scope:

FOREWORD

The intent of this addendum is to reduce inconsistencies between ASHRAE Standard 90.4, Energy Standard for Data Centers, and ASHRE/IES Standard 90.1, Energy Standard for Buildings Except Low-Rise Residential Buildings. A broad overview of the changes is given below.

• Section 3, "Definitions": Addendum d replaces existing definitions for some terms with cross references to their corresponding definitions in Standard 90.1, which are reproduced in Annex 1). This change promotes consistency in use of terminology across related documents.

• Section 4, "Administration and Enforcement": Addendum d more clearly conveys to designers, contractors, and enforcement staff the intent that data center spaces are subject to the requirements of Standard 90.4 and that other spaces in a building are subject to the requirements in Standard 90.1. This clarity is especially important for mixed-use buildings in urban areas where the data center spaces are typically only a portion of a multistory building that often contains other unassociated office tenants as well as street-level retail shops and restaurants.

This addendum also reorganization parts of Section 4 so that it parallels the structure of Standard 90.1 in order to reduce potential confusion for users of both documents. Toward this end, a new Section 4.1.9 is added to address Reference Standard Reproduction Annexes, with the new language matching Standard 90.1; Section 4.2.2.4 is moved to Appendix C to be located with companion figures; and a new Section 4.2.5 is added to address verification and commissioning reporting, with the new language matching Standard 90.1.

• Section 5, "Building Envelope"; Section 7, "Service Water Heating"; Section 9, "Lighting"; and Section 10, "Other Equipment": Addendum d makes several revisions to the numbering and organization of these four sections so that they have a consistent, parallel organization.

• Section 6, "Heating Ventilating and Air Conditioning": Currently, most of the requirements for HVAC for data center spaces, including several compliance options, are all located in Section 6.2, which has a number of subsections and extends for many pages. To alleviate confusion, this addendum renumbers the sections to parallel the structure of Standard 90.1. The resulting organization is as follows:

General: Existing sections to remain

Compliance: Compliance remains; all other criteria moved to sections below

Simplified/Small Building: (Not used)

Mandatory Provisions: Former Sections 6.2.3 and 6.2.2 (renumber only, no changes to text)

Maximum Design Mechanical Load Component (Design MLC) Option: Former Section 6.2.1.1 (renumber only, no changes to text)

Maximum Annualized Mechanical Load Component (Annualized MLC) Option: Former Section 6.2.1.2 (renumber only, no changes to text)

Submittals: Former Section 6.3 (renumber, revised to match Standard 90.1)

Minimum Efficiency Tables: Former Section 6.4 (renumber only, not used)

In terms of text changes, Section 6.1, "General," and Section 6.2, "Compliance," are revised to parallel the corresponding portions of Sections 5, 7, 9, and 10 summarized above. Section 6.7, "Submittals," adds the completion requirements for drawings and manuals from Standard 90.1 for consistency. (System balancing and system commissioning will be addressed in a future addendum.)

• Section 8, "Power": Similar to Section 6, currently most of the requirements for electrical systems providing power for data center spaces all fit into Section 8.2, which has many subsections and extends for many pages. To alleviate confusion, this addendum renumbers the sections to parallel the structure of Standard 90.1. The resulting organization is as follows:

General: Existing sections to remain

Compliance: Compliance to remain; all other criteria moved to sections below

Simplified/Small Building: (Not used)

Mandatory Provisions: Former Sections 8.3 and 8.2.1 (renumber only, very limited changes to text)

Maximum Design Electrical Loss Component (Design ELC) Option for Designs Involving Electrical Systems Only: Former Section 8.2.1.1 (renumber only, no changes to text)

Maximum Design Electrical Loss Component (Design ELC) Option for Designs Involving Both Electrical and Mechanical Systems: Former Section 8.2.1.2 (renumber only, no changes to text) 8.7 Submittals: Former Section 8.4 (renumber, revised to match Standard 90.1)

Product Information: (Not used)

In terms of text changes, Section 8.1, "General," and Section 8.2, "Compliance," are revised to parallel the corresponding portions of Sections 5, 7, 9, and 10 summarized above.

• Section 11, "Alternative Compliance Method": Section 11.1, "General," and Section 11.2, "Compliance," are revised to parallel the corresponding portions of Section 11 of Standard 90.1.

Note that the focus of this addendum is to reduce inconsistencies between Standard 90.4 and Standard 90.1. The issue of alterations to existing data center spaces was addressed in separate addendum a, and the issue of additions to existing data center spaces was addressed in separate addendum b. The text in this addendum incorporates the changes in addendum a and addendum b. System balancing and system commissioning will be addressed in a future addendum.

Note: In this addendum, changes to the current standard are indicated in the text by underlining (for additions) and (for deletions) unless the instructions specifically mention some other means of indicating the changes.