Heat and insulation, how does it actually work?
Everyone needs heat in our houses to not freeze and to have a nice and comfortable indoor climate. How much is needed depends on the outdoor temperature, but also how well the house is about retaining the heat already available. This with heat, insulation and heat transfer is not always easy to understand. Here you will get a quick idea that will hopefully give you an insight into how things are all together.
How much is a kWh?
Kilowattimme (kWh) is a measure of the amount of energy you use, regardless of the heating method you selected. A kWh corresponds to the amount of energy required to heat 10 liters of water from 0 ° C to 100 ° C.
1 m³ of oil corresponds to 10,000 kWh
1 m³ of wood corresponds to 1,630 kWh
1,000 kg pellets correspond to 4,700 kWh
Central heating
In solid materials, such as metals, heat is transferred from hot to cold part through wire. Even liquids and gases lead heat, but radiation and convection also plays a big role. As a comparison, it can be mentioned that aluminum conducts heat approx. 10,000 times better than stagnant air.
Heat radiation
Heat radiation (infrared radiation) occurs in liquids and gases as well as in vacuum. A common example of radiation effect is when you experience certain places as draggy. Then it's actually your body that emits radiation heat to the cold surface, for example in a window.
Heat radiation
Heat radiation (infrared radiation) occurs in liquids and gases as well as in vacuum. A common example of radiation effect is when you experience certain places as draggy. Then it's actually your body that emits radiation heat to the cold surface, for example in a window.
Convection
There are two types of convection, self-convection and forced convection. Self-convection (natural air movement) may occur in gases and liquids when subjected to a temperature difference. Because hot air (gas) is lighter than cold, the hot air rises. The air moves and comes into contact with colder surfaces, cools and falls. Through this process, the heat can spread far. Forced convection is caused by winds, for example, differences in air pressure. For example, it is important to have a windscreen on the outside of the outer wall body.
How does insulation work?
On the market there are several different insulation materials and most have a good thermal insulation ability. The design is made to make it difficult for the heat to transition from the hot side to the cold. The reason is a "skeleton" that looks a little different depending on what material it is; for example stone wool & glass wool. Between this "skeleton" is a gas that is usually air.The role of isolation is to balance the three heat transfer modes. The fibers in the stone wool are long and thin which impairs the heat conduction (wire). By having many fibers, there will be many fiber walls (barriers) in the insulation which reduces the risk of heat radiating directly from the hot side to the cold (radiation). The fibers also keep the air still and minimize self-convection (hot air rises, cools down to a colder surface and decreases) (convection). To describe the amount of heat passing through a material, the term thermal conductivity (thermal conductivity) is used. It is called λ (lambda) and is often called lambda value.