The aim of the HVAC design is to provide a comfortable and healthy environment for the building occupants at a minimum cost. Although this definition applies to all kind of occupancies, the design of a hospital is more challenging because many of the hospital spaces present a health risk, and the elimination or the reduction of these risks through the HVAC systems should be addressed as well. The comfort can be achieved by controlling the temperature, the humidity, the air movement, and the level of noise. In hospitals, the temperature and humidity could become factors in patient therapy. A healthy environment can be attained by minimizing the risk of contamination thorough adequate air distribution, directing the flow of air from less contaminated space to the more contaminated space, evacuating the pollutants as close as possible to the source, introducing the minimum outside air to every space of the building, and cleaning the air through filtration and other cleaning devices. These conditions can be achieved at all times by designing systems that are reliable, not only during normal operation, but also during unusual or catastrophic events and are adaptable to future changes and easy to be maintained. A minimum cost can be accomplished by reducing each of the cost elements: investment cost, annually recurring operation costs, such as energy and maintenance; future nonrecurring costs, such as spare parts and replacements; future non-recurring costs due to occupancy changes. To achieve all these goals, the design should be approached in a systematic manner, by defining the design criteria at the beginning of the project during the planning phase and selecting the HVAC systems based on life-cycle cost analysis.

Units: Dual