Duct Systems In New Homes
If you are building a new home, you have the opportunity to make sure that the duct system will deliver "top-notch" comfort and efficiency by specifying to the builder that you want a leak-free, insulated duct system. Even better, discuss with your builder the option of locating the ducts within the conditioned space and hiding them so that they don't show. It is possible to box in ductwork installed near the intersection of a wall and the ceiling, or to use other builders' tricks so that the raw duct materials will not be visible. This isn't as tough as it might seem because an energy-efficient duct system in a energy-efficient home can be less bulky than a "standard" duct system. This is because the heating and air conditioning loads are smaller permitting the use of a smaller furnace and air conditioner which requires less air flow through the duct system.
When it is possible to reduce the size of the duct system and the central unit, you save on equipment, materials, and installation costs, (possibly enough to pay for the cost to hide ducts that are located within the conditioned space). In that case, energy savings will begin immediately. Even if some additional cost is involved, a duct system properly installed inside the conditioned space is energy-loss-free and will likely be one of your best investments.
The ductwork should be designed to provide adequate airflow to each area of your home. Too often, contractors rely on rules of thumb, such as a four-inch diameter duct for a bedroom, rather than calculating the optimum-size duct to meet the specific heating and cooling needs for a room. Insist that your ducts be designed using industry standards (i.e. Manual D, published by the Air Conditioning Contractor's Association).