3. Air Flow. Proper air flow around the home is important for even and efficient distribution of conditioned air, so these LEED credits help builders ensure their homes are comfortable throughout. Foss said one common problem is poor duct installation—kinked or sagging ducts, long runs, or too many bends. Another is missing air flow return pathways in the bedrooms.

Foss suggested some fixes to avoid any issues during certification. First, use the duct design. Ducts are a commonly changed site-built item, but following a plan can avoid errors. Second, discuss what type of start-up the HVAC contractor will perform and how they’ll be on the hook for the design they gave you. Third, install dedicated return jumper ducts or transfer grilles in rooms with a door. Using the Energy Star Version 3 HVAC installer checklist and companion guidebook can help ensure installation is completed properly.

4. Air Filters. Be ready for inspection by walking the site and looking for any of the original blue air filters that weren’t replaced with higher-MERV versions. Foss said green raters often see this issue as an indication the builder may have missed other details. “If the builder isn’t clear on it, how will the homeowner know?” she asked.

5. Bath and Kitchen Fan Exhaust. Foss said a common problem is that homes don’t meet the exhaust fan testing requirements of 50 CFM for bath fans and 100 CFM for kitchen fans. The most common reason is that the builder buys a bath fan with too low of a nominal rating. You can’t just buy a 50-CFM fan to meet the requirements, she said, because the rating doesn’t take into account the ducting or other obstacles. You’ll often need an 80- or 100-CFM bath fan to meet the testing requirements. A common issue in the kitchen is improper installation of the microwave, preventing the dampers from opening. Make sure different trades are communicating to double check that the fans work after installation.

To diagnose potential problems, turn on the fans and listen. If it sounds wrong, Foss said, something is going on. Try the toilet paper test—the exhaust fan’s air flow should be able to hold up a square of it. And finally, double-check to make sure dampers aren’t painted shut at the exterior.