Reducing the Carbon Footprint through New Chemistries

Raman Trikala
MD, Wacker Chemie India Pvt Ltd
Greenhouse gas emissions can only be limited if energy is used more efficiently than it has been to date. Home heating, air conditioning and hot water account for the lionís share of private energy consumption. This is unlikely to change in the near future, since nobody wants to make do without hot water and comfortable living, nor should they have to. Nevertheless, there are ways to reduce domestic energy demand. In recent years, the construction and chemical industries have developed innovative technologies and products that contribute significantly to increased energy efficiency and to an improved carbon footprint.

One of the most reliable methods of preventing energy losses in buildings is using External Thermal Insulation Composite Systems (ETICS). The better a building is insulated, the less energy is needed to create a permanently comfortable interior climate - regardless of whether the building needs to be heated or cooled. ETICS reduce temperature differences between indoor air and wall surfaces, thus significantly improving the comfort level inside. Independent studies, calculating the long-term effect of an ETICS in a typical one-family or duplex house with 24-cm walls, found that over a period of 40 years, the annual energy consumption can be slashed from roughly 24,200 kWh to 9,600 kWh. Seen over the entire period, this translates into a saving of about 65,000 liters of crude oil and reduces the carbon footprint of a residential home significantly.

Originally, ETICS were used to reduce heating costs in the cooler regions of Europe. However, they are also becoming increasingly popular in warmer regions, as a facade covered with an ETICS also wards off heat very efficiently. Applied to the outside of a building, the insulation prevents unnecessary heating of exterior walls during the hottest days of summer. In addition, ETICS reduce temperature differences between the indoor air and the wall surfaces, thereby greatly improving the comfort level inside. Insulation systems can be incorporated in the design of new buildings right from the start, but they can also be applied to buildings under renovation .

ETICS consist of a multi-layered material composite, the various components of which each perform a different task. The most important thing is that the different layers bond well to one another and to the substrate. Mineral -based mortars by themselves don't actually adhere to modern insulation materials like polystyrene at all. A firm bond to the insulating material, resulting in a permanently stable insulation system, can be achieved only by adding specialised dispersible polymer powders such as VINNAPAS. Just two to three percent of VINNAPAS in the mortar is sufficient for creating a durable and stable bond between the polystyrene board and the adhesive respectively embedding mortar. This, by the way, is true for improved adhesion to all substrates, be they concrete, brickwork or wood. External thermal insulation composite systems are therefore ideal for anyone looking for sustainable energy savings.

Interior insulation measures play an increasingly important role in reducing carbon footprints as well. Even for insulation materials conventionally in use indoors, innovative technology can improve energy savings still further. For instance, rendering insulation materials such as aerated concrete or mineral wool water-repellent (hydrophobic) saves heating as well as air-conditioning costs. Since damp construction materials insulate far less efficiently, such a measure alone can save a lot of energy and money .

The insulating capacity of such materials decreases enormously with moisture . Tests show that a moisture content of five per cent in a plain brick wall, for example, can lower insulation performance by up to 50 percent. One single square meter of uninsulated damp brickwork leads to twelve extra liters of home heating oil consumed each year.

This is caused by the significantly higher thermal conductivity of damp materials. Dry insulation materials have a vast number of air-filled cavities reducing the exchange of heat to a minimum. But if moisture collects in the pores of the material, a lot more heat is transferred than would be possible if the cavities were filled with air. Whereas thermal conductivity in mineral-based construction materials such as aerated concrete increases directly in proportion with the water content, thermal conductivity in mineral wool is already increased by very little moisture .

On construction sites, insulation materials are often left unprotected and exposed to moisture. Left untreated, perlite or mineral wool can absorb large amounts of moisture, in some cases up to nine times their own weight. Such water reservoirs in the wall will later lead to mold formation and salt efflorescence in the home, and even to frost cracks in extreme cases.

To prevent this, many manufacturers choose to make their insulation materials water-repellent. In this way, the glass wool retains its insulating capacity even if it is not stored properly in a dry place prior to use. In addition, water vapor can get out, but liquid water cannot penetrate indoors. Experts at Wacker have developed a range of specialized silicone emulsions, sold under the name SILRES BS, to make insulation materials hydrophobic. These emulsions are free of solvents and can be diluted with water; they align with the surface layer and make it water -repellent.

When treated with water-repellent additives from Wacker, these insulation materials help save energy. They contribute to a reduction in CO2 emissions and provide a more comfortable indoor climate. In addition, they contribute to a more sustainable use of construction materials as regards longevity and durability. For us, sustainability also means enabling effective protection against improper treatment.

Innovative chemicals can also help reduce CO2 emissions in manufacturing processes of the construction industry. An example is the production of clay bricks, in which the density, and thus the quality, is specifically governed by the firing temperature. Lowering the firing temperature can save energy and reduce greenhouse gas emissions. This is of particular interest for the largest brick market in the world: India. Most of the manufacturing facilities do not have energy-efficient high-tech furnaces. Energy savings can be achieved if the bricks are sprayed with a mixture of water and silicones before the bricks are fired.

Using the right kind of tile adhesive is another example. In most Asian countries, tiles are usually laid in an unmodified mortar bed which is at least 15 to 30 mm thick in order to obtain sufficient adhesion to the wall. Although quite common, the thick bed technique has drawbacks: it is difficult to handle, it is fault-prone and it consumes a considerable amount of mortar. Therefore, chemical companies like Wacker developed dispersible polymer powders which improve the adhesion and flexibility of the mortar significantly. These dry-mix mortars are usually pre-packed and ready-to-use . All you have to do is mix it with water on site. The polymeric binder which is an integral part of the mixture allows you to reduce the thickness of the mortar layer down to 2-4 mm - which saves up to 15 per cent material. Dry-mix mortars also simplify transport and storage, which in turn helps to reduce the carbon dioxide footprint during construction work.

Altogether, modern construction chemicals can contribute decisively to a more cost-effective, 'greener' energy balance for buildings, and to reduce carbon dioxide emissions effectively.