Energy efficiency in cleanrooms – Dangers of overdesign or under-design
Since the global energy crisis hit, companies in pharmaceutical manufacturing started improving their energy efficiency to contribute to the economy as well as to their budget. Heating, ventilation, and air conditioning (HVAC) systems are typically the biggest energy consumers in pharmaceutical facilities, and design is the best stage at which to influence them.
The energy efficiency of the system typically takes a backseat to the functionality of the system in the world of cleanrooms. These are controlled environments where particle concentration and its generation are the main criteria for performing sensitive pharma operations, in which good manufacturing practices (GMP) must be followed.
Increasing energy efficiency is crucial for both top-line growth and cost reductions. For it to be more successful, significant internal organizational cultural changes are required that demonstrate a desire to act on environmental issues.
The biggest energy-saving potential is usually found in HVAC
HVAC can be a crucial component that influences a facility’s ability to provide safe and effective products when contamination control is desired. For most of these manufacturing plants, HVAC is typically the largest consumer of energy.
Many factors need to be considered when designing low-energy HVAC systems for pharmaceutical facilities, especially regarding maintaining a clean and safe operational environment. Environmental control systems that are properly planned, constructed, installed, configured, maintained, and operated can assist in ensuring the quality of goods produced at a facility. This increases dependability and lowers a facility’s upfront and ongoing operating expenses.
The importance of design
It is hard and expensive to change a design during or after construction, and there is more impact on capital cost and schedule. As the design develops, input from all interested parties should be considered to avoid later changes.
Several goals are achieved through the process of assessing drawings and specifications, as a design progresses from concept to issued-for-construction status:
- Confirm that a design adheres to accepted tradition and practice
- Ensure that the concepts proposed are meeting user expectations
- Make sure a design reduces the risk to product quality or process safety
- Ensure that a design is reliable and that it performs as expected
- Validate that the hazards have been identified and considered while also ensuring that the suggested design is cost-effective.
A cost model helps to estimate the need for energy
An HVAC system’s life-cycle cost is typically significantly higher than its initial cost. Hence, the overall cost is a key consideration when selecting HVAC systems.
It is customary to assess various design possibilities using techniques such as net present value or the rate of return. Engineers that aim for the most robust design regardless of cost frequently lack familiarity with these ideas. However, the layout of a manufacturing facility must be developed around the needs of that facility. Hence, separating “must” goals from “want” goals requires work, because each department must reassess its operations in relation to what is necessary for successful operations.
When working on the design, a cost model helps to determine the facility’s final maintenance, consumables, and energy needs. Net present value and investment rate of return are common components of systems. Early on in a project, the cost model should serve as the benchmark for evaluating judgments about life-cycle costs, and it can be utilized to contest choices regarding user requirements.
Things to consider in design
The basis for all consumption estimations is the number of air changes per hour. If this is overdesigned, the air-handling units will have larger flows than necessary, necessitating larger fans and more cooling or heating loads. On the other hand, under-design would compromise the system’s usability and dependability, which are critical factors in any facility where contamination control is required.
Furthermore, when designing the HVAC system of ductwork or pipework, it is not just important to ensure that all ducts reach their location, it is also important how they get there. Every elbow, bend, reducer, and transition contribute to a higher static pressure drop, which increases the capacity of the fans, which in turn consumes more energy.
As the technology is modernizing, good designers are considering implementing modern technologies in the design, to contribute to energy efficiency. Proper design tools (CADMATIC, REVIT, AUTO CAD MEP) help to superpose all the systems in the project, and to ensure that the best distribution routes for the energy in the system are considered.
Automation helps especially in complex systems
Better automation of the facility can provide fine-tuning of the system, which will reduce unnecessary consumption. Some clients do not trust it, but the rule of thumb is that the more complex the system, the better the control of energy efficiency.
If the project has less than 24/7 working time, the building monitoring system can be programmed during the downtime to operate with minimal capacity. This ECO mode can be used on weekends or evenings when the process is not running. If the HVAC system is designed so that the amount of fresh air entering can be controlled through the building monitoring system, this can be a great asset at times when the outside air is within the required parameters.
The air-flow strategy used in the building layout, along with the analysis of the physical flows within the facility, is a key factor to consider. It is preferable to keep similarly classified areas physically close to one another as much as possible, so that they can be connected to the same air-handling system. Duct runs, energy distribution costs, and air system complexity will all be reduced as a result.
Energy consumption depends on the HVAC system
Once-through air systems provide the most acceptable form of preventing cross-contamination. Without any mixing or recirculation, the air leaving the supplied room or space is fully vented to the outside of the building. Therefore, potential contaminants from one space are not transferred to another through the return side of the air-handling system.
This strategy necessitates a lot of energy expenditure. However, a once-through system is recommended in locations where potent processes are handled and where the product is directly exposed to the environment.
Recirculated air systems increase the energy savings in the facility. This type of system circulates conditioned air into the room before returning it to the air-handling unit, where some of it is combined with fresh air and reconditioned, while the remainder is vented outside of the building. When using air recirculation technology, care should be taken to prevent the contaminated air from one location from contaminating the supply air for another.
Installing a heat recovery unit may be considered as a typical method in all HVAC systems in some parts of the world. Despite the high cost of the initial investment, this strategy offers effective energy savings. Some companies use constant recirculation of fluid through heat recovery units. However, at some time when the outside conditions are ideal, the design must ensure that the three-way valve may not transfer the additional loads.
There are several options for air drying
The best solution should be chosen based on the energy consumption or budget when determining how to dry the air required for process control.
- Cooling and drying. Relative humidity is typically achieved by cooling the air as much as feasible, then heating it to the desired room temperature to meet design requirements. This can be done with a water system.
- Dehumidifiers with silica gel. Drying a portion of the recirculated air to a very low relative humidity level before combining it with the remaining air. It is necessary to determine whether this design is suited to delivering greater energy efficiency throughout the design calculation.
- Devices for dehumidification. Despite being the most expensive solution and providing the best control over low humidity, these units use the most energy, as they dehumidify all the air that has been prepared for the cleanrooms. Even when steam or electricity can be used, a significant amount is still needed.
The significance of training
Personnel involved in the manufacture and testing of GMP facilities must be sufficiently knowledgeable and trained for their role. At a minimum, personnel must understand the fundamental principles of GMP operations, as well as the critical documents specific to their area of work. For more important operations, employees may need to demonstrate operational skills, and operators may need to undergo formal qualification tests.
Training is a crucial component in developing skills, competence, and a high work performance culture, all of which are necessary to enhance maintenance performance. Lower operational energy costs could also come from properly implementing some well-known maintenance procedures, such as preventative maintenance and predictive maintenance.