everything you wanted to know about insulation ?· everything you wanted to know about insulation*...
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Everything you wanted to know about insulation*
*BUT WERE AFRAID TO ASK
Insulat ion3rd Issue March 2018
1. Introduction 3
2. Howdoesinsulationwork? 4
3. CondensationRiskAnalysis 13
4. Howitsmade 14
5.Testing&quality 206. BuildingRegulations&Standards 22
7. ProductSelector 268. Buildit 32
9. Glossary 49
This guide aims to provide you with everything you need to know about Kingspans insulation, from how it works, to its
manufacture, and finally its installation.
We will run through building regulations and show you how to comply with them for your projects.
Thermal insulation is commonly used to prevent heat loss / gain in buildings and so reduce energy usage.
The control of heat flowHeat flow is how heat moves. Heat moves from warmer to colder areas. This movement is what causes buildings to get colder in winter (heat leaking from a building into the colder environment outside) and hotter in summer (heat moving from the warmer outside environment into a building). This happens through one or more of three heat transfer mechanisms:
l conduction; l convection; andl radiation
Thermal insulation is designed to restrict and resist heat transfer via these three mechanisms.
Conduction is how heat moves from one place to another as energy is transferred from molecule to molecule. This can happen in solids, liquids and gases and the ability of matter to conduct heat depends on its composition.
In buildings it is important that insulation materials have a low thermal conductivity (lambda value) as the lower the thermal conductivity, the better the ability of the material to resist heat transfer via conduction.
Convection is how heat moves through liquids and gases. This form of heat transfer cannot happen in solids or in a vacuum. When the temperature of a liquid or gas increases the density of molecules change, warmer air or liquid becomes less dense and rises. Closed cell insulation, such as a phenolic or PIR board inhibits convection of neighbouring cells, making them less prone to affecting neighbouring cells.
Cold air Warm air
Radiation is the transfer of heat as energy, in the form of electromagnetic waves. This form of heat transfer does not need gases, liquids or solids to take place and it can happen in a vacuum as it does not rely on particles to move heat from one space to another. The rate at which heat is transferred through radiation is controlled by three key things:
(a) Temperature as the temperature increases the total amount of radiation also increases. For example, without insulation, a building that is heated loses more heat through radiation, this increases the warmer the building is;
(b) Distance the distance between the surfaces; and
(c) Emissivity how effective a material is at emitting heat energy (thermal radiation). The shinier the surface the lower its emissivity (ability to transfer heat) is. For example, an insulation with a foil facing has low emissivity as the foil inhibits the radiation of heat out of a building.
Measuring insulation performance The effectiveness of thermal insulation is measured by its ability to restrict heat transfer either its thermal conductivity or its thermal resistance. These are known as the lambda value and Rvalue respectively.
Lambda value (thermal conductivity, kvalue, value)Firstly, the value shows how well a material can conduct heat and is measured in units of W/mK. A good insulation will have a low value to reduce heat loss. This is a general measurement. To assess how a certain thickness of a material affects heat transfer, you need to calculate the Rvalue (thermal resistance).
Rvalue (thermal resistance)By dividing a materials thickness (in metres) by its value, you can find out how well it resists heat transfer at a specific thickness. Thermal resistance is measured in units of m2.K/W. The best insulation will have a higher Rvalue which shows it is better at reducing heat loss.
The basic equation for calculating Rvalues is shown below:
Thickness (m)Thermal conductivity (l)
Uvalue (thermal transmittance)The Uvalue is a sum of the thermal resistances of the layers that make up a building element (i.e. walls, floors, roofs etc.). It includes adjustments for any fixings, air gaps etc. This value is given in units of W/m.2K and this shows the ability of an element to transmit heat from a warm space to a cold space in a building and vice versa. The lower the Uvalue, the better insulated the building element is. The basic equation for calculating the Uvalue is shown below:
Envelopes & Thermal BridgesThe elements of a building make up the building envelope (the barrier between inside and outside). For insulation in the building envelope to reduce heat loss through conduction, convection and radiation it must have as few thermal bridges as possible.
[ ]U = + U R = The Sum of all the RValuesU = Any corrections for fixings, air gaps etc.
Thermal bridges (heat bridges or cold bridges).These are pathways through which heat can escape. The principal types of thermal bridges are shown below:l repeating (linear and point). Repeating thermal bridges occur where there are regular interruptions for example,
timber studwork in a timberframe wall construction (linear) or repeating fixings or fasteners e.g. wall ties (point). These are accounted for as an adjustment to a Uvalue calculation.
l point (nonrepeating). A nonrepeating point thermal bridge might arise where a steel beam or a flue passes through a wall construction.
l linear and geometrical (nonrepeating). Linear and geometrical (non repeating) thermal bridging occurs at the junctions of a buildings elements (e.g. between roofs and walls), or where the thermal insulation layer is interrupted (e.g. around windows).
Generally, you can reduce the level of thermal bridging by ensuring either continuity of the insulation layer, or overlapping insulation layers where possible; using lower conductivity materials wherever possible can also reduce heat losses from bridging.
Ventilation & Air TightnessHeat transfer can take place in gases through convection, so it is important to control air movement in the building envelope. This can be done through air tightness and ventilation.l Air tightness will reduce the amount of heat loss at thermal bridges by preventing air leaking through the building
envelope.l Ventilation is used to help the movement of air through cavities in the building envelope. This movement will
significantly reduce the chances of condensation forming.
Controlling moistureHeat transfer can also take place in a liquid, so it is essential to avoid moisture buildup in the building envelope. Condensation can reduce the performance of insulation.
Condensation This takes place when water vapour in warm moist air meets cold surfaces that are resistant to water vapour. The water vapour condenses into liquid water droplets as either surface condensation or interstitial condensation.
l Surface condensation takes place on the visible surfaces of a building. Indoors, this can increase the risk of mould, which reduces air quality, and can cause staining. When thermal bridging is not addressed properly, cold spots on the internal surface of the construction can occur. When the warm air escaping the construction hits these spots it can lead to a risk of condensation and mould growth.
30 g/m2 fine mist 3050 g/m2 droplets run down windows and walls
51250 g/m2 droplets run down sloping surfaces
>250 g/m2 droplets drip from horizontal surfaces
l Interstitial condensation happens between the layers in a construction, i.e. inside the roof, wall or floor. It can damage these elements or even cause them to fail completely. Building elements can be designed to resist interstitial condensation, or ventilation can be used to remove any condensation that forms before it causes any damage.
Did You Know:The average person produces up to
40 g of moisture per hour by breathing.
If insulation is installed correctly, the risk of condensation can be reduced or even completely avoided. A Condensation Risk Analysis (CRA) assesses the risk of condensation forming once insulation is installed. They are available alongside Uvalues from our Technical Service Department. Here is an example:
The top line (T) shows the temperature and the bottom line (D) represents the materials predicted dewpoint temperature. The dewpoint temperature is normally lower than the air temperature and describes the point at which moisture in the air will condense. This depends on the amount of moisture in the air. If it is very humid, the dewpoint temperature will be higher. The amount of insulation you use and how you place it is key to keeping materials above their dewpoint temperature, and so avoiding condensation. You can use a vapour control layer like polythene on the inside (warm side) of insulation to reduce water vapour from passing from warm to cold sides of the construction and condensing.
Top layer of facing Oven
Bottom layer of facing
Benefits: Thermal conductivity of 0.0180.023 W/m.K The thinnest commonly used insulation products f