Considerations for the On-Board Environment
The provision of a healthy and workable on-board environment is essential in the maritime market to ensure crew comfort and productivity. Today’s commercial vessels demand the highest standards in every aspect of production - inside and out - and working alongside specialist system suppliers could be critical to achieving this.
With today’s tug, workboat and commercial vessels becoming increasingly sophisticated, crew are now expecting to have access to facilities aboard that are more closely aligned with their experiences ashore. The availability of a modern and comfortable working and living space is a key element of this expectation and a hot, stuffy and smelly environment on-board can have a detrimental impact on crew retention and productivity. This combined with advances in legislation for vessel operators to provide workable surroundings has meant air temperature and quality have become critical.
Behind the scenes, HVAC (heating ventilation and air conditioning) manufacturers face on-going pressure from commercial builders to reduce system size to meet more stringent space requirements in the engine room, while also taking increased ownership of system design, installation, operation and maintenance. The requirement to simultaneously cool and ventilate larger on-board spaces and individual cabin areas in the commercial sector has resulted in the development of intricate chilled water systems which can be designed in accordance with very detailed specifications.
“Creating a vessel’s ideal on-board environment can be quite a complex process with many factors to consider,” comments Ed Todd, Director of National OEM Sales, Dometic Marine. “A common misconception of an air conditioning system’s capability is that it simply controls temperature, when to effectively maintain comfort, the air’s humidity must also be properly managed.”
Due to the nature of the marine environment, humidity is a key issue which if not controlled can lead to dampness, mildew and mold growth, making the environment physically uncomfortable and even causing damage to sensitive on-board equipment. Todd continues: “Our air conditioning systems for commercial application are designed to monitor and control temperature and humidity simultaneously which enhances the condition of the air. We are also able to take the system one stage further by introducing an air purification solution which enhances the air quality by removing airborne contaminants, mold spores and odors.”
One of the most effective air purification systems currently available to the commercial, workboat and military sector is Dometic’s In-Duct Breathe Easy™, a tube-shaped unit which can be simply and cost-effectively installed within the ducting line and uses the HVAC system’s blower to move air through the purifier. Once fitted, the unit operates silently, purifying and cleansing air using Photocatalytic Nano-Mesh Technology with non-ozone-producing UV light. According to Dometic Marine, the system has been well received, even winning an IBEX Innovation Award in 2010.
“Air purification systems have been on the market for some time, but we feel the In-Duct Breathe Easy captures the best use of this technology in terms of its components and arrangement. By fitting easily within the ducting, the solution complements HVAC systems perfectly by ensuring the provision of clean air aboard, and it’s quickly becoming one of our most demanded products.” Todd adds.
Reducing Noise Levels
Aside from ensuring the air on-board is provided at the ideal temperature, humidity and quality for a comfortable environment, air conditioning systems should also perform quietly. System noise is a major consideration for HVAC manufacturers as to ensure the air conditioning system is not disruptive noise levels should be minimal.
Todd explains: “Although a certain level of noise is expected on commercial vessels, crew don’t want to hear the systems aboard operating to the point where it’s distracting, so minimizing noise is important for HVAC manufacturers. In addition to using the latest technology, placement, sound proofing and correct sizing of equipment can all contribute to noise level reduction.”
“When air enters the blower its speed changes from slow to fast and this velocity change often creates noise. Therefore the blower should be set at a low speed and isolated as much as possible from areas likely to be occupied by crew. In addition, the system’s return-air grilles should be placed at a low level which ensures the noise generated by the equipment is below ear level. The discharge point or supply-air grille should be placed at a high level which again keeps the noise away from the occupants’ ear level, and also maximizes the circulation of air through the space,” Todd adds.
“For instance, if an air handler can be placed in a bulkhead that is away from living spaces and quarters, versus in a ceiling that is close to one of these areas, the former is obviously a better option. The challenge for manufacturers and installation engineers is that the preferable choice is not always available, but it’s a case of making the best possible selection.”
In addition to correct placement of equipment, builders can consider integrating quieter technology, which will reduce noise as much as possible. Dometic Marine currently offers the WhisperCool series of air handlers which have been specifically designed to eliminate ‘motor hum’ that can occur with traditional air conditioning blowers when the motor speed is low.
Todd: “For customers seeking to further reduce system noise, we recommend moving away from any standard air handlers and blowers to a more technologically advanced solution such as our WhisperCool product line. These air handlers feature an inverter-driven DC blower which allows for infinite speed control, while generating no motor noise.”
With many HVAC systems for commercial vessels now being custom-built to satisfy specific requirements, the need to involve manufacturers at the earliest possible stage has never been so important. Specialist HVAC manufacturers such as Dometic Marine are available to work with naval architects and builders to review and interpret layout drawings to ensure sufficient space is allocated for the air conditioning system, while also designing a solution to fit the engine room and the allotted on-board areas.
“Despite being core to the provision of a healthy and comfortable on-board environment, air conditioning is often not given enough priority by architects and operators. It is common for us to find that not enough space has been allocated for the HVAC system, which can lead to a range of secondary problems,” Todd explains.
“Poor planning of the air conditioning system’s design, placement and capacity requirement can negatively impact the system’s performance. For these reasons we urge designers and builders to involve us as early as possible during a vessel’s design or initial refit stages. We can then customize systems to fit the allocated on-board space, while also providing the required capacity for the cabin environment.”
Dometic also offers a wide range of standard and custom configurations suitable for a vessel’s refit and refurbishment, and offers high levels of support to these customers in the same way the company supports new build projects. Todd adds: “Often, we can make modifications to standard units to accommodate a special situation, which will provide the vessel with greater performance and efficiency. Also, whenever we develop new technology and bring new equipment features to market, we evaluate the features from the perspective of ‘can they be added to an existing system’. This enables us to upgrade existing systems with new technology, for example Breathe Easy air purifiers and WhisperCool DC blowers, allowing customers to take advantage of the most advanced technology available to them.”
As for future developments, with continuous advancements in technology it can be difficult to comprehend what’s next, which is why it’s important for HVAC manufacturers such as Dometic Marine to always look ahead. Todd adds: “HVAC technology for commercial application has come a long way, but with technology constantly evolving, it is always possible to review existing products to introduce new features which may enhance the equipment’s performance. A key focus for us throughout 2011 and beyond is further improving the energy efficiency of our systems to support ongoing requirements for vessels in general to become more efficient.”
While developments in HVAC technology have led to a vast improvement in the condition of the vessel’s air, allowing advanced control of its temperature, humidity and quality, manufacturers have also been able to improve the flexibility of systems, reducing size and noise as well as building customized solutions. All of these elements fulfill the requirement for an ideal and healthy on-board environment.