Abstract:
A building protection system comprises a filtration unit, an air handling unit, an emergency exhaust subsystem, a first damper positioned between the filtration unit and the air handling unit, and a second damper positioned between the emergency exhaust subsystem and the filtration unit. The first damper is selectively opened and the second damper is selectively closed to filter outside air as it enters a building, and the first damper is selectively closed and the second damper is selectively opened to filter inside air as it is exhausted from, the building.

Description:
BACKGROUND  
       [0001]     The present invention generally relates to heating, ventilating, and air-conditioning, (HVAC), and more particularly to use of a common filtration unit for building makeup air and emergency exhaust.  
         [0002]     Nuclear, biological, and chemical (NBC) attacks are an increasing threat in the modern world. Occupants of a building can be protected from the release of NBC agents outside or inside the building by filtering the air with NBC filtration units. An NBC filtration unit typically only allows one particle greater than one micrometer in a million to pass through the filtration unit. This requires very high construction standards. In addition, a powerful blower is required to maintain airflow due to a pressure drop through the filtration unit. These filtration units with blowers can cost between $100,000 and $250,000 or more for a typical 16,000 cubic feet per minute (CFM) unit.  
         [0003]     Typically, the best defense against an outside release of an NBC agent is to filter the contaminated air before it enters the building through a makeup air unit. For internal releases, the most effective general protection strategy is to exhaust the building from the vicinity of the release of the NBC agent. The exhausted contaminated air is filtered before it is released outside to prevent contamination of neighboring buildings. Typically, the intake air filtration system and the emergency exhaust filtration system require two separate NBC filtration units. Installing and maintaining two NBC filtration units in a building is expensive.  
       SUMMARY  
       [0004]     One aspect of the invention provides a building protection system. The building protection system comprises a filtration unit, an air handling unit, an emergency exhaust subsystem, a first damper positioned between the filtration unit and the air handling unit, and a second damper positioned between the emergency exhaust subsystem and the filtration unit. The first damper is selectively opened and the second damper is selectively closed to filter outside air as it enters a building, and the first damper is selectively closed and the second damper is selectively opened to filter inside air as it is exhausted from the building. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]     In the following Detailed Description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. In this regard, directional terminology, such as “top,” “bottom,” “front,” “back,” “leading,” “trailing,” etc., is used with reference to the orientation of the Figure(s) being described. Because components of embodiments of the present invention can be positioned in a number of different orientations, the directional terminology is used for purposes of illustration and is in no way limiting. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.  
         [0006]      FIG. 1  is a schematic diagram illustrating one embodiment of a building protection system.  
         [0007]      FIG. 2  is a block diagram illustrating one embodiment of a building protection system.  
         [0008]      FIG. 3  is a schematic diagram illustrating one embodiment of a building protection system operating in an unprotected mode.  
         [0009]      FIG. 4  is a schematic diagram illustrating one embodiment of a building protection system operating in an external release protection mode.  
         [0010]      FIG. 5  is a schematic diagram illustrating one embodiment of a building protection system operating in an internal release protection mode.  
         [0011]      FIG. 6  is a flow diagram illustrating one embodiment of a method for protecting building occupants from a release of a nuclear, biological, or chemical (NBC) agent. 
     
    
     DETAILED DESCRIPTION  
       [0012]      FIG. 1  is a schematic diagram illustrating one embodiment of a building protection system  100 . Building protection system  100  is a heating, ventilation, and air conditioning (HVAC) system that protects building occupants from the release of nuclear, biological, or chemical (NBC) agents in the air inside or outside building  162 . Building protection system  100  includes filtration unit  108 , blower A  110 , blower B  114 , blower C  116 , emergency exhaust subsystem  112 , air handling unit  118 , damper A  120 , damper B  122 , damper C  124 , damper D  126 , damper E  128 , outside sensor(s)  156 , and inside sensor(s)  158 . Building protection system  100  also includes air ducting  130 - 154 . Building  162  includes overhead plenum  149 , work/living area  102 , restroom A  104 , and restroom B  106 . Work/living area  102  can be partitioned into office areas, conference rooms, “bull pens”, etc. One or more of these rooms can be assembled into a protective zone, with sensor  158  coverage and an exhaust duct  150 . If multiple protective zones are implemented, then dampers are used to direct the flow of air from the area(s) of known or suspected contamination.  
         [0013]     Air duct  130  is coupled to air duct  132  through damper A  120 . Air duct  132  is coupled to air duct  134  through damper B  122  and to filtration unit  108 . Filtration unit  108  is coupled to blower B  114  through air duct  136 . Blower B  114  is coupled to air duct  138 . Air duct  138  is coupled to air duct  140  through damper C  124  and to air duct  144  through damper D  126 . Air duct  144  is coupled to air duct  142  through damper E  128  and to blower C  116 . Blower C  116  is coupled to air handling unit  118  through air duct  146 . Air handling unit  118  is coupled to work/living area  102  through supply air ducting  148  and return air from, typically, the overhead plenum  149 . Work/living area  102  is coupled to emergency exhaust subsystem  112  through emergency exhaust air ducting  150 . Emergency exhaust subsystem  112  is coupled to air duct  134 . Restroom A  104  and restroom B  106  are coupled to blower A  110  through exhaust air ducting  154 . Blower A  110  is coupled to air duct  152 . Inside sensor(s)  158  is located in work/living area  102 , and outside sensor(s)  156  is located near air handing unit  118  and blower C  116 .  
         [0014]     Damper A  120 , damper B  122 , damper C  1 . 24 , damper D  126 , and damper E  128  are guillotine, butterfly, louver, or any other suitable type of damper. Damper A  120 , damper B  122 , damper C  124 , damper D  126 , and damper E  128  are activated pneumatically, hydraulically, electrically, or by using any other suitable method of activation. In one form of the invention, damper A  120 , damper B  122 , damper C  124 , damper D  126 , and damper E  128  are rapid response dampers. In one embodiment, damper A  120 , damper B  122 , damper C  124 , damper D  126 , and damper E  128  are air tight when in the closed position so that no air passes through the dampers.  
         [0015]     Damper A  120  controls the flow of air between air duct  130  and air duct  132 . With damper A  120  in an open position, air flows from outside building  162  into air duct  130  to air duct  132 . With damper A  120  in a closed position, outside air does not flow into air duct  132  from air duct  130 . Damper B  122  controls the flow of air between air duct  134  and air duct  132 . With damper B  122  in an open position, air flows from air duct  134  to air duct  132 . With damper B  122  in a closed position, air from air duct  134  does not flow into air duct  132 . Damper C  124  controls the flow of air from air duct  138  to air duct  140 . With damper  124  in an open position, air flows from air duct  138  to air duct  140  to the outside of building  162 . With damper C  124  in a closed position, air does not flow from air duct  138  to the outside of building  162 . Damper D  126  controls the flow of air between air duct  138  and air duct  144 . With damper D  126  in an open position, air flows from air duct  138  to air duct  144 . With damper D  126  in a closed position, air does not flow from air duct  126  to air duct  144 . Damper E  128  controls the flow of air between air duct  142  and air duct  144 . With damper E  128  in an open position, air flows from the outside of building  162  through air duct  142  to air duct  144 . With damper E  128  in a closed position, air does not flow from outside of building  162  through air duct  142  to air duct  144 . In one embodiment, additional dampers (not shown) can be used for controlling the flow of air into and out of building  162 .  
         [0016]     In one form of the invention, outside sensor(s)  156  and inside sensor(s)  158  each include a plurality of sensors for detecting the presence of nuclear, biological, and chemical agents. In one embodiment, a sensor, such as inside sensor(s)  158 , is provided in each portion of building  162  having separate emergency exhaust air ducting to detect the release of an NBC agent in that portion of building  162 .  
         [0017]     Filtration unit  108  filters out nuclear, biological, and/or chemical agents from air passing though filtration unit  108  from air duct  132  to air duct  136 . In one embodiment, filtration unit  108  includes a filter set. In one form of the invention, the filter set includes a filter for aerosol and absorption, such as a high-efficiency particulate air (HEPA)/ultra low penetration air (ULPA) particulate filter and a carbon gas filter. In one embodiment, filtration unit  108  includes lysing technologies (i.e., UV sterilization lamps).  
         [0018]     Blower B  114  draws air through filtration unit  108  from air duct  136  to air duct  138 . Blower B  114  is sized to maintain air flow by overcoming a pressure drop through filtration unit  108 . In one embodiment, blower B  114  draws air through emergency exhaust subsystem  112 .  
         [0019]     Blower C  116  draws air from air duct  144  to air duct  146  to air handling unit  118 . Air handling unit  118  supplies makeup air to work/living area  102  through supply air ducting  148 . In one embodiment, other supply air ducting supplies makeup air to other portions of building  162 .  
         [0020]     Emergency exhaust subsystem  112  exhausts air from work/living area  102  through emergency exhaust air ducting  150  to air duct  134  in an emergency. In one embodiment, other emergency exhaust air ducting exhausts air from other portions of building  162  in an emergency. In one embodiment, separate emergency exhaust air ducting is provided to separately exhaust air from portions of building  162  where the release of NBC agents has occurred to prevent the spread of the NBC agents to other portions of building  162 .  
         [0021]     Blower A  110  exhausts air from restroom A  104  and restroom B  106  to the outside of building  162  through exhaust air ducting  154  and air duct  152 . In one embodiment, exhaust air ducting  154  exhausts air from kitchens, maintenance closets, laboratories, and/or other rooms in building  162 .  
         [0022]      FIG. 2  is a block diagram illustrating one embodiment of building protection system  100 . In addition to blower A  110 , blower B  114 , blower C  116 , inside sensor(s)  158 , outside sensor(s)  156 , damper A  120 , damper B  122 , damper C  124 , damper D  126 , and damper E  128 , building protection system  100  also includes controller  160 . Controller  160  is electrically coupled to blower A  110  through communication link  111 , blower B  114  through communication link  115 , and blower C  116  through communication link  117 . Controller  160  is electrically coupled to inside sensor(s)  158  through communication link  159  and outside sensor(s)  156  through communication link  157 . Controller  160  is also electrically coupled to damper A  120  through communication link  121 , damper B  122  through communication link  123 , damper C  124  through communication link  125 , damper D  126  through communication link  127 , and damper E  128  through communication link  129 .  
         [0023]     Controller  160  controls the operation of building protection system  100 . Controller  160  includes a combination of hardware and firmware and/or software for controlling blower A  110 , blower B  114 , blower C  116 , damper A  120 , damper B  122 , damper C  124 , damper D  126 , and damper E  128 , and for receiving sensor data from inside sensor(s)  158  and outside sensor(s)  156 .  
         [0024]     Controller  160  enables, disables, and controls the speeds of blower A  110 , blower B  114 , and blower C  116 . Controller  160  receives input signals from inside sensor(s)  158  and outside sensor(s)  156  indicating the presence of an NBC agent either inside or outside of building  162  ( FIG. 1 ). Controller  160  opens and closes damper A  120 , damper B  122 , damper C  124 , damper D  126 , and damper E  128  based on an operating mode of building protection system  100 .  
         [0025]      FIGS. 3-5  illustrate three operational modes for building protection system  100 . In one embodiment, the operational modes for building protection system  100  include an unprotected mode, an external release protection mode, and an internal release protection mode. For simplicity, some of the air ducting that is not used in each operational mode is omitted in  FIGS. 3-5 .  
         [0026]      FIG. 3  is a schematic diagram illustrating one embodiment of building protection system  100  operating in the unprotected mode. In the unprotected mode, neither inside sensor(s)  158  nor outside sensor(s)  156  detects NBC agents in the air. In the unprotected mode, controller  160  disables blower B  114 , closes damper A  120 , damper B  122 , damper C  124 , and damper D  126 , and opens damper E  128 . The direction of air flow is indicated by arrows  141  and  153 .  
         [0027]     In the unprotected mode, controller  160  enables blower C to draw unfiltered air from the outside of building  162  to air handling unit  118  and to work/living area  102 . Controller  160  also enables blower A  110  to exhaust air to the outside of building  162  from restroom A  104  and restroom B  106 . Building protection system  100  remains in the unprotected mode as long as inside sensor(s)  158  and outside sensor(s)  156  do not detect NBC agents in the air.  
         [0028]      FIG. 4  is a schematic diagram illustrating one embodiment of building protection system  100  operating in the external release protection mode. The external release protection mode is activated if outside sensor(s)  156  detects NBC agents in the air. In the external release protection mode, controller  160  opens damper A  120  and damper D  126 , and closes damper B  122 , damper C  124 , and damper E  128 . In the external release protection mode, controller  160  enables blower A  110 , blower B  114 , and blower C  116 . The direction of air flow is indicated by arrows  129  and  153 .  
         [0029]     Blower B  114  draws air through filtration unit  108  from outside building  162  and supplies the filtered air to blower C  116 . Blower C  116  supplies the air to air handling unit  118  and to the work/living area  102 . In one embodiment, controller  160  reduces the flow of air exhausted from restroom A  104  and restroom B  106  by reducing the speed of blower A  110 . The speed of blower A  104  is controlled to create a positive pressure within building  162  such that any air leaking through cracks or crevices in building  162  flows from inside building  162  to the outside of building  162  to prevent unfiltered air from entering building  162 . Building protection system  100  remains in the external release protection mode until NBC agents are no longer detected outside building  162 .  
         [0030]      FIG. 5  is a schematic diagram illustrating one embodiment of building protection system  100  operating in an internal release protection mode. The internal release protection mode is activated if inside sensor(s)  158  detects an NBC agent in the air in work/living area  102 . In the internal release protection mode, controller  160  closes damper A  120  and damper D  126 , and opens damper B  122 , damper C  124 , and damper E  128 . Controller  160  enables blower B  114  and blower C  116 . Controller  160  disables blower A  110  so that no unfiltered air is exhausted from restroom A  104  and restroom B  106 . The direction of air flow is indicated by arrows  141  and  143 .  
         [0031]     Blower B  114  draws contaminated air from work/living area  102  through emergency exhaust air ducting  150 , emergency exhaust subsystem  112 , air ducts  134  and  132  and filtration unit  108 , and exhaust the filtered air to the outside of building  162 . At the same time, blower C  116  draws uncontaminated fresh air from the outside of building  162  to air handling unit  118  and work/living area  102 . Building protection system  100  remains in the internal release protection mode until the NBC agents are no longer detected inside building  162 .  
         [0032]      FIG. 6  is a flow diagram illustrating one embodiment of a method  200  for protecting building occupants from a release of an NBC agent either inside or outside of building  162 . At  202 , the HVAC system is operated in unprotected mode. At  204 , sensors inside and outside the building test for the presence of NBC agents. At  206 , controller  160  determines whether NBC agents have been detected based on data received from inside sensor(s)  158  and outside sensor(s)  156 . If no NBC agents are detected, control returns to block  202  where the HVAC system continues operating in unprotected mode. If NBC agents are detected, controller  160  determines whether the NBC agents are inside or outside of building  162  based on the data received from inside sensor(s)  158  and outside sensor(s)  156 .  
         [0033]     If the NBC agents are detected inside of building  162 , at  210 , controller  160  disables the restroom exhaust blower A  110 . At  212 , controller  160  activates the internal release protection mode to filter the exhausted air before it is released to the outside of building  162 . At  214 , the air inside building  162  is filtered as it is exhausted to the outside of building  162  until the NBC agents are abated.  
         [0034]     If the NBC agents are detected outside building  162 , then at  216 , controller  160  reduces the flow of air from restroom exhaust blower A  110  to pressurize building  162 . At  218 , controller  160  activates the external release protection mode to filter the outside air before the air is introduced into building  162 . At  220 , the outside air continues to be filtered before it enters building  162  until the NBC agents are abated.  
         [0035]     Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific embodiments shown and described without departing from the scope of the present invention. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this invention be limited only by the claims and the equivalents thereof.