Heat exchange

Christopher Sell looks at where companies are going wrong and how modern cladding techniques and materials can alleviate this.

ANALYSIS, Materials

As temperatures in the region almost touch 50 degrees centigrade, the performance of a building, and more specifically its ability to modulate and moderate its temperature, is especially important. In the summer months in the Middle East, a building's make-up, particularly its cladding, comes to the fore, with poorly constructed buildings and the use of inadequate materials resulting in massively inefficient energy usage.

 

Regarding facades, there should be no excuse for using light flammable material.

"Hot countries often have poor insulation standards in planning and application," says Marco Vincenz, general manager, Pittsburgh Corning Europe - Middle East. "When you hear that cooling needs 30% more energy than heating, it is not surprising that the use of energy in hot countries is higher than in the cold northern European countries for temperature regulations in buildings."

The façade is the biggest surface of a building and contains huge potential for bringing the right solution, both ecologically and economically, for a building, Vincenz adds. But the fact is that 50% of thermal performance is lost through poor construction, due to employing cladding systems that are not adapted to the demanding climatic conditions of the region, such as wind, humidity and heat.
 

This issue is exacerbated by a lack of awareness over poorly fixed insulation and its impact on building efficiency.

"Nobody considers wind forces during application and everybody is happy to cover the insulation layer," says Vincenz.

"This function should be checked by the party in charge, otherwise the client could win or lose money in the future. The high humidity in the months of July to September is miserable as much for the construction materials as for the insulation. A good working vapour barrier is a must, and it must be joint-less," says Vincenz. If this is not in place, hot wet air flows to the cool wall and condensates. It is estimated that insulation with 3% moisture absorption will reduce thermal performance by 50%.

"Because of the air tightness of Foamglas we don't face air flow in the material and even with additional adhesive on the back wall, air flow is totally prevented."

Foamglas is a cellular glass insulation used in buildings for facades, roofs and floors.

Fire prevention is also a major consideration for cladding manufacturers in Dubai. But regulations are changing, with an adherence to British standards being introduced in the future. "Regarding facades, especially for a high rise building, there should be no excuse for using light flammable material," adds Vincenz.

Ultimately, if anything is to be changed, a significant shift must take place in the mindset of those in the industry. If anything, there is more concern to ensure approval is obtained and regulations met than ensuring the product is the most effective.

To some extent, this can already be seen in the emirate's changing emphasis on cladding materials. Over the last few years companies have begun to tailor their production to meet with developer's demands.

"Over the last five years we have seen a growing preference and change in the cladding industry, from the use of traditional cladding materials such as stone, marble, granite and solid aluminium sheets to aluminium composite panels (ACP)," explains Mehul Raj, project manager, Almaxco.

"ACP is a much more cost effective solution than these other materials. It is lighter, hence allowing less dead load on the building, which allows less structural support resulting in lower construction costs. It is also a good insulating material allowing heat from outside the building to enter, thus reducing utility bills."

Having been involved in projects in Dubai, Ras Al Khaimah, Abu Dhabi, Kish Island (Iran), Doha and Sharjah over the past five years, Almaxco estimates that the annual requirement of ACP in the UAE market alone is between six to eight million m2.

Dubai's growing demands on materials has seen the company expand its production capacity from 8000 m2 to 13,000 m2 per day. It recently acquired new land adjacent to the existing factory where there are further expansion plans to increase to one more paint coating line and two more compositing lines. This will be completed by the third quarter of 2008 and will bring daily production capacity up to over 18,000 m2 per day.

Cladding is also not impervious to the growing demands for a more sustainable and environmentally sound outlook on construction and building in general. Almaxco has budgeted in excess of $1 million for 2007 and Raj explains that the company has a panel of in-house and contracted engineers from the industry to improve production procedures and development of new products.

Besides the normal PVDF and polyester coated panels, Almaxco has also introduced a new range of anti-bacterial panels which are used in clean room environments for industries such as semi-conductor manufacturing facilities, hospitals and laboratories. The company has also developed a nano PVDF coated composite panel. This water-based polymer is applied as a fourth coating, shielding the three-layer PVDF by preventing dirt or pollutants emitted from cars and the environment from penetrating into the air gaps between the PVDF paint molecules, hence repelling any dirt or soil.

"This allows the paint to remain bright and look like ‘new' for a longer period of time and drastically reduces the cost of maintenance of the building after construction is complete, as there is no requirement to use expensive and environmentally unfriendly chemicals to clean the building. Pure water or rain will simply wash off the dirt from these panels, allowing the buildings to look good for more years than the standard PVDF panels which is what is currently used on most buildings.

"I can't speak for other manufacturers but we are constantly investing in R&D to introduce a newer range of products, colour offerings, finishes, and looking for methods to produce more green products, which are bio-degradable and recyclable."

The popularity of ACP panels in the future, coupled with material price rises, is going to impact heavily on the market, with Raj estimating an increase in demand for ACP of between 25-35% in the next 12-18 months. This will be compounded, he adds, through price increases of oil and aluminium as well as freight costs.

Furthermore, China - the world's largest supplier of painted aluminium coils, announced on 1 July plans to reduce tax incentives on exports. "Such actions will continue to put pressure on pricing for all manufacturers regardless of where they are made, hence there is going to be an upward trend in pricing in the coming 12 to 18 months. The use of ACP will continue to grow as this is the best cladding out there and construction is growing at a pace never before seen in history."

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