Block-Built vs. Modular Test Facilities

The automotive industry (and the propulsion industry as a whole) is rapidly changing. Not only are internal combustion engines (ICEs) getting more powerful and often more complex, the introduction of hybridization as well as full electric vehicles of various configurations is putting an increased pressure on development teams to invest in new test capability and increased capacity. This burden is even higher when existing test capacity is required to maintain ongoing ICE projects, which is still the case for most automotive OEMs and test houses.

This poses the question: "Where is the limited amount of test budget available best spent?"

What is a Modular Test Cell?

As the name suggests, modular test cells are built from modules. Originally, these were most commonly standard shipping containers, modified for purpose to make them structurally and environmentally suitable. Some vendors (including Proventia) have since developed this concept to offer purpose-built modules, to overcome some of the limitations of shipping containers. These upgrades include extra height, extra width, insulated walls, and greater structural integrity. For a small test cell, one module is often enough to contain all the required components and is also user friendly and accessible to staff. For larger applications, such as multi-axis testing or full vehicle test, multiple modules can be combined to provide enough floor space. The modules are also structurally capable of taking heavy roof loads, so plant material can be installed on the roof, reducing the overall footprint of a cell. A modular cell can be placed inside or outside, which means that they can either replace existing test capacity indoors or allow for the creation of an entirely new facility that does not require extensive construction work.

What is a Block-Built Test Cell?

Again, the name says it all really. Whether the test facility was designed from scratch or whether test cells have been added to an existing building, it has traditionally been built from standard concrete construction blocks, with appropriate noise dampening insulation in between. In most cases, the building needs standard foundations and cells inside the building can be built to any size and shape. Considerations do need to be taken if heavy loads are to be placed above the test cell, but with prior planning this can be achieved.

Advantages of Modular Test Cells

• Portability - Modular test cells can be moved using standard shipping and haulage equipment. The cell can be packed down at the factory and loaded using a crane onto a lorry for transit. The system is then unloaded and re-commissioned at the location. For a small test cell, relocation takes approximately 1-2 weeks.
• Planning and Construction Requirements - A modular solution needs very little construction work, so planning requirements are minimal. The test cells typically require a level concrete base, and as a minimum, electricity, and water supply.
• Construction and Commissioning Speed - By building the test cells in modules, the equipment can be installed in parallel with any construction work being completed. As the on-site construction requirements are also reduced, the overall project delivery time can be considerably less than a block-built cell.
• Off-Site FAT - As the test cell can be assembled entirely off-site, a full factory acceptance test of a test cell can be made prior to shipping. This can be particularly beneficial when there are environmental control features, as it would otherwise be impossible to test these features in the cell, before the equipment is shipped to site. A FAT can also drastically reduce commissioning time, as snags can be worked out ahead of delivery.
• Self-Contained - The test cells can be built to be almost entirely self-contained. This includes local water chilling and de-ionization, transformer, and regeneration for the electrical supply, as well as the possibility for local fire suppression systems. This means that new test cells can be added to an existing facility or to a facility with no existing test plant equipment, without needing to modify the existing building.
• Safety - For safety critical applications, such as hydrogen fuel cell testing and battery testing, it can be advantageous to be able to locate the cells in safe distance from other buildings.
• Cost Spreading - In the case that more test cells may be needed in the future, a modular, solution can be added to over time, and the cost outlay is spread evenly across each cell. As the modular cells are self-contained, adding a new one can be done on an ad-hoc basis.

Limitations of Modular Approach

• Size Limitations - Modular facilities are built from smaller blocks. These blocks have some fixed dimensions, which means that the overall facility will need to be built from these component dimensions. Whilst this is not typically an issue for new facilities, there may be some instances, such as limited space availability, awkward layouts, or extra headroom requirements, which are difficult to achieve with a modular approach. Site access can also be a limiting factor to where a modular cell can be installed.
• Physical Limitations - There are some extreme types of testing which are not easy to accomplish in a modular solution. This includes very large dynamometers, which require a large mass to be embedded below the floor, or altitude testing, where the module needs to be gas-tight and structurally rugged to withstand large pressure differences.
• Cost - From a capital expenditure point of view, modular cells are not typically cheaper than their block-built equivalents.

Advantages of Block-Built

• Lack of Physical Restrictions - A block-built cell can be designed in any configuration. There is no limitations in the size and shape of the cell, which may allow for a test cell to be constructed where a modular cell would not fit. , It is easier to create a gas-tight cell using blocks, or build a cell with extra headroom for maneuvering larger equipment. It is also easier to implement any under floor equipment and to achieve extremely low vibration requirements.
• Modifying Existing Indoor Facilities - If there is an existing indoor test cell, it will typically be cheaper to retrofit the cell with new equipment. It is often possible to re-purpose existing ICE test equipment for hybridization and electrification projects, which can save a considerable amount of money. Often, the requirements for upgrading an existing cell for electrification testing include adding battery emulators and additional electrical drive units. These units are typically bulky, so it may be advantageous to locate them in a container next to an existing test cell, if the site layout permits.
• Cost - From a capital expenditure perspective, a block-built cell may be cheaper than a modular build. This is because there may be some additional overheads in building each module that would be shared in a block-built construction. However, the costs for a block-built facility can vary massively depending on whether there are existing foundations and plant equipment, and whether the equipment is being retrofitted into an existing test cell.

Limitations of Block-Built

• Long Project Lead Times - For a new block-built facility it can take several years before test cells are ready to be used. The facility must be built in chronological order; foundations, then building framework, then walls and roof. Then electrical and plumbing installation, before the test cells can be installed and commissioned. It can take months up front to get planning permission for this type of project.
• Internal Project Management Burden - For a full-scale block-built facility, it requires a full-time Project Manager (whether this is outsourced or not), and the procurement process is much more complex. The PM will need to manage health and safety, building construction, test cell construction and facilities, and ensure that the various stages of the project can be handed over at the correct times between parties. This will be a full-time role and may require more than one person to cover all aspects of the project.
• Fixed Construction - A more obvious drawback of a block-built cell is that once completed, the cell itself is a permanent structure. This means it cannot be moved, so any relocation of the facility would require the construction of new block-built cells.

Case Study: EV Test Facility, Modular vs. Block-Built

Requirements:

Medium sized EV powertrain research centre as an example:

• 1 x New 4WD Hybrid full vehicle test cell with hub-dynos
• 1 x New 1-axis high speed dyno (for eMachine testing or similar)
• 1 x New 2-axis transmission dyno
• All supporting plant equipment
• Site drainage and external work such as fencing etc. already available

Cost Comparison

As discussed above, the key differences between the modular approach and the block-built approach are in the planning and construction phases of the project. Whilst the block-built approach typically requires considerably more planning and professional services up front, the actual construction costs for the basic building are around half the price of the modular approach. Interestingly, whilst the construction is cheaper, the expenditure usually comes earlier in the project timeline.

One of the benefits of the modular building method is the shorter timeline, as discussed below. This produces some cost reductions for professional services like Site Management, Health and Safety, and Project Management.

However, the largest cost in these projects (especially for dynamometer cells) is the test equipment itself. This can include electric drives, battery simulators, motors, automation systems and many other tertiary systems. As can be seen in the table, these dwarf the construction costs. Other than the professional services and construction costs, the costs are very similar between the two build approaches, including test equipment, infrastructure, and commissioning. The modular approach does require one additional outlay in the form of shipping costs for the containers, which can be quite significant.

Overall, as shown in the table, the traditional, block-built approach comes in slightly cheaper - at around 3% in this case.

Timeline Comparison

From a project timeline perspective, there are two key differences between the modular approach and the block-built approach. The first difference is the additional time required at the start of the project for the block-built facility to get the planning permission, and then complete the basic construction. This means it could be 7 months from project kick-off to get through planning and construction for the block-built facility, compared with 4 months for the modular built. In some cases, it is even possible to build the modular building without planning permission, although these cases are not common. This can shorten the build phase even further for the modular built facility.

The second key difference between the construction methods is that the modular build allows for a large amount of the process to be carried out in parallel. The modules themselves can be constructed at the same time as the planning and foundations are being put in place. The majority of infrastructure and test equipment can be installed prior to shipping, which means that not only can this be completed in parallel with any site preparation, the required installation and commissioning time once the modules are installed on site is reduced as well.

As shown in the Gantt charts, the overall project delivery time for a modular facility can be less than half the time for the block-built approach.

Conclusions

Whilst the block-built approach yields a slightly cheaper overall project cost (approximately 3%), the project timeline is significantly shorter, and the project management burden and overall risk is less for modular facility. As well as the obvious logistical benefits to project delivery, there is the added advantage that the modular cells are almost entirely self-sufficient, so can be installed wherever there is space, and can be moved to a new location with fairly minimal effort. Each project needs to be assessed individually, however the modular approach is particularly relevant in today's fast-moving propulsion industry, where space is limited, and requirements change quickly. Furthermore, for battery pack testing and fuel cell testing, where there are safety implications, it can be beneficial to locate a test cell away from the main building without having to consider major construction work.

Learn more about modular test solutions>>

Christopher Garratt UK Sales Director