[BLDG-SIM] "Cool Roofing"

[Marcus Sheffer <sheffer@xxxxxxxxxxxx>]

Whenever we have modeled this in the Northeast we also have seen
negligible savings using PowerDOE and others.

We have come to the conclusion that the savings depend upon the amount of
roof insulation and type of building.  If we enter minimal
insulation the effect of a white roof is larger especially in a cooling
dominated building, high internal loads, etc. 

If you are installing even moderate amounts of insulation (R15 or more)
then the effect of a white roof in the Northeast is virtually nil for
most any building type.

Now when it comes to the urban heat island effect it can have a
tremendously positive impact . . . but that is another issue.


At 01:55 PM 10/07/2002 -0400, you wrote:
> Has
> anyone had any success modeling cool roofing options (i.e. reflective or
> light colored surfaces) in PowerDOE?  So far, I have seen negligible
> results from the adjustment of roof construction absorptance values
> (emissivity is also known to play a role, but there is no input for this
> in PowerDOE).  I have seen data showing cooling energy savings from
> 0.06 to 0.54 kWh/sqft/yr, depending on building type.  I am getting
> only a very small fraction of this.  Data collected in the study was
> from facilities in the southern and western US, and I work primarily on
> buildings in the Northeast.
>  
> My questions:
> How well can I expect PowerDOE to simulate
> this?  Is there a better way to simulate cool roofing?  Is the
> sun simply too low in the sky in New England to yield substantial
> savings?
>  
> Your thoughts are appreciated.
>  
> Wade McLaughlin
> DMI

Marcus B. Sheffer                          energy & environmental consulting
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