Now imagine the look on their faces when you tell them that only 1 out of 7 of the homes constructed in their subdivision were actually inspected!  For the mathematicians out there, that comes in at just under 15%.  I suspect your new subdivision is less than pleased.

For those that don't know, sampling is an acceptable strategy for RESNET Sampling Providers to implement in order to certify a large amount of homes instead of testing each one individually.  There are many benefits to the builder (less cost) as well as the rater (charge per certification not per inspection) but there are huge drawbacks to this strategy as well.

Before we get started, there are rules to sampling... for instance you need a "first seven" or "first three" lots to pass consecutively before the sampling process can begin.  And if a home fails, you test two more... if one of those fails, you test the remaining "batch" of 7 homes.  I get all that, I once helped certify thousands of homes per year for ENERGY STAR.  And yes, it was all due to the sampling process.

The theory behind sampling is sound.  If you see a problem, you fail it and reinspect on the next houses that normally wouldn't have been inspected had the item passed initially.  It is built off the premise that if the same contractors are doing the work at all the houses, their craftsmanship should be the same.  This is problem #1.  

All framing/insulation/air sealing/etc crews are not created equal.  The construction industry in general is made up of a lot of temporary employees in large part to due to the volatility of our market with respect to the economy.  So assuming that one skeleton crew is going to outperform another is no guarantee.

The 2nd problem with sampling is that not all homes have the same design features.  So if the inspected home was a one story without a band joist but houses 3 and 4 of the batch are a two story home with a band joist-- there could be issues that go unnoticed.  This could be repeated several times before the problem is caught in a test home.  But once it's caught, there is no going back in time to fix the problems of the previously certified two story homes.  Those homes are flawed but receive the same certification and marketing label that the inspected homes receive.

Moving forward.  "Builder Sign Offs" are a method of allowing problems with a lot to be fixed and repaired without triggering sampling protocol.  The following passage from ENERGY STAR v3 Checklist Rev07 shows that you can have up to eight (!) problems and have them corrected and move forward... but what about the other six houses in the batch?  Do we honestly believe that all builders are going to go through and verify that each of these issues is being resolved at their other active lots?  And the problem with this oversight is the Builder Sign Off could be repeated again and again!