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What I find interesting here is the idea that we don't necessarily have to destroy the "undesirable" structure but rather rethink how it can be used.
A video presentation of the proposed changes (author's note: who the hell thought it'd be a good idea to use a smooth-jazz instrumental version of a Coldplay song? Recommended volume setting: Mute) can be seen here:
http://www.ranwebber.com/Movie/skywaymovie.html
Ran Webber's proposal is ambitious but I think the basic idea is a good one, especially in cities with underutilized infrastructure. (Anybody know what's happening with the pyramid in Memphis these days?)
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Maybe this ability to adaptively reuse old structures should be considered in urban change modeling. Something conceptually simple to think about is the function of buildings in a region and how they serve a local population. Structures that have fallen out of use could be potential locations for adaptive reuse or a replacement structure (based on economic/ecological costs). Of course an implementation would need to take into account a diverse and dynamic population with different perceptions of the region and other social factors - but this could be an important part of representing dynamic urban landscapes in long-term urban simulations.
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As energy costs continue to increase, the utility of demolition is something to consider. If a structure is physically sound, then the total costs (including supply chain costs) of completely replacing it may not be feasible. I'd be interested in seeing a comparison of the environmental impact of demolition and replacement versus adaptive reuse.
Are there any neglected (but stable) structures in your city that could be adapted? When do you think adaptive reuse would be a good strategy? When might it not be? Is this just another form of gentrification?
Website on adaptive reuse: http://adaptivereuse.net/