I want to model the Ice Box Challenge project (https://iceboxchallenge.com/) in EnergyPlus. The project features two empty rooms, one built based on local building codes and one based on Passive House standards. A one-ton block of ice is left in the middle of each room in the sun for 18 days. The amount of ice left in the rooms would help measure and compare the energy performance of a Passive House and a code-based envelope design.

For my question in EnergyPlus, it basically means I need to model a block of ice naturally melting in the middle of an empty room without any air conditioning or other heat sources present (the only heat transfer is through the walls with the outdoor air). Do you have any suggestions on how to approach this model? Or do you have any recommendations on how to model an HVAC system that would imitate the same behavior as melting ice?