As the earthquake rescue and recovery comes to an end, Christchurch is shifting its attention to reconstruction.
Given the scale of damage wrought by a series of earthquakes, the city is faced with big questions about its future form. Initial estimates suggest that up to half of the inner city will have to be demolished. The number of condemned suburban houses is estimated at 10,000. Yet with characteristic pragmatism, many Cantabrians are looking for the silver lining in this dark cloud. This is a unique opportunity to rethink the inner city in light of what we now know about the environment, solving old problems and adopting new ideas on an ambitious scale.
Despite its green image, Christchurch has some long-standing environmental issues, particularly regarding air pollution, water usage, traffic congestion, and urban sprawl. In this regard, the national and local governments have already used the earthquakes as an opportunity to fast-forward existing environmental policies. The original September 2010 earthquake resulted in some 32,000 claims related to chimneys, with many old brick chimneys crashing through the rooves and floors of houses. Thus, the Energy Efficiency and Conservation Authority (EECA) arranged to cover the replacement costs of clean efficient heating systems by claims to the Earthquake Commission, the government-owned insurer for disasters. This simple policy advances Christchurch’s long struggle against smog, reducing emissions of climate-forcing black carbon in the process.
Also, since July 2009, the EECA has been encouraging the insulation of New Zealand homes by subsidizing a third of the total cost. With a large amount of repairs and reconstruction due in coming months and years, this is an unprecedented opportunity to improve the energy efficiency of the city, reversing the colonial legacy of thin walls and single-glazed windows. Whether home-owners take up the offer, however, will depend on their financial position, many of whom are facing job uncertainty on top of the burden of repairs. Certainly, as the city rebuilds over the next decade, the government could take a even more proactive role in encouraging warmer houses.
But the earthquake of February 22nd 2011, wrecking much of the inner city, has cleared the way for grander proposals. Suggestions are already being made and it is encouraging to note the prevalence of green ideas. One notable proposal imagines a low-lying inner city with interlinked rooftop gardens. There is also talk of wooden high-rise buildings of up to thirty storeys, a construction technique that improves flexibility and offsets carbon emissions from concrete production. The proposals reflect a widespread enthusiasm to not only solve some of Christchurch’s nagging problems, but to re-invent itself as an eco-city.
Whatever the eventual plan, though, the principal rule for reconstruction will be safety. Aftershocks continue to rock the city and are expected to continue for months or even years, a constant reminder of the seismic forces that buildings must tolerate. Emotions are raw, nerves are jangled—and this will inform all planning decisions.
Certainly, there will be little support for high-rises in Christchurch, a constraint for any advocates of compact vertical cities. Many high-rises that survived are now on irredeemable leans, tilting after the earth liquified beneath them. A friend told me that the building he worked in swayed so vigorously that it collided with the building next door, leaving visible scrapes at the top.
In one sense, then, the modern high-rises showed remarkable resilience, surpassing the earthquake conditions they were engineered for. However many are irreparably damaged and the collapse of two modern buildings— the Pyne Gould Guiness building from 1963 and the Canterbury Television building from 1975—accounted for many of the city’s predicted 182 deaths.
So the emphasis will is on low and light architecture, a style that will exacerbate the city’s tendency to sprawl. Coordinating this trend with principles of energy efficiency, especially in transport, is going to be a major engineering challenge. By rising to that challenge, however, Christchurch could become a flagship for future cities, built on what we now know about the fragility of the eco-system and the fragility of urban construction.