Thermal Insulation in Buildings Useful Information ...
Before giving general information about thermal insulation and material properties in buildings, it is useful to take a look at the ways in which heat moves, is lost or gained.
Heat is a type of energy and manifests itself in the transfer of energy. For example, a substance with very high temperature is also a substance with very high energy. And in nature, heat movement is in the direction of cold regions from hot regions. The transfer of heat occurs in three different ways: Conduction, radiation, and convection . (conduction - radiation - convection) Autodesk Sustainability Workshop in terms of visualizing this issue in the video on the right You can watch the presentation prepared by.
How does this heat dissipation occur in buildings, to explain briefly with examples;
The spread of heat in the form of transmission occurs by touching with contact. In the buildings, the balcony flooring, for example, that comes out as a console, is also the continuation of the flooring inside the building. The floor elements (concrete and iron reinforcement) remaining in the interior of the house, which is warmed in winter, heat loss occurs with heat conduction towards the balcony floor at the same height / elevation. In another example, when thermal insulation is not made on the basis of the building, the heat will be transmitted from the upper columns to the ground by the columns contacting the ground through the upper columns.
Especially materials with high thermal conductivity, such as concrete, steel reinforcement, from building elements allow heat transfer, and in cases where there is no required insulation, such internal structural elements in contact with the external environment may cause heat losses in winter and unwanted heat gains in summer.
Radiation is the propagation of heat by rays. The best example of this is the increase in temperature values of indoor spaces that come into contact with sunlight in buildings. In cold climates in the winter months, making use of the sun's rays, and in the hot climates in the summer, the sun's rays are avoided because unwanted heat is generated.
As shown in the picture to the right, when a house design has the proper location and orientation, it is an ideal method to make use of the rays coming from the Sun through radiance. Solutions such as cantilever protrusion on the windows, awning, and leaving the roof width longer do not allow the heat to enter the building directly with the radiation in hot climates.
Convection is the movement of particles of heat in a matter of displacement. In other words, it is the transfer of heat from one place to another by the moving gas or liquid. Heat movement occurs from hot air to cold air as mentioned before. In terms of buildings, heat losses or unwanted excess heat gain occur in places where air passages cannot be prevented such as window and door connection points. The hot air emitted by convection from a source (this may be a heater, stove, heater, etc.) moves towards the cold air currents and if it cannot be controlled, it spreads to the environment from the areas where there is no heat insulation in the buildings and where there are air gaps.
If you can prevent heat losses in buildings by taking these three factors into account, you may not need to heat your house, which you have heated once, over and over again.
Thermal Insulation Materials:
Heat insulating material, conductivity values (λ = (W / mK) should be very low. In buildings, such as exterior walls are opaque elements, floor, ceiling, the extent of value are subjected to the heat losses of elements such as roof (W / m2K) thermal we call We determine with the value of thermal transmittance . For this, we need to know the concepts in the formula below:
U = λ
λ: material conductivity coefficient used (W / mK)
d: thickness used (m)
* K: Kelvin - Unit of temperature
* W: Watt - Power unit
Heat gain / loss in buildings through conduction
Buildings are heated by solar radiation.
By means of convection, heat moves from hot regions to cold regions.
Major building materials and conductivity values (λ)
In the table below, for example , the thicknesses of the building materials with a conductivity coefficient to achieve the U value of 0.13 W / m2K (according to Passive House standards, external wall thermal permeability value (1)) are given together. In this way , the relationship between conductivity coefficient (λ) , U value and material thickness can be understood more easily.
The photo is of the middle house in Hereford, England, after the restoration to the Passivhaus standard. In the photo taken with a thermal camera on the right, the temperature indicator decreases in the order of red - yellow - green and blue. Accordingly, it can be clearly determined that the middle house emits relatively little heat to the outside compared to the adjacent houses. http://www.superhomes.org.uk/resources/insulating-a-solid-wall/
The higher the conductivity coefficient values of a material, the more our heat loss will be. If we cannot change the material, it may be necessary to increase the thickness of the material considerably to provide the desired insulation as shown in the table above.
If more than one material is used (for example, overlapping siding), each new material is added to the formula for the U value calculation as follows:
U = λ1 + ... + λn
Importance of Application
Another very important factor for the realization of the thermal insulation and materials mentioned here is the application / workmanship part in buildings. No matter how high-quality the material we use and has low heat permeability, we cannot get the expected efficiency unless the application is done carefully.
Note : If you are considering thermal insulation / mantle in your building or want to get more detailed information, you can consult many companies that apply thermal insulation / sheathing.