When planning to construct a “Cold Room” or “Seed Storage Room” for the purpose of preserving seed viability, one must first consider principles for optimum seed storage. In ECHO Asia Note 14 (July 2012), we shared results from our comparison of vacuum sealing versus refrigeration, and highlighted the importance of moisture control and temperature control in seed storage. We found moisture control (vacuum sealing) to be more effective in maintaining seed viability than temperature control (refrigeration). It is ECHO Asia’s experience that seeds are best stored in the tropics by first using vacuum sealing after drying (to preserve low seed moisture content), then storing the packaged seeds in cool temperatures. When designing a cold room for optimum seed storage conditions, good insulation and cooling are important; however, without a proper moisture barrier, the cooling process will draw moisture from the outside and create condensation, leading to increased moisture content. In cases where seeds are not also stored in vacuum sealed bags themselves, or when the seal on the vacuum-sealed bags breaks, this additional moisture can damage seeds.