ADAPTIVE, RESPONSIVE, DYNAMIC BUILDING VENTILATION CONTROL SYSTEM

Abstract

Examples herein describe systems and methods for dynamic building ventilation control. A control system can include a controller that receives information from the indoor and outdoor sensor packages. The control system can compare indoor and outdoor air quality using information from the indoor and outdoor sensor packages. The controller can also determine a current operational state of a heating, ventilation, and air conditioning (HVAC) system, such as heating, cooling, and fan status. Based on the air quality comparison and current operational state, the controller can open a first damper and closing a second damper to change ventilation of a building.

Claims

1. A dynamic ventilation control system comprising: an indoor sensor package; an outdoor sensor package; and a controller communicatively coupled to the indoor and outdoor sensor packages, wherein the controller performs stages comprising: receiving indoor air quality (IAQ) information from the indoor sensor package and outdoor air quality (OAQ) information from the outdoor sensor package; making an air quality comparison based on the IAQ and OAQ information; receiving a current operational state of a heating, ventilation, and air conditioning (HVAC) system, wherein the operational state includes at least one of heating and cooling; and generating a first damper command to close an indoor damper and open an outdoor damper of a building, wherein the first damper command is based on at least the air quality comparison favoring OAQ over IAQ and an outside air dewpoint being below indoor air temperature.

2. The system of claim 1, further comprising an opto-isolator that detects a voltage on a control line of the HVAC system, wherein the opto-isolator supplies a lower voltage to the controller when voltage on the control line is present, wherein the stages further comprise: based on comparing outdoor and indoor air temperatures, interrupting supply of voltage to the HVAC system on the control line, turning off at least one of a compressor and a blower, wherein the interruption includes deactivating a relay switch for the control line.

3. The system of claim 1, wherein the outside air dewpoint is determined based on outside humidity and outside temperature, and wherein the stages further comprise: generating a second damper command to open the indoor damper and close the outdoor damper, wherein the second damper command is based on the outside air dewpoint being greater than the indoor air temperature, and wherein closing the outside damper substantially disallows outside air from entering the building through the outside damper.

4. The system of claim 1, the stages further comprising: detecting, with a noise sensor and audio detection algorithm, a siren indicating the presence of smoke or carbon monoxide; and based on the siren detection, opening the outside damper and closing the inside damper for smoke exhaust ventilation of a building.

5. The system of claim 1, wherein the first damper command also is based on comparing IAQ and OAQ information with an economizer to determine respective energy levels of the indoor and outdoor air, wherein the first damper command activates an energy recovery ventilator to by exchanging inside air to be exhausted from a building with incoming outdoor ventilation air.

6. The system of claim 1, the stages further comprising: generating an additional damper command to interrupt a heating call from the HVAC system and open the outside damper, wherein the additional damper command is based on at least: the current operational state being heating, the indoor air temperature exceeding outdoor dewpoint, an outside air temperature exceeding indoor air temperature, and OAQ being greater than IAQ.

7. The system of claim 1, the stages further comprising: storing sensor information including IAQ information, OAQ information, indoor noise pollution (INP) information from an indoor sensor package, outdoor noise pollution (ONP) information from an outdoor sensor package; and water pollution (WP) information from a water sensor package; and uploading sensor information to a server for use in determining social health.

8. A method for whole-building dynamic ventilation control, comprising: receiving, at a controller, indoor air quality (IAQ) information from the indoor sensor package and outdoor air quality (OAQ) information from the outdoor sensor package; making an air quality comparison based on the IAQ and OAQ information; receiving a current operational state of a heating, ventilation, and air conditioning (HVAC) system, wherein the operational state includes at least one of heating and cooling; and generating a first damper command to close an indoor damper and open an outdoor damper of a building, wherein the first damper command is based on at least the air quality comparison favoring OAQ over IAQ and an outside air dewpoint being below indoor air temperature.

9. The method of claim 8, further comprising: detecting, with an opto-isolator, a voltage on a control line of the HVAC system; supplying a lower voltage to the controller when the voltage is present on the control line; and interrupting supply of the voltage to the HVAC system on the control line, turning off at least one of a compressor or blower, wherein the interruption includes deactivating a relay switch for the control line.

10. The method of claim 8, wherein the outside air dewpoint is determined based on outside humidity and outside temperature, the method further comprising: generating a second damper command to open the indoor damper and close the outdoor damper, wherein the second damper command is based on the outside air dewpoint being greater than the indoor air temperature, and wherein closing the outside damper substantially disallows outside air from entering the building through the outside damper.

11. The method of claim 8, further comprising: detecting, with a noise sensor and audio detection algorithm, a siren indicating the presence of smoke or carbon monoxide; and based on the siren detection, opening the outside damper and closing the inside damper for smoke exhaust ventilation of a building.

12. The method of claim 8, wherein the first damper command also is based on comparing IAQ and OAQ information with an economizer to determine respective energy levels of the indoor and outdoor air, wherein the first damper command activates an energy recovery ventilator to by exchanging inside air to be exhausted from a building with incoming outdoor ventilation air.

13. The method of claim 8, further comprising: generating an additional damper command to interrupt a heating call from the HVAC system and open the outside damper, wherein the additional command is based on at least: the current operational state being heating, the indoor air temperature exceeding outdoor dewpoint, an outside air temperature exceeding indoor air temperature, and OAQ being greater than IAQ.

14. The method of claim 8, further comprising: receiving inputs regarding a building square footage and number of bedrooms and/or maximum permitted number of occupants; determining a ventilation requirement based on the inputs; and when the ventilation requirement is unmet for a time interval and the HVAC system fan is on, partially opening the outside damper and partially closing the inside damper.

15. A non-transitory, computer-readable medium containing including instructions to a dynamic ventilation control system, the instructions being executed by a controller to perform stages comprising: receiving, at a controller, indoor air quality (IAQ) information from the indoor sensor package and outdoor air quality (OAQ) information from the outdoor sensor package; making an air quality comparison based on the IAQ and OAQ information; receiving a current operational state of a heating, ventilation, and air conditioning (HVAC) system, wherein the operational state includes at least one of heating and cooling; and generating a first damper command to close an indoor damper and open an outdoor damper of a building, wherein the first damper command is based on at least the air quality comparison favoring OAQ over IAQ and an outside air dewpoint being below indoor air temperature.

16. The non-transitory, computer-readable medium of claim 15, the stages further comprising: detecting, with an opto-isolator, a voltage on a control line of the HVAC system; supplying a lower voltage to the controller when the voltage is present on the control line; and interrupting supply of the voltage to the HVAC system on the control line, turning off at least one of a compressor or blower, wherein the interruption includes making a state change to a switch for the control line.

17. The non-transitory, computer-readable medium of claim 15, wherein the outside air dewpoint is determined based on outside humidity and outside temperature, the stages further comprising: generating a second damper command to open the indoor damper and close the outdoor damper, wherein the second damper command is based on the outside air dewpoint being greater than the indoor air temperature, and wherein closing the outside damper substantially disallows outside air from entering the building through the outside damper.

18. The non-transitory, computer-readable medium of claim 15, the stages further comprising: detecting, with a noise sensor and audio detection algorithm, a siren indicating the presence of smoke or carbon monoxide; and based on the siren detection, opening the outside damper and closing the inside damper for smoke exhaust ventilation of a building.

19. The non-transitory, computer-readable medium of claim 15, wherein the first damper command also is based on comparing IAQ and OAQ information with an economizer to determine respective energy levels of the indoor and outdoor air, wherein the first damper command activates an energy recovery ventilator to by exchanging inside air to be exhausted from a building with incoming outdoor ventilation air.

20. The non-transitory, computer-readable medium of claim 15, the stages further comprising: generating an additional damper command to interrupt a heating call from the HVAC system and open the outside damper, wherein the additional damper command is based on at least: the current operational state being heating, the indoor air temperature exceeding outdoor dewpoint, an outside air temperature exceeding indoor air temperature, and OAQ being greater than IAQ.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 is a flowchart of an example method for performing dynamic building ventilation control.

[0024] FIG. 2 is a basic sequence diagram of a dynamic building ventilation control system.

[0025] FIG. 3 is an example block diagram of components for operation with a dynamic building ventilation control system.

[0026] FIG. 4A is an example schematic of components used in an example system.

[0027] FIG. 4B is an example schematic of components used in an example system.

[0028] FIG. 5 is an example illustration of components used in an example system.

DESCRIPTION OF THE EXAMPLES

[0029] Reference will now be made in detail to the present examples, including examples illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

[0030] FIG. 1 is an example method 100 for whole-building dynamic ventilation control. At stage 110, a controller can receive air quality information from indoor and outdoor sensor packages. The sensor packages can be sensor arrays and in one example can include a processor for formatting the air quality information. The IAQ and OAQ information can be separately determined from indoor and outdoor sensor readings, respectively.

[0031] The IAQ and OAQ can each contain multiple different information types relevant to air quality. In one example, the sensor packages can include a microprocessor board with memory and I/O connections, an air particle sensor array, a static pressure sensor, and a gas sensor array that contains a VOC sensor. The sensor packages can further include an ozone and air pollutant sensor, a carbon monoxide and combustion gas sensor, a temperature sensor, a humidity sensor, and a radon sensor. Noise pollution sensors can also be incorporated.

[0032] The sensor arrays can be placed at an indoor air return, outdoor air intake, HVAC output duct, and an exhaust duct, in an example.

[0033] At stage 120, the controller can then make an air quality comparison that includes using information from the indoor sensor package for IAQ and using information from the outdoor sensor package for OAQ. The comparison can occur for each sensor type. The comparisons can include temperature, humidity, VOCs, sulfurous and nitrous pollutant gas levels, carbon dioxide, carbon monoxide, airborne particulates (e.g., dust, smoke, pollen) and environmental noise pollution. For example, indoor VOC can be compared to outdoor VOC, indoor combustion gas to outdoor combustion gas, indoor temperature to outdoor temperature, and so on. The different information type comparisons can be weighted according to which type of information is most important. Additionally, the difference amounts can be important to determining the differences between IAQ or OAQ. For example, if IAQ is worse than OAQ for several information types but OAQ shows a dangerous level of VOC, IAQ can still be considered superior to OAQ.

[0034] At stage 130, the controller can receive a current operational state of an HVAC system. The operational state can include at least one of heating, cooling, and fan status. The controller can receive an input from a thermostat in one example, allowing the controller to read the calls from the thermostat to the HVAC units. Whether the thermostat is calling for heating, cooling, or fan can be used as part of determining whether to supply inside or outsider air to the HVAC system. In one example, an opto-isolator on the HVAC control line can supply voltage to the controller. The supplied voltage can indicate the operational mode of the system.

[0035] At stage 140, the controller can, based on the air quality comparison and current operational state of the HVAC system, open a first damper and close a second damper to change the ventilation of a building. This can include generating a first damper command to use outside air when OAQ is greater than IAQ, or a second damper command to use indoor air when IAQ is greater than OAQ. For example, the first damper command can close an indoor damper and open an outdoor damper of a building, wherein the first damper command is based on at least the air quality comparison favoring OAQ over IAQ and an outside air dewpoint being below indoor air temperature.

[0036] The damper command can also take the operational state into account. For example, if the HVAC is cooling then the outdoor air may need to be below a threshold temperature, such as 10 degrees Fahrenheit above the thermostat temperature.

[0037] FIG. 2 illustrates an example sequence diagram with stages for dynamically controlling intake of an HVAC system. At stage 210, the controller can read a thermostat control signal. The controller can likewise receive IAQ and OAQ information at stages 215 and 220.

[0038] Using these inputs, the controller can make an air quality comparison at stage 225. The air quality comparison can be an indoor versus outdoor comparison of pollution levels, VOC levels, temperature, pressure, humidity, and dewpoint. The controller can also consider the HVAC operational state at stage 230, such as whether the fan is on and the HVAC is cooling or heating. Based on if the outdoor-to-indoor temperature difference is within a threshold level for the respective operational state, the HVAC can issue commands to use or disuse outdoor air.

[0039] At stage 245, the controller can determine that OAQ is greater than IAQ. This would favor using outdoor air as an intake. If the outdoor air also falls within a threshold difference from the indoor air and/or the temperature of the thermostat, then the controller can issue a first damper command at stage 250. The first damper command can close an inside damper and open an outside damper, causing the HVAC to use outdoor air as an intake.

[0040] At stage 255, the controller can determine that OAQ is less than IAQ. The controller can issue a second command at stage 260, causing the indoor damper to open and the outside damper to close. This can switch the HVAC to an indoor air intake. For example, if it begins raining heavily outside, this switch could occur to prevent excess humidity in the HVAC system.

[0041] At stage 265, the controller can determine than indoor air temperature (IAT) can be compared against outside air dewpoint (ODP). ODP can be calculated as shown in Equation 1, below.

[00001]$\begin{array}{cc}\mathrm{ODP}=\{\left[\left({\left(\frac{\mathrm{Outside}.Math..Math.\mathrm{Humidity}}{1.Math.0.Math.0}\right)}^{0.1.Math.2.Math.5}*\left(17.Math.2.8+0.9*\mathrm{Outside}.Math..Math.\mathrm{Temperature}\right)\right]+\left(0.1*\mathrm{Outside}.Math..Math.\mathrm{Temperature}\right)-172.8\right\}& \mathrm{Equation}.Math..Math.1\end{array}$

[0042] When IAT is less than ODP and there is a heating call as a current operational state, the controller can issue a damper command at stage 270. This can cause the inside damper to open and the outside damper to close.

[0043] In addition, the damper commands can include interrupts. For example, if the current operational state is cool and outdoor air temperature (OAT) is less than indoor air temperature (IAT) at stage 275, the first command of stage 250 can include an interrupt at stage 280. The interrupt can save the HVAC from continuing to cool while instead relying on the cooler outside air. Similarly, if at stage 285 the operational state is heating and the OAT is greater than IAT, the first command of stage 250 can include an interrupt at stage 290 to stop the HVAC from heating, instead relying on the warmer outside air.

[0044] FIG. 3 illustrates example system components. The system can include a plastic box, where the Main Controller, buffer boards, wireless communications interface board, noise sensor, and relay board reside. The noise sensor can include a microphone usable by the controller for detecting sirens and other noise pollution. The plastic box can contain the display unit, such as touch screen module 316 and associated components, and two cylindrical plastic tubes where the air sensor arrays are housed. The touch screen module 316 can provide the options of Table 1, below, in an example.

TABLE-US-00001 TABLE 1 Display Indoor Air Quality by category (VOC, CO, CO2, NO, SO, Particulate) Display Radon (if enhanced indoor air quality sensor present) Display Indoor Air Temp, Humidity and Dew Point Display Outdoor Air Quality by category (VOC, CO, CO2, NO, SO, Particulate) Display Outdoor Air Temp, Humidity and Dew Point Graph Indoor and Outdoor Temp, Humidity, Dew Point and Air Quality Parameters over time Pause/Activate/Deactivate Timed Manual Demand Ventilation Pause/Activate/Deactivate Automated Outdoor Air Ventilation Set-Up and Update of Installation Parameters including Building Square Footage, Number of Bedrooms, Air Handler Fan CFM, Sensor Types and wireless communications interface set-up.

[0045] The system can use a noise sensor and audio detection algorithm to determine if a smoke detector, and/or carbon monoxide detector siren is sounding, and if outside air quality is not significantly worse than inside air quality, the system can command the dampers to allow outside air into the building, prevent the recirculation of inside air by the air handler, and signal the air handler blower to activate (i.e., fan=ON). This smoke exhaust ventilation is designed to increase escape and survival times during emergencies by pushing outdoor air into sleeping rooms and forcing toxic gasses and smoke out of the building through passive dampers that can be installed in the common area.

[0046] The Main Controller Unit of the system can be accessed by multiple connecton terminals wired into an existing HVAC system and air sensor units. Wiring from the thermostat can be connected to a portion of the Main Controller Unit connection terminals using commercial off-the-shelf (COTS) six-wire or eight-wire thermostat cable. Wiring from the air-handler can connect to another portion of the Main Controller Unit connection terminals using a COTS six-wire or eight-wire thermostat cable. The air sensor units, display unit, evaporator coil sensors and current sensors can each have a four-wire connection terminal to connect to the Main Controller Unit connection terminals using a COTS shielded four-conductor cable.

[0047] The system can also include components for buffering between the Controller and HVAC system. Since an HVAC system typically uses 24-volt AC and the Main Controller uses DC voltage to operate, buffering between the two environments can be handled via a custom circuitone circuit per HVAC line required to be monitored. In one example, the system detects the presence of 24-volt AC on a control line. For example, an optical isolator (opto-isolator) can be used to allow for this detection without imposing a burden onto the HVAC system. Resistors on the AC side allow for the opto-isolator to interface with the HVAC system while resistors and capacitors on the DC voltage side allow for a stead output dependent on the state of the monitored HVAC line. The output on the DC voltage side can be tied to an input on the processor board so the system can read the output state.

[0048] In another example, a system allows the Main Controller Unit to be installed within the air-handler housing of a new or pre-existing HVAC system and wired between the thermostat wiring cables and air-handler wiring terminals. Alternatively, the Main Controller Unit may be mounted anywhere between the thermostat and the air handler where the unit can be wired to the thermostat and air handler. Sensor units can be installed at the entrance of the outside air intake duct and in the indoor air return duct. The optional display unit can be installed on the outside of the air handler of any location chosen by the installer, and/or user at a distance from the controller 310.

[0049] For example, as frequently as twelve times an hour and every time there is a fan on signal 334 from the thermostat 330, the controller 310 can send requests for data to the remote sensor packages 312, 314. The sensor packages 312, 314 can respond with the latest measurements captured. The controller 310 can use the sensor information to compare IAQ and OAQ. When a fan on signal is received from the thermostat 330, the controller 310 can determine if the air quality of the outside air is better than the inside air by evaluating quantity of air-borne contaminates.

[0050] If the outside air quality is better than inside air quality, the controller 310 can command dampers 320, 322 to allow outside air into the building. This can also include controlling an economizer or energy recovery ventilator (ERV) by sending commands to those respective controllers 324, 326. If the controller 310 determines that the outside air quality is not better than inside air quality, the controller 310 can command dampers to prevent the outside air from entering into building. Additionally, if an ERV is present and the outside air quality is better than inside air quality, the controller 310 can activate the ERV to ventilate the building.

[0051] Simultaneously, when a fan on signal 334 is received from the thermostat 330, the controller 310 can determine if the temperature and humidity of outside air is appropriate for whole building fan cooling/heating by determining if IAT is greater than ODP. ODP can be calculated using Equation 1, above.

[0052] Regardless of whether the thermostat signals a cooling call or a heating call 333, if the controller 310 determines that the outside air temperature and/or humidity is not appropriate for whole building fan cooling/heating, the controller 310 can command dampers to not allow the outside air into building.

[0053] If the thermostat signals a cooling call 332, 333 and outside air temperature and humidity is appropriate for whole building fan cooling/heating and the outside temperature is less than the inside air temperature and outside air quality is better than inside air quality, the controller 310 can command dampers to allow outside air into the building. The controller 310 can interrupt the cooling call 332, 333, instead relying on outside air for cooling. This can also include overriding a thermostat's ventilation call 331, which may specify a conflicting damper configuration. The controller 310 can also interrupt the call to the compressor 335, relieving the condenser unit 350 from its duties. This can allow the air handler 340 to continue to heat or cool, but do so using the outside air, which can be at an advantageous temperature.

[0054] If the thermostat signals a heating call 332, 333, OAT and ODP meet threshold levels (i.e., humidity is appropriate for whole building fan cooling/heating), OAT is greater than the IAT, and OAQ is better than IAQ, the controller 310 can command dampers to allow outside air into the building. The controller 310 can also interrupt the heating call.

[0055] Additionally, if an economizer is present, the controller 310 can look to the input of this device to determine if OAT and humidity are at threshold levels appropriate for whole building fan cooling/heating when the thermostat signals a cooling call or heating call.

[0056] When an economizer is present, the system can use the Economizer to determine the enthalpy of the outside and inside air. With this information from the Economizer, the Control System can better assess the appropriateness of using outside air to cool or heat the inside of the building thus leveraging the capability of multiple sensor systems and enthalpy comparators to maximize energy efficiency of the HVAC system. When an Energy Recovery Ventilator is present, the control system controls the ERV to recover energy by exchanging (recycling) the energy contained in inside air to be exhausted from a building and using it to treat the incoming outdoor ventilation air in order to achieve energy efficiency improvements in residential and commercial HVAC systems.

[0057] When temperature needs have been met and the thermostat 330 removes the call to heat or cool, the blower 340, and compressor 350, will shut down and the controller 310 will await further commands from the thermostat.

[0058] The controller 310, can also continuously monitor outdoor air ventilation time to ensure ASHRAE 62.2 ventilation requirements are met based on a rotating 24-hour period. In one example, this is done based on Equation 2, below.

[00002]$\begin{array}{cc}\mathrm{Ventilation}.Math..Math.\mathrm{Requirement}.Math..Math.\left(\mathrm{mins}\right)=\frac{\left\{\left[\begin{array}{c}\left(\frac{\mathrm{Building}.Math..Math.\mathrm{Square}.Math..Math.\mathrm{Footage}}{100}\right)+\\ \left(\#.Math..Math.\mathrm{Bedrooms}+1\right)*7.5\end{array}\right]*1440\right\}}{\mathrm{Air}.Math..Math.\mathrm{Handler}.Math..Math.\mathrm{Fan}.Math..Math.\mathrm{CFM}}& \mathrm{Equation}.Math..Math.2\end{array}$

[0059] Regardless of cooling call or heating call 333, if ASHRAE 62.2 ventilation requirements have not been met for the preceding 24 hours and outdoor air quality is better than indoor air quality based on combined sensors, the Control System will command dampers to allow outside air into the building on all fan on signals 334, until ASHRAE 62.2 ventilation requirements are met for the preceding 24 hours.

[0060] If ASHRAE 62.2 ventilation requirements have not been met for the preceding 24 hours and outdoor air quality is not better than indoor air quality based on combined sensors, the controller 310 can command dampers to not allow outside air into the building. If an energy recovery ventilator is present and ASHRAE 62.2 ventilation requirements have not been met for the preceding 24 hours and the outside air quality is better than inside air quality, the Control System will activate the ERV to ventilate the building, until ASHRAE 62.2 ventilation requirements are met for the preceding 24 hours.

[0061] The controller 310 can also continuously monitor indoor air sensors to ensure dilutional ventilation requirements to minimize spread of air borne contagions are met. The monitoring can be done based on a rotating 60-minute period. In one example, this is done based on Equation 3, below.

IA.sub.CO2 ppm>OA.sub.CO2 ppm+(2343.75/n) Equation 3

[0062] In one example, regardless of cooling call or heating call 333, if dilutional ventilation requirements have not been met for the preceding 60 minutes and outdoor air quality is better than indoor air quality based on combined sensors, the controller 310 can command dampers to allow outside air into the building on all fan on signals 334. The controller 310 can maintain this state until dilutional ventilation requirements are met for the preceding 60 minutes.

[0063] If dilutional ventilation requirements have not been met for the preceding 60 minutes and outdoor air quality is not better than indoor air quality based on combined sensors, the controller 310 can command dampers to allow a minimal fraction of outside air into the building to meet dilutional ventilation requirements. For example, the controller 310 can partially open the outside damper and partially close the inside damper, allowing a mix of air for the air intake.

[0064] If an energy recovery ventilator is present and dilutional ventilation requirements have not been met for the preceding 60 minutes, the controller 310 can activate the ERV to ventilate the building, until the dilutional ventilation requirements are met for the preceding 60 minutes, regardless of whether or not the outside air quality is better than inside air quality.

[0065] The system can include a network interface 318 for controlling the system over a network, such as a local network or using an app from over the internet.

[0066] In one example, the controller 310 can also activate an ultraviolet sanitizer module (UVM) 341 that sanitizes the evaporator coils of the air handler. The UV sanitizer module 341 can be powered by a 240V A/C source in one example. The UV sanitizer module 341 can include two or three UV sanitizer illumination panels positioned inside the air handler to sanitize the surfaces of the evaporator coil, drip pan and air handler walls.

[0067] The UV sanitizer module can be attached to an air handler 340, which may be part of the HVAC system. The air handler 340 can be part of any type of air conditioning system, such as a heat pump system. The controller 310 can be located indoors on or inside the air handler unit 340, in various examples. UV sanitizer illumination panels can be mounted inside the air handler 340 above and below the evaporator coil(s). A safety switch can be located at the access panel to deenergize the UV sanitizer illumination panel when the air handler access panel is open.

[0068] The controller 310 can selectively sanitize the evaporator coils using the UV sanitizer module 341. First, the controller can detect that the air handler 340 fan is on. This can be based on current sensor information from one or more sensors or on the detection of a fan on signal from the thermostat. As will be described, the controller can control the UV sanitizer module 341. Next, the controller can detect that the air handler 340 access panel is closed. In one example, there can be a safety switch that signals the controller that the access panel is closed. Then, the controller can energize the UV sanitizer 341 illumination panels. The controller 310 can energize the UV sanitizer module 341 by sending a sanitation signal 336, in an example.

[0069] This process can continue indefinitely, generating substantial operational safety for the building occupants served by the HVAC system while avoiding issues related to excess moisture at the air handler and ducts.

[0070] FIG. 4A includes an example schematic for detecting a control signal from an HVAC system at a controller. This is an example opto-isolator configuration but other configurations are possible. FIG. 4B includes an example schematic for interrupting a signal to the HVAC system based on the controller determining to use outdoor air without a need for additional cooling or heating by the HVAC system. However, any other control interrupt, including one without a relay board, is also possible.

[0071] FIG. 5 is an example illustration of an air handler unit 500 equipped with UV sanitizer illumination panel components 510. In one example, UV sanitizer 341 illumination panels 510 are mounted to the air handler unit 500 above and below the evaporator coil unit 520.

[0072] Other examples of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the examples disclosed herein. Though some of the described methods have been presented as a series of steps, it should be appreciated that one or more steps can occur simultaneously, in an overlapping fashion, or in a different order. The orders of steps presented are only illustrative of the possibilities and those steps can be executed or performed in any suitable fashion. Moreover, the various features of the examples described here are not mutually exclusive. Rather any feature of any example described here can be incorporated into any other suitable example. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.