We have a project in Colombia South America 180 single-family homes, 1-floor design, to be built in 5 phases. 
For the project's energy rater,  midpoint, and final inspections: Are we allowed to sample the homes? or do the energy rater has to inspect each at the midpoint and final? (it would be cost prohibited without sampling). 
If sampling is allowed, what is the ratio?
Thank you