Has anyone tried a simulation with insulating ceramic paint additive?
How does USGBC think about this for LEED? How is the R value defined?
I appreciate any comment or suggestion about this.
I'm pretty sure the ceramic additives do not really affect R-value. They affect the emittance of the paint surface (low-e paints use this). As far as I know you cannot account for surface emittance in eQUEST.
I'm not saying that it doesn't work or it doesn't have benefits - however you need to be careful when you mix thermal metaphors. It may be ok to assume an added R-value for this paint, but I doubt it. Its probablye more effective in hot climates than in cool climates - but additional R-value will have more effect in cold climates than in hotter ones. (this is a guess - I haven't done any simulations to support this).
Other simulation programs like E+ or IESVE might be able to simulate emittance better, but I can't speak to that.
I have no experience using ceramic paint additives. This document
provides some engineering background, and also concludes that, "the
benefit of this product over time on exterior walls... very likely may
be small.":
You can, however, try modeling this in eQUEST. Using the values
discussed in the link, adjust both the absorptance and emissivity of the
walls. ABSORPTANCE - CONSTRUCTION is a property of the exterior wall
construction. OUTSIDE-EMISS - EXTERIOR WALL is under the Daylighting -
Shading - Other tab of each wall surface.
You will probably find that the energy impact is minimal, and therefore
not cost-justified. Appendix G only allows for different absorptance
(1-reflectance) for white/cool roofs, and does not address emissivity.
Therefore, I think you would have to submit a CIR with good supporting
documentation to justify using different absorptance and emissivity
values for the Proposed and Baseline exterior walls.
I thought I should share this article about ceramic "insulating" paints from
GreenBuildingAdvisor.com. The author had done significant research pointing
to his conclusion that insulating paints are a scam. Apparently they do not
qualify as low-e coatings either. It's worth reading the comments at the
end as well, where various people likely to be associated with the product
attempt to argue with Holladay's points but provide no scientific evidence
of their claims.
Thanks all! Background on the project: Non profit police station in a
low budget neighborhood in a tropical and warm climate. Walls are
specified as hollow concrete block only, and compared to a R-13 wall,
heat transfer is somewhat higher. I was trying to seek cheap
alternatives for this, since there is no budget to add additional
insulation layers. I'm guessing filled block would be a better option
then.
Yes it would help or try external shading devices to stop the solar loads on the walls and windows from penetrating into the occupied conditioned spaces of the building. This is a passive solar design approach to consider.
If the project is going for LEED you're going to want to try to exceed the
assembly R-values specified in the 90.1 baseline for your climate zone.
The example assembly calculation in my ASHRAE Fundamentals for filled
concrete block shows a value of approximately R-3. Assuming you are
cooling the building, the Design model will use a lot more cooling energy if
you have almost no insulation compared to the Baseline. Pashalu's
suggestion of shading to mitigate direct solar gains is a good idea but it
won't stop heat transfer from high delta T's between the indoors and
outdoors.
Another way to reduce heat gain is to build a vented rainscreen type wall assembly and use stack venting to remove additional heat from solar gain. The stack venting will not get you below outdoor air temperatures though - so you will still have to deal with basic delta Ts. However - if it's a tropical climate you might not have a huge delta T.
I'm pretty sure the ceramic additives do not really affect R-value. They affect the emittance of the paint surface (low-e paints use this). As far as I know you cannot account for surface emittance in eQUEST.
I'm not saying that it doesn't work or it doesn't have benefits - however you need to be careful when you mix thermal metaphors. It may be ok to assume an added R-value for this paint, but I doubt it. Its probablye more effective in hot climates than in cool climates - but additional R-value will have more effect in cold climates than in hotter ones. (this is a guess - I haven't done any simulations to support this).
Other simulation programs like E+ or IESVE might be able to simulate emittance better, but I can't speak to that.
Good luck.
-Vikram
Federico,
I have no experience using ceramic paint additives. This document
provides some engineering background, and also concludes that, "the
benefit of this product over time on exterior walls... very likely may
be small.":
http://www.energy.wsu.edu/documents/AHT_Insuladd%5B1%5D.pdf%20Ceramic-ba
sed%20paint%20additive.pdf
You can, however, try modeling this in eQUEST. Using the values
discussed in the link, adjust both the absorptance and emissivity of the
walls. ABSORPTANCE - CONSTRUCTION is a property of the exterior wall
construction. OUTSIDE-EMISS - EXTERIOR WALL is under the Daylighting -
Shading - Other tab of each wall surface.
You will probably find that the energy impact is minimal, and therefore
not cost-justified. Appendix G only allows for different absorptance
(1-reflectance) for white/cool roofs, and does not address emissivity.
Therefore, I think you would have to submit a CIR with good supporting
documentation to justify using different absorptance and emissivity
values for the Proposed and Baseline exterior walls.
Regards,
Bill
Federico,
I thought I should share this article about ceramic "insulating" paints from
GreenBuildingAdvisor.com. The author had done significant research pointing
to his conclusion that insulating paints are a scam. Apparently they do not
qualify as low-e coatings either. It's worth reading the comments at the
end as well, where various people likely to be associated with the product
attempt to argue with Holladay's points but provide no scientific evidence
of their claims.
http://www.greenbuildingadvisor.com/blogs/dept/musings/insulating-paint-merc
hants-dupe-gullible-homeowners
And this one:
http://www.greenbuildingadvisor.com/blogs/dept/musings/insulating-paint-sale
sman-tripped-his-own-product
Hope this helps.
Rosie
Roselin Osser, BEMP, LEED AP
Thanks all! Background on the project: Non profit police station in a
low budget neighborhood in a tropical and warm climate. Walls are
specified as hollow concrete block only, and compared to a R-13 wall,
heat transfer is somewhat higher. I was trying to seek cheap
alternatives for this, since there is no budget to add additional
insulation layers. I'm guessing filled block would be a better option
then.
Thanks,
Federico
Yes it would help or try external shading devices to stop the solar loads on the walls and windows from penetrating into the occupied conditioned spaces of the building. This is a passive solar design approach to consider.
Pashalu
Hi Federico,
If the project is going for LEED you're going to want to try to exceed the
assembly R-values specified in the 90.1 baseline for your climate zone.
The example assembly calculation in my ASHRAE Fundamentals for filled
concrete block shows a value of approximately R-3. Assuming you are
cooling the building, the Design model will use a lot more cooling energy if
you have almost no insulation compared to the Baseline. Pashalu's
suggestion of shading to mitigate direct solar gains is a good idea but it
won't stop heat transfer from high delta T's between the indoors and
outdoors.
Rosie
Another way to reduce heat gain is to build a vented rainscreen type wall assembly and use stack venting to remove additional heat from solar gain. The stack venting will not get you below outdoor air temperatures though - so you will still have to deal with basic delta Ts. However - if it's a tropical climate you might not have a huge delta T.
Vikram Sami, LEED AP BD+C