Glossary of Insulation Terms
Glossary of Insulation Terms
A-Scale A weighting filter often applied to decibel ratings to emphasise the characteristics of human hearing at low frequencies, written dBA or dB(A).
Accredited Construction Details Accredited construction details are details of junctions at openings and at junctions between elements (such as wall/floor junction) that are designed to minimise thermal bridging and air leakage.
Air Infiltration Air ingress into a building through cracks or gaps.
BIM (Building Information Modelling) BIM is an acroynm for Building Information Modelling. BIM is defined as 'The shared use of structured data' within the design, construction (or retrofit), operations / maintenance and deconstruction of a building. BIM enables those who interact with the building to optimise their actions, resulting in a greater whole life value for the asset.
Blown Wool Loose mineral wool insulation applied by blowing, usually into cavity walls or lofts.
BR443 BR443 (2006) edition - There are various standards dealing with the calculation of U-values of building elements. The conventions provide guidance on the use of the standards, indicating the methods of calculation that are appropriate for different construction types, providing additional information about using the methods, and providing data relevant to typical UK constructions.
Breather Membrane A breather membrane repels water that penetrates an outer cladding material but is permeable to water vapour escaping from the structure. It is defined as a material with a vapour resistance between 0.1 and 2.0 MNs/g, although the norm is for breather membranes to have a maximum vapour resistance of 0.6 MNs/g.

Building Research Establishment Environmental Assessment Method (BREEAM) is a methodology used to assess the environmental impact of a building.

BREEAM evaluates the procurement, design, construction and operation of a development against targets that are based on performance benchmarks. Assessments are carried out by licensed assessors, and dvelopments are rated and certified on a scale of Pass, Good, Very good, Excellent and Outstanding.

BS 6946 Provides the method of calculation of the thermal resistance and thermal transmittance of building components and building elements.
BS EN ISO 10211 BS EN ISO 10211 sets out the specifications for a three-dimensional and a two-dimensional geometrical model of a thermal bridge for the numerical calculation of heat flows, in order to assess the overall heat loss from a building or part of it, and minimum surface temperatures, in order to assess the risk of surface condensation.
Cavity Tray A damp-proof membrane or pre-formed tray crossing the cavity of a wall at interruptions in the cavity. Rises from the outside of the cavity upwards at least 150mm
Cavity Wall A wall, normally external, comprising an inner and outer leaf with a space between the two.

The European Committee for Standardisation (CEN) is one of three European Standardisation Organisations (together with CENELEC and ETSI) that have been officially recognised by the European Union and by the European Free Trade Association (EFTA) as being responsible for developing and defining voluntary standards at European level.

CEN provides a platform for the development of European Standards and other technical documents in relation to various kinds of products, materials, services and processes.

CEN 442 WG4 CEN 442 WG4 is the working group which is tasked with agreeing data dictionaries and standards for BIM.
COBie Construction Operations Building Information Exchange (COBie) is a non-proprietary data format for the publication of a subset of building information models (BIM) focused on delivering asset data as distinct from geometric information.
Condensation When water vapour from the air comes into contact with cold surfaces, the vapour condenses on the cooler surface.
Conduction The transmission of heat through, along or from one material to another material in contact with it.
Convection The transfer of heat by movement of air.
Dewpoint A calculated temperature at which water vapour will condense.
Di-isocyanates An isocyanate that has two isocyanate groups is known as a di-isocyanate. Di-isocyanates are manufactured for reactions with polyols in the production of polyurethanes.
Durapak The high strength polypropylene packaging applied to most Knauf Insulation roll products
ECOSE® Technology ECOSE Technology is a revolutionary, no-added formaldehyde binder technology used in mineral wool products manufactured by Knauf Insulation. It is based on rapidly renewable materials instead of petro-based chemicals, reduces embodied energy and delivers superior environmental sustainability.
Embodies Energy Embodied energy is the energy consumed by all of the processes associated with the production of a building, from the sourcing of raw materials and processing of those materials, to manufacturing, transport and product delivery.
Emissivity Emissivity is a measure of the radiation emitted from a surface. 'Black bodies' (materials with matt black surfaces) have a high emissivity & emit large amounts of radiation. In contrast shiny surfaces, such as polished aluminium, have a low emissivity. This characteristic can be exploited in buildings by providing aluminium foil facings on insulation materials, facing out towards cavities to reduce the radiated heat loss. Matt black has a typical emissivity of 0.95, compared to 0.08 for polished aluminium. But most building surfaces, even white painted surfaces, have high emissivities, of around 0.90 to 0.95.
Energy Saving Trust (EST) A non-profit making company set up by Government and the major energy companies. Its purpose is to work through partnerships towards the sustainable and efficient use of energy in the domestic and small business sectors.
Environmental Product Declaration

An EPD is an Environmental Product Declaration and is the environmental equivalent of a technical data sheet.

It contains information about the embodied environmental impacts associated with a product, which are established by carrying out a life-cycle assessment (LCA).

The relevant standard for Environmental Product Declarations is ISO 14025, where they are referred to as "type III environmental declarations". A type III environmental declaration is created and registered in the framework of a programme, such as the International EPD® System.

EURISOL The UK Mineral Wool Association, a trade association that was founded to represent the mineral wool industry to the government, business and the public.
Fiberisation The manufacturing process of turining molten raw material (e.g. for insulation; glass or stone) into fibres.
Fire-resistance The ability of an element of structure to maintain its stability for a specific period of time as determined by the use and size of the building
Fire-resistance: heat transmission Contains flames and inflammable gas for a short period of time, but does not prevent the transmission of heat to the other side of the construction (example: wired glass).
Flanking transmission The transmission of sound into an area via an indirect route (e.g. between an upper and lower floor via common walls)
Frequency of sound The frequency of sound is measured in Hz (hertz). The higher the value, the lighter the tone (bass - treble). The frequency of speech lies primarily between 125 and 8000 Hz, while audible sound lies between 20 and 20 000 Hz.
Glass Mineral Wool Glass mineral wool is made from sand and recycled glass, limestone and soda ash. These are the same ingredients that are used to make familiar glass objects such as window panes or glass bottles. The glass is spun to form millions of fine strands of wool. These are then either formed into rolls and slabs or collected as a loose product. The formed product is sprayed with a resin which is used to bind the wool together to form a mat of material and then cured in an oven and cut to size and packaged as rolls or slabs to create the finished product. The loose glass mineral wool is packed in bales and formed in situ within the building element during installation. 
Global Warming Potential A measure of how the manufacturing process of a product contributes to global warming.
Green Guide The Green Guide, which is part of BREEAM (BRE Environmental Assessment Method), is a guide provided for specifiers covering the environmental performance and impact of a wide range of building materials and components. The data is set out in an A+ to E ranking system, where A+ represents the best environmental performance/least environmental impact, and E the worst environmental performance/most environmental impact.
Green Roofs A green roof is a roof which is partially or completely covered by vegetation and a growing medium. Green roofs can be either extensive or intensive. Extensive green roofs have shallow (typically 7–10cm) soil layers. They support sedums, moss, herbs and grasses and other vegetation where low or no maintenance is required. They are the lightest type of green roof. Intensive green roofs have a deeper soil layer (15cm upwards) and a wider variety of plant types can be grown, from lawns to ornamental bushes and semi mature trees.
Green/Garden Roof A flat roof, often combining grass, plants and paving,  that is used to provide an outside area for social activities.
Heat Loss Heat transfer from internal spaces to external areas through conduction, convection and radiation.
HEAT3 HEAT3 is a computer program used for assessing three-dimensional transient and steady-state heat transfer.
Home Energy Efficiency Scheme (HEES) Designed to tackle fuel poverty among the most vulnerable by providing grants for comprehensive packages of insulation and heating improvements.
I-Beam Timber beam or steel girder constructed so that, in cross-section, it resembles a capital letter 'I'.
IFC Industry Foundation Class (IFC) is a platform neutral, open file format specification that is not controlled by a single vendor or group of vendors. It is an object-based file format with a data model developed by buildingSMART (formerly the International Alliance for Interoperability, IAI) to facilitate interoperability in the architecture, engineering and construction (AEC) industry, and is a commonly used collaboration format in Building information modelling (BIM) based projects.
Impact Sound Sound transmitted between two areas by direct impact upon the dividing element (e.g. sound of footsteps on an internal floor)
Internal Floor Any internal floor that is not a 'Separating Floor'
Internal Wall An internal wall is defined by the Building Regulations as a wall between a bedroom or room containing a W.C. and other rooms.
Interstitial condensation Interstitial condensation is condensation that occurs within a building element. It can be very harmful if interstitial condensation occurs on surfaces within the structure, as this can lead to the rot of timber or oxidation of metal surfaces, and other problems. There are many instances when condensation can form on the surface or interface of two materials without causing problems i.e. the cavity side of an external brick or block leaf.
Joist Horizontal structural element often used to support floorboards and celings.
Kelvin An absolute temperature scale in which the temperature intervals correspond to those of the Celsius scale and the freezing point of water is 273 Kelvin (written 273K). When referring to temperatures on the Kelvin scale, refer to "Kelvin" and not "degrees Kelvin". Zero Kelvin (0K) is known as "absolute zero".
LCA Life-cycle assessment or life-cycle analysis (LCA), is a technique to assess environmental impacts associated with the stages of a products life from cradle through to grave.
LEED Leadership in Energy and Environmental Design (LEED), is a building certification programme designed to assess the environmental impact of a building. It includes a set of rating systems for the design, construction, operation, and maintenance of green buildings, homes, and neighbourhoods. Projects pursuing LEED certification earn points across several areas that address sustainability issues. Based on the number of points achieved, a project then receives one of four LEED rating levels: Certified, Silver, Gold and Platinum.
m²K/W m2K/W is the metric used to measure the thermal resistance of a material or construction element.
Noise Reduction Coefficient (NRC) A single value for sound absorption, derived as the mean value of 4 frequencies in the range 250-2000 Hz.
Notional Dwelling The notional dwelling is the benchmark against which energy saving is assessed. The reference values to be used are set out in Appendix R1 of SAP.
Ozone Depletion Potential (ODP) A relative index indicating the extent to which a chemical product may cause ozone depletion.
Party Wall See 'Separating Wall'
Polyisocyanurate olyisocyanurate, also referred to as PIR, polyiso, or ISO, is a thermoset plastic typically produced as a foam and used as rigid thermal insulation. Its chemistry is similar to polyurethane (PUR) except that the proportion of methylene diphenyl diisocyanate (MDI) is higher and a polyester-derived polyol is used in the reaction instead of a polyether polyol. Catalysts and additives used in PIR formulations also differ from those used in PUR. The reaction of MDI and polyol takes place at higher temperatures compared with the reaction temperature for the manufacture of PUR.

Polyurethane (PUR and PU) is a polymer composed of organic units joined by carbamate (urethane) links.

Polyurethane polymers are traditionally and most commonly formed by reacting a di-or polyisocyanate with a polyol. Both the isocyanates and polyols used to make polyurethanes contain, on average, two or more functional groups per molecule.

Product Data Template A product data template is a structured ‘questionnaire’ for each construction product type that sets out groups of ‘properties’ that manufacturers have to fill in as ‘values’ in order to provide their data to the supply chain in a way consistent with BIM Level 2. 
Psi values Psi values (W/mK) are used to calculate the Y value (W/m²K) for use in the SAP 2009 calculator for the effect of none repeating thermal bridges. Accredited construction details and associated Psi values for a new build design are available from the Planning Portal web site.
Radiation The process by which heat is emitted from a body through open space, for example, sunlight.
Rafters Inclined structural element used to support pitched roofs.
RdSAP Reduced Data SAP (RDSAP) is as a lower cost method of assessing the energy performance of existing dwellings. The Standard Assessment Procedure (SAP) is the methodology used by the government to assess and compare the energy and environmental performance of dwellings. SAP was developed by the Building Research Establishment (BRE). The SAP methodology is based on the BRE Domestic Energy Model (BREDEM), which provides a framework for calculating the energy consumption of dwellings.
Rock Mineral Wool

Rock mineral wool (or stonewool), is an insulation material manufactured predominantly from volcanic rock, specifically basalt. The ‘recipe’ (charge) varies between manufacturers but other ‘ingredients’ typically include blast furnace and steel slags as well as dolomite.

These are heated to over 1,000°C, melted together and then spun (fiberised) into fine strands. These strands are sprayed with a ‘glue’ (binder) to form a mat of insulation before being ‘baked’ (cured) in an oven to create the finished product. Rock mineral wool has a high melting point, insulates through a wide temperature range, is an excellent acoustic insulant, and can be manufactured in a broad range of densities to suit many applications.

SAP (Standard Assessment Procedure) This is the Government's Standard Assessment Procedure. It is the calculation method that must be used for calculating the carbon emission rate for dwellings. It calculates the energy requirement for heating, hot water, ventilation and internal lighting for the dwelling. As well as producing a SAP rating, on a scale from 1-100, it also gives the carbon emission rate in terms of kg/m²/yr.
Separating floors A separating floor is defined by the Building Regulations as a floor separating one dwelling from another.
Separating wall A separating wall is defined by the Building Regulations as a wall separating one dwelling from another.
Soffit The underside of any construction element, but commonly used to decribe the area below a roof overhang or exposed floor (e.g. an outside, multi-storey carpark).
Sound Absorption Sound energy converted into mechanical vibration energy and/or heat energy. Sound absorption is usually expressed as a sound absorption coefficient.
Sound Insulation The ability of a building element or building structure to reduce the sound transmission through it. The sound insulation is measured at different frequencies, normally 100-4000 Hz. Airborne sound insulation is expressed by a single value, Dn,c,w , Rw or R'w. Impact sound insulation is expressed by a single value Ln,w or L' n,w .
Sound Strength (dB) Measured in dB (deciBel). dB is measured at different frequencies.
Stud A vertical framing element, usually timber or metal, used as part of the frame in a wall or partition.
Supakube The palletised, weatherproofed, compressed unit of delivery for most Knauf Insulation roll products. A Supakube normally contains 24 rolls of "Durapak"d insulation.
Surface resistance Surface resistance (Rs) is the reciprocal of surface coefficient. Its units are m2/K/W.
Target Emission Rate Target CO2 emission rate - this is the energy performance target that must be achieved to comply with the requirements of Building Regulations. It is expressed in terms of kg/m²/yr. The TER is calculated using SAP software.
Target Fabric Energy Efficiency A high, yet practical energy performance level for all new homes, which focuses on the dwellings fabric in order to ensure that energy efficiency plays a significant role in the delivery of low and zero carbon homes. Fabric energy efficiency limits are set in kWh/m2/yr.
Temperature Temperature levels are commonly measured in degrees Celsius (°C) whereas temperature differences are measured in Kelvin (K). Each unit Celsius is the same size as each unit Kelvin, so that, if the outside temperature was 3°C and the internal temperature was 18°C the difference in temperature would be 15K. Note that the degree symbol ° is used with degrees Celsius but not with Kelvin.
The Standard Assessment Procedure (SAP) SAP is the Government's standard for home energy rating. SAP ratings provide a simple indicator of the efficiency of energy use for space and water heating in new and existing dwellings. SAP ratings are expressed on a scale of 1 (poor) to 120 (excellent).
Thermal Bridging

A thermal bridge (or cold bridge), is an area of a building which has a significantly higher heat transfer than the surrounding materials resulting in an overall reduction in thermal insulation of the object or building.

A thermal bridge describes a situation in a building where there is a direct connection between the inside and outside through one or more elements that are more thermally conductive than the rest of the building envelope.

Thermal conductivity The rate at which heat is transmitted through a material, measured in watts per square metre of surface area for a temperature gradient of one Kelvin per metre thickness, simplified to W/mK.
Thermal Mass The mass in a structure which is used to absorb solar heat during the day and then release the heat in the evening.
Thermal Modelling Building Regulations require that thermal bridging be taken into account in SAP and SBEM calculations. The junctions that need to be accounted for include wall-floor junctions, wall-roof junctions, lintels, jambs, cills, intermediate floors, balconies, corners, party walls and other significant junctions. Their effects are expressed in terms of Ψ-values, or linear thermal transmittance values, and, unless they are recognised accredited details, they should be evaluated using thermal simulation software through 'thermal modelling', following agreed conventions and standards.
Thermal Resistance A measure of the thermal resistance of a particular thickness of material. It is measured in m2K/W and is equal to the thickness of the material (in metres) divided by the conductivity of that material. Surfaces and cavities also provide thermal resistance and there are standard figures for these resistances that must be taken into account when calculating U-values. The resistances of each material within an element are added together to determine the overall resistance of the element. The reciprocal of the overall resistance is the U-value.
Thermal Resistivity Resistivity is a measure of a material's thermal resistance and is the reciprocal of its conductivity. It is a measure of the thermal characteristic of a material and is independent of its thickness.
Thermal Transmittence Thermal transmittance is the measure of the rate of heat loss of a building component. It is expressed as watts per square metre, per degree Kelvin (W/m²K) - more commonly known as the U-value. The U-value is calculated from the reciprocal of the combined thermal resistances of the materials in the element, air spaces and surfaces, also taking into account the effect of thermal bridges, air gaps and fixings.
U-value (thermal transmittance) Commonly known as the U-value, it is a measure of the rate of heat loss of a building component. It is expressed as watts per square metre, per degree Kelvin, W/m2K. The U-value is calculated from the reciprocal of the combined thermal resistances of the materials in the element , air spaces and surfaces, also taken into account is the effect of thermal bridges, air gaps and fixings.
Vapour control layer A vapour control layer is defined as a material that substantially reduces the water vapour transfer through a building element into which it is incorporated i.e. polythene sheet materials or foil backed plasterboard. Vapour control layers are sometimes required on the warm side of the insulation, to reduce the possible risk of interstitial condensation within the construction element.
Vapour permeable underlayer A vapour permeable underlay repels water that penetrates a roofing finish but is permeable to water vapour escaping from the structure. It is usually defined as a material with a vapour resistance of not more than 0.25MNs/g.
W/mK Thermal conductivity (also known as Lambda) is the rate at which heat passes through a material, measured in watts per square metre of surface area for a temperature gradient of one kelvin for every metre thickness. This is then expressed as W/mK.
W/m²K Is the metric used to express a U-value which is the metric used to express thermal transmittance.