Overview
ASHRAE has announced a 90.4-2025 edition that expands the standard's scope beyond just energy efficiency to include greenhouse gas emissions and water usage. ashrae 904 pdf upd
Standard 904 provides a standardized mathematical method for comparing two or more HVAC&R system alternatives. It moves beyond "first cost" (the purchase and installation price) to calculate the Life Cycle Cost (LCC). The standard accounts for: Overview 3