Automatisation of Basement Windows

Grove - Temperature & Humidity Sensor, I2C

Arduino UNO

Power Supply 12 V

MAX RS485

Reed Relay Axicom V23100-V4005-A010

Arduino Nano R3

LCDKeypad Shield

Our basement was generally too humid. The 6 windows were open in summer and closed in winter time.When the windows are open, the outside air gets inside, but because the temperature of the incoming air takes on the inside temperature, also the relative humidity changes (mainly in summer, when windows are open, the relative humidity inside gets very high).Solution: Measure the temperature and the relative humidity inside and outside and calculate the absolute humidity for both, inside and outside. If inside absolute humidity is higher than outside, windows will open, the other way round (with a certain hysteresis) windows will close. [Second condition for opening the windows: the temperature inside is not allowed to fall below 12 degrees Celsius (because of the stored food) - in winter time, the absolute humidity inside is nevertheless very low.]Because the sensors are in relative big distances (ca. 20 m), we use the RS 485 communication protocol.<figure><img src=https://projects.arduinocontent.cc/1c966715-7943-45e6-92d3-a7ff17b3e77e.jpg /><figcaption>Block Diagram</figcaption></figure><figure><img src=https://projects.arduinocontent.cc/5d4af582-42d7-43fa-b9f4-135fa57d37f3.jpg /><figcaption>Master</figcaption></figure><figure><img src=https://projects.arduinocontent.cc/ed2e07b5-8a40-46ba-a164-1703891975c1.jpg /><figcaption>Slave outside</figcaption></figure><figure><img src=https://projects.arduinocontent.cc/2f4f51b2-9c31-459e-9f54-e95e517b5d74.jpg /><figcaption>slave inside</figcaption></figure><figure><img src=https://projects.arduinocontent.cc/4513d643-0639-4d68-8a23-f822d6743466.jpg /><figcaption>slave inside, open</figcaption></figure>

Master, schematics

Slave

Slave, schematics

Master

Automatisation of Basement Windows

Open the windows if the absolute humidity outside is lower than inside and close them if not.