On September 4, 2010 a magnitude 7.1 earthquake struck New Zealand’s third most populous urban area, Christchurch. Despite the damaged infrastructure, no casualties were reported.
On February 22, 2011, nearly six months after the first earthquake, Christchurch was struck with a magnitude 6.3 earthquake. The epicentre was located close to the city centre and at a depth of just 5 km (3 mi). The shallow depth and previously weakened infrastructure lead to the collapse of many major buildings within the city and the death of 182 people (NZ Police).
The six storey Canterbury Television (CTV) building, which was declared structurally safe after the 2010 earthquake, collapsed and killed 115 people. A report released by New Zealand’s Department of Building and Housing after the collapse claimed that the structure, built in 1986, was not up to either previous or current standards (New Zealand Ministry).
Cantebury Television Building After the 2011 Earthquake. Photo Credit: news.com.au
The aftermath of these two earthquakes brought the city to a halt, and a ‘Red Zone’ perimeter was established to keep people away from the damaged infrastructure. However, the city of Christchurch has since made huge progress in bringing life back into the city centre. As part of re-building the city, architects and engineers have used the blank canvas to develop new, cutting edge building techniques.
In my previous post entitled “Cardboard: An Alternative Construction Material“, I profiled the new cathedral that was constructed out of cardboard. In addition, a new shopping complex has been constructed in the city centre using recycled shipping containers. The project, which was completed in just eight weeks, has help bring life back into the city. The construction and opening of the shopping complex are presented in the following documentary.
In the past few decades, the terms ‘green’, ‘eco-friendly’ and ‘sustainable’ have emerged as buzz words used to market new products and ideas. Their grasp has not evaded the building industry, as more and more projects are now using ‘sustainable’ construction practices. However, in order to build sustainably, one must be able to define it. In 1987, the United Nations defined sustainability as, “development that meets the needs of the present without compromising the ability of future generations to meet their own needs” (United Nations)
In 1998, the U.S. Green Building Council (USGBC) developed the Leadership in Energy and Environmental Design (LEED) program to act as a third party recognition for green buildings. By using a pre-set rating system, buildings can earn points which allow for different levels of certification (Certified, Silver, Gold and Platinum). It has been proven that the use of the LEED system can lead to lower operating costs, increased asset value, reduction in energy/resource use, and healthier/safer environment for occupants (USGBC). In addition, meeting LEED standards allows buildings to apply for money-savings incentives and tax rebates.
In the United States alone, USGBC estimates that more than 4.3 million people live and work in LEED certified buildings. It is also estimated that 44% of all commercial and institutional construction in America is “green”, the majority of these associated with the LEED program. USGBC estimates that this percentage will surpass 55% as early as 2016 (USGBC Report).
International Implementation
Due to it’s success, the LEED certification program is now being implemented throughout the world. Taipei 101, located in Taiwan, is one of the tallest buildings in the world and boasts a LEED Platinum certification.
One of the key features of Taipei 101’s environmentally friendly setup is a 30% decrease in potable water usage (compared to average building consumption), saving about 28,000,000 litres of potable water annually (USGBC Taipei 101 Summary).
Canada’s Response
In 2002, Canada developed the Canadian Green Building Council (CaGBC). The CaGBC acts similarly to the USGBC, providing resources to projects aiming for LEED certification, as well as training LEED accredited professionals.
This has lead to an increasing number of LEED certified buildings throughout the country. A building located in Waterloo Ontario was one of the first student residences to achieve LEED Platinum accreditation. Despite costing the developer 10% more to build than traditional construction, this building boats low energy consumption and very low maintenance costs (The Record). In addition, the Waterloo region has a number of other developments looking to achieve similar LEED credentials. This is a promising sign for Canada’s version of ‘Silicon Valley’.
In Vancouver, a construction permit has been submitted for what will be one of Canada’s tallest office towers with LEED Platinum certification. Construction of the $200 million building will begin in October, and is expected to be completed in 2017 (CBC Report).
Proposed ‘Green’ Offic Tower in Vancouver. Photo Credit: Buzz Buzz Home
The new tower will use half the energy of traditional office buildings that are similar in size, greatly reducing the operating costs for tenants. This marks the beginning of what many hope will be the ‘green revolution’ in Vancouver. Herbert Meier, director of real estate asset management for the project stated, “We believe in Vancouver’s economy and its future…We believe in supporting the City of Vancouver’s vision to become the world’s ‘greenest’ city by 2020.” (CBC Report)
It is apparent that the current standards for construction are inadequate. As a result, the industry must continue to embrace the ‘green’ movement by implementing new techniques. It is encouraging however that as the industry begins to incorporate the principles set forth by LEED, cities will begin to finally take action on the growing issue of climate change.
Precisely placed explosives have traditionally been used in the demolition of old buildings. Over the years, the process has been refined, and buildings are now demolished with minimal disturbances to adjacent structures. An example of this is the Landmark Tower in Fort Worth, USA, which was demolished in 2006. The below video captures the elegance of the buildings demolition:
Despite advances in the industry, there are many issues associated with this type of demolition. For one, the explosions cause dust and debris, and the clean up process can be quite gruelling. In addition, buildings demolished in dense urban areas run the risk of causing damage to nearby structures. In 1997, the implosion of the Royal Canberra Hospital in Australia killed a spectator after debris was thrown over 400m (Canberra Times Report).
As a result, researchers in Japan have developed a safer process for demolishing buildings in dense areas. Instead of imploding the building, it is disassembled from the top down. A multi-storey scaffolding system is used to hide the demolition of individual floors. Columns and beams are removed, and temporary jacks are used to lower each floor, leading to minimal disturbances to nearby infrastructure. The process can be seen in this CNN report:
This process, although slow and costly, does circumvent much of the risk traditionally associated with building demolitions.
Recycling Demolition Waste
One of the biggest concerns with demolishing older structures is disposing of the old material. To deal with this, the crushed concrete by-product of demolition is now being collected, cleaned and reused as aggregate in new concrete structures (Concrete Recycling). This process provides a number of benefits, including: a reduction in disposal and transportation costs, minimal project carbon footprint, and an increase in the projects efficiency as the aggregate can be re-used directly on site.
However this process is impractical and cannot be used in the majority of construction projects. In addition, a tremendous amount of water is used to prevent dust from the demolition. As a result, researchers have been looking to refine the process.
Omer Haciomeroglu, a recent graduate of Umea Institue of design in Sweden, has developed a revolutionary design for recycling concrete on site (International Design Excellence Awards). The idea is simple: by pumping high pressurized water, the concrete is crushed into smaller pieces, and the the water-concrete mixture is collected. This slurry is then filtered, and all the aggregate retained from the process is sorted and bagged on site. The water from the slurry is later used as grey water to clean the site after demolition. By not using highly destructive methods, the reinforcing bars can be recycled for future use.
New Concrete Vacuum Creates “Clean” Solution to Concrete Recycling. Photo Credit: Gizmodo
This product, despite only being in the concept stage, is the catalyst that the industry needs. As new ideas for safer, more environmentally friendly processes emerge, the risk associated with building demolition can be mitigated, and future disasters can be avoided.
