ARLINGTON, Va. - The Air Conditioning Contractors of America (ACCA) released a completely revised version of Manual N, the industry standard for calculating heat gain and heat loss for light commercial buildings.

According to ACCA, the new fifth edition of Manual N represents the first complete rewrite of the light commercial load calculation procedure in over two decades, addressing the many advances and changes in the construction industry that have taken shape, such as new materials, methods of assembly, and operational requirements. Authored by Hank Rutkowski, with the oversight of a committee comprised of representatives from across the HVACR industry, the fifth edition provides instruction to help contractors and designers satisfy new energy, ventilation, and comfort requirements for light commercial buildings.

With enhanced procedures, capabilities, sensitivities, and applications, the manual is divided into four sections, providing both a basic and comprehensive procedure for performing light commercial load calculations:

Section 1, Abridged Procedure:Basic instructions to perform commercial load calculations on buildings of three stories or less. Supports a simplified hand calculation.

Section 2, Advanced Topics:Provides enhanced procedures, capabilities, and sensitivities.

Section 3, Tables:Provides input for the worksheets and determinations needed for the abridged (N5ae) and full (N5) procedures.

Section 4, Appendices:Provides supporting materials and details on the N5ae and N5 applications.

To assist users in the use of this new manual, ACCA has scheduled two upcoming training classes and provided a free spreadsheet program that can be used in conjunction with the abridged Manual N procedure.

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Publication date:03/10/2008