A Heating, Ventilating Air Conditioning (HVAC) fan control method comprising: detecting a HVAC fan is controlled by a fan-on setting, determining a HVAC fan-on operating time (F6) is greater than a Threshold Fan-on Time (TFT); and performing at least one action selected from the group consisting of: providing a HVAC fan-on alarm message, overriding the fan-on setting, and turning off the HVAC fan. The method may also include turning off an ultraviolet lamp after the HVAC fan is turned off, and turning on the ultraviolet lamp after the HVAC fan is turned on. Turning off the HVAC fan comprises: turning off the HVAC fan for a variable duration, skipping a scheduled fan-on setting, turning off the HVAC fan based on a call for cooling/heating, turning off the HVAC fan based on an indoor air quality measurement, and turning off the HVAC fan based on a geofencing or occupancy sensor signal.

A method includes obtaining a first indoor air quality model that predicts a first indoor air quality of a first building space based on a first occupancy of the first building space and a control action for building equipment that operate to affect the first indoor air quality of the first building space and performing a predictive control process using the first indoor air quality model to generate a control decision for building equipment and an occupancy decision for the first occupancy of the first building space. Both the control decision and the occupancy decision are decision variables adjusted when performing the predictive control process and are provided as outputs of the predictive control process.

Computer-implemented systems and methods for estimating a replacement status of an HVAC air filter. Outdoor weather data (e.g., outdoor temperature information), is obtained. A Total Runtime Value of the HVAC system is determined based upon the obtained outdoor weather data. Finally, a replacement status of the air filter is estimated as a function of a comparison of the Total Runtime Value with a Baseline Value. By correlating air filter replacement status with an estimated runtime of the HVAC system, a credible predictor of air filter usage is provided. By estimating fan runtime based on easily-obtained outdoor weather data, the methods are readily implemented with any existing HVAC system and do not require installation of sensors or other mechanical or electrical components to the HVAC system.

In various embodiments, an air quality-monitoring system (100) may include at least one sensor (106) configured to detect operation of a mechanism (110) within or at a boundary of an indoor environment. The mechanism may be external to an air purifier (102) associated with the indoor environment. The system may include a persistent memory (124) for storing data about the indoor environment observed by the at least one sensor (106). A controller (104) may be communicatively coupled with the at least one sensor and configured to: assemble the data into an air quality profile associated with that environment; determine, based on a signal from the at least one sensor and on the air quality profile, a likelihood that operation of the mechanism will cause a measure of air quality within the indoor environment to fail one or more air quality criteria; and selectively provide, based on the likelihood, an indication that operation of the mechanism will cause the measure of air quality within the indoor environment to fail the one or more air quality criteria.

An air-quality network system for homes, the air-quality network system having an air inlet unit, an air outlet unit, and a monitoring unit. The monitoring unit monitors, measures, and transmits information regarding the air quality to a network. The data management algorithm in the network compares the air quality information against preset/user-defined values and accordingly, determines the operating parameters of the air inlet and/or air outlet units. The system provides real-time monitoring and visualization of the air quality in the home, and provides emergency alerts if air quality exceeds safety limits.

Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, purging carbon monoxide (CO) from within a property. The methods, systems, and apparatus include actions of obtaining a reading from a carbon monoxide sensor in a property, determining that carbon monoxide in a property satisfies a carbon monoxide criteria based on the reading from the carbon monoxide sensor, obtaining a reading from a fire sensor, determining that a fire is not in the property based on the reading from the fire sensor, and in response to determining that carbon monoxide in the property satisfies the carbon monoxide criteria and that a fire is not in the property, triggering air in the property to be vented outside the property.

An apparatus for improving vehicle indoor air quality, may include a controller configured to correct and verify air dust concentration data; determine dust concentration outside a vehicle based on the verified data; and control an operation mode of an air conditioning device according to the determination; and the air conditioning device, wherein an operation of an intake door configured to control an introduction of outdoor air into the vehicle is controlled in response to signals of the controller.

Computer-implemented systems and methods for estimating a replacement status of an HVAC air filter. Outdoor weather data (e.g., outdoor temperature information), is obtained. A Total Runtime Value of the HVAC system is determined based upon the obtained outdoor weather data. Finally, a replacement status of the air filter is estimated as a function of a comparison of the Total Runtime Value with a Baseline Value. By correlating air filter replacement status with an estimated runtime of the HVAC system, a credible predictor of air filter usage is provided. By estimating fan runtime based on easily-obtained outdoor weather data, the methods are readily implemented with any existing HVAC system and do not require installation of sensors or other mechanical or electrical components to the HVAC system.

A ventilation unit is for ventilating an indoor space, and incorporates an air cleaning device and mechanical restrictor for controlling a restriction to a flow resulting from a pressure differential across the unit. There is determination of the inside and outside air pressures in the vicinity of the unit and of air quality parameters inside and outside. The air cleaning device and the mechanical restrictor are controlled in dependence on the determined air pressures and air quality parameters. This provides a fan-less, and hence low-power ventilation unit, which relies on throttling the natural air flow across the unit to provide flow control, and hence enable control of air quality. The air cleaning device may be operated only when the flow is into the inside space, saving power.

A method for improving the effectiveness of a building air circulation system having motorized blower and a contamination filter. The method including predicting a cost of operation of the system over an operational duration based on at least electricity consumption of the motor (115), and an operational cost to operate the filter (148), predicting a cost of maintenance of the system over the operational duration based on at least one of, a condition of the filter (148), a cost of a filter (148), a cost of labor to clean or replace the filter (148), and an effectiveness of the filter (148) over the operational duration, and balancing the cost of operation of the circulation system versus the cost of maintenance of the circulation system over the duration to recommend at least one of a filter use/bypass schedule, a filter maintenance schedule, and a fresh air input schedule satisfying an operation objective and an operational constraint.