Thermal insulation of buildings | constguide.com

Thermal insulation of buildings

Thermal insulation products for buildings have evolved dramatically with technological advancements, laws have acted as a catalyst for development, and compliance with government carbon reduction targets, driven by advanced programmes such as the Sustainable Homes Act, is a requirement under certain building codes.

Color, surface finish, texture, basic composition, and, most significantly, performance vary widely among thermal insulation solutions for buildings. Insulation material specification is a scientific decision, but successful specifications require an awareness of not just the determinant of high performance, but also the surrounding elements that can affect performance.

The importance of thermal insulation for buildings

The purpose of building thermal insulation is to keep heat inside during the winter and outside during the summer. Buildings account for 18 percent of worldwide energy usage. The following are the three primary methods for insulating an apartment building:

• Rock wool insulation panels for external cladding

• Roofing tiles that are insulated

• instead of a ventilation chimney, a solar chimney is used.

The first two solutions can give thermal insulation of 1 to 1.6 perm, but the solar chimney creates more than 6 layers of thermal insulation, meaning the subfloor is almost as cold as the ground outside; nonetheless, there are concerns regarding leaks and maintenance work on the system.

To address these issues and achieve adequate thermal insulation, a pilot project was implemented that included the integration of the following three methods: external cladding made of rock wool panels, roofing tiles with thermal insulation properties, and a chimney that uses solar energy stoves at the top instead of natural ventilation smoke from stoves Firewood, this last method is not ideal.

Both rockwool and tile external cladding with thermal insulation properties provide good protection against extreme cold (below 0°C/32°F), and all three solutions have been tested for their ability to protect the building from extreme cold. These are the two methods: The insulation in the room breaks when the temperature dips below 5°C/41°F, exposing the building to heat loss.

The only way to avoid this requirement is to install an insulated exterior cladding made of rock wool panels and use a chimney that uses solar stoves on top instead of the natural ventilation smoke from wood stoves.

Indoor heat radiation

Heat exchange occurs when an object's temperature is higher than the temperature of the surrounding surfaces. Radiant heat can only move in straight lines, so if you put a solid item between points A and B, the radiant heat will not be exchanged immediately. Radiation is the only method of heat transmission that can pass through the spaces. Types of heat radiation include:

heat conduction

Conduction is dependent on physical contact; if there is no contact, conduction cannot occur. When two materials of different temperatures come into contact, heat is transferred from one to the other: the bigger the temperature difference, the faster the heat transfer.

Heat radiation by convection

The most typical mechanism for this phenomenon is from steel to gas, i.e. body to air, and then back again, commonly when air contacts a cloth Exterior structure.

The process starts with energy transfer by conduction and is hampered by the amount of water vapour carried by the air; the water molecules store the heat transferred via conduction from warm surfaces. Air and steam separate only when saturated vapour pressure is reached, which occurs when the volume of water (although in the form of steam) surpasses the amount of heat available to be preserved as a gas (steam) and therefore condenses.

The temperature to water vapour ratio changes as a result of condensation, and once it changes enough, the process begins again; the world's weather systems follow a very similar cycle.

If the air can be kept constant and dry, it will perform very well as an insulator; however, if the air is heated, its molecular structure expands and becomes less dense in comparison to the surrounding air, thus rising as it moves away from the heat source; when the air cools, the molecules contract and increase their density and regression; air molecules are in a state of constant expansion and regression.

The fact that the air cools at a rate that depends on the amount of water vapour saturation complicates the heat transfer process; the higher the saturation, the slower the cooling.

Types of materials used in thermal insulation of buildings

The thermal conductivity of the insulation, or the rate at which a constant amount of energy is transmitted through a known thickness of the material, limits the flow of energy (heat) between two objects that are not of the same temperature. The greater insulation performance is directly attributable to the thermal conductivity of the insulation.

The thermal resistance of a substance, which evaluates a material's ability to resist heat transmission, is the polar opposite of this idea. There are two types of insulating materials and they are:

open cell materials

Expanded Polystyrene (EPS) insulators, like mineral insulation and sheep's wool, are technically "closed cell," but their performance is comparable to that of an open cell material thanks to the cross-linking structure of air pockets that surround the blown cell granules that form the core of their formation.

The open cell's nature allows heat to pass through its core, but the path is convoluted, resulting in minimal heat loss owing to convection. The fundamental in the process is the production of microscopic air pockets that bring air movement to a virtual, but not complete, halt.

Because glass filaments and their binders are poor heat conductors, heat loss by radiation is low.

closed cell materials

Extruded polystyrene and chemical foam boards are examples of closed cell insulators. Closed cell technology creates a denser matrix of individual cells than glass wool or EPS by introducing gases in a controlled manner during the manufacturing process. When you combine the fact that the cells form as gas bubbles with a thermal conductivity substantially lower than that of air, and the fact that water vapour cannot easily contaminate the cells, you get a remarkable high-performance insulator.