FOREWORDThe purpose of the Heating@ Ventilating@ and Air-Conditioning (HVAC) Design Guide for Department of Energy (DOE) Nuclear Facilities is to help ensure consistency in establishing the design basis for HVAC systems serving such facilities.Any design for DOE facilities must fulfill the requirements stated in DOE Order 6430.1A@ General Design Criteria. However@ the order references many documents@ such as ERDA 76-21@ Nuclear Air Cleaning Handbook; NRC Regulatory Guides; and the ACGIH Industrial Ventilation Manual. Order 6430.lA also has many void areas with respect to HVAC design that have generated confusion and inconsistent application of sound HVAC principles. This design guide is a document that combines applicable information from all of these resources to provide HVAC guidance for the design engineer. The intent of this document is to not only state the Department of Energy??s design requirements for HVAC systems@ but also to express some of the engineering judgment used in designing the systems.This design guide was developed by members of ASHRAE TC 9.2@ Industrial Air Conditioning@ Subcommittee on Nuclear Facilities. The information in each section was obtained from researching DOE orders@ technical documents@ and site procedures and from discussions with experienced personnel at DOE sites.This document should be used by design agencies@ liaison groups@ health protection organizations@ and other persons or groups involved in the design@ installation@ and operation of HVAC systems. The use of this document is most effective when preparing design criteria for a project. By incorporating the appropriate sections of this design guide in this phase@ the document can provide the design agency with appropriate HVAC system design parameters that will fulfill the needs of the customer and satisfy code and regulatory requirements.Although this document is considered a design guide@ it should be understood that the information presented reflects both the current DOE requirements and the generally accepted requirements with respect to HVAC. However@ the responsibility for satisfying applicable codes and regulations remains with the designer. All new project installations and future modifications should consider these design guidelines.