Heat capacity of bricks in comparison with other materials. Brick: fireclay Vs ceramic. Comparative characteristics of the heat capacity of the main building materials

The choice of brick as a building material for the construction of walls of any premises, stoves or fireplaces is carried out on the basis of its properties associated with the ability to conduct, retain heat or cold, withstand exposure to high or low temperatures. The most important thermal characteristics are: thermal conductivity coefficient, heat capacity and frost resistance.

This name was previously understood only as elements of a standard size (250x120x65) made of fired clay. Now they produce and sell construction products made from any suitable components, having the shape of a regular parallelepiped and dimensions similar to the dimensions of the classic ceramic version.

Main varieties:

ordinary ceramic (building) - a classic red stone made of baked clay;
ceramic face - it has better external qualities, increased resistance to weathering, usually has a cavity inside;
solid silicate - light gray in color from a pressed sand-limestone mixture, inferior to ceramic in all respects (including heat engineering), except for strength;
silicate hollow - characterized by the presence of cavities that increase the ability of the walls to retain heat;
hyperpressed - from cement with pigments that give shades of natural material, aggregates of the mixture are limestone, marble chips, granules of blast-furnace slag;
fireclay - designed for laying stoves, fireplaces, chimneys;
clinker - differs from the usual one in that special types of clay and higher firing temperatures are used in its production;
warm ceramics (porous stone) - its characteristics far exceed the thermal conductivity of red brick, this is achieved due to the presence of air-filled pores in the clay mass, and the special design of the element, which has a large number of voids inside.

Coefficient of thermal conductivity

Thermal conductivity of a substance is a quantitative characteristic of its ability to conduct energy (heat). To compare it, different building materials use the coefficient of thermal conductivity - the amount of heat passing through a sample of unit length and area per unit of time at a unit temperature difference. Measured in Watt / meter * Kelvin (W / m * K).

When choosing a brick for the construction of walls, attention is paid to the indicator of thermal conductivity, since the minimum allowable thickness of the structure depends on it. The lower the value, the better the wall retains heat and the thinner it can be, the more economical is the consumption. The same parameter is taken into account when choosing the type of insulation, the size of its layer and technology.

Thermal conductivity depends on such factors:

material: the best indicators are for warm porous ceramics, the worst for hyper-pressed or silicate bricks;
density - the higher it is, the worse the heat is retained;
the presence of voids in products - cavities inside a slotted wall stone after installation fills with air, due to this, heat or coolness in the room is better preserved.

According to the coefficient of thermal conductivity in a dry state, the following types of masonry are distinguished:

highly effective - up to 0.20;
increased efficiency - from 0.21 to 0.24;
effective - from 0.25 to 0.36;
conditionally effective - from 0.37 to 0.46;
ordinary - more than 0.46.

When performing calculations, choosing facing and building bricks and insulation, it is taken into account that the ability of a wall to conduct heat depends not only on the properties of the material, but is also characterized by the coefficient of thermal conductivity of the solution and the thickness of the seams.

Heat capacity

This is the amount of heat (energy) that must be supplied to the body in order to raise its temperature by 1 Kelvin. The unit of measurement for this indicator is Joule per Kelvin (J / K). Specific heat is its ratio to the mass of a substance, the unit is Joule / kg * Kelvin (J / kg * K). For a brick, its value is from 700 to 1250 J / kg * K. More accurate numbers depend on the material from which a particular look is made.

The parameter affects the energy consumption required for heating the house: the lower the value, the faster the room heats up and the less money will be spent on payment. It is especially important if the residence in the house is not permanent, that is, it is periodically required to warm up the walls. The best option is silicate, but it is recommended to entrust the exact calculations to a specialist. It is necessary to take into account not only the heat capacity of the wall, but also its thickness, the heat capacity of the masonry mortar, the width of the joints, the features of the location of the room and the heat transfer coefficient.

Frost resistance

It is expressed in the number of freeze-thaw cycles that the element withstands without significant deterioration in properties. It is not the lower temperature level that matters, but the frequency of freezing of moisture in the pores. Water, turning into ice, expands, which contributes to the destruction of the stone.

Usually, frost resistance is indicated by an index, which contains a large Latin letter F and numbers. For example: the F50 marking indicates that this material begins to lose strength no earlier than after 50 freeze-thaw cycles. Possible brands of bricks for frost resistance (GOST 530-2012): F25; F35; F50; F100; F200; F300. Focusing on the indicated number, you need to understand that the number of cycles does not coincide with the number of seasons.

In some regions, abrupt temperature changes can occur many times during one winter. For load-bearing walls, it is recommended to use a minimum of F35, for cladding - from F75. Options with lower rates are only suitable for regions with mild climates.

Brick is widely used in private and professional construction. There are many varieties of this material. When choosing a building material for the construction or cladding of structures, its characteristics play an important role.

Characteristics affecting quality

The following properties of the product must be taken into account:

thermal conductivity- is the ability to transfer heat received from indoor air to the outside;
heat capacity- the amount of heat that allows one kilogram of building material to be heated by one degree Celsius;
density- determined by the presence of internal pores.

Below will be a description of the different types of products.

Ceramic

They are made from clay with the addition of certain substances. After manufacturing, they are heat treated in specialized ovens. The specific heat index is 0.7–0.9 kJ, and the density is about 1300–1500 kg / m 3.

Today, many manufacturers produce ceramic products. Such products differ not only in size, but also in their properties. For example, the thermal conductivity of a ceramic block is much lower than that of a conventional block. This is achieved due to the large number of voids inside. There is air in the voids, which does not conduct heat well.

Silicate

Silicate bricks are in high demand in construction, their popularity is due to their strength, availability and low cost. The specific heat index is 0.75 - 0.85 kJ, and its density is from 1000 to 2200 kg / m 3.

The product has good sound insulation properties. A wall made of silicate products will insulate the structure from the penetration of various kinds of noise. It is most often used for the construction of partitions. The product is widely used as an intermediate layer in masonry, which acts as a sound insulator.

Facing

Cladding blocks are widespread in the decoration of the external walls of buildings, not only because of their attractive appearance. The specific heat capacity of a brick is 900 J, and the density value is within 2700 kg / m 3. This value makes it possible for the material to resist well the penetration of moisture through the masonry.

Refractory

Refractory blocks can be divided into several types:

carborundum;
magnesite;
dinas;
fireclay.

Fire-resistant products are used for the construction of high-temperature furnaces. Their density is 2700 kg / m 3. The heat capacity of each type depends on the manufacturing conditions. Thus, the heat capacity index of a carborundum brick at a temperature of 1000 ° C is 780 J. Fireclay brick at a temperature of 100 ° C has an index of 840 J, and at 1500 ° C this parameter will increase to 1.25 kJ.

Influence of temperature conditions

The quality is greatly influenced by the temperature regime. So, with an average density of the material, the heat capacity may differ, depending on the ambient temperature.

From the above it follows that it is necessary to select a building material based on its characteristics and further scope of its application. So it will be possible to build a room that will meet the necessary requirements.

In construction, it is a very important characteristic. The thermal insulation characteristics of the walls of the building depend on it, and, accordingly, the possibility of a comfortable stay inside the building. Before proceeding to familiarize yourself with the thermal insulation characteristics of individual building materials, it is necessary to understand what the heat capacity is and how it is determined.

Heat capacity of building materials

Specific heat of materials

Heat capacity is a physical quantity that describes the ability of a material to accumulate temperature in itself from a heated environment. Quantitatively, the specific heat is equal to the amount of energy, measured in J, required to heat a body weighing 1 kg by 1 degree.
Below is a table of the specific heat capacity of the most common materials in construction.

type and volume of heated material (V);
the indicator of the specific heat capacity of this material (Court);
specific gravity (msp);
start and end temperatures of the material.

Heat capacity of building materials

The heat capacity of materials, the table for which is given above, depends on the density and thermal conductivity of the material.

And the coefficient of thermal conductivity, in turn, depends on the size and closure of the pores. A fine-porous material with a closed system of pores has a higher thermal insulation and, accordingly, a lower thermal conductivity than a large-porous one.

It is very easy to follow the example of the most common materials in construction. The figure below shows how the coefficient of thermal conductivity and the thickness of the material affect the heat-shielding qualities of external fences.

The figure shows that building materials with a lower density have a lower coefficient of thermal conductivity.
However, this is not always the case. For example, there are fibrous types of thermal insulation, for which the opposite pattern applies: the lower the density of the material, the higher the thermal conductivity coefficient.

Therefore, one cannot trust exclusively the indicator of the relative density of the material, but its other characteristics should also be taken into account.

Comparative characteristics of the heat capacity of the main building materials

In order to compare the heat capacity of the most popular building materials, such as wood, brick and concrete, it is necessary to calculate the heat capacity for each of them.

First of all, you need to decide on the specific gravity of wood, brick and concrete. It is known that 1 m3 of wood weighs 500 kg, brick - 1700 kg, and concrete - 2300 kg.
whether we take a wall, the thickness of which is 35 cm, then by simple calculations we get that the specific gravity of 1 square meter of wood will be 175 kg, brick - 595 kg, and concrete - 805 kg.
Next, we select the temperature value at which heat energy will accumulate in the walls. For example, this will happen on a hot summer day with an air temperature of 270C. For the selected conditions, we calculate the heat capacity of the selected materials:

Wall made of wood: С = SudhmudhΔT; Sder = 2.3x175x27 = 10867.5 (kJ);
Concrete wall: С = SudhmudhΔT; Sbet = 0.84x805x27 = 18257.4 (kJ);
Brick wall: С = SudhmudhΔT; Skirp = 0.88x595x27 = 14137.2 (kJ).

The calculations show that with the same wall thickness, concrete has the highest heat capacity, and wood has the lowest. What does this mean? This suggests that on a hot summer day, the maximum amount of heat will accumulate in a house made of concrete, and the least amount of wood.

This explains the fact that it is cool in a wooden house in hot weather, and warm in cold weather. Brick and concrete easily accumulate in themselves a fairly large amount of heat from the environment, but they just as easily part with it.

Heat capacity and thermal conductivity of materials

Thermal conductivity is a physical quantity of materials that describes the ability of temperature to penetrate from one wall surface to another.

To create comfortable conditions in the room, it is necessary that the walls have a high heat capacity and a low coefficient of thermal conductivity. In this case, the walls of the house will be able to accumulate the thermal energy of the environment, but at the same time prevent the penetration of thermal radiation into the room.

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TYPES OF BRICKS

In order to answer the question: "how to build a warm brick house?", You need to find out which type is best to use. Since the modern market offers a huge selection of this building material. Let's consider the most common types.

SILICATE

The most popular and widespread in construction in Russia are silicate bricks. This type is made by mixing lime and sand. This material was highly prevalent due to its wide range of applications in everyday life, and also due to the fact that the price for it is not quite high.

However, if we turn to the physical values of this product, then not everything is so smooth.

Consider a double silicate brick M 150. The M 150 grade speaks of high strength, so that it even comes close to natural stone. The dimensions are 250x120x138 mm.

The thermal conductivity of this type is on average 0.7 W / (m oC). This is a fairly low figure compared to other materials. Therefore, warm walls of this type of brick most likely will not work.

An important advantage of such a brick in comparison with ceramic is its soundproofing properties, which have a very favorable effect on the construction of walls enclosing apartments or dividing rooms.

CERAMIC

The second place in popularity of building bricks is reasonably given to ceramic ones. For their production, various mixtures of clays are fired.

This type is divided into two types:

Building,
Facing.

Building bricks are used for the construction of foundations, walls of houses, stoves, etc., and facing bricks for finishing buildings and premises. Such material is more suitable for DIY construction, since it is much lighter than silicate.

The thermal conductivity of the ceramic block is determined by the thermal conductivity coefficient and is numerically equal to:

Corpulent - 0.6 W / m * oC;
Hollow brick - 0.5 W / m * oC;
Slotted - 0.38 W / m * оС.

The average heat capacity of a brick is about 0.92 kJ.

WARM CERAMICS

Warm brick is a relatively new building material. Basically, it is an improvement on the conventional ceramic block.

This type of product is much larger than usual, its dimensions can be 14 times larger than standard ones. But this does not greatly affect the overall weight of the structure.

Thermal insulation properties are almost 2 times better than ceramic bricks. The thermal conductivity is approximately 0.15 W / m * oC.

The warm ceramic block has many small voids in the form of vertical channels. And as mentioned above, the more air in the material, the higher the thermal insulation properties of this construction material. Heat loss can occur mainly on internal partitions or in the seams of the masonry.

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How is the specific heat determined?

Specific heat is determined in the course of laboratory research. This indicator depends entirely on what kind of temperature the material has. The heat capacity parameter is necessary so that in the end it is possible to understand how heat-resistant the outer walls of the heated building will be. After all, the walls of structures must be built from materials, the specific heat capacity of which tends to the maximum.

In addition, this indicator is necessary for accurate calculations in the process of heating various kinds of solutions, as well as in a situation when work is carried out at sub-zero temperatures.

One cannot but say about solid bricks. It is this material that boasts a high thermal conductivity. Therefore, in order to save money, a hollow brick will come in handy.

Types and nuances of brick blocks

In order to eventually build a sufficiently warm brick building, you first need to understand what kind of this material is most suitable for this. Currently, a huge assortment of bricks is presented in the markets and in construction stores. So which one to give preference to?

On the territory of our country, silicate bricks are very popular with buyers. This material is obtained by mixing lime with sand.

The demand for silicate bricks is due to the fact that it is often used in everyday life and has a fairly reasonable price. If we touch on the issue of physical quantities, then this material, of course, is in many ways inferior to its counterparts. Due to the low thermal conductivity, it is unlikely that it will be possible to build a truly warm house from silicate bricks.

But, of course, like any material, sand-lime brick has its advantages. For example, it has a high sound insulation rate. It is for this reason that it is very often used for the construction of partitions and walls in city apartments.

The second place of honor in the ranking of demand is occupied by ceramic bricks. It is obtained from stirring various types of clays, which are subsequently fired. This material is used for the direct construction of buildings and their cladding. The building type is used for the construction of buildings, and the facing type is used for their decoration. It should be said about the fact that a brick based on ceramics is very light in weight, so it is an ideal material for independent construction work.

Warm brick is a novelty in the construction market. It is nothing more than an advanced ceramic block. This type in size can exceed the standard by about fourteen times. But this does not in any way affect the total mass of the building.

If we compare this material with ceramic bricks, then the first option in terms of thermal insulation is twice as good. A warm block has a large number of small voids that look like channels located in a vertical plane.

And as you know, the more air space is present in the material, the higher the thermal conductivity. Heat loss in this situation occurs in most cases on partitions inside or in the seams of the masonry.

Thermal conductivity of bricks and foam blocks: features

This calculation is necessary in order to be able to reflect the properties of a material, which are expressed in terms of the ratio of the density of the material to its ability to conduct heat.

Thermal uniformity is an indicator that is equal to the inverse ratio of the heat flux passing through the wall structure to the amount of heat passing through the conditional barrier and equal to the total wall area.

In fact, both the one and the other version of the calculation is a rather complicated process. It is for this reason that if you do not have experience in this matter, then it is best to seek help from a specialist who can accurately make all the calculations.

So, summing up, we can say that physical quantities are very important when choosing a building material. As you can see, different types of bricks, depending on their properties, have a number of advantages and disadvantages. For example, if you want to build a really warm building, then it is best for you to give preference to a warm type of brick, in which the thermal insulation indicator is at the maximum level. If you are limited in money, then the best option for you would be to buy a silicate brick, which, although minimally retains heat, but perfectly removes the room from extraneous sounds.

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Definition and formula of heat capacity

Each substance, to one degree or another, is capable of absorbing, storing and retaining thermal energy. To describe this process, the concept of heat capacity was introduced, which is the property of a material to absorb thermal energy when the surrounding air is heated.

To heat any material of mass m from the temperature t start to the temperature t end, you will need to spend a certain amount of thermal energy Q, which will be proportional to the mass and the temperature difference ΔT (t end -t start). Therefore, the heat capacity formula will look like this: Q = c * m * ΔT, where c is the heat capacity coefficient (specific value). It can be calculated using the formula: с = Q / (m * ΔТ) (kcal / (kg * ° C)).

Conditionally assuming that the mass of a substance is 1 kg, and ΔТ = 1 ° C, we can obtain that c = Q (kcal). This means that the specific heat is equal to the amount of thermal energy that is consumed to heat a material weighing 1 kg per 1 ° C.

Using heat capacity in practice

Building materials with high heat capacity are used for the construction of heat-resistant structures. This is very important for private houses where people live permanently. The fact is that such structures allow you to store (accumulate) heat, due to which a comfortable temperature is maintained in the house for a long time. First, the heater heats up the air and walls, after which the walls themselves warm up the air. This saves money on heating and makes your stay more comfortable. For a house in which people live periodically (for example, on weekends), the high heat capacity of the building material will have the opposite effect: it will be quite difficult to heat such a building quickly.

The values of the heat capacity of building materials are given in SNiP II-3-79. Below is a table of the main building materials and the values of their specific heat capacity.

Table 1

Speaking about the heat capacity, it should be noted that it is recommended to build heating stoves from bricks, since the value of its heat capacity is quite high. This allows the oven to be used as a kind of heat accumulator. Heat accumulators in heating systems (especially in hot water heating systems) are used more and more every year. Such devices are convenient in that it is enough to heat them once well with an intensive furnace of a solid fuel boiler, after which they will heat your house for a whole day and even more. This will significantly save your budget.

Heat capacity of building materials

What should be the walls of a private house in order to comply with building codes? The answer to this question has several nuances. To deal with them, an example of the heat capacity of the 2 most popular building materials will be given: concrete and wood. The heat capacity of concrete is 0.84 kJ / (kg * ° C), and of wood - 2.3 kJ / (kg * ° C).

At first glance, one might think that wood is a more heat-consuming material than concrete. This is true, because wood contains almost 3 times more heat energy than concrete. To heat 1 kg of wood, you need to spend 2.3 kJ of thermal energy, but when it cools, it will also give 2.3 kJ into space. At the same time, 1 kg of concrete structure is capable of accumulating and, accordingly, giving only 0.84 kJ.

But don't jump to conclusions. For example, you need to find out what heat capacity 1 m 2 of a concrete and wooden wall with a thickness of 30 cm will have. To do this, you first need to calculate the weight of such structures. 1 m 2 of this concrete wall will weigh: 2300 kg / m 3 * 0.3 m 3 = 690 kg. 1 m 2 of a wooden wall will weigh: 500 kg / m 3 * 0.3 m 3 = 150 kg.

for a concrete wall: 0.84 * 690 * 22 = 12751 kJ;
for a wooden structure: 2.3 * 150 * 22 = 7590 kJ.

From the result obtained, we can conclude that 1 m 3 of wood will accumulate heat almost 2 times less than concrete. An intermediate material in terms of heat capacity between concrete and wood is brickwork, in a unit volume of which, under the same conditions, 9199 kJ of thermal energy will be contained. At the same time, aerated concrete, as a building material, will contain only 3326 kJ, which will be significantly less than wood. However, in practice, the thickness of a wooden structure can be 15-20 cm, when aerated concrete can be laid in several rows, significantly increasing the specific heat capacity of the wall.

The use of various materials in construction

Wood

For a comfortable stay in a house, it is very important that the material has a high heat capacity and low thermal conductivity.

In this regard, wood is the best option for houses not only permanent, but also temporary. A wooden building that has not been heated for a long time will respond well to changes in air temperature. Therefore, such a building will be heated quickly and efficiently.

Conifers are mainly used in construction: pine, spruce, cedar, fir. In terms of value for money, pine is the best option. Whatever you choose to design a wooden house, you need to consider the following rule: the thicker the walls, the better. However, here you also need to take into account your financial capabilities, since with an increase in the thickness of the timber, its cost will increase significantly.

Brick

This building material has always been a symbol of stability and strength. The brick has good strength and resistance to negative environmental influences. However, if we take into account the fact that brick walls are mainly constructed with a thickness of 51 and 64 cm, then in order to create good thermal insulation, they additionally need to be covered with a layer of thermal insulation material. Brick houses are great for permanent living. When heated, such structures are capable of releasing the heat accumulated in them into space for a long time.

When choosing a material for building a house, one should take into account not only its thermal conductivity and heat capacity, but also how often people will live in such a house. The right choice will keep your home cozy and comfortable throughout the year.

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What it is?

The physical characteristic of heat capacity is inherent in any substance. It denotes the amount of heat that a physical body absorbs when heated by 1 degree Celsius or Kelvin. It is a mistake to identify the general concept with the specific one, since the latter implies the temperature required to heat one kilogram of a substance. It seems possible to accurately determine its number only in laboratory conditions. The indicator is necessary to determine the thermal stability of the walls of the building and in the case when construction work is carried out at subzero temperatures. For the construction of private and multi-storey residential buildings and premises, materials with high thermal conductivity are used, since they accumulate heat and maintain the temperature in the room.

The advantage of brick buildings is that they save on heating costs.

In fact, when choosing building materials for the construction of a particular building, it is imperative to pay attention to their physical values. And the specific heat capacity of a brick in this issue is no exception. But, of course, in order to understand what effect a physical quantity has on a brick, you must first understand what it actually is.

What indicators should you pay attention to when choosing a brick?

Specific heat is an indicator of how much heat is required to heat 1 kg of a substance per 1 ° C.
Also of great importance for bricks is the thermal conductivity index. It indicates how much the material can transfer heat both from the inside and from the outside at different temperature conditions.
What the heat transfer rate will be depends entirely on what kind of material you purchase for the construction of the building. In order to find out the final figure for a wall with multiple layers, it is necessary to proceed from the thermal conductivity value for each individual layer.

How is the specific heat determined?

Silicate brick is very popular. It is obtained by mixing lime with sand.

In addition, this indicator is necessary for accurate calculations in the process of heating various kinds of solutions, as well as in a situation when work is carried out at sub-zero temperatures.

One cannot but say about solid bricks. It is this material that boasts a high thermal conductivity. Therefore, in order to save money, a hollow brick will come in handy.

Types and nuances of brick blocks

On the territory of our country, silicate bricks are very popular with buyers. This material is obtained by mixing lime with sand.

Thermal conductivity of bricks and foam blocks: features

This calculation is necessary in order to be able to reflect the properties of a material, which are expressed in terms of the ratio of the density of the material to its ability to conduct heat.

So, summing up, we can say that physical quantities are very important when choosing a building material. As you can see, different, depending on their properties, have a number of advantages and disadvantages. For example, if you want to build a really warm building, then it is best for you to give preference to a warm type of brick, in which the thermal insulation indicator is at the maximum level. If you are limited in money, then the best option for you would be to buy a silicate brick, which, although minimally retains heat, but perfectly removes the room from extraneous sounds.

In construction, a very important characteristic is the heat capacity of building materials. The thermal insulation characteristics of the walls of the building depend on it, and, accordingly, the possibility of a comfortable stay inside the building. Before proceeding to familiarize yourself with the thermal insulation characteristics of individual building materials, it is necessary to understand what the heat capacity is and how it is determined.

Specific heat of materials

type and volume of heated material (V);
the indicator of the specific heat capacity of this material (Court);
specific gravity (msp);
start and end temperatures of the material.

Heat capacity of building materials

The heat capacity of materials, the table for which is given above, depends on the density and thermal conductivity of the material.

Therefore, one cannot trust exclusively the indicator of the relative density of the material, but its other characteristics should also be taken into account.

Comparative characteristics of the heat capacity of the main building materials

In order to compare the heat capacity of the most popular building materials, such as wood, brick and concrete, it is necessary to calculate the heat capacity for each of them.

First of all, you need to decide on the specific gravity of wood, brick and concrete. It is known that 1 m3 of wood weighs 500 kg, brick - 1700 kg, and concrete - 2300 kg. If we take a wall, the thickness of which is 35 cm, then by simple calculations we get that the specific gravity of 1 square meter of wood will be 175 kg, brick - 595 kg, and concrete - 805 kg.
Next, we select the temperature value at which heat energy will accumulate in the walls. For example, this will happen on a hot summer day with an air temperature of 270C. For the selected conditions, we calculate the heat capacity of the selected materials:

Wall made of wood: С = SudhmudhΔT; Sder = 2.3x175x27 = 10867.5 (kJ);
Concrete wall: С = SudhmudhΔT; Sbet = 0.84x805x27 = 18257.4 (kJ);
Brick wall: С = SudhmudhΔT; Skirp = 0.88x595x27 = 14137.2 (kJ).

Heat capacity and thermal conductivity of materials

Thermal conductivity is a physical quantity of materials that describes the ability of temperature to penetrate from one wall surface to another.