Rebar and grout frequency can significantly alter the thermal performance of a wall system. Omni Block (with the assistance of the Masonry Institute of Michigan) has developed an accurate short-cut to determine whether or not Omni Block will prescriptively meet the International Energy Conservation Code (IECC) per ASHRAE 90.1 (2013).

The tan fields contain value options in their drop-down menus. Select the options that meet the design criteria of your specific project including the climate zone per ASHRAE 90.1.

Step 1: Select either 8 or 12 in the top drop-down menu cell. 8 means Omni Block System 8 and 12 means Omni Block System 12.

Step 2: Select the expected concrete density. Lightweight concrete density starts at 85 pounds per cubic foot and ends at a heavyweight density of 135. The heavier the concrete the less the thermal performance.

Step 3: Enter the expected vertical rebar frequency. For this calculator the cell frequency matters, but the size of the rebar does not.

Step 4: Enter the project’s climate zone or region per ASHRAE 90.1.

The maximum allowable U-factor per ASHRAE 90.1 is automatically entered in the bottom cell.

As long as the resulting Corrected U-Factor field is green, Omni Block passes the International Energy Conservation Code prescriptively.