Managers of existing laboratories will face serious problems in the near future. More than 1,000,000 existing laboratory fume hoods along with their companion makeup air systems may have to be retrofitted to comply with pending Occupational Safety and Health Administration (OSI-IA) regulations and various state "Right to Know" laws. Even if many present.day hoods maintain adequate capture velocity at the maximum sash position, they most likely have excessive face velocity at lower sash positions. Existing bypass and auxiliary air type hoods do not adequately compensate for varying sash positions and the manager will have to insist on improvement in orderto protect his employer from future litigation.

Faced with this situation, what can the facilities engineer do to make his laboratory safe, not to mention more energy efficient? Newly constructed facilities can incorporate state-of-the-art systems and controls including constant face velocity hoods, room pressurization control, and properly located exhausts and intakes. Unfortunately, existing facilities, for the most part, will not have this luxury.

Many engineers are anticipating this problem and looking over the systems available. Hardware and systems vendors already are selling products, while others are being developed. Prices vary considerably, as do claims for performance and energy efficiency. In this paper, the author re/ates how some organizations have tackled the problem. Examples of control methods applied, tested, and documented are presented, as well as available tools and procedures to assist the facilities manager. The various types of existing hoods and supply systems the facilities engineer may encounter will be illustrated, as we//as some proven practical solutions. Case histories, test data, and owners’ experiences and comments are part of this paper. Some of the pitfalls to avoid, such as recycling of contaminants and room air incursion, are shown