The goal of this Tech Set is to decrease the cost of construction, while improving the maintenance and energy efficiency of housing by promoting the effective systems integration of the conditioned air delivery network into the structural framework.
In this section, we examine in detail how to best implement the recommendations from this Tech Set.
The IRC requires that the heating and cooling equipment be sized based on building loads calculated in accordance with ACCA Manual J® or other approved calculating methodologies. ACCA's Manual J is now published as Edition 8 (MJ8™) and four Addenda to this Edition are currently available. Each Addendum covers design features of MJ8™ that can be undermined by making assumptions about the facts of construction. Using old editions of the Manual and failure to input actual design conditions could result in a design that is inefficient and uncomfortable-meaning unhappy customers and costly call backs.
Typically, Manual J calculations are performed by the HVAC subcontractor, and submitted with the filing for a mechanical permit while the house is under construction. However, the design process should include the HVAC subcontractor at the design stage. Larger ducts can be accommodated in the floor plan and energy performance details of the structure can be adequately communicated to the HVAC designer. This will ensure that the system is designed as efficiently as possible, and will likely decrease the time it takes to install the ducts and reduce the equipment size-both of which will lower costs.
Develop a User's Guide
We recommend that builders provide equipment specs and a User's Guide for homeowner that includes a regular maintenance schedule for equipment tune-up and efficiency calibration. This guide should also include an isometric of duct layout for the owner's efficient use of register grilles to balance airflow within the home.
Content updated on 12/7/2005