In the previous article, we managed to control our electric blinds and awnings from the mobile, knowing exactly their position (0-100%). However, if you have to open the app yourself every time it's sunny, your home isn't "smart", it's just... remote controlled.
The real magic of building automation (and what we engineers call Bioclimatic Control) happens when the house "senses" the external environment and reacts autonomously. Proper shading management has two main goals: Equipment Protection (Safety) and Thermal Comfort (Economy).
Let's see how we can combine our smart shutters with weather data to create automations that work in the background, 365 days a year.
A 5-meter awning or a bioclimatic pergola in a sudden summer storm or a strong nor'easter acts like the sail of a sailboat. Damage (torn sail or broken booms) often costs over €1,000. Air defense automation is therefore an electronic insurance policy.
How it is implemented (The Hardware vs. Software Dilemma):
Many beginners make a script using free weather data (eg OpenWeatherMap): "If the forecast for my city shows wind > 40 km/h, pack the awning". This is dangerous. The weather has microclimates. The airport giving the measurement may have apnea, but your 5th floor balcony may have 6 Beaufort gusts. Also, if the internet goes down, the script crashes.
We place a natural wind sensor (anemometer) on the railings or on the roof. In KNX installations it is standard equipment (Weather Station). For DIY/Smart Home, there are solutions with Z-Wave sensors or even simple anemometers that command a relay (like the Shelly Plus 1). The relay "reads" the actual wind gust at that moment and gives an instant, local command to the motors to retract the awnings.
In summer, heat enters the house mainly through radiation that penetrates the glazing. If you wait for the room to warm up to turn on the A/C, you've already lost the energy game. The secret is to stop the sun before it hits the glass.
The "Smart" Summer Algorithm: Inside the Central Hub of the Smart Home (eg Home Assistant or SmartThings), we don't just make a "roll down the blinds at 14:00" scenario. The sun changes its angle every day of the year. We use an algorithm that combines 3 parameters:
The Perfect Scenario (West Front Example):
Once the sun sets (Azimuth > 290°), the blinds are automatically raised to 100% again to ventilate the house.
If the outside temperature is > 25°C AND the light level is > 20,000 Lux.
When the Azimuth of the sun reaches 240° (ie the sun begins to "see" the western windows).
Lower the western blinds to 60% (so they block the radiation, but still let some light in from below for you to see through).
The exact same algorithm works in reverse in winter. When it's 10°C outside but the sun is shining, solar radiation is free heating energy.
The Smart Home "understands" that it is cold, reads the high Lux of the sun, and makes sure that the shutters on the south and west sides of the house remain wide open throughout the afternoon, "trapping" the heat. When the sun goes down, the blinds go down to 0% immediately, acting as a "thermal blanket" for the windows, so that the heat does not escape outside at night.
If you have garden furniture under the awning or a wooden pergola with movable blinds, rain is an additional factor.
(Tip: Good rain sensors have a small heating resistor built in. That way, when the rain stops, they "dry" the board immediately, to signal the system that the danger has passed).
The motors of the blinds and awnings are the "hands" of your home, but the weather sensors are its "eyes". By joining these two, the house passively adapts to its surroundings. The energy savings from the air conditioner in the summer—because the blinds went down on time without you lifting a finger—are huge and quantifiable, making this upgrade one of the most meaningful energy engineering moves.
Next Step: We set up the sun and wind outside. It's time to look inside and tame our home's heating system (boiler or pump).
We continue with one of the hottest products on the market: Smart Thermostats (Nest, Tado, Netatmo, etc.): Are they worth their money to save in Greece and how are they connected to the boiler?
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