Control method for tintable windows

1. A method of controlling tint of a tintable window, the method comprising:

determining a current time;

receiving weather feed data from one or more data services over a communication network and determining a weather condition at the current time based on the weather feed data;

determining if the current time is during a time delay period between a sunrise time and a first time delay after the sunrise time or between a second time delay before a sunset time and running to the sunset time;

if it is determined that the current time is during the time delay period, determining a tint level for the tintable window based on the weather condition;

if it is determined that the current time is not during the time delay period, determining the tint level based on a calculation of sunlight penetration into a building having the tintable window and/or based on a calculation of clear sky irradiance at the current time; and

sending a tint command to transition the tintable window to the tint level.

2. The method of controlling tint of the tintable window of claim 1 ,

further comprising calculating a solar azimuthal angle based on the current time and a latitude and a longitude of the building having the tintable window and

determining whether the solar azimuthal angle is between or outside critical angles of the tintable window;

wherein if the solar azimuthal angle is determined to be outside the critical angles of the tintable window, the tint level is determined also based on the calculation of clear sky irradiance at the current time; and

wherein if the solar azimuthal angle is determined to be between the critical angles of the tintable window, the tint level is determined also based on the calculation of sunlight penetration into the building having the tintable window and the calculation of clear sky irradiance at the current time.

3. The method of controlling tint of the tintable window of claim 2 ,

further comprising determining whether a sensor reading is between a lower limit and an upper limit; and

if the sensor is determined to be not between the lower limit and the upper limit, then the tint level is determined also based on the sensor reading.

4. The method of controlling tint of the tintable window of claim 1 ,

wherein the weather condition determined is a cloudy condition if it is determined that a cloud coverage percentage is above a threshold, and

wherein the weather condition determined is a not cloudy condition if it is determined that the cloud coverage percentage is at or below the threshold.

5. The method of controlling tint of the tintable window of claim 4 , wherein

if determined to be the cloudy condition, the tint level is determined also based on the calculation of clear sky irradiance at the current time; and

if determined to be the not cloudy condition, the tint level is clear and the tint command is to clear the tintable window.

6. A method of controlling tint of a tintable window to account for occupancy comfort in a building with the tintable window, the method comprising:

if a current time is before a sunrise time or after a time delay after the sunrise time, then determining whether a light sensor reading is between the lower limit and the upper limit, and if the light sensor reading is between the lower limit and the upper limit, determining an end tint state based on a calculation of sunlight penetration into the building and/or a calculation of clear sky irradiance, and if the light sensor reading is not between the lower limit and the upper limit, determining the end tint state based on the light sensor reading; and

if the current time is after the sunrise time and before the time delay after the sunrise time or the tintable window is in a demo mode, determining whether it is a cloudy condition or a not cloudy condition based on weather feed data received from one or more data sources over a communication network, wherein if it is determined to be the cloudy condition, then setting the end tint state to a clear state and wherein if it is determined to be the not cloudy condition, then determining the end tint state based on the calculation of sunlight penetration into the building and/or the calculation of clear sky irradiance.

7. The method of controlling tint of the tintable window of claim 6 , wherein determining whether it is the cloudy condition or the not cloudy condition based on the weather feed data from the one or more data sources comprises:

receiving the weather feed data with a cloud coverage percentage from the one or more data sources;

determining the cloudy condition if the cloud coverage percentage is greater than a threshold cloud coverage level; and

determining the not cloudy condition if the cloud coverage percentage is less than the threshold cloud coverage level.

8. The method of controlling tint of the tintable window of claim 6 , wherein determining whether it is the cloudy condition or the not cloudy condition based on the weather feed data from the one or more data sources comprises:

applying a filter to the weather feed data received from the one or more data sources; and

determining that it is the cloudy condition or the not cloudy condition based on the filtered weather feed data.

9. The method of controlling tint of the tintable window of claim 8 , wherein determining whether it is the cloudy condition or the not cloudy condition based on the weather feed data from the one or more data sources further comprises:

determining the cloudy condition if a cloud coverage percentage from the weather feed data is greater than a threshold cloud coverage level; and

determining the not cloudy condition if the cloud coverage percentage from the weather feed data is less than the threshold cloud coverage level.

10. The method of controlling tint of the tintable window of claim 8 , wherein applying the filter to the weather feed data received from the one or more data sources comprises:

selecting one or more of the one or more data sources based on a prioritized list of data sources; and

using weather feed data from the selected one or more data sources to determine the filtered weather feed data.

11. The method of controlling tint of the tintable window of claim 8 , wherein applying the filter to the weather feed data received from the one or more data sources comprises:

combining the weather feed data from the one or more data sources to determine the filtered weather feed data.

12. The method of controlling tint of the tintable window of claim 6 , wherein determining whether it is the cloudy condition or the not cloudy condition based on the weather feed data from the one or more data sources further comprises:

sending a signal with a request for the weather feed data to each of the one or more data sources over the communication network; and

receiving the weather feed data from the one or more data sources.

13. The method of controlling tint of the tintable window of claim 6 , further comprising determining the sunrise time based on a longitude and a latitude of location of the tintable window.

14. The method of controlling tint of the tintable window of claim 13 , further comprising determining whether the current time is after the sunrise time and before the time delay after the sunrise time.

15. The method of controlling tint of the tintable window of claim 6 , wherein determining the end tint state based on the calculation of sunlight penetration and/or the calculation of clear sky irradiance, comprises:

calculating a sun azimuth at the current time based on a latitude and a longitude of location of the tintable window;

determining whether the calculated sun azimuth is between critical angles;

if the calculated sun azimuth is outside the critical angles, determining the end tint state based on the calculation of clear sky irradiance; and

if the calculated sun azimuth is between the critical angles, determining a first tint level based on sunlight penetration into the building and a second tint level based on the calculation of clear sky irradiance, and determining the end tint state based on a greater of the first tint level and the second tint level.

16. The method of controlling tint of the tintable window of claim 6 , further comprising

sending a signal with tint instructions to transition tint of the tintable window to the end tint state.

17. A controller for controlling tint of a tintable window to account for occupancy comfort in a building having the tintable window, the controller comprising:

an interface with a communication network; and

a processor in communication with the interface, the processor configured to execute instructions to:

determine whether a current time is before a sunrise time or after a time delay after the sunrise time,

if the current time is determined to be before the sunrise time or after the time delay after the sunrise time, the processor determines whether a light sensor reading received from at least one light sensor is between a lower limit and an upper limit, wherein if the light sensor reading is between the lower limit and the upper limit, the processor determines an end tint state based on a calculation of sunlight penetration and/or a calculation of clear sky irradiance, and if the light sensor reading is not between the lower limit and the upper limit, the processor determines the end tint state based on the light sensor reading, and

if the current time is determined to be after the sunrise time and before the time delay after the sunrise time or the tintable window is in a demo mode, the processor determines whether it is a cloudy condition or a not cloudy condition based on weather feed data received from one or more data sources over the communication network, wherein if the processor determines it to be the cloudy condition, the processor sets the end tint state to a clear state and wherein if the processor determines it to be the not cloudy condition, then the processor determines the end tint state based on the calculation of sunlight penetration and/or the calculation of clear sky irradiance.

18. The controller of claim 17 , further comprising a pulse width modulator in communication with the processor and with the tintable window,

the pulse width modulator configured to:

receive the end tint state from the processor; and

send a signal with tint instructions to transition tint of the tintable window to the end tint state.

19. The controller of claim 17 , wherein the processor is configured to determine whether it is the cloudy condition or the not cloudy condition based on the weather feed data from the one or more data sources by being configured to:

receiving the weather feed data with a cloud coverage percentage from the one or more data sources;

determining the cloudy condition if the cloud coverage percentage is greater than a threshold cloud coverage level; and

determining the not cloudy condition if the cloud coverage percentage is less than the threshold cloud coverage level.

20. The controller of claim 17 , wherein the processor is configured to determine whether it is the cloudy condition or the not cloudy condition based on the weather feed data from the one or more data sources by being configured to:

apply a filter to the weather feed data received from the one or more data sources; and

determine that it is the cloudy condition or the not cloudy condition based on the filtered weather feed data.

21. The controller of claim 20 , wherein the processor is configured to apply the filter to the weather feed data received from the one or more data sources by being configured to:

select one or more of the one or more data sources based on a prioritized list of data sources; and

use weather feed data from the selected one or more data sources to determine the filtered weather feed data.

22. The controller of claim 20 , wherein the processor is configured to apply the filter to the weather feed data received from the one or more data sources by being configured to:

combine the weather feed data from the one or more data sources to determine the filtered weather feed data.

23. The controller of claim 17 , wherein the processor is configured to determine whether it is the cloudy condition or the not cloudy condition based on the weather feed data from the one or more data sources further by being configured to:

send a signal with a request for the weather feed data to each of the one or more data sources over the communication network; and

receive the weather feed data from the one or more data sources.

24. The controller of claim 23 , wherein the processor is configured to determine whether it is the cloudy condition or the not cloudy condition based on the weather feed data from the one or more data sources by being further configured to:

determine the cloudy condition if a cloud coverage percentage from the weather feed data is greater than a threshold cloud coverage level; and

determine the not cloudy condition if the cloud coverage percentage from the weather feed data is less than the threshold cloud coverage level.

25. The controller of claim 17 , wherein the processor is further configured to determine the sunrise time based on a longitude and a latitude of location of the tintable window.

26. The controller of claim 25 , wherein the processor is further configured to determine whether the current time is after the sunrise time and before the time delay after the sunrise time.

27. The controller of claim 17 , wherein the processor is configured to determine the end tint state based on the calculation of sunlight penetration into the building and/or the calculation of clear sky irradiance, by being configured to:

calculate a sun azimuth at the current time based on latitude and longitude of location of the tintable window;

determine whether the calculated sun azimuth is between critical angles;

if the calculated sun azimuth is outside the critical angles, determine the end tint state based on the calculation of clear sky irradiance; and

if the calculated sun azimuth is between the critical angles, determine a first tint level based on sunlight penetration and a second tint level based on clear sky irradiance, and determining the end tint state based on a greater of the first tint level and the second tint level.