments, using other indexes and by measuring the particle concentrations, this only provided data for those very particular points, you can't be sure about every place inside the room. This is why CFD is valuable - you can visualise every location or every point inside the cleanroom.
Even at lower air change rates, the CFD results were quite similar to the results we found experimentally. So, it us gives confidence that we can remain within compliance while still saving energy, which is the most important outcome for us.” - Muhammad Yasir, Energy & Products Engineer at EECO2
The study was presented at the CIBSE Technical Symposium 2024. To read more, you can download the full paper here: CIBSE Technical Symposium Papers 2024
For more information on the tool, you can also check out our MicroFlo-CFD page.
