Most VDP charts are DUMB!!! Because they don't relate to WHAT YOU ARE ACTUAL GROWING. Each type of plant has different Photosynthesis & Transpiration rates, for example a tomato plant grows the best, and produces the most fruit if a VPD of 0.80 kPa is maintained no matter what the environment temperature is. So, say you ran a light ON temp of 75F, and a light OFF temp of 66F, then your light ON RH percentage to maintain a VPD of 0.80 kPa at 75F would be 70% RH, then your light OFF RH percentage to maintain a VPD of 0.80 kPa at 66F would be 65% RH. Cannabis/Hemp plants are different than tomato plants, they grow best maintaining a VPD of 1.10 kPa, so if you ran a light ON temp of 75F, and a light OFF temp of 66F, then your light ON RH percentage to maintain a VPD of 1.10 kPa at 75F would be 65% RH, then your light OFF RH percentage to maintain a VPD of 1.10 kPa at 66F would be 50% RH.
Other notes...
Ones environment RH (%) should always match the environments temperature (C/F), based exclusively on the proper VPD/kPa rate for whatever type of plant one is growing!