Sigil of Temperature Control

This item is a palm sized flat disk that can be set into an item,  hung on a wall, placed on a surface, or worn. When activated, the user thinks of a desired temperature and the magic of the sigil will will change the air temperature of an enclosed area of a maximum of a 30 foot cube. The air outside of the cube will either slowly regulate to be slightly warmer or colder than the air around it. Outside of Enclosed area's this range is limited to 15 feet. In an enclosed space, it is limited to the boundary of the space. Should it be opened, some of the temperature will slowly radiate out to spread beyond it for an extended period of time.

The spell of the sigil will remain active until either dispelled, altered by a new command, or it is deactivated by a user.

While it is incapable of causing direct damage, it can create an area of heat or cold capable of leading to exhaustion in prolonged exposure of 3 uninterrupted hours.

Is sometimes a common item among nobility, well to do merchants, and higher level casters that either learn or reinvent their on variation of it, it is often used for food preservation and creating a comfortable space within one's dwelling, and may go by various names.