My family and I planned for a home renovation project in the beginning of 2015 to build more comfort and joy in the house. Each of us made a list of home improvement types that must be done. Mom and dad suggested new flooring installation and plumbing repair. My older sister put replacing wall paint in the list. I personally paid attention to the HVAC system especially air duct. Ideally, air duct cleaning and inspection is performed once or twice a year.