Method of controlling a motorized window treatment
View Patent ↗A method comprises measuring a light intensity at a window; determining if the light intensity exceeds a cloudy-day threshold; operating in a sunlight penetration limiting mode to control the motorized window treatment to control the sunlight penetration distance in the space; enabling the sunlight penetration limiting mode if the light intensity is greater than the cloudy-day threshold; and disabling the sunlight penetration limiting mode if the total lighting intensity is less than the cloudy-day threshold. The cloudy-day threshold is maintained at a constant threshold if a calculated solar elevation angle is greater than a predetermined solar elevation angle, and the cloudy-day threshold varies with time if the calculated solar elevation angle is less than the predetermined solar elevation angle. The cloudy-day threshold is a function of the calculated solar elevation angle if the calculated solar elevation angle is less than the predetermined solar elevation angle.
1. A method of controlling a motorized window treatment for adjusting an amount of sunlight entering a space of a building through a window to control a sunlight penetration distance in the space, the method comprising:
measuring a total light intensity at the window;
calculating a solar elevation angle;
calculating a cloudy-day threshold as a function of the calculated solar elevation angle;
determining if the total light intensity exceeds the cloudy-day threshold;
enabling a sunlight penetration limiting mode when the total light intensity is greater than the cloudy-day threshold; and
operating in the sunlight penetration limiting mode to control the motorized window treatment to thus control the sunlight penetration distance in the space.
2. The method of claim 1 , wherein the cloudy-day threshold is maintained at a constant threshold when the calculated solar elevation angle is greater than a predetermined solar elevation angle, and the cloudy-day threshold is a function of the calculated solar elevation angle when the calculated solar elevation angle is less than the predetermined solar elevation angle.
3. The method of claim 2 , wherein the cloudy-day threshold is a linear function of the calculated solar elevation angle when the calculated solar elevation angle is less than the predetermined solar elevation angle.
4. The method of claim 1 , further comprising:
disabling the sunlight penetration limiting mode when the total lighting intensity is less than the cloudy-day threshold; and
controlling the motorized window treatment to a predetermined position when the sunlight penetration limiting mode is disabled.
5. A system for controlling a motorized window treatment for adjusting an amount of sunlight entering a space of a building through a window to control a sunlight penetration distance in the space, comprising:
a sensor for measuring a total light intensity at the window; and
a processor configured to:
calculate a solar elevation angle;
calculate a cloudy-day threshold as a function of the calculated solar elevation angle;
determine if the total light intensity exceeds the cloudy-day threshold;
enable a sunlight penetration limiting mode when the total light intensity is greater than the cloudy-day threshold;
operate in the sunlight penetration limiting mode to control the motorized window treatment to thus control the sunlight penetration distance in the space; and
disable the sunlight penetration limiting mode when the total lighting intensity is less than the cloudy-day threshold.
6. The system of claim 5 , wherein the cloudy-day threshold is maintained at a constant threshold when the calculated solar elevation angle is greater than a predetermined solar elevation angle, and the cloudy-day threshold is a function of the calculated solar elevation angle when the calculated solar elevation angle is less than the predetermined solar elevation angle.
7. The system of claim 6 , wherein the cloudy-day threshold is a linear function of the calculated solar elevation angle when the calculated solar elevation angle is less than the predetermined solar elevation angle.
8. The system of claim 5 , wherein the processor is configured to control the motorized window treatment to a predetermined position when the sunlight penetration limiting mode is disabled.
9. An apparatus comprising:
at least one processor; and
a computer readable medium communicatively coupled to the at least one processor and having instructions stored thereon that when executed by the at least one processor direct the at least one processor to:
determine from a sensor a total light intensity at a window of a building;
calculate a solar elevation angle;
calculate a cloudy-day threshold as a function of the calculated solar elevation angle;
determine if the total light intensity exceeds the cloudy-day threshold;
enable a sunlight penetration limiting mode when the total light intensity is greater than the cloudy-day threshold;
operate in the sunlight penetration limiting mode to control a motorized window treatment to thus control a sunlight penetration distance of sunlight entering a space of the building through the window; and
disable the sunlight penetration limiting mode when the total lighting intensity is less than the cloudy-day threshold.
10. The apparatus of claim 9 , wherein the cloudy-day threshold is maintained at a constant threshold when the calculated solar elevation angle is greater than a predetermined solar elevation angle, and the cloudy-day threshold is a function of the calculated solar elevation angle when the calculated solar elevation angle is less than the predetermined solar elevation angle.
11. The apparatus of claim 10 , wherein the cloudy-day threshold is a linear function of the calculated solar elevation angle when the calculated solar elevation angle is less than the predetermined solar elevation angle.
12. The apparatus of claim 9 , wherein the at least one processor is further configured to control the motorized window treatment to a predetermined position when the sunlight penetration limiting mode is disabled.