Omni Block is a patented insulated cementitious masonry unit (CMU) wall system which combines the benefits of indigenous aggregates, Expanded Polystyrene foam insulation, thermal lag (the delay, disruption and redirection of heat flow), exposed thermal mass on the interior side which allows the absorption of heat and air tightness. This combination results in a thermally efficient wall system with a high R-value and is consistent with well-known and widely accepted thermal performance concepts.