ASHRAE Standard 90.1-1989R Now Available for Public Review

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From the editor...

This issue of the Engineers Newsletter is special. Obviously, it introduces

a new look for this publication. Of much greater significance, however, is

its message. ASHRAE Standard 90.1-1989, " Energy Efficient Design of New

Buildings Except Low-Rise Residential Buildings, " has exerted a profound

impact on the HVAC community, serving as a basis for model codes proposed by

the Department of Energy (DOE) and building official organizations such as

the Building Officials and Code Administrators (BOCA), the International

Conference of Building Officials (ICBO) and the Southern Building Code

Congress (SBCC).

The revised version, once approved, will be no less influential as its

adoption into state codes is almost certain to be mandated by the DOE.

Our thanks to Ron Jarnagin, chairman of ASHRAE Standing Standards Project

Committee (SSPC) 90.1, for contributing this article. Ron has more than 20

years of energy-related research experience and is presently a senior

research engineer for Pacific Northwest National Laboratory in Richland,

Washington.

The American Society of Heating, Refrigerating and Air-Conditioning

Engineers, Inc. (ASHRAE) recently announced the public review of a revision

to Standard 90.1-1989, " Energy Code for Buildings Except Low-Rise

Residential Buildings " . Formally identified as ASHRAE/IESNA Standard

90.1-1989R, the standard is developed jointly with the Illuminating

Engineering Society of North America (IESNA). It provides minimum energy

efficiency requirements for building systems and components, and is written

in regulatory language to facilitate adoption into building codes.

This article provides background on the standard, a summary of its contents

and instructions for obtaining a copy of the public review draft. It is not

meant to give a detailed explanation of the entire standard nor does it

offer any comments about the requirements contained therein.

Purpose and Background

Section 1 of the Standard 90.1 draft, approved by ASHRAE, clearly states its

intent:

" The purposed of this standard (hereafter referred to as code) is to provide

minimum requirements for the energy-efficient design of buildings except

low-rise residential buildings. "

Like all ASHRAE standards, Standard 90.1 is a consensus standard.

" Consensus " implies a substantial agreement of the affected parties, but

does not indicate complete agreement by all.

Economics, rather than simply maximum energy savings, served as the basis

for development of many of the standard's requirements. Use of a consistent

economic methodology based on life-cycle cost (LCC) analyses resulted in the

criteria from each section of the standard meeting the same level of

economic stringency.

" Paths " to Compliance

Compliance with Standard 90.1-1989R entails meeting the mandatory

requirements of each section as well as the prescriptive requirements. For

some sections, such as " Envelope, " an alternative performance method is

allowed for demonstrating compliance. A full performance method based on an

energy cost budget, which allows tradeoffs among the major building systems,

also provides an alternative for satisfying the prescriptive requirements.

Facets Covered

Standard 90.1-1989R applies to the major building components and systems

that affect energy usage. Sections of the standard specifically address the

building envelope, HVAC systems and equipment, service water heating,

lighting and motors.

The standard also advances a " second tier " of energy efficiency guidelines

that is more stringent than the base requirements. This tier is voluntary

and is intended for use with incentive programs offered by utilities and

other organizations. Tier II is specifically not intended for adoption by

code bodies.

Examples of the prescriptive requirements contained in Standard 90.1-1989R

include:

Building envelope - Walls, roof, glazing (e.g., window) requirements.

U-values, solar heat gain coefficients and allowable area.

HVAC - Chiller coefficients of performance (COP's), unitary energy

efficiency ratios (EER's), system power limitations and controls.

Service water heating - Thermal efficiency, standby loss, piping and

insulation.

Lighting - Levels and control.

Motors - Efficiencies.

Highlights of some of the requirements in each of these sections follow.

Also identified are some of the revisions contained in the public review

draft.

Envelope. This section of Standard 90.1 provides both prescriptive and

performance criteria for determining whether envelope requirements (based on

climate and building class, i.e. residential, nonresidential and semiheated)

have been met. The draft presently in public review expands the ENVelope

STandarD (ENVSTD) tradeoff program to permit exchanges among additional

envelope components.

HVAC. The draft standard revises this section's equipment efficiency tables;

other changes include economizer requirements based on climate and fan power

limitations expressed in terms of nameplate horsepower. The draft also adds

several equipment categories (e.g. ground-source heat pumps, absorption

cooling equipment, cooling towers), as well as control requirements for

larger systems and heat recovery requisites.

Along with these additions and changes, the HVAC section was substantially

reorganized. Unlike the 90.1-1989 version, the draft standard now in public

review presents HVAC-related requirements in order of complexity, beginning

with the simplest, most common building design obligations.

Service Water Heating (SWH). This section is now more straightforward. It

includes revised test procedures and adds hot water supply boilers.

Lighting. The most significant change in this section is the inclusion of

lighting controls as a mandatory requirement. There are also fewer " exempt "

building areas. The interior lighting power allowance can be calculated

using either the " building area " or " space function " method.

Motors. As its title implies, this section of the standard states the

requirements for electric motors and belts.

Energy Cost Budget (ECB). Standard 90.1-1989R provides a sample compliance

supplement for the ECB method. The supplement describes the requisites for

an energy simulation program and provides relevant details for conducting an

analysis based on those requirements. It also explains the Systems Analysis

Tradeoff Procedure which allows designers, using the ECB method, to examine

various systems and controls that may yield additional energy savings.

States can decide to implement this sample compliance supplement or develop

their own.

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