VENTILATION SYSTEM FOR HIGH-RISE STRUCTURES
A ventilation system for providing fresh outdoor directly to each floor through an intake damper on the floor and for admitting only as much air as is required to meet the required outdoor air requirements when the temperature of the outdoor is at extreme ambient temperatures. The system utilizes a compartment unit on each floor and a plurality of VAV's which are located in zones on the floor for achieving desired temperatures in each zone by combining the recirculating air with the outdoor fresh air for delivering to the VAV's at about 55° F.
This application is a regular application of U.S. application 60/829,648 entitled VENTILATION SYSTEM FOR HIGH-RISE STRUCTURES filed Oct. 16, 2006, from which this application claims priority, the entirety of which is incorporated herein by reference.
FIELD OF THE INVENTIONEmbodiments of the invention relate to ventilation systems for structures and more particularly to structures having a plurality of zones on a plurality of separate floors which require ventilation and temperature control.
BACKGROUND OF THE INVENTIONAs shown in
The VAV boxes are typically thermostatically or sensor-controlled and regulate the quantity of conditioned air, typically at 55° F., which is supplied to each zone.
Typically, standards require that outdoor air be provided at a minimum of about 20 cfm/person or 1 cfm/square foot. Typical high-rises often have about 15,000-20,000 square feet per floor or more and thus, large volumes of circulating air of about 15,000-20,000 cfm/floor or more are required. Optional monitoring, using other sensors such as CO2 sensors, is known to regulate the amount of outdoor air based on actual loads per zone and therefore the amounts required may be lower than design loads when the number of people in the building is reduced.
At moderate temperature, such as the typical design temperature of 55° F., theoretically all air provided to the VAV's could be fresh air. Unfortunately, the main duct cannot be sized large enough for this scenario. Accordingly, energy is typically expended to cool recirculating air.
In addition to the large amounts of energy utilized to draw the large volumes of air required into the main duct and to exhaust excess air from the building, as well as the energy required to heat the air delivered to the main duct, particularly during fall and winter seasons, energy is also consumed in either heating or re-cooling the air at each compartmental unit and/or VAV to mix with recirculating air therein to provide desired ambient temperatures at the plurality of zones on each of the floors.
There is interest in the industry in providing a ventilation system which meets the requirements for fresh air supply to all zones in a high-rise building while minimizing energy consumption.
SUMMARY OF THE INVENTIONA novel ventilation system utilizes a damper on each floor which is fluidly connected through an external wall of each floor to the outdoors for directly admitting fresh outdoor air to the floor to satisfy regulated outdoor air requirements and to provide conditioned air at a design temperature of about 55° F. to conventional thermostatically or sensor-controlled distributors, such as VAV's or about 65° F. through controlled variable diffusers from a floor plenum, situated in zones on the floor.
When ambient temperatures are about the design temperature, no additional energy is expended to heat and or cool the air circulated to the distributors and the entirety of the air provided can be admitted through the intake damper which is sized accordingly.
When temperatures are very low or very high, only sufficient outdoor air to meet the minimum fresh air requirements is admitted and is mixed with recirculating air from the zones in the floor at a compartment unit for providing conditioned air at about 55° F. to the VAV's. At extreme temperatures, the conditioned air may need to be further cooled, using heat exchangers at the compartment unit or heated, typically at the VAV's, to satisfy zonal temperature requirements.
Therefore in a broad aspect of the invention a ventilation system for a high rise building having a plurality of conditioned floors, comprises: a compartment unit at each of the plurality of conditioned floors for mixing outdoor air and returned air therein for delivering conditioned air to each floor at a design temperature; an intake damper at each of the plurality of floors for directly connecting between the compartment unit and the outdoors, each intake damper directly admitting outdoor air from the outdoors to the compartment unit and capable of admitting a volume of outdoor air up to a total volume of conditioned air for the floor; one or more distributors on each conditioned floor for receiving the conditioned air from the compartment unit at the design temperature and for controlling the amount of conditioned air delivered to each of one or more zones on the conditioned floor so as to achieve a desired zonal temperature in the one or more zones; and an exhaust damper for each conditioned floor for exhausting excess air in an amount equal to or less than the admitted outdoor air.
In an embodiment of the invention the distributors are conventional variable air volume boxes, which deliver the conditioned air from the compartment unit to the zones on the floor under the control of a thermostat for achieving a desired temperature in each of the zones. Re-heat coils may be provided in the VAV's for heating the conditioned air to meet zonal temperature requirements. Similarly, heat exchangers in the system may be used to cool the conditioned air for delivery to the zones on the floor.
In an embodiment of the invention wherein the distributors are zonally controlled variable diffusers connecting the zone to a floor plenum, conditioned air is provided to the floor plenum at about 65° F. and the recirculated air is returned to the compartment unit through a ceiling plenum.
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The system 10 further comprises an exhaust damper 13 fluidly connected to the outdoors for exhausting at least a portion of excess air EA from the floor typically in an amount equal to or less than the admitted outdoor air FA.
Further, the system typically comprises an exhaust duct 14 connecting between the floors 5 for venting at least a small amount of excess air EA to the base 4 of the building, typically the parkade.
Outdoor air FA is drawn directly from outdoors into each conditioned floor 5, at ambient temperature, through the outdoor intake damper 11 in amounts sufficient to satisfy at least a minimum requirement for outdoor air FA, which is typically about 1 cfm per square foot and at a minimum of about 20 cfm per person. The outdoor air FA is drawn into the compartment unit 6, such as by fans, where the outdoor air FA is mixed with return air RA from the conditioned floor 5 as required, for delivery as conditioned air CA by the VAV units 12 to each of the zones Z1, Z2, Z3 . . . at a design temperature of 55° F. Each of the zones Z1, Z2, Z3 . . . is independently thermostatically controlled and therefore each zone Z1, Z2, Z3 . . . may require a different amount of conditioned air CA to be discharged to the air circulating in the zone Z1, Z2, Z3 . . . to achieve a desired zonal temperature.
Typically at least the minimum 20 cfm/person is exhausted from each conditioned floor 5 to the parkade, such as through the exhaust duct 14, and a small amount of loss from each conditioned floor 5 occurs through elevator shafts 15 and the like. Any additional excess air EA is exhausted from each conditioned floor 5 through the exhaust damper 13 so as to balance a pressure on the conditioned floor 5.
For example, if a minimum required volume of outdoor air FA of 2000 cfm is drawn in through the intake damper 11, about 1500 cfm is exhausted to the parkade from bathrooms and generally from the conditioned floor 5 typically through the exhaust duct 14 and about 500 cfm is lost in the elevator shafts 15 and the like. In this case, no excess air would be exhausted through the exhaust damper 13.
Where 15,000 cfm of outdoor air FA is drawn in through the intake damper 11, the amount vented to the parkade, being about 1500 cfm is maintained as is the about 500 cfm which is lost in the elevator shafts 15 and the like. In this case, about 13,000 cfm of excess air EA remains to be exhausted through the exhaust damper 13. In embodiments of the invention, the exhaust damper 13 is a barometric damper.
As one of skill would understand, accommodations are made to meet local code regarding smoke evacuation. One such method is to extend the exhaust duct 14 to the roof 3 and to size the exhaust duct 14 accordingly so that smoke can be evacuated through the duct 14 when required.
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Alternatively, as shown in
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As the ambient temperature of the outdoor air FA decreases, the amount of outdoor air FA drawn into the intake damper 11 is decreased. Only sufficient outdoor air FA is admitted and combined with re-circulating air in the compartment unit 6 so as to result in a distribution mixture of conditioned air CA at design temperature, being about 55° F., being discharged at the VAV units 12 in each zone Z1, Z2, Z3 . . . and to meet the minimum outdoor air FA requirements. Clearly when the ambient temperatures are very low, such as about −20° F. or lower, only the minimum amount of outdoor air FA is drawn into the intake damper 11 to satisfy air quality requirements.
In order to result in a desired zonal temperature, one may need to heat the delivered 55° F. air at the VAV units 12. Typically, re-heating coils 16 are provided in some or all of the VAV units 12. Re-heating coils 16 may be provided only in VAV's 16 serving peripherally located zones Z1, Z2, Z3 . . . and may be optionally used for heating the building at night. Alternatively, a heating coil may be provided at the compartment unit 6 for heating the air provided to the VAV's 12.
Added benefits and an even greater reduction in very cold outdoor air FA intake is possible by incorporating sensors 17, such as CO2 monitors, into the ventilation system 10. The CO2 monitors 17 sense the actual load in the building and can reduce the amount of outdoor air FA admitted below the minimum design amounts when the number of people in the building is reduced, such as on weekends and during the evening. Thus, energy savings are realized by reducing the amount of conditioning required.
When ambient air temperatures are above 55° F., the amount of outdoor air FA drawn into the intake damper 11 is similarly reduced to minimum levels to minimize cooling requirements for cooling the air delivered to the VAV's 12. A heat exchanger in the compartment unit 6 conditions the air, such as by cooling the returned air RA combined with the minimum amount of outdoor warmer air FA for delivery of conditioned air CA to the VAV units 12 in the zones Z1, Z2, Z3 . . . at about 55° F. Typically, a chiller supplies cooling fluid to the heat exchangers in the compartment units 6, and is sized to accommodate maximum local ambient summer temperatures.
In one embodiment, sensors 17, such as CO2 sensors, are incorporated into the ventilation system 10 for sensing actual occupant loads, the outdoor air FA intake through the intake damper 11 is controlled based on the actual load and may be reduced below a typical or design minimum which is calculated based on a hypothetical number of occupants. As previously stated, incorporating such sensors 17 is particularly advantageous for weekends, evenings and other times when occupant loads are typically very low. Rather than energize an entire ventilation system to satisfy only a few occupants on one or more of the floors 5 during these off-peak times, such as is done with many conventional systems, the ventilation system 10 according to embodiments of the invention is controlled by the sensors 17 to intake and potentially condition only the required amount of outdoor air FA for a particular conditioned floor 5 which is in use.
For example, a typical occupant density of 100 people per floor 5 may require a minimum of about 2000 cfm of fresh outdoor air FA. In conventional systems, the intake of the 2000 cfm would be maintained regardless the number of occupants, to meet the minimum design amount. However, in the ventilation system 10 according to this embodiment, if only 10 people were present on a floor, the CO2 monitors 17 sense the reduced occupant load and reduce the minimum outdoor air FA intake to about 200 cfm which meets the minimum required amount of fresh outdoor air FA per person for that floor 5.
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Optionally, additional embodiments are possible wherein heating and cooling of the air is augmented using geothermal heat sinks and cold sinks created for the purpose. In one such embodiment, cold outdoor air FA is exchanged in a heat exchanger with glycol circulated in the ground to freeze a portion of the ground situated below the building. The cold from the ground is subsequently circulated through the heat exchanger during summer to cool the air in the building. Similarly, a heat sink may be created by exchanging heat from the outdoor air FA during the summer with the ground so as to store heat for use in the winter.
Claims
1. A ventilation system for a high rise building having a plurality of conditioned floors, the system comprising:
- a compartment unit at each of the plurality of conditioned floors for mixing outdoor air and returned air therein for delivering conditioned air to each floor at a design temperature;
- an intake damper at each of the plurality of floors for directly connecting between the compartment unit and the outdoors, each intake damper directly admitting outdoor air from the outdoors to the compartment unit and capable of admitting a volume of outdoor air up to a total volume of conditioned air for the floor;
- one or more distributors on each conditioned floor for receiving the conditioned air from the compartment unit at the design temperature and for controlling the amount of conditioned air delivered to each of one or more zones on the conditioned floor so as to achieve a desired zonal temperature in the one or more zones; and
- an exhaust damper for each conditioned floor for exhausting excess air in an amount equal to or less than the admitted outdoor air.
2. The system of claim 1 wherein the one or more distributors are variable air volume boxes.
3. The system of claim 1 further comprising an exhaust duct fluidly connected to each of the plurality of floors for exhausting at least some of the air from each of the plurality of floors to a base of the building.
4. The system of claim 2 wherein the design temperature is about 55° F.
5. The system of claim 1 wherein a re-heating coil is provided for heating the conditioned air for delivery to at least some of the one or more zones for achieving the desired zonal temperature.
6. The system of claim 2 further comprising a re-heating coil in at least some of the variable air volume boxes on the conditioned floor for heating the conditioned air from the compartment unit for delivery to at least some of the one or more zones so as to achieve the desired zonal temperature.
7. The system of claim 1 further comprising a heat exchanger for cooling the conditioned air to the design temperature when outdoor air temperatures are elevated.
8. The system of claim 1 wherein the compartment unit is located centrally on the floor.
9. The system of claim 1 wherein the compartment unit is located peripherally on the floor adjacent the intake damper.
10. The system of claim 1 further comprising sensors for determining an actual occupant load for admitting fresh outdoor air sufficient to meet at least a minimum fresh air requirement based on the actual occupant load.
11. The system of claim 10 wherein the sensors are CO2 monitors.
12. The system of claim 7 wherein the heat exchanger is in the compartment unit.
13. The system of claim 1 wherein the distributor further comprises:
- a floor plenum for receiving the conditioned air from the compartment unit;
- one or more variable flow diffusers fluidly connected between the floor plenum and each of the one or more zones;
- a ceiling space fluidly connected to the compartment unit; and
- one or more return air grilles fluidly connected between each of the one or more zones and the ceiling space for re-circulating air from each of the one or more zones to the ceiling space for returning the re-circulated air to the compartment unit, and wherein
- the exhaust damper is fluidly connected to the ceiling space; and
- the one or more variable flow diffusers is adjustable for obtaining a desired zonal temperature.
14. The system of claim 13 wherein the design temperature is about 65° F.
15. The system of claim 13 further comprising one or more heating coils at the compartment unit for heating the conditioned air therein for delivery to the floor plenum.
Type: Application
Filed: Oct 16, 2007
Publication Date: Jul 24, 2008
Inventor: Ross SINCLAIRE (Calgary)
Application Number: 11/872,871
International Classification: F24F 7/00 (20060101); F24F 13/04 (20060101); F24F 11/00 (20060101); F24F 3/00 (20060101);