Aside from asking my tenant to please close windows when they are not in the unit in the winter months what can I do? The heat in our building is natural gas and we (landlords) pay it. we have seen a increase in our bill due to the tenant leaving the thermostat up and windows open. We have asked repeatedly for them to close their windows, not just one window but multiple windows. Even in the weeks when we had negative temps in Jan. the windows were left open over night and throughout the day. As a landlord what other options do I have?