Off-limits to the heat and the cold!
   
  40 percent of the energy consumed in highly industrialized countries is used for heating buildings. It is therefore not surprising that more and more attention is being paid to seeking – and finding – new possibilities for heat insulation.
   
  It was dirty and cold. Heavy curtains were hung up at the windows in an attempt to protect the occupants of the house from the wind that whistled through the gaps. The few people who could afford it draped carpets in front of the cracks in the wall, but that did not help very much either. The large, usually open fire was able at best to provide a little bit of warmth. Consequently, the walls and floors were usually damp, and the dense smoke from the fish-oil lamp also irritated the eyes and nose. There can be no doubt that living in Europe in the Middle Ages was not particularly cozy.
   
 

One of the reasons why things have changed so drastically in this respect is that people building houses have realized how important it is to include some kind of insulating materials in the structure. Consequently, it is nowadays no longer a case of making buildings livable-in in some way or other, but of using as little energy as possible to heat them.
   
  But it was a long route from straw and loam to rockwool and polystyrene, and with chemists and engineers constantly working on the optimization of such insulating materials, the end of the line is not yet in sight. Every piece of progress made in research is quickly turned into tangible products. A good example can be found in Germany, in the Munich suburb of Lehel. The five-story building with apartments and businesses looks at first sight like any other: It is attractively designed and certainly modern. Even a second look does not reveal the secret, because the large window fronts and rounded corners are both typical features of contemporary sophisticated architecture
   
  But in one respect the building is many times superior to all the other buildings in the neighborhood: in its energy consumption. It needs no more than 20 kilowatt-hours per square meter per year. Expressed another way, that is just two liters of heating fuel, which is why it is also referred to as “the two-liter house". By comparison, an average Munich building consumes about ten times that amount of energy, and consequently also incurs about ten times the heating costs. One of the main reasons for this frugality is to be found in the outer wall of the building, where vacuum insulation panels have been used in combination with rigid foam insulating panels. The fact that they are made of polyurethane – and therefore have a thermal conductivity level of 030 – is a major factor here.
   
  At least equally important, however, is how these moisture-resistant sheets are mounted on the outer wall of the building. Above all, it is essential to prevent thermal bridges. The builders did this successfully using strips of the polyurethane construction material Purenit®, cast into the outer concrete wall at intervals of approximately 50 cm. Spacers, also made of Purenit®, were screwed into them and the gap filled with vacuum insulating panels. Finally, the PURWALL® polyurethane heat insulation system was put in place. The polyurethane sheets are only 8 cm thick considerably less than chipboard, which is at least 12 cm thick. The difference may sound small, but it actually means extra living space of over ten square meters. And in Munich, ten square meters are worth more than e30,000.
   
  An “ultra-low-energy house” such as this brings together the expertise from a wide range of different companies. The polyurethane heat insulating system, for example, comes from Hasit Trockenmörtel. The insulating panels are manufactured by Puren Schaumstoff, which, in turn, uses polyurethane materials from Bayer MaterialScience. The joint development is now so far advanced that the system is marketed throughout the world under the name PURWALL®.
   
  The extra gain in space is a major advantage not only with new buildings. The true market of the future lies more in the renovation segment, because especially in old buildings, every centimeter is important. The thinner the insulating structure on the walls, the easier the renovation project. In this respect, China has an enormous amount of catching up to do. Joachim Kleser, a heat insulation expert at Bayer MaterialScience, estimates that “around 30 million square meters of wall area are heat-insulated in Germany every year. The figure in China is a good ten times that."
   
  The reason is that in no other country in the world is so much building work going on as in China. The Chinese construction industry is currently growing at an average annual rate of 12 percent. At the same time, however, Chinese energy consumption is also growing at an alarming rate, and this has prompted the government to push through stringent energy-saving measures, including tough regulations on heat insulation. In every region of China where heating is required – and that is 82 percent of the country – savings of up to 50 percent must have been implemented in the heating segment by 2005 (compared with 1981). For 40 percent of the country, cuts of 65 percent have been stipulated. Joachim Kleser is in no doubt that “this will open up numerous new opportunities for PURWALL®."
   
  One particular advantage of the Chinese market is that it is easier to gain a foothold there than in other countries. In Europe, for example, the situation is one of cut-throat competition because materials like polystyrene have been established for such a long time. In China, on the other hand, the business is only just beginning. Kleser: “And then the better heat-insulating properties of polyurethane compared with polystyrene really come into their own."
Polyurethane's excellent insulating performance can be attributed to the material's high content of fine closed cells. Because the heat conduction properties of the gas inside the cells are far inferior to those of ambient air, neither mineral wool nor polystyrene can match polyurethane’s thermal conductivity figures.
   
  When we hear the term “heat insulation" in northern latitudes, we think of protecting rooms against the cold, but the people nearer the equator see the problem very differently. In many countries they insulate buildings to keep them cool and save energy on air conditioning. For this, too, increasing use is being made of polyurethane. One example is Dubai (United Arab Emirates), where insulating panels made of polyurethane are used in the building of luxury hotels. The goal was to cool the entire building as energy-efficiently as possible, not only for economic reasons but also to comply with regulations stipulating the use of insulating materials in new construction.
   
  Contact
Rowena Wang
Tel.: +86 21 6146 8152
E-mail: rowena.wang@bayerbms.com
   
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