Good insulation

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 percent. In a subsequent phase, beginning in 2012, the requirements will be raised further—by up to another 30 percent.

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 a foam that can be sprayed on to flat roofs or facades, for example.

Key advantage: extremely low thermal conductivity

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. “We’re seeing a growing demand for thin insulating materials,” says Petra Steimle of the IVPU, the German association of manufacturers of polyurethane rigid foam, “because it gives architects more freedom of design. Window lintels with rigid foam insulation need not be so deep, for example.”

The material owes its unique properties to Evonik‘s special expertise in foam stabilizers. The stabilizer ensures 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.

Impressive energy balance

The energy balance for the rigid foam is also impressive. 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. And thinner insulation allows greater freedom of design.