The thermal conductivity (k-value) is the ability of a material to conduct heat; hence, the lower the k-value, the better the material is for insulation. Expanded polystyrene (EPS) has a k-value of around 0.033 W/(m⋅K).

The effect of temperature on thermal conductivity is different for metals and nonmetals. In metals, heat conductivity is primarily due to free electrons. In alloys the change in electrical conductivity is usually smaller and thus thermal conductivity increases with temperature, often proportionally to temperature.

Thus, the thermal conductivity of a gas increases with increase in temperature. In liquids, as we have seen earlier, thermal conductivity depends predominantly on molecular diffusion effect. As temperature increases, the randomness of molecular movements increases. This obstructs transport of heat through liquids.

To indicate to what extent a material is thermally insulating, the term thermal transmittance or U-value (formerly known as K-value) is used in the construction industry. The lower the U-value, the higher the heat resistance of a material, meaning the better the insulation.

Write the equilibrium constant expression for the reaction. Substitute the known K value and the final concentrations to solve for x. Calculate the final concentration of each substance in the reaction mixture. Check your answers by substituting these values into the equilibrium constant expression to obtain K.

U Value is the reciprocal of all resistances of the materials found in the building element. To calculate the U-Value of the building element the R-Value of all the different components that make up that element will be considered. U-Value (of building element) = 1 / (Rso + Rsi + R1 + R2 …)

The best insulating materials have a U-value of close to zero – the lower the better. Building regulations currently stipulate that for a new building, the elements must have maximum U-values as follows: Wall – 0.3 W/m2k. Roof – 0.15 W/m2k.

England. * A U-value of 0.55 W/m²·K is used for cavity insulation and 0.30 W/m²·K for internal or external wall insulation.

A U-value is a measure of thermal transmittance, or the amount of heat energy that moves through a floor, wall or roof, from the warm (heated) side to the cold side. It is the number of Watts per square metre of the construction, per degree of temperature difference between one side and the other (W/m2K).

CEC Director of Customer & Energy Services U-Value is a thermal transmittance, or the heat loss through a structural element. Most notably we see R-Value used as a rating on insulation, and U-Value (or sometimes U-Factor) represented as a rating on windows and doors.

The lower the U-value of an element of a building’s fabric, the more slowly heat is able to transmit through it, and so the better it performs as an insulator. Very broadly, the better (i.e. lower) the U-value of a building’s fabric, the less energy is required to maintain comfortable conditions inside the building.

Diamond – 2000 – 2200 W/m•K. Diamond is the leading thermally conductive material and has conductivity values measured 5x’s higher than copper, the most manufactured metal in the United States. Diamond atoms are composed of a simple carbon backbone that is an ideal molecular structure for effective heat transfer.

As you can see, out of the more common metals, copper and aluminum have the highest thermal conductivity while steel and bronze have the lowest. Heat conductivity is a very important property when deciding which metal to use for a specific application.

Aluminum is probably the best low cost stuff. Its light weight and easy to work with. It dissipates heat well so any air going by will cool it down. Remember heat transfers three ways; conduction, convection and radiation.

Which Metal Conducts Electricity The Best?

The most effective electrical conductors are:

• Silver.
• Gold.
• Copper.
• Aluminum.
• Mercury.
• Steel.
• Iron.
• Seawater.

Solution : Bismuth and tungsten are poor conductors of electricity.

Though silver is a very good conductor of electricity but still that is not used in electric wiring primarily due to its cost. It’s very expensive compared to the widely used wiring material copper. Another reason for not using silver is that , it oxidizes easily and tarnishes when it comes in contact with air.

The most electrically conductive element is silver, followed by copper and gold. Silver is the best conductor because its electrons are freer to move than those of the other elements, thereby making it more suitable for the conduction of electricity and heat than any other element.

Silver is the best conductor of both heat & electricity among metals with a thermal conduction value of about 430 W/(mK). ❖ Gold & copper both come respectably close to silver. ❖ Silver also has the highest thermal conductivity of any element & the highest light reflectance.