Can commercial landlord raise rent based on new subtenant?

Some lease agreements impose specific limits on space use

Question: I have been leasing an office for the past year. Since I typically use my office only four days a week I informed the landlord that a professional counseling peer and friend of mine was interested in the possibility of sharing my office. We have worked out our schedules so that they would only be using my office the one day a week that I am out of the office. The landlord said that he would need to raise my rent since the office would be used more and there would be increased use of electricity. Is this legal?