Comfort in a constructed building depends on manyfactors. The microclimate in the room, for example, is affected by the coefficient of thermal conductivity of building materials. The table of these parameters will allow choosing the most suitable material for creating comfortable conditions in the house.
Due to correctly calculated calculation, infurther it is possible to save on heating of the house. Even if at the initial stage of construction to produce from more expensive materials, in due course they will fully pay off. In the case of materials that use heat-intensive materials for construction, it is necessary to carry out additional work on the insulation of the house. It is carried out both outside and inside buildings. But in any case it bears additional costs and time and money.
The concept of heat conduction
In physics, heat conductivity is understood as the transferHeat from more heated particles to less heated as a result of their direct contact. By particles here means atoms, molecules or free electrons.
In simple terms, the thermal conductivityIs the ability of a particular material to pass heat. It is worth noting that the heat transfer will continue until a temperature equilibrium is reached.
The loss of heat for different parts of buildings is different. If we talk about a private house, before heat loss will occur:
- through the roof - up to 30 percent;
- through chimneys, natural ventilation and so on - up to 25 percent;
- through walls - up to 15 percent;
- through sex - up to 15 percent;
- through windows - up to 15 percent;
- through contiguity - up to 15 percent.
For multi-family houses, these indicators are slightly different. Losses through the roof and walls will be lower. But through the windows will leave much more heat.
Coefficient of thermal conductivity
The thermal conductivity of the material is characterizeda time interval during which temperature values reach equilibrium. This is evidenced by the coefficient of thermal conductivity of building materials. The table shows that there is an inverse relationship between time and heat conduction in this case. That is, the less time it takes to transfer heat, the greater the value of thermal conductivity.
In practice, this means that the building will cool downfaster, if there is more coefficient of thermal conductivity of building materials. The table of values in this case is simply necessary. It shows how much heat the building will lose through a unit of area.
Let's consider an example. The brick has a thermal conductivity of 0.67 kW / (m2* K) (the value is taken from the corresponding tables).This means that 1 square meter of a surface with a thickness of one meter will pass 0.67 watts of heat. This value will be provided that the difference in the temperatures of the two surfaces is one degree. With an increase in the difference to 10 degrees, heat loss is already 6.7 watts. Under such conditions, if the wall thickness is reduced by a factor of 10 (i.e., up to 10 centimeters), the heat loss is 67 watts.
The change in thermal conductivity
The coefficients of thermal conductivity of building materials are influenced by various factors. The main parameters are:
- Плотность материала.If the density is higher, then the particles inside the material interact with each other more strongly. Accordingly, the transfer of heat energy and the establishment of a temperature equilibrium will occur faster. Consequently, the higher the density, the better the material passes the heat.
- Porosity.Here the opposite situation is observed. Materials with large porosity have a heterogeneous structure. Most of the volume is occupied by air, which has a minimum coefficient. Transmission of thermal energy through small pores is difficult. Accordingly, the thermal conductivity will increase.
- Humidity. With increasing humidity, the thermal conductivity of building materials will also be higher.
The table above shows the exact values for some materials.
Comparison of the thermal conductivity of materials in practice
It is difficult for an inexperienced person to understand what the coefficients of thermal conductivity of building materials are. SNiP gives the exact values that are contained in the table.
To better understand the difference of these values,consider an example. Let's compare several different materials. The amount of heat transmitted by them can be made the same if the thickness of the wall is changed. So, a wall of concrete panels (with a heater) with a thickness of 14 centimeters will correspond to a wooden wall with a thickness of 15 centimeters. The same value of thermal conductivity will be typical for expanded clay concrete 30 cm thick, hollow bricks 51 cm thick. If you take a brick, then to get this thermal conductivity you need to build a wall with a thickness of 64 centimeters.
State Standards
The coefficient of thermal conductivitybuilding materials (table) SNiP and other documents. So, to compile the table that was placed above, such documents as SNiP 11-3-79, SNiP 23-02-2003, SP 50.13330.2012 were used.
If the standards do not give a coefficient valueheat conductivity of the necessary building material, it can be obtained from the manufacturer. Look at the packaging, if this parameter is not specified there. Another way out is to go to the official website of the manufacturer.
As can be seen, the calculation of heat loss plays an important rolein the process of building construction. This will determine the level of comfort in the room. Therefore, even at the design stage, it is necessary to approach the issue of choice of building materials with utmost care. This will reduce the cost of financial resources for heating. The thickness of the selected material for each region will differ. And it will depend on the climatic conditions of the zone of residence.
