When we did life-cycle costing for non-structural building elements and 
equipment, we used 30 years as the basis for calculations on maintenance 
and payback costs. Some of these calcs were done on materials 
(partitions, etc) that we were proposing to replace in a building with 
some years on it already, so I'm not sure if that is a rule of thumb for 
new construction or not. Some of this was done to encourage customers to 
think along these lines instead of what's cheapest right now.

At this time we use 30 years for payback calculations for photovoltaic 
arrays when educating consumers about energy options. We use 25 years 
for solar thermal applications.
~deb

Martin C. Tangora wrote:
> I'm a couple of weeks behind reading my Pinhead digests,
> but I think I have something for Rudy Christian.
>
> A friend of mine, a lawyer with a strong interest
> in planning and preservation, was told by one of the partners
> in SOM, back around 1975, that the Sears Tower 
> (or whatever its new name might be)
> is "a 75-year building."  I guess as of 2009 
> it's about a 40-year building.
>
> Apparently in "modern" architectural "theory"
> one sets out the expected lifetime of a building,
> which then affects the planning of its systems.
>
> This is one of the ways in which 20th-century architects
> made progress over the cathedral builders.  Or not.
> Possibly the recycling culture will cause
> some rethinking.  Or not.
>
> But I ramble ... Have you all (or all y'all)
> heard this kind of tidbit about other buildings?
>
>   
>> Date:    Sun, 1 Mar 2009 17:27:44 -0500
>> From:    Rudy R Christian <[log in to unmask]>
>>
>> OK. I’ve stayed out of this so far but can no longer resist.
>> What is the target date for required maintenance
>> on everything we create or restore? Shouldn’t we be looking at
>> both new build and maintenance as something we judge in centuries not decades?
>>
>> Grumpily confused Rudy
>>
>>     
>>> It would not be uncommon to do 100% repointing on a building of this age ... .
>>>       
>
> Martin C. Tangora
> University of Illinois at Chicago
> [log in to unmask]
>
> --
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>
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>   

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