Clean rooms have been integral part of dharma manufacturing since 1960s. They were born after World War II when advances in HEPA (high efficiency particle air) filters were applied by NASA to further the space programme.

Clean room is an enclosed area or space which has controlled environment in terms of airborne particulates, microbes, contaminants of dust, pollutants and chemical vapours. Clean room also provide regulation of environment in terms of temperature, humidity and pressure. A more specialized meaning is defined by the International Organization for Standardization (ISO) in the international cleanroom standard ISO14644, where ‘clean’ is defined by a maximum permitted concentration of airborne particles according to an assigned class.

The most frequently used standard is the Federal Standard 209E. The 209E is a document that establishes standard classes of air cleanliness for airborne particulate levels in cleanrooms and clean zones. Clean rooms are rated as "Class 10,000,"where there exists no more than 10,000 particles larger than 0.5 microns in any given cubic foot of air; "Class 1000," where there exists no more than 1000 particles; and "Class 100,"where there exists no more than 100 particles.

The comprehensive regulatory requirements for cleanrooms are given by EU, GMP and FDA. The FDA clean room regulations require strict environmental controls, beginning with planning and construction of the rooms, to achieve clean air standards in clean rooms. Regulations require a monitoring system for environmental conditions in the clean room, which must be a separate, adequately-sized room that has equipment to control humidity, dust, air pressure, temperature and microorganisms. Regulations also require an air filtration system, as well as written procedures for preventing contamination, and for cleaning and sanitizing all surfaces and equipment.

All clean rooms are not identical. They vary depending on the size or scale of an operation, the types of materials that are being handled, the operation's budget, and various other factors. Clean room technologies today offer hard wall construction for higher budget and more permanent clean room installations, while soft wall construction will lower clean room costs for temporary or portable contaminant free operations.

The clean room technology has advanced greatly in recent years helping to reduce both the risk of contamination and also streamline process operations. The majority of the developments not only focus on design but also consider monitoring equipment, filtering equipment, apparel, and proper training for clean room workers as the important aspects of clean rooms. According to the experts the pharmaceutical companies are seeking efficiency, energy savings, sustainability and functionality in the clean room design.

 To design the clean room, the following factors must be accounted for: Minimize clean space,  correct cleanliness level, optimize air change rate, consider use of mini-environments, optimize ceiling coverage, consider clean room protocol and cleanliness class, minimize pressure drop (air flow resistance), consider location of large air handlers, provide adequate sizing and minimize length of ductwork , provide adequate space for low pressure drop air flow, low face velocity, use of variable speed fans, optimize pressurization, consider air flow reduction when unoccupied etc. Clean room designs that provide solutions to contamination potentials and maximize usable space are in demand.

A mode of construction that provides better solutions to contamination is in demand. The pharmaceutical clean rooms construction are inclined towards the architectural features such as coved surfaces, smooth component transitions and seamless, heat weld seams. The companies are becoming more selective about functionality by adopting modular building project execution plan with high quality construction which allows becoming accustomed to shorter project execution model.

 Becky Wiseman, president of Hutchins & Hutchins, a company that has been serving the clean room industry since 1984, agrees that flexible, modular designs are a current trend. "Flexible facilities that can be reconfigured for different products are becoming the trend due to product lines being disapproved or dropped -- a wide-open layout with modular areas is better designed for multi-product flexibility", he says.

The pharmaceutical production must effectively control the contamination from people, raw materials, finished products as well as accommodating-services, process plant and equipment. The main purpose of building a clean room is to provide a vital element in the assurance of product quality according to whole concept of good pharmaceutical manufacturing operation. The resultant facility should prevent contamination of the product and should be seen to be doing so by the incorporation of effective monitoring devices. The staff is also a main component of clean room environment. People should be trained and well qualified to work and maintain in the clean room. They need to wear special clothing that can protect both a product and a human.

To maintain ultra low particle concentration, clean rooms require several hundred air changes per hour making them more energy-intensive because of high air flow rates, system static pressures and process requirements that result in high cooling loads. A considerable amount of energy is also used to achieve:

• The necessary temperature and relative humidity for the process in the clean room and for personnel comfort
• The necessary pressurization of the space
• In some cases, the necessary airflow volume flow rate for unidirectional airflow and to a reduced extent non-unidirectional airflow.

Some firms using clean rooms report that heating and ventilating systems consume up to 80 per cent of the total energy used in their manufacturing facility simply to deliver clean, conditioned air to critical operations. This energy is consumed by heating, cooling, humidification and fan power. Of this, fans required to move air can account for 35 to 50 per cent, much of this being due to the extra energy required to overcome the high pressure differential required for the high efficiency filters and other ventilation components used in clean rooms. There is therefore a significant potential for energy saving by diligent design in the installation of new clean rooms, and by retrofit improvements and upgrades to existing facilities.

To address the global need to reduce energy usage and help the clean room industry to meet its energy reduction targets and manage future growing energy costs, a new British Standard (BS 8568) is created which gives recommendations on reducing energy consumption and maintaining energy efficiency in new and existing clean rooms and clean air devices.

"Energy conservation is critical in today's clean rooms," says Tim Marrs, a sales engineer at the clean room design and build company,Clean Rooms West, "Clean room designers can no longer use systems that waste energy." He explains that it will take innovation to create clean rooms that conserve energy without compromising cleanliness -- future designs could include monitoring systems that speed up or slow down fans when particulate levels change, using only the energy it needs to maintain particle levels.

The five energy savings opportunities according to experts are: low face velocity in air handlers, variable speed chillers, free cooling for process loads, dual temperature cooling loops and recirculation air set back. However, energy and operating cost- efficiency must be achieved by taking into account the variables that do not affect clean room performance. Thus overall growth and new developments in clean room technology are  on the horizon and is poised  to embrace newer areas.