DP is design pressure. There is a forumula, but generally the greater the DP, means it keeps wind and water out better. If you were in Florida in Dade county, the building code would specify a DP 70. For this reason most buidings (commercial or residential) have aluminum windows, (not clad, but all aluminum). They resemble commercial windows even in homes.

Any casement, (crank out) by any manufacturer will be better at keeping wind and water out. Instead of sliding up and down like a double hung, the close like a hatch on a boat.

A 40-50 rating is fairly common for most American made windows depending on style. (DH vs case). With all things equal, (U rating) and price / asthetics. a window with a higher DP rating is likely better constructed to achieve that rating.

Champion is a pretty decent quality window as is Simonton. DP means Design Pressure. Generally any window with a DP rating of 50 is a pretty sturdy window and will serve you well for your purpose.

I am curious why you are considering the Simonton Pro-Finish over the Reflections 5500/Prism Platinum or 7300 or 7500 if you are in the Western US?

I would also check with your contractor about those energy numbers. I don't believe any of the Pro-Finish line has an overall U-factor of .28 nor do they qualify for the tax credit.

Here's a link to Simontos website where they list which windows qualify.

Here is a link that might be useful: Simonton Tax Credit Qualifying Windows

Thank you for reviewing my posting. We are just building and new constructions does not qualify for the tax break. Also the 5500 is primarily for replacement although it can be used in new construction.

I am in Texas and when I contacted the Simonton rep I was told the main difference is in the warranty but performace compared to the 5500 was about the same. She said this was because of the window package added to the profinish selection.

The "west side" of the home which includes a picture window pre-mulled-medium between two 3X5 single hung windor. The notations state...reinforced, double strength, double glazed, argon, Low-e Softcoard ProSolar. U-29 and SHGC 30. I did notice none of my other windows meet the qualification and note "regular strength, no reinforcement, U32 SHGC 28.

The price difference for the 5500 was notable but we may still consider them. Thanks for suggesting them.

You noted Champion was decent compared to the Profinish. Do you thing the same when comparing them to the 5500 series?

Thanks again for you input.

If I had to choose between the Pro-Finish and the Champion with 365 glass, I'd go with the Champion. If I had to choose between the Champion with 365 glass and the Simonton 5500 with the 366 Solar System glass including Super Spacer, I'd go with the Simonton.

How do I know what the air and water filteration measurements are?

Since AAMA doesn't post the results anymore, I would let the DP rating be my guide. DP ratings are based partially on water infiltration but not air infiltration. However it's unlikely a window with a DP 50 would have a high air infiltration rate.

A DP50 rated product is good for 140 MPH wind zone.