A trained and certified HERS rater may do an audit either by visiting the home or by using blueprints.
Many quality builders will have their plans rated prior to construction. This allows them to make design choices that will give their customers the benefits of owning an energy efficient home and also be economical and affordable.
The rater determines what elements are designed into the home and how these will affect the performance of the home. The area of the walls are measured. The construction of the walls is determined, including the framing, insulation levels, sheathing, siding, drywall, etc. This allows the heat loss/gain through the walls to be calculated
The size, type and orientation of the doors and windows are determined. Choices can then be made regarding upgrading the quality. The orientation of the home may be changed to take into account the solar gain through windows.
The type and size of the heating and cooling equipment are either entered based on the specifications, or a better choice is to let the computer program calculate the necessary size. This ensures proper sizing and maximizes the efficiency and comfort of the home.