Abstract: An ultra low temperature freezer is optimized with a combination of vacuum and fiberglass insulation for long-term biological storage with accurate process cooling with critical temperature performance. A programmable cooling and cryogenic freezing system uses sealed liquid nitrogen for cooling and freezing. A hybrid completely non-mechanical system exhibits temperature uniformity and reliability, saves space, requires extremely low operating energy and minimizes need for air conditioning in the operating environment. Top-located components control the flow of liquid nitrogen even under flooding conditions. Sectioned inner doors mitigate thermal transfer to other samples and maintain ULT while accessing the freezer.