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Oxygen Not Included Wiki
This article has not been revised for the current version (U40-494396). It was last updated for an unknown version. It may contain inaccuracies.
This article has not been revised for the current version (U40-494396). It was last updated for an unknown version. It may contain inaccuracies.

Heat transfer is an important mechanic in the game, but one that is not well understood by most players. Every object in contact with another object of a different temperature will either transfer some heat to it or accept some of its heat. Amount of heat transferred depends on temperature difference between the objects, heat conductivity of materials that make up the objects in contact, but also heat capacity of both objects, and thickness of the more isolated object.

Thermal Conductivity[]

Thermal conductivity is a material property measured in (DTU/m)/K, that is: DTUs per meter per Kelvin.

Heat transfer is multiplied by the minimum of thermal conductivities of both objects (except for non-insulated pipes and buildings). That is, Liquid Chlorine traveling through a Granite Insulated Liquid Pipe will not transfer heat with the pipe much faster than if the pipe was made of Igneous Rock, as conductivity of Liquid Chlorine is well below that of Granite. For more detailed formula see Thermal Conductivity.

Since all Raw Minerals have higher heat conductivity than all commonly piped Resources, using Wolframite or Granite over Sandstone will not result in faster heat transfer from the piped resources to the surroundings of the pipe. One might think that pipes with higher conductivites would exchange heat better between pipe segments, but as of AU-221295, no heat is exchanged between pipe segments; heat is only exchanged between the contents, the individual pipe segment the contents are in, and the contents of the tile the pipe is in.

The Raw Mineral with highest thermal conductivity is Granite. The Metal Ore with the highest thermal conductivity is Aluminum Ore.

Heat Capacity[]

Heat capacity -- or specific heat -- is a material property measured in (DTU/g)/K, that is: DTUs per gram per Kelvin.

Heat capacity determines how much heat energy must be transferred for the object to change temperature. For example, if one object has twice the heat capacity of another, but is otherwise identical, it will take twice as much heat energy to heat it up by 1 Kelvin.

Objects with high heat capacity may take a long time to heat up or cool down, but the actual amount of energy transferred is higher than for objects with low capacities.

The Raw Mineral with the highest heat capacity is Igneous Rock. The Metal Ore with the highest heat capacity is Aluminum Ore.

Insulation Thickness[]

A Duplicant can change their own heat transfer thickness by wearing clothing created in Textile Factory. Doubling thickness halves heat transfer (and vice versa).

Insulated Tile, Insulated Gas Pipe, and Insulated Liquid Pipe use a mechanic similar to thickness, where their heat transfers are divided by 20.

Surface area[]

Surface area within a tile seems to have a negligible - if any - effect on heat transfer. For example, a small puddle transfers heat just as fast as a whole tile full of same liquid.

Multiple tile buildings transfer heat on every single one of their tiles.

Fluid Ports[]

Heat transfer does not occur for fluids at fluid ports. The entry and exit of fluids at the ports appear to override scripts for heat transfer. This is true as of version EX1-456169.


  • Aluminum Ore is not necessary for most heat transfer applications, as in most cases it is barely more effective at it than Wolframite
  • Use Aluminum Ore and Igneous Rock for heat transfer with liquids and gases
  • Small puddles of cold Water can cool down Duplicants who stand in them just as fast as full immersion
  • Small amounts of liquid will change phase faster than large amounts. Boiling a quantity of water, or freezing ice out of salt or pure water will take the same amount of time to convert the total whether it is done all at once, or using a slow drip. The slow drip, however, will provide a steady small supply of clean steam or ice, while the wait will be significantly longer if the volume is converted at once.