1. A low HERS Score touted.
A HERS Score standard by which a home's energy efficiency is measured. The HERS or Home Energy Rating System was developed by RESNET and is the nationally recognized system for inspecting and calculating a new home's energy performance. It is used to Certify Energy Star Homes, LEED for Homes and is recognized by the mortgage industry. The fact the the home has a HERS score means very little in a new home community. Why? It's because that HERS score was given to a model home which was tested by a HERS Rater, but that HERS Rater does not test every home in the community and the fact is that every home in the community needs to be tested. We have done energy audits on new homes less than one year old that supposedly had a low HERS Rating and found zero insulation above an office, unsealed ductwork, and direct connections to the attic from the interior walls of the house. Just because the model homes have a low HERS Score does not mean your home will have a low HERS score. You need to have a the HERS Rater or independent energy auditor come out to your home to inspect it was truly done right.
2. An energy efficient homes means the attic is well insulated.
Wrong again! Builder and their subcontractors will take short cuts even these days post housing bubble because no one checks their work and they are not liable to anyone but their share holders. If you are looking into buying a new build from a major builder you need to get in writing the R-value before you sign anything, while you still have some power over the builder. Insulating a house to code is not being energy efficient. We have a saying that code is the worst you can legally build a home. Many builders will actually just insulate the attic to code! You need to insulate up to Energy Star Standards per your climate zone. In Phoenix, Arizona we need our attics up to at least an R-38 and our code is R-30.
3. Builders cut corners by considering the drywall and ceiling wood frame as part of the insulation to give you even less insulation to reach the code.
That means if 10" of cellulose is R-30, a builder may only give you 9" of insulation because they are counting the drywall and wood stud to be a total of R-30, so you don't need that extra inch of insulation.
4. The R-value of the insulation is taken from the manufacturers specifications, not Energy Stars.
The manufacturer says that under laboratory conditions, an R-30 is 8" of cellulose. Energy Star, BPI and RESNET all state that an R-30 is 10" of cellulose. Who is right? The independent non-profit agencies or the private company?
5. Duct design best practices are non-existent.
The advantage of flex duct is that anyone can install it, the disadvantage is that no one knows how to properly install it anymore. A duct design can tell you what is required to deliver the air to each room but no one checks if the installation actually followed the Manual D Duct Design specifications or if airflow best practices were followed. This leads to a brand new home you paid for with hot uncomfortable rooms in the summer.
6. The windows are super efficient.
Even the best, triple pane gas filled windows are going to be the weak spot in the home, allowing for more heat gain and loss than any other area. Don't listen to the superintendent when they say you won't need shade screens or shading because the windows are so good. To that I invite them to sit in front of a sun struck window in the middle of July in Arizona and tell me how comfortable it is.
By being diligent in your homework and on top of your builder, you will increase your chances that your home gets built with the best quality you are paying for.