You have to absolutely love clients who really want green.

The concrete precast heating/cooling is really neat stuff. Canada's been doing it for a long time. We hoping to implement it on a few projects in Upstate NY.

Why I posted though. We need to redefine durability. I'd argue that 75 years is not durable! We can build for 7 to 10 generations, and longer, especially buildings like schools. We should be talking 300 year buildings, not 75.

JS, I completely agree with you on the 300 year buildings.
We should be putting more into our exteriors. Good solid well build to last. Make our cities look like Paris or Munich. The interiors can change with time and with needs.

I too was concerned about the 75 years of longevity, but realized that any current building over the age of 75 is not "green" in today's standards (high polluting or plain uncomfortable to reside/work in; therefore not used to potential). Buildings get torn down for growth and other sorts of development in a span much less that 75 years. To realistically look at the life of a building, accounting for developments in technology and sustainability is pretty smart in my opinon.

Just a note, munich was 90% destroyed in WWII, all those buildings are no more than 60 years old. Try Prague, they were built to last.

OK, It's Paruge then.

The longer the design life, the greater the acceptability of resource intensive materials: i.e.energy embodiment high.

Conversely, the shorter the design life, the more important easy recylcability becomes.

I don't quite agree with the longevity statement. As much as I appreciate 100 year+ old buildings, technological advances often make it impossible to retrofit them, and replacement is actually the greener option. A 100% sustainable proposal might not be possible for site X at the moment, but in 25 years it might - given the reality of fossil fuels running out and global warming - and make it without question off-grid (or even + power producing), carbon free and what not. If we build with huge longevities in mind, the incentive of replacing old clunkers and those that might look like them in a few decades are limited. And on another level aesthetics might also change to the degree that 300 year old looks might simply not be the desirable design in 2306 - if human kind makes it that long.
Having said that I would always encourage clever, sustainable quality, but let's keep in mind that architecture is also an evolving matter and like life itself it needs to embrace "dying" as well.

Building longevity is, to me, not a clear cut issue.

First, right now we have buildings with foreseeable lifespans. Even better and sturdier buildings will still have forseeable lifespans. Therefore, at some point, they'll have to be deconstructed and disposed of.

So, if we are going to have to deconstruct them anyways, maybe its a better idea to concentrate on creating a building that will have little environmental impact at the end of its life cycle.

So, if you had the choice between a building that would last you 70 years but would be difficult to dispose of in its 'grave' stage, or a building that will last you 40 years, but would be very easy to take apart, recycle, and build upon the land again, which would you pick?

Keep in mind, longer lasting buildings might not last as long as they're supposed to, anyways. The area might become urbanized and the space could be put to better use. Or, 30 years, current architechure designs could be way too outdated or impractical as platinum LEED type buildings become standard.

I live in an 80 year old apartment building. It has a classic design and will still look good in another 40-80 years (which can't be said about many of the new buildings going up). My heating bill is extremely low and I don't have to even use the heat for most of the year (just a few extremely cold days of the year).

By all means, we need to make building that last a long time. Not only does it save the labor used in rebuilding, but it also sets a style for a neighborhood (so people aren't always tearing down and replacing it with the hot-new-thing).

I understand your points, but still don't see 75 years as "durable" for a building.

I believe in this principle from Iroquois Great Law - “In our every deliberation we must consider the impact of our decisions on the next seven generations.” We're approximately 7 to 10 generations out from the design/build of the American revolution, and had generations followed that principle through time, through our industrial revolution, where would we be today?

Design will change, technology will improve...but looking at Europe's cathedrals and old buildings, I see a timeless sense of Sustainability in them. There's certain design elements that I'd argue are timeless. Sunlight. Natural daylighting.

Sure, if design for deconstruction achieves the best of cradle to cradle and Natural Step philosophy in separating technical and natural nutrients to eliminate Waste and positively balance embodied and other energy flows over a lifecycle, I'm all for it. That's ala McDonough's buildings as trees, cities as forests idea, where the idea of criticizing an apple tree for its multitude of blossoms is a ridiculous thing. Same goes for buildings...if building's could somehow grow, live and die as natural organisms co-adapted within the natural environment, then sure, no need to emphasize durability. I don't believe we're there yet.

But there's another aspect lost in a rapidly recyclable society...a sense of history, connection to community and anscestors. I live in Upstate NY and, only in incredibly rare areas, can I see the same Erie Canal weighlocks where my great-grandfather cared for Erie Canal horses. But if I can sense that history, be humbled by it, I can find that awe and inspiration necessary to build FOR future generations, to inspire future generations. I can see that in Europe's cathedrals and history. We're past the point of building London Towers. We know the benefits of natural daylight & ventilation, how to build positive energy buildings...why not take these timeless design elements and build forever.

Many times "progess" isn't necessarily progress. We knock down historical treasures claiming they're too expensive to fix. I'd argue that we don't measure costs accurately.

Maybe I just don't believe we need to be completely consumeristic in our built environment, always trading in our current model for the next with a few improvements, even if sustainable. We should design for adaptability sure, but why adapt to new buildings with engineered stone or brick veneers (even if 100% recycled, forgetting the embodied energy equation for a second), when at least some of us are surrounded by those stones and bricks built by our ancestors out of optimism, love and inspiration for their children?

That and I just see some aesthetics as timeless. I think we too often lose sight of the fact that the most sustainable thing to do is not consume, at least until we do achieve 100% C2C. So that next generation recycled IPOD case or carbon offset company reduces environmental impact, but it certainly doesn't create any positive one...but when you are awed by history, you tend to want to preserve the future. I'd rather see the building that my great-great grandfather built than say, "my great-great grandfather completely recycled his building on that site!"

I think Treehugger ate my last comment?