A couple of recent posts on people looking for power bricks caused me to wander the web looking for the appropriate efficiency standards in the US. From what I could glean:Energy Star 5.2
for computers is the current version (effective July 2009). Energy Star 6 specs are under review, but, there aren't any improvements to the internal PSU or external power supply efficiencies. As an aside, the current internal PSU specs are equivalent to 80+ bronze.
The version 2.0 external power supply spec can be found here
and has been in place since Nov 2008.
Here's the formula for external AC-AC and AC-DC bricks, if you don't want to wander the pdf.
Output power Efficiency
1W or less (0.48 * Power out) + 0.14
>1W to 49W (0.0626 * Ln(Power out)) + 0.622 or better
>49W 87% or better
1W -> 62%
10W -> 76.6%
20W -> 81%
30W -> 83.5%
40W -> 85.3%
I've also seen a reference to the California Energy Code Level 5 and 87% efficiency at load...but don't have the heart/patience to find/slog thru the documents.
So, that's the baseline for finding a brick that doesn't have crappy effiiciency. Seems like the fortron, etc bricks are already at 87-90%.
In the EU, there is Commision Regulation 278/2009 that was implemented in April 2011 to meet the same Level V spec.
I did come across this little tutorial
on wall plug adapters from CUI on Digi-Key's website.