I've eat 1 -2 days old sandwiches of peanut butter and a lot of other things (ham, chiken, chocolate, cheese...) without problems ;) 15-20 hours is not too much. I think, only raw eeg could be unsafe.
Part of the Smart grid glossary: The International Telecommunication Union (ITU) is an agency of the United Nations (UN) whose purpose is to coordinate telecommunication operations and services throughout the world. Originally founded in 1865, as the International Telegraph Union, the ITU is the oldest existing international organization.
An RTU is a type of AHU. AHU stands for Air Handling Unit and the acronym RTU means Rooftop Unit. The Roof Top Unit is an outdoor AHU. As RTUs are mounted on the roof, there is no concern about creating extra space indoors for it as would be the case for the other types of AHU.