Coating systems offer key benefits
HATHEM AL SAYEGH, the managing director of TeknCoat of the UAE, describes how the company's polyurethane-based coatings can be effectively used to insulate buildings.
01 December 2001
Polyurethane is today's material of choice in the insulation industry, as it has the highest insulation value over any material in the commercial market today.
Keeping this in mind, Technicoat International Factory (TeknCoat) has spared no effort in research and development to come up with a new and very improved insulation alternative.
TeknCoat's easy-to-apply polyurethane-based products offer efficient characteristics that outperform conventionally-used materials and can be termed as a technological breakthrough.
The climate in the Gulf gets extremely hot in the summer and this leads to soaring demand for power to provide big loads of cooling. In this situation, thermal insulation can be used to effectively reduce the heat transfer in buildings and thereby save energy. According to standards of the ASHRAE (American Society of Heating, Refrigeration and Air-conditioning Engineers), the following U values are to be considered for calculating the cooling load for buildings in the UAE: 0.30 btu/hr sq ft deg F for buildings with no insulation and walls with no glass panelling; and 0.4 btu/hr sq ft deg F for roofs.
The Dubai Municipality has issued new regulations that set the following limits on values of heat transfer coefficients (U value) for thermal insulation in buildings.
This would appear to be the first time that the municipality has introduced rules to help reduce heat transmission through walls in buildings and in order to comply with these stringent requirements, it has become imperative to use insulating materials on walls.
Walls are normally painted over their plastered surfaces. However, this is done primarily for decorative purposes and conventional paints do not offer any insulation benefits. Therefore it is necessary to have a material that can be applied like paint and this coated surface should then be compatible for application of any desired paints for decorative purposes. What is needed is an external finish that provides adequate insulation as well as an aesthetic appearance.
Heat flows by conduction, convection and radiation and materials with low thermal conductivity offer effective thermal insulation as they delay the process of heat being transferred to a building. In this aspect, materials such as polystyrene and polyurethane coatings have a low thermal conductivity 0.02 W/sq m K.
For most insulating materials, the conductivity increases with mean temperature. If the coating has less absorption of solar radiation, then the mean temperature goes down, the conductance is minimised and the insulation's effectiveness increases.
The other factor that affects insulation is the amount of solar radiation that is absorbed by a building. The lower the absorption, the less heat builds up on the coated surface available for conduction. Aluminium has low absorption rates ranging from 30 to 50 per cent, whereas brick and concrete have an absorption rate of 65 to 80 per cent.
TeknCoat's W1 coating can be used to help provide effective thermal insulation. These coatings can be applied over a dry, plastered and cured surface and will act as a humidity barrier in extreme temperatures ranging from -40 deg C to 150 deg C and protect against moisture, water and corrosive salts.
During the application process, W1 should be allowed to cure for two to four hours and then followed by W2, which acts as an insulating barrier and is elastic in nature. W2 is a single-component polyurethane-based coating containing aluminium and calcined amorphous silica, which absorbs less heat and increases the reflectivity of rays falling on a building's surface. Thus, the build-up of heat is reduced and the insulation effect is increased.
Tekn W2 should be allowed to cure for 24 hours before the application of any decorative paints, or other such finishes.
TeknCoat offers a 10-year guarantee against any kind of paint peeling, that is, for any painting work carried out on the above protective coatings.
Wl and W2 are compatible with most paints available in the market. In some cases, Tekncoat supplies a special external weatherproof paint on request called Technotex.
TeknCoat's insulating coatings conform to technical specifications for thermal insulation systems set and approved by the Dubai Municipality (under administrative order No. 77 of 2001).
The specifications for insulation material for walls and roofs in article 9 are detailed below, and it can be seen how TeknCoat coatings meet and match them.
According to the specifications, materials used for outdoor walls and roof should:
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