Lighting Design + Application • October 2003 - Illuminating ...

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .DESIGN TRENDSAlthough “teardrop” fixtures are sometimes used because oflimited ceiling space, they have a number of serious–andsometimes critical—drawbacks.be extremely tight and that an effective technique forinterfacing the housing with the ceiling is essential.The integrity of these leak-prevention characteristics hasto last long after installation, since clean rooms must notonly be certified upon completion, but recertified eachtime a containment wall or ceiling is compromised—something that can occur during the performance of routinemaintenance or repairs. These maintenance andrepair procedures are so interruptive to the function of thespace, that many organizations close down clean roomoperations up to several weeks each year to perform them,also providing a window for such routine operations asrelamping fixtures.• Multiple Visual Tasks. Historically, research laboratorieswere either “wet” or “dry” in their function, with wetsciences such as biology and chemistry residing in onespace and dry disciplines such as computer science andstatistics in another.A new generation of laboratories, however, combinesboth wet and dry disciplines within the same researchgroups, resulting in compound lighting requirements.Clean Room GuidelinesSuccessfully addressing these issues from a lighting layoutand luminaire specification perspective calls for a lightingprofessional’s traditional skills combined with specializedclean room knowledge. And, while a comprehensivediscussion of all necessary clean room information isn’tpossible in a single article, there are some key points thatcan be extremely helpful to those involved (or who plan onbecoming involved) in clean room lighting.• Bring Lighting Into the Picture Early in theDesign Process. Dealing successfully with the problemof too little ceiling real estate for proper lighting calls forcoordination between the architect, mechanical engineerand lighting specifier early in the design process.Typically, the need for the appropriate level of cleanlinesscertification puts the mechanical engineer in the driver’sseat, since the M.E. is responsible for such things as meetingair filtration requirements and providing the necessarymechanical and life safety systems. When mechanicalsystem designs are completed before lighting is considered,an effectively lit environment is nearly impossibleto achieve. And, while working together on lightingneeds up-front can’t change the M.E.’s primary responsibilities,it can provide the opportunity for a coordinateddesign effort that allows the M.E. to make whateveraccommodations are possible.• Choose Fixtures with Materials Appropriate toSpecific Cleaning Protocols. Knowing how fixtures willbe cleaned and maintained informs the specifier about thematerials requirement while also potentially increasinglighting calculation accuracy. The first part is obvious, sinceLensed, flush-mounted 2x4 troffers are the preferred fixture-typefor most clean room applications, but they must be speciallydesigned, constructed and tested to ensure they won’tcompromise the facility’s ongoing cleanliness requirements.. . . . . . . . . . . . . . . . . . . November . . . . . 2003 . . . LD+A . . . . 64. . www.iesna.org. . . . . . . . . . . . . . . . . . . . . . . . . . . . .