Q. What is one to do with the sensors (when staying Shabbos in a hotel) in the room and at the balcony door?

A. If the motion sensors (they could be standing separately or be integrated into the thermostat) are to avoid the air conditioner/heater from going on or for turning off lights when the guest is out of his room, and would therefore turn them back on when he returns, they would have to be disabled before the onset of Shabbos or Yom Tov. This should preferably be done by the staff or can be usually achieved by temporarily taping a piece of aluminum foil or even just paper on the front of the sensor (contributed by Sinai Security Services.) The same will apply to the balcony door if one wants to open or close it during Shabbos. Other sensors such as smoke alarms or security devices should not be tempered with and are permitted

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a