There are a lot of things you can do to improve the air quality in your home. Since you are in the process of building your house you may want to use steel contruction rather then wood as wood gives of moisture which can breed bacteria. Also you may look at hardwood floors instead of carpet for sure in your bedroom. Make sure you choose a prefinished floor, as the stains and protectants used by installers give off an abundance of gases or VOC's which are not good for the lungs. Central vacuum with the unit positioned in the garage will eliminate the off-dusting that occurs with regular vacuum cleaners. I would suggest you purchase dust covers for pillows and matress these reduce the amount of dust mites in your house as they feed of the dead skin that drops from you body when you sleep. In terms of air systems, I have a "whole house" system which includes the following parts that are installed directly to your furnace:1. Electronic air filter 2. Hepa air filter with a charcoal drum filter (the charcoal) is an add-on but it reduces the amount of VOC's3. HRV this constantly brings in fresh air into the house (in winter when the heat is on it reduces the amount of condensation on your windows which breeds mold and bacteria) turn it off during allergy season because you will continue to bring the allergens into you rhouse.4. Sanovox - this is an ultraviolet light that shines in your airducts to kill any air borne bacteria/viruses etc.5. Humdifier - make sure it a flow through (as apposed to drum) which keeps the humidity in the house b/n 40-50% (perfect for the lungs)6. Air conditioner to ensure the temperature remains constant.The systems works works very well. Typically the air outside is cleaner then the air inside your home, the last time I had the air tested the air outside my home was 1,500,000 million particle parts, while the air in my house was only 240,000 million parts.Hope this helps.