U - value
U-value is the most common measure and it incorporates the thermal conductance of a structure along with heat transfer due to convection and radiation. For all building constructions there is a maximal admissible thermal transmittance, which indicates the amount of heat flow in watts per square meter of construction with the temperature difference of 1 Kelvin (W/m²K).
U-value should not be confused with the coefficient of thermal conductivity, which is defined as a simplified U-value of the wall thickness of 1 meter. For example, a brick with a coefficient of thermal conductivity of 0.21 at 37 cm thick wall has a U-value of 0.52.
You can calculate the heat input needed to maintain a given temperature difference yourself by checking the tables of U-values and adding up the various areas of the room, but getting an estimate from an expert is highly recommended. Strictest limitations of thermal conductivity are related to the outer layers of the building, in case of pitched roofs, heated attics, ceilings over unheated basements, and external walls (see table below).
The lower the U-value, the lower the heat flow and the result is a greater energy savings due to a lower amount of energy required to maintain a pleasant and constant room temperature.
The European Union has passed a regulation on energy efficiency in buildings, which envisages reduction of energy use by 30%.
Building regulations determine the maximum allowed U-value:
Windows and doors:1.80W/m²K.
You should really aim to cut in half these U-values and achieve higher level energy savings.
Thermal insulation of building materials is closely linked with the need for heating energy. U-value of 1.0 W / m² K means that we need, for example, a year round 10 liters of heating oil per square meter of external wall surface, if we want to maintain room temperature at 20°C.
Another table is showing the maximum thermal transmittance U max (W/m²K) for building structures (recommended, not mandatory):
U max ,W/(m2K)
1. Exterior walls and walls against unheated rooms
2. The walls between heated rooms
3. The external wall adjacent to the ground
4. Soffit between heated rooms
5. The ceiling against the unheated attic
6. The ceiling of an unheated basement
7. Ceiling or floor bordering the outside air or an open passage
8. Pitched roof over a heated attic
9. Flat roof
10. Lightweight building constructions, except for roofs (less than 150 kg/m2)
by type of material:
Glass and Rock Wool Insulation
- Loft insulation
- Cavity slabs, batts
- Acoustic insulation
- Insulation slabs
BRITISH GYPSUM, KNAUF, ISOVER, ROCKWOOL, URSA
PIR (polyisocyanurate) Boards
PIR rigid board is the most efficient thermal insulation material used in construction.
BRITISH GYPSUM, CELOTEX, ECOTHERM, KINGSPAN, RECTICEL, KNAUF, XTRATHERM
Phenolic Insulation Boards
- External walls,
- Pitched roofs,
BRITISH GYPSUM, KINGSPAN, XTRATHERM
- EPS boards,
- XPS boards,
- Shrinkable boards,
- EWI Insulation Panels
Insulation Bonded to Other Material
An optimum performance "2 in 1" insulation product to enhance thermal insulation for walls and roof projects.
BRITISH GYPSUM, KINGSPAN, CELOTEX, CELLECTA, XTRATHERM, RECTICEL
Reflective Foil Insulation
- Radiant barrier
- Roof insulation
- Walls insulation
- Floors and Ceilings
- Cool in summer warm in winter
ALUMAFLEX, LOW-E, THINSULEX
Gypsum Based Boards
Gypsum board is the premier building material for wall, ceiling and partition systems.
BRITISH GYPSUM, FREMACELL
Cement Based Boards
- Exterior siding,
- Backer boards,
- Underlayment for flooring
EUROFORM, JAMES HARDIE, KNAUF, RCM
Calcium Silicate Boards
An asbestos-free thermal insulation that withstands continuous high operating temperatures.
Acoustic | Soundproofing
- Acoustic wool
- Partition walls
- Acoustic ceilings
- Soundproof floors
- Vibration cushioning
BG, CELLECTA, ISOMASS, KARMA, KNAUF, ROCKWOOL, URSA
External Wall Insulation Systems
٠ Mineral wool
٠ Primers, Adhesives
KINGSPAN, KNAUF, CERESIT, JABLITE
Cladding and Weatherboards
Cladding and weatherboards are available in uPVC, fibre-cement that gives the visual appeal of natural timber.
We sell roof insulating products from leading manufacturers.
CELLECTA, CELOTEX, ECOTHERM, ISOVER, JABLITE, KINGSPAN, KNAUF, ROCKWOOL, XTRATHERM
Installing loft insulation could cut down your energy bills significantly and the payback time is also very quick, within about 2 years. About 25% of heat is lost through the roof in an uninsulated home, so this is a big saving!
Premium quality plasterboards, insulated plasterboards and accessories for acoustic and heat insulation for under ceiling mounting.
PIR boards, Polystyrene, Glass and Mineral Wool Slabs, Batts and Rolls.
URSA, KNAUF, LOW-E, KARMA,XTRATHERM, KAY-METZELER, CELOTEX, CELLECTA
Cavity walls, External walls, Partition walls, Plasterboard
CELOTEX, KNAUF, URSA, ROCKWOOL, PROMAT, XTRATHERM, KAY-METZELER, CELLECTA, LOW-E
Bagged products, Insulated plasterboards, Galvanised dry wall fixings, Metal frame systems
BRITISH GYPSUM, CELOTEX, CEMBRIT, ECOTHERM, KNAUF, KINGSPAN, XTRATHERM
Pipe insulation materials are used to retard the flow of heat energy by reducing heat loss or gain from pipe work and also as acoustic insulation.
ROCKWOOL ROCKLAP, KOOLTHERM FM
Void Former is a lightweight material in structural concrete in foundations, beam and slabs to fill structurally non-working areas and against clay heave.
CLAYBOARD, CLAYLITE, CLAYMASTER
Slabs and Batts
Glass wool insulation, Rock wool insulation, Multifoil insulation, Insulated wallpaper
URSA, KNAUF, LOW-E, THINSULEX, MOULD GROWTH CONSULTANTS