Rigid polyurethane foam demonstrates versatility both through its physical strengths and mechanical properties. These qualities enable it to be used in a wide variety of multi-functional building products which combine insulation with load-bearing, sealing, impact resistance, weight and space-saving, together with ease of maintenance. Effective insulation in buildings plays a vital role in the conservation of non-renewable fossil fuels. Properties of rigid polyurethane (PU) foam as per Huntsman website: Low thermal conductivity: Rigid PU foam has one of the lowest thermal conductivity ratings of any insulant, which allows efficient retention of heat or, alternatively, maintenance of a refrigerated or frozen environment. Strength: Rigid PU foam provides a high level of compression and shear strength, which is further enhanced by bonding with facing materials. Adhesion: During the short period between mixing and final curing, rigid PU foam is extremely adhesive, which allows it to bond effectively with a wide range of building facings. The adhesion is so strong that the bond strength is usually higher than the tensile or shear strength of the foam. Compatibility: Rigid PU foam is compatible with a large number of building facings, including paper, foil, glass fibre, aluminium, plasterboard, plywood and bitumen. These can complement the inherent strengths of the foam, enabling use as semi-structural panels and cladding and allowing foam to accept cosmetic finishes such as plaster to operate effectively as moisture barriers in conditions of high humidity. In-situ stability: Rigid PU foam can be used in applications which experience exceptional extremes of temperature, from -200°C to +100°C. Water absorption: The water vapor permeability of rigid PU foam is low and is enhanced in most building applications by the incorporation of a moisture barrier of polyethylene film or aluminium foil. Fire properties: Though PU foam is combustible, its ignitability and rate of burning can be modified to suit a variety of building applications and it can be formulated to meet the relevant national regulations. Rigid PU foams are usually used at lower thicknesses than other insulants, which means that their heat or fuel contribution to a fire is low compared to other, thicker insulating materials. Lightness: At low densities (e.g. 30kg/m3), the volume of PU in rigid PU foam is around 3%. The remaining 97% of the foam is gas trapped within the cells, which provides the low thermal conductivity properties. The lightness of the foam is an important aspect in terms of transportation, handling and ease of installation. Chemical resistance: Rigid PU foam provides excellent resistance to a wide range of chemicals, solvents and oils. Buildings with inadequate thermal insulation are one of the biggest wasters of energy; so this is a major area where people should start reducing carbon dioxide emissions. The German Energy Conservation Ordinance, which came into force in October, seeks to reduce energy requirements for heating and hot water in buildings by about 30%. In a subsequent phase, beginning in 2012, the requirements will be raised further—by up to another 30%. PU rigid foam panels have excellent insulation properties and are especially thin, too, thanks to Evonik’s expertise special foam stabilizers ensure that the air bubbles in the foam are small and evenly dispersed and that the structure is free of defects. Both are essential properties of a high-end insulation material. The more fine-celled the foam, the better is the insulation; a special method is therefore used to check the foam closely. Insulating panels with a polyurethane foam core sandwiched between two layers of roofing felt or aluminum foil are especially suitable for insulating walls, roofs, floors, and ceilings. The material is also available as foam that can be sprayed on to flat roofs or facades, for example. Another key advantage of polyurethane insulation materials is their extremely low thermal conductivity. To obtain the same degree of insulation with other materials, such as rock wool or Styrofoam, one would need significantly thicker elements. Polyurethane insulation, however, is particularly light and thin. Demand for thin insulating materials is growing because it gives architects more freedom of design. Window lintels with rigid foam insulation need not be so deep. Foam stabilizers ensure that a large number of microscopically small air bubbles are generated when the foam is made. Individual cells are formed from these bubbles during the foaming of the material. The more fine-celled the foam, the better are its insulating properties. The stabilizer also decisively influences other properties such as structural uniformity (the absence of holes and of hard or soft areas), compressive strength, and durability in heat and cold. It results in the best possible emulsification (mixing) of the two substances from which the foam is produced—an important step in the production of high-grade foams. A further advantage is good adhesion of the rigid foam to metal, roofing felt, and aluminum paper. Sandwich elements with these facings are therefore particularly well equipped to resist aging. Finally, a good stabilizer accelerates the production process, because when the raw materials are emulsified faster, a manufacturing plant can turn out more insulating panels. During their useful lives, polyurethane insulating materials save many times the amount of energy needed to produce them: In most cases, the energy expenditure for production has paid for itself after the very first heating period. The relatively high costs of the materials are also recovered within a few years. The two polyurethane systems Baydur® and Baytherm® from BaySystems played a major role in the development of Top Therm 90, a concept for slimline windows and facades with excellent insulating properties that cut heat losses by around half compared with the solutions currently on offer. This meets the requirements for use in passive houses. The Uf-value as a measure for the amount of heat that passes through one square meter of frame in the space of an hour is just 0.8 W/m2•K. The profiles with a thickness of just 90 millimeters owe their outstanding insulating properties to a combination of Baytherm® polyurethane insulating foam and a thin, weather-resistant and dimensionally stable outer shell made using the Baydur® casting system. As a result, they more than satisfy the growing demands for thermal insulation of buildings that now apply in a number of countries, for example the provisions of the new EnEV energy-saving regulations in Germany. This solution also offers advantages over aluminum and PVC, due to a more cost-efficient production process. The concept is based on an integrated approach that views the windows and frames as a single unit in thermal and structural terms. The aim is to develop and test slimline profile designs and highly efficient glazing. In this design, a layer of polyurethane insulating foam ensures there is virtually no contact between the warm and cold sides of the frame profiles. The material adapts perfectly to the dimensionally stable and weather-resistant polyurethane shell that surrounds it. The process of manufacturing and installing the frame system is straightforward and thus cost-effective. It would also be conceivable to apply corrosion-resistant foam to cables, reinforcements and pipes for applications such as facade heating during the manufacturing stage.