Heat loss via radiation is usually underestimated. And this, although it is precisely the surface temperature in our immediate surroundings, such as walls, floors or ceilings, that have a crucial influence on our personal comfort. The U value describes the heat flow in watts (W) that passes through all the layers surrounding a building element, over a surface area of 1 m², due to a temperature difference of 1 K (W/m²K). The smaller the U value is, the less heat is lost by the building element. "The U value is a means of providing realistic information on the heat losses by various building elements or combinations thereof," explains Klaus Bonin, technical expert at WACKER's Construction Polymers business unit.
For outside walls, the U value is an important parameter for realistic estimations of heat losses and energy-saving potential. A well insulated building will have U values between 0.3 and 0.4 W/m2K, while poorly insulated walls may have U values well above 1.5. External insulation and finish systems (EIFS) are the simplest and most reliable method of preventing energy losses.
Poor Insulation Traps Summer Heat
An Effective way to Ward off the Heat:A facade covered with an EIFS wards off heat very efficiently. The EIFS is applied to the exterior and thus prevents the wall material from heating up unnecessarily in mid-summer. New buildings can be designed with EIFS right from the start, but they can also be applied to old buildings under renovation.
Perfectly Matched Compo– nents:The high flexibility of an EIFS is due to a clever combination of materials. The core element of an EIFS is a combined adhesive, assembly and coating system in which heat-insulating materials such as polystyrene, rock wool, slabs of expanded mineral materials or even cork panels are fixed to the outside walls of a building and then coated. Through its VINNAPAS® polymer powders, WACKER has played an integral role in the development of exterior insulation and finish systems since they first came on the market. This is because insulating materials such as polystyrene board do not form a stable bond with cement.
"By contrast, adhesive mortar with just three to four percent of VINNAPAS® added to it will form a stable and permanent bond with the polystyrene board," explains Bonin. Improved adhesion to all other substrates is obtained, too, from concrete through to brick or wood.
Allergy Sufferers can Breathe Again:Since EIFS reduce the temperature between the air in the interior of a building and the wall surfaces; they greatly improve the building's living quality. The movement of hot or cold air caused by a radiator or an air conditioner means that the air circulates continuously within the rooms. As a result, dust, bacteria and excrement from household dust mites are stirred up and impair the quality of the respiratory air. The polluted air can trigger allergies and burden mucous membranes.
Added Value Beckons:The benefits of modern exterior insulation and finish systems are not limited to reduced energy costs and a healthy indoor ambience. EIFS also add considerable value to an object. As confirmed by the German EIFS Technical Association, these systems have the supplementary bonus of effectively protecting masonry from moisture damage and cracking. Irrespective thereof, EIFS offer a broad range of options for adding aesthetic value to a building because every façade can be designed individually. It is of no consequence whatsoever in this context whether EIFS are to be applied to old buildings under renovation or to a large, modern building that is still on the drawing board.
Ideal Thermal Insulation—A Complex System of Several Layers
The reinforcing layer is followed by an alkali-resistant glass scrim fabric that increases the mechanical stability of the EIFS. The outermost layer, which may be a decorative plaster, paint or a ceramic cladding, permits almost unlimited freedom of design.