Ashrae 90.4 Pdf

If you work for a large engineering firm or a data center operator, check your internal document management system. Many firms purchase site licenses for ASHRAE standards.

Even with the ASHRAE 90.4 PDF in hand, engineers frequently make these mistakes:

Choose your cooling strategy (DX, chilled water, economizers, liquid cooling). Calculate your proposed mechanical power draw at design conditions. If your Proposed MLC ≤ Allowable MLC – you comply. ashrae 90.4 pdf

There are three primary reasons why the PDF version is highly sought after:

ASHRAE 90.4 uses the same climate zones as 90.1 (0 through 8). But unlike 90.1, the MLC allowance varies significantly. You must look up your location in the PDF’s annex tables. If you work for a large engineering firm

What if your data center occupies one floor of an office building? Solution: You must submeter the data center exclusively. The standard allows you to exclude the non-data center loads from the calculations.

This is the heart of the standard. The MLC limits the total mechanical system power (fans, pumps, chillers, compressors) relative to the Critical IT Load (CITL). The formula is simplified as: The allowable MLC varies based on your location's

The allowable MLC varies based on your location's Dry-Bulb 0.4% temperature (a statistical weather metric). Colder climates allow higher MLC (because compressors work less often), while hot climates have stricter limits.

A: No. It is a consensus standard. It becomes law only when a local or state building code adopts it by reference (e.g., California Title 24, New York City Local Law 97).