Blinds Adjustment According to Sun

The Blinds adjustment according to sun smart rule automatically adjusts the position and slat angle of your blinds to control how much sunlight goes through. It tracks the sun’s position relative to each window throughout the day, and can optionally integrate with your heating/cooling system and a brightness sensor.

Getting started

Setting up this smart rule takes three steps:

1. Add blinds — select which blinds or shutters to control.
2. Choose what to adjust — blind position, slat angle, or both.
3. Set the time window — when the smart rule should be active during the day.

Basic example

You have south-facing blinds in your living room and want them to close automatically when the sun shines directly through the window during the cooling season.

1. Create a new Blinds adjustment according to sun smart rule.
2. In the Blinds section, tap Add blinds and select the living room blinds.
3. In the Position of the sun affects section, make sure the Position of the blinds / awning checkbox is enabled. Choose Heating & Cooling mode.
4. Set When cooling set level of blinds to to 100% (fully closed).
5. Ignore When heating, set level of blinds to — the mode will always be Fixed cooling so this setting will be ignored.
6. In the Heating & Cooling Mode section, select Fixed cooling.
7. Leave the time window at its default (5:00 to 20:00).
8. Tap Save.

When the sun shines through the window during the active time, the blinds close fully to block the sun. When the sun moves past the window, the smart rule stops adjusting the blinds.

The smart rule requires each blind device to have its Sun orientation configured in the device’s service settings. This tells the smart rule which direction the window faces — without it, the smart rule cannot determine whether the sun actually shines through the window.

Blinds

Tap Add blinds to select one or more blinds or shutters. The smart rule evaluates each device independently — each blind is checked against its own Sun orientation settings to determine if the sun shines through that specific window.

You can mix blinds from different rooms and facing different directions in a single smart rule. Each blind receives its own position and angle based on its own Sun orientation settings.

Time adjustment

Time window

The Time interval (From/To) slider defines when the smart rule is active during the day. Outside this window, the smart rule does not adjust the blinds.

Change interval

The smart rule checks conditions and applies blind position and slat angle every minute during the active time window. However, it only recalculates fresh values at the interval set by the Make adjustment every slider. Between recalculations, the smart rule re-applies the previously computed values.

A shorter interval means the smart rule recalculates positions more often to track the sun’s movement more closely, but may cause more motor wear.

If the sun has not reached a specific window yet at the scheduled recalculation time, the smart rule recalculates values for the corresponding blind as soon as the sun reaches it — it does not wait for the next interval.

Sun position prediction

When recalculating, the smart rule uses the sun’s predicted position half of the change interval ahead — for example, with a 60-minute interval, it calculates values for where the sun will be in 30 minutes. This keeps the blind position closer to being optimal throughout the interval, because the values are set for the midpoint rather than the start. If the predicted sun position is below the horizon (near sunset), the smart rule uses the current position instead.

Position of the sun affects

The sun position section controls two independent features: Position of the blinds / awning and Angle of slats. You can enable them in any combination.

Position of the blinds / awning

Under the Position of the sun affects section, enable Position of the blinds / awning to have the smart rule adjust how far the blinds are open or closed. Two modes are available:

Heating & Cooling — The smart rule sets the blind position to a fixed value depending on whether the smart rule is in heating or cooling mode:

Depth of sun ray — The smart rule calculates how deep sunlight penetrates into the room and adjusts the blind position to limit it to the specified distance from the window:

In Depth of sun ray mode, the smart rule uses the sun’s elevation angle to compute how far the sun ray would reach across the floor — see Window height (vertical dimension) and Distance from floor to window in the device’s service settings. When the sun is high (steep angle), it stays close to the window and the blinds open more. When the sun is low, it reaches deeper into the room and the blinds close further. As with the other calculations, the smart rule uses the predicted sun position for better accuracy.

Angle of slats

Enable the Angle of slats checkbox to have the smart rule adjust slat angles. The angle is computed from slat angle tables stored in the service settings of each blind (see Slats angle adjustment) — these tables map sun elevation angles to optimal slat positions for heating and cooling.

If the Slats angle adjustment table is not configured, the slat angle adjustment is skipped for that blind.

You can enable both Position of the blinds / awning and Angle of slats simultaneously. The smart rule sets both the blind position and the slat angle in one go.

Brightness sensor

When Position of the blinds / awning or Angle of slats is enabled, you can optionally add a brightness sensor to gate the smart rule’s activation.

By default, the smart rule estimates whether the sun is shining through the window by calculating its position. A brightness sensor additionally checks if the sun is actually reaching the window rather than being obscured, for example by clouds.

Brightness threshold

Set the minimum brightness level (as a percentage) that must be exceeded before the smart rule activates.

Tap Configure on the brightness sensor section to open additional settings.

Threshold sensitivity

Controls how long the brightness must continuously exceed the threshold before the smart rule activates. This prevents the blinds from reacting to brief moments of sunshine.

Brightness drop behavior

When the smart rule is actively adjusting the blinds and brightness drops back below the threshold, you can choose how the smart rule responds:

Do not allow interruption — The smart rule keeps adjusting the blinds for the rest of the day, even if brightness drops.

Allow interruption — When brightness drops below the threshold, a countdown begins. If brightness does not recover before the countdown expires, the smart rule deactivates. If brightness recovers before the timeout, the countdown resets.

Heating & Cooling Mode

When either Position of the blinds / awning or Angle of slats is set to Heating & Cooling Mode, a Heating & Cooling Mode section appears. This determines how the smart rule chooses which mode is currently active (heating or cooling), which in turn affects how it positions the blinds.

You can set the mode source in two ways:

Fixed value — Choose a fixed mode that always applies:

• Fixed heating
• Fixed cooling
• Fixed heating/cooling

Device — Select a multi-value switch with device type Heating & Cooling Mode. The smart rule reads the device’s current mode dynamically.

When using a device as the mode source, an additional toggle appears: whether to allow the Off state. If disabled, the smart rule stops when the mode device is off. If enabled, the smart rule continues adjusting using cooling settings as a fallback.

When the Heating & Cooling Mode device is off and Allow blinds adjustment when (device name) is set to Off. is enabled, the smart rule uses cooling settings (blind position and slat angle) as the fallback. Configure your cooling values accordingly if the device can be off.

Thermostat

When the smart rule uses Heating & Cooling Mode (for either Position of the blinds / awning or Angle of slats), you can optionally add a thermostat. The thermostat enables temperature-based refinement: instead of relying solely on the Heating & Cooling Mode device, the smart rule compares the actual room temperature against the thermostat setpoint to decide whether it should be heating or cooling the room.

When a thermostat is added

• Heating/cooling — The smart rule decides whether to heat or cool the room based on the thermostat — instead of relying on the Heating & Cooling Mode setting.
• Temperature offset — The Heating & Cooling Mode setting determines how the offset is applied, allowing the smart rule to target a point above or below the thermostat setpoint.

Tap Configure on the thermostat section to open additional settings.

Temperature offset

The temperature offset shifts the target temperature away from the thermostat setpoint. The direction depends on the current Heating & Cooling Mode value (whether from a fixed setting or a device):

• Heating: offset is added to the setpoint — target moves up
• Cooling: offset is subtracted from the setpoint — target moves down
• Heating & Cooling: offset has no effect — the raw setpoint is used

Example: If the thermostat is set to 22 °C and the offset is 5 °C:

• In heating mode, the adjusted target is 22 + 5 = 27 °C — the smart rule keeps using heating settings (blinds open) until the room reaches 27 °C
• In cooling mode, the adjusted target is 22 - 5 = 17 °C — the smart rule keeps using cooling settings (blinds closed) until the room drops to 17 °C

Hysteresis range

When set, the smart rule will only switch between heating and cooling modes if the temperature deviates far enough from the target. This prevents frequent mode switching when the temperature fluctuates near the target — each mode switch triggers an immediate blind adjustment, so without hysteresis the blinds could move back and forth repeatedly.

Example: With an adjusted target of 27 °C and hysteresis of 1 °C:

• Above 28 °C (target + 1): switch to cooling mode
• Below 26 °C (target - 1): switch to heating mode
• Between 26 °C and 28 °C: keep the current mode (no switching)

Smart rule evaluation

Evaluation flow

The smart rule evaluates every minute during the active time window, and also whenever a relevant device value changes (thermostat, brightness sensor, or mode device). Each evaluation checks a series of conditions in order:

1. At least one feature enabled — Position of the blinds / awning or Angle of slats must be enabled.
2. Active time window — Current time must be within the configured time range.
3. Heating & Cooling Mode — if the mode device is off and the allow Off setting is disabled, the smart rule pauses.
4. Sun above horizon — The sun must be above the horizon.
5. Brightness threshold — If a brightness sensor is configured, brightness must meet the threshold (subject to sensitivity).

If all conditions pass, the smart rule evaluates each blind individually. Whether the smart rule recalculates fresh values or re-sends cached ones depends on the change interval.

Per-blind evaluation

For each blind device, the smart rule checks:

1. Sun orientation — The device must have Sun orientation configured.
2. Sun in window range — The sun’s azimuth must be within +/- 90 degrees of the window’s facing direction. Sun orientation offsets further narrow this range.
3. Sun elevation in range — The sun must be high enough to shine through the window, accounting for any configured elevation offsets.

If the sun shines through the window, the smart rule computes the appropriate Position of the blinds / awning and/or Angle of slats values and sends them to the device.

Mode changes

When the Heating & Cooling Mode or thermostat setpoint changes, the smart rule forces all blinds to update immediately on the next evaluation — it does not wait for the change interval. This ensures blinds respond promptly to mode transitions.

Thermostat error

If the thermostat device becomes unavailable or reports an error, the smart rule stops adjusting blind positions but keeps the current slat angle. This prevents blinds from being stuck in an incorrect position when temperature data is unreliable.

Examples and scenarios

Example 1: South-facing living room — basic sun protection

Goal: Close the south-facing blinds when the sun shines directly through the window during summer to reduce heat gain.

Configuration:

• Blinds: living room south-facing blinds
• Time window: 5:00 to 20:00 (default)
• Make adjustment every: 60 minutes (default)
• Brightness sensor: none — blinds should react to sun position alone, regardless of cloud cover
• Position of the blinds / awning: enabled, Heating & Cooling
• When heating, set level of blinds to: not used (mode is fixed to cooling)

• When cooling set level of blinds to: 100% (fully closed — blocks sun to keep the room cool)
• Angle of slats: disabled — these blinds do not have adjustable slats
• Heating & Cooling Mode: Fixed cooling
• Indoor temperature: none — not needed because the mode is fixed (no temperature-based switching)

Behavior: During the active time window, whenever the sun is above the horizon and its azimuth is within the south-facing window’s range, the smart rule sets the blinds to 100% (fully closed). When the sun moves past the window (for example, late afternoon when it shifts to the west), the smart rule stops adjusting the blinds.

Example 2: Sun ray depth — limit sunlight penetration on sunny days

Goal: Allow natural light into the office, but prevent direct sun from reaching more than 2 meters into the room. Only activate when it is actually sunny outside.

Configuration:

• Blinds: office blinds
• Time window: 6:00 to 20:00
• Make adjustment every: 60 minutes (default)
• Brightness sensor: office outdoor brightness sensor
• Brightness: 40%
• Threshold sensitivity: Medium — brightness must exceed the threshold for roughly 10 minutes before activating
• Brightness drop: Do not allow interruption — once activated, protection stays for the rest of the day
• Position of the blinds / awning: enabled, Depth of sun ray
• Depth of sun ray: 2.0 m
• Angle of slats: disabled — these blinds do not have adjustable slats

Behavior: On sunny days, once the brightness exceeds 40% for approximately 10 minutes, the smart rule activates. It calculates how far the sun ray would reach across the floor based on the sun’s elevation angle and the window’s height. When the sun is high at midday, rays stay close to the window and the blinds open more. As the sun lowers in the afternoon, rays reach deeper into the room — the smart rule progressively closes the blinds to keep sunlight within 2 meters. Once activated, the smart rule keeps adjusting the blinds for the rest of the day even if clouds temporarily reduce brightness.

Example 3: Combined Position of the blinds / awning and Angle of slats with thermostat

Goal: Automate both blind position and slat angle based on whether the room needs heating or cooling, using actual room temperature to decide.

Configuration:

• Blinds: bedroom blinds
• Time window: 7:00 to 21:00
• Make adjustment every: 60 minutes (default)
• Brightness sensor: none — blinds should react whenever the sun shines through, regardless of cloud cover
• Position of the blinds / awning: enabled, Heating & Cooling
• When heating, set level of blinds to: 0% (fully open — lets sun warm the room)
• When cooling set level of blinds to: 70% (partially closed — reduces direct solar heat gain while allowing some daylight)
• Angle of slats: enabled — slat angle tables are configured in the device’s service settings
• Heating & Cooling Mode: Fixed cooling
• Indoor temperature: bedroom thermostat (setpoint 23 °C)
• Temperature offset: 5 °C
• Hysteresis range: 1 °C

Behavior: The smart rule reads the room temperature and compares it to the adjusted setpoint. The fixed mode is set to cooling, so the adjusted target is 23 - 5 = 18 °C. The hysteresis of 1 °C creates a deadband around 18 °C:

• Above 19 °C (target + hysteresis): smart rule uses cooling settings — blinds at 70% (partially closed), slat angle from the device’s cooling angle table
• Below 17 °C (target - hysteresis): smart rule switches to heating settings — blinds at 0% (fully open), slat angle from the heating angle table
• Between 17 and 19 °C: smart rule keeps the previous mode to avoid rapid switching

The slat angle is interpolated from the device’s slat angle tables based on the sun’s elevation — optimizing for heat gain (heating) or glare reduction (cooling). When the thermostat setpoint changes, the smart rule forces an immediate update without waiting for the next change interval.

Example 4: Brightness sensor with interruption and recovery timer

Goal: Protect a south-facing conservatory from overheating on sunny days, but re-open the blinds if clouds persist for more than 30 minutes.

Configuration:

• Blinds: conservatory blinds
• Time window: 7:00 to 19:00
• Make adjustment every: 60 minutes (default)
• Brightness sensor: outdoor brightness sensor
• Brightness: 50%
• Threshold sensitivity: High — activates after roughly 5 minutes above threshold
• Brightness drop: Allow interruption — blinds return to normal if brightness drops
• Return back to normal after: 30 minutes
• Position of the blinds / awning: enabled, Heating & Cooling
• When heating, set level of blinds to: 0% (fully open — lets sun warm the conservatory in winter)
• When cooling set level of blinds to: 100% (fully closed — blocks sun to prevent overheating)
• Angle of slats: disabled — roller blinds without slats
• Heating & Cooling Mode: Fixed heating/cooling
• Indoor temperature: conservatory thermostat (setpoint 21 °C)
• Temperature offset: not used — with Fixed heating/cooling mode, the smart rule uses the raw thermostat setpoint without offset adjustment
• Hysteresis range: 1 °C

Behavior: On a sunny morning, once outdoor brightness stays above 50% for approximately 5 minutes, the smart rule activates. With Fixed heating/cooling mode, the thermostat’s setpoint (21 °C) is used directly — the temperature offset has no effect in this mode. The hysteresis of 1 °C creates a deadband:

• Above 22 °C (setpoint + hysteresis): smart rule uses cooling settings — blinds close fully (100%)
• Below 20 °C (setpoint - hysteresis): smart rule uses heating settings — blinds open fully (0%)
• Between 20 and 22 °C: keeps the previous mode

If clouds roll in and brightness drops below 50%, a 30-minute countdown begins. If the sun returns before the countdown expires, the timer resets and protection continues. If clouds persist longer than 30 minutes, the smart rule deactivates and the blinds return to manual control. To re-activate, brightness must once again sustain above the threshold long enough to satisfy the sensitivity setting.

Example 5: Multiple blinds across rooms with a mode device

Goal: Control blinds in several rooms with a single smart rule, each responding to its own window orientation. Use the home’s Heating & Cooling Mode device to determine the season.

Configuration:

• Blinds: living room (south), kitchen (west), bedroom (east)
• Time window: 5:00 to 20:00 (default)
• Make adjustment every: 30 minutes (more frequent updates to track the sun closely)
• Brightness sensor: none — react to sun position regardless of cloud cover
• Position of the blinds / awning: enabled, Heating & Cooling
• When heating, set level of blinds to: 0% (fully open — lets sun warm the rooms in winter)
• When cooling set level of blinds to: 100% (fully closed — blocks sun to keep rooms cool)
• Angle of slats: enabled — slat angle tables configured per device
• Heating & Cooling Mode: a multi-value switch with device type Heating & Cooling Mode
• Allow blinds adjustment when (device name) is set to Off.: yes — smart rule continues adjusting using cooling settings when the device is off
• Indoor temperature: none — using the mode device directly, not temperature-based switching

Behavior: Each blind is evaluated independently against its own Sun orientation settings. When the mode device reports cooling, the blinds close to 100% (fully closed) when the sun shines through; when it reports heating, the blinds open to 0% (fully open) to let sun warm the room. In the morning, the east-facing bedroom blinds adjust first (sun shines through the east window) while the south and west blinds stay unaffected. Around midday, the south-facing living room blinds adjust. In the afternoon, the west-facing kitchen blinds adjust as the sun moves west. Each blind only reacts when the sun actually shines through its specific window.

When the mode device reports Off, the smart rule falls back to cooling settings and continues adjusting. Because Allow blinds adjustment when (device name) is set to Off. is enabled, the smart rule does not stop — it treats the off state as cooling.