NO! humidity is not the same as VPD!
While humidity is a part of the growing equation, VPD (vapor pressure deficit) is the measure of how much remaining moisture the air can hold. Humidity is the measurement of how much moisture is currently in the air. This is important to understand as it allows for us to determine the best temperature and humidity for the grow room!
Curios how you can calculate this? Well, thanks to a Swedish scientist named Svante Arrhenius we can do this, he created the Arrhenius equation. For the sake of time and lack of mathematical understanding, I use a calculator like this online. There are also several great charts online like this.
Now we know what VPD is and how we can calculate it. The important question now is how we measure and control it. Thanks to companies like TC Controls, who represent Argus and Johnson Controls, they install room humid sensors (sensor blog here) so you can accuracy measure and store humidity/VPD trends. In fact, the software and hardware that TC Controls provide can make any necessary changes of the environment via communication with the rooms HVAC and lighting equipment. By understanding and creating the correct environment for your crops, you will end up with larger, healthier yields. Choosing to automate your grow reduces risk and ensures consistent outcomes.
So go check out your crops ideal growing conditions and create the ideal environment!
If you want to learn more about creating the ideal environment, contact TC Controls, we would be happy to talk with you.