Materials that reduce heat, or thermal insulators, are those with a low thermal conductivity. This means that they do not easily transfer heat from one part of the material to another. Here are some examples of materials with low thermal conductivity:

- Air: Air is a very good thermal insulator, which is why it is often used in double-paned windows and other insulation applications.

- Fiberglass: Fiberglass is a type of glass wool that is made up of thin, glass fibers. It is commonly used as insulation in buildings and appliances.

- Cellulose: Cellulose is a natural fiber that is made up of plant cell walls. It is often used as insulation in buildings and furniture.

- Polystyrene: Polystyrene is a synthetic plastic that is often used as insulation in buildings and packaging.

- Polyethylene: Polyethylene is another synthetic plastic that is often used as insulation in buildings and packaging.

- Rubber: Rubber is a natural or synthetic material that is often used as insulation in tires, hoses, and other products.

- Wood: Wood is a natural material that is often used as insulation in buildings and furniture.

The thickness and density of a material also affect its thermal conductivity. The thicker a material is, the more effective it is at insulating heat. The denser a material is, the more heat it can store.

In addition to these materials, there are also a number of other factors that can affect heat transfer, such as the temperature difference between the two surfaces, the surface area of the material, and the amount of time that the material is exposed to the heat source.