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NBS TECHNICAL NOTE 938

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U.S. DEPARTMENT OF COMMERCE/ 1 National Bureau of Standards

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Recommended

Practice for the

Use of Metric

(SI) Units in

Building Design

and Construction
NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards 1 was established by an act of Congress March 3, 1901. The Bureau's overall goal is to strengthen and advance the Nation's science and technology and facilitate their effective application for public benefit. To this end, the Bureau conducts research and provides: (1) a basis for the Nation's physical measurement system, (2) scientific and

technological services for industry and government, (3) a technical basis for equity in trade, and (4) technical services to pro- mote public safety. The Bureau consists of the Institute for Basic Standards, the Institute for Materials Research, the Institute for Applied Technology, the Institute for Computer Sciences and Technology, the Office for Information Programs, and the

Office of Experimental Technology Incentives Program.

THE ENSTITUTE FOR BASIC STANDARDS provides the central basis within the United States of a complete and consist- ent system of physical measurement; coordinates that system with measurement systems of other nations; and furnishes essential services leading to accurate and uniform physical measurements throughout the Nation's scientific community, industry, and commerce. The Institute consists of the Office of Measurement Services, and the following center and divisions: Applied Mathematics — Electricity — Mechanics — Heat — Optical Physics — Center for Radiation Research — Laboratory Astrophysics 2 — Cryogenics 2 — Electromagnetics 2 — Time and Frequency3

. THE ESSTTTUTE FOR MATERIALS RESEARCH conducts materials research leading to improved methods of measurement, standards, and data on the properties of well-characterized materials needed by industry, commerce, educational insti- tutions, and Government; provides advisory and research services to other Government agencies; and develops, produces, and

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1 Headquarters and Laboratories at Gaithersburg, Maryland, unless otherwise noted; mailing address Washington, D.C. 20234.

a Located at Boulder, Colorado 80302.
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Rational Bureau at Standards

APR 2 5 »77 Recommended Practice vo'v * cc" l! for the Use of Metric (SI) Units \©o

in Building Design and Construction .w±y\

Hans J. Milton

Institute for Applied Technology

National Bureau of Standards

Washington, D.C. 20234

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U.S. DEPARTMENT OF COMMERCE, Juanita M. Kreps, Secretary

Dr. Betsy Ancker-Johnson, Assistant Secretary for Science and Technology

\ .£ NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Acting Director

Issued April 1977
National Bureau of Standards Technical Note 938

Nat. Bur. Stand. (U.S.), Tech. Note 938, 47 pages (Apr. 1977) CODEN. NBTNAE

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 1977

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 (Order by SD Catalog No. 03.46:938). Stock No. 003-003-01761-2. Price $1.60. (Add 25 percent additional for other than U.S. mailing).
RECOMMENDED PRACTICE FOR THE USE OF

METRIC (SI) UNITS IN BUILDING DESIGN AND CONSTRUCTION

Hans J . Milton

Abstract : This Technical Note contains a comprehensive set of recommendations for the use

of metric (SI) units in building design and construction.

It includes descriptive material dealing with the structure of the International

System of Units (SI) ; rules and recommendations for the presentation of SI units

and symbols, and of numerical values associated with SI; a set of tables showing

working units and typical applications for SI units in building design and construction; and a section dealing with special considerations in the selection and

use of SI units in design and construction. Appendixes show conversion factors

for the most common units; superseded metric units not recommended for use with

SI; an SI units and relationships chart; and appropriate references.

This document was prepared to provide the technical basis for an ASTM reference

standard on recommended practice for the use of metric (SI) units in building

design and construction.

Key Words : International System of Units (SI) ; metric design and construction; recommended

SI practice .

iii
PREFACE

This Technical Note has been prepared in response to requests irom the American Society ior

Testing and Materials ( ASTM Committee E6 - VeK.iohma.nce oi Building Constructions ) and the

American Motional Metric Council [ Con4tA.uctA.on Industries Coordinating Committee ) ior the

development oi a "recommended practice ior the uAe oft metric (SI) units in building design

and construction."

The ilrst droit oft this document was -submitted to ASTM Subcommittee E6.62, Coordination oft dimensions ior Building Materials and Systems, in November 1976, and has had a unanimous

affirmative ballot with some editorial comment. This edited version has been submitted to the main committee o{ E6 ior ballot.

In keeping with the "Metric Conversion Act oi 7975" [Public Law 94-1 6 S), the metric units

contained in thijs document are those iound in the International System oi Units (SI), as interpreted or modified ior the United States by the Secretary oi Commerce. It includes an extensive Listing o\ SI units ior use in design and construction, working ranges and typical

applications, and relevant explanatory material relating to the use oi SI units lor specific

quantities.

This report has the following objectivesa. to share the information contained in the document more widely among all sectors,

associated with the construction community; and

b. to invite constructive comment irom parties not actuated with ASTM Committee E6.

The principal author oi the document Is Hans J. Hilton, B. Arch., M. Bldg. Sc, M.B.A., PRAIA,

technical consultant to the Center ior Building Technology on metrication and coordination

oi dimensions in building. In the period irom 1970 to 1974, Mr. Hilton was a key figure in

the Australian change to metric measurement in building design and construction. He Is now

the Assistant Secretary ior Housing Research in the Australian Government Service, and has

been made available to the National Bureau oi Standards to assist in the research and

planning ior metrication in the U.S. building community.

Technical and editorial comments on earlier drafts were received irom a number oi experts on the International System oi Units (SI). Major contributors oi constructive comment were:

Mr. Louis Barbrow, National Bureau oi Standards; Mr. Andrew Lolly, American Institute oi

Steel Construction, Inc.; Mr. Robert Lukens, American Society ior Testing and Materials

[editorial review); and Vroiessor Cornelius Wandmacher, University oi Cincinnati and Chairman

oi the ANMC/CICC Engineering Design Subsector Committee.

James G. Gross

Chlei, OHice oi Building Standards

and Codes Services

Center ior Building Technology, IAT

iv
TABLE OF CONTENTS Page

PREFACE • iv

INTRODUCTION vi

1. SCOPE 1

2. DEFINITIONS 1

3. THE CONCEPT OF SI 2

4. SI UNITS & *\

Table A - UNITS IN THE INTERNATIONAL SYSTEM - SI (Fold-out)

5. NON-SI UNITS FOR USE WITH SI 3 Table B - OTHER UNITS WHOSE USE IS PERMITTED WITH SI 4

6. SI UNIT PREFIXES 4 Table C - PREFERRED MULTIPLES AND PREFIXES 5 Table D - OTHER MULTIPLES AND PREFIXES 5

7. RULES AND RECOMMENDATIONS FOR THE USE OF SI 5 Table E - RULES AND RECOMMENDATIONS FOR THE PRESENTATION OF SI UNITS AND UNIT SYMBOLS 6 Table F - PRESENTATION OF NUMERICAL VALUES IN CONJUNCTION WITH SI .... 8

8. SI UNITS FOR USE IN DESIGN AND CONSTRUCTION 10 Table G - SPACE AND TIME: GEOMETRY, KINEMATICS, AND PERIODIC PHENOMENA . . 11 Table H - MECHANICS: STATICS AND DYNAMICS 14 Table J - HEAT: THERMAL EFFECTS, HEAT TRANSFER 16 Table K - ELECTRICITY AND MAGNETISM 18 Table L - LIGHTING ZO

Table M - ACOUSTICS 21

9. SPECIAL CONSIDERATIONS IN THE USE OF SI UNITS IN BUILDING DESIGN

AND CONSTRUCTION 22

9.1 Linear Measurement (Length) 22

9.2 Area 23

9.3 Volume and Fluid Capacity 23

9.4 Geometrical Cross-Sectional Properties 24

9.5 Plane Angle 24

9.6 Time Interval 25

9.7 Temperature and Temperature Interval 25

9.8 Mass, Weight, and Force 26

9.9 Pressure, Stress, and Elastic Modulus 27

9.10 Energy, Work, and Quantity of Heat 27

9.11 Rotational Dynamics 27

9.12 Power and Heat Flow Rate 28

9.13 Electrical Units 28

9.14 Lighting Units 28

9.15 Dimensionless Quantities 2 9 9.16 Constants for Use in Building Design Calculations 29

10. APPENDIXES 31 A. Conversion Factors for the Most Common Units 32

B. SI Units and Relationships Chart - Explanations 36

C. Superseded Metric Units Not Recommended for Use with SI 38

REFERENCES 39

v

«X
INTRODUCTION

The International System of Units (SI) was developed by the General Conference of Weights and

Measures (CGPM) , which is an international treaty organization. The abbreviation SI, derived

from the French "Systeme International d

1 Unites," is used in all languages.

SI is a rational, coherent, international, and preferred measurement system which is derived

from earlier decimal metric systems but supersedes all of them.

The use of the metric system in the United States was legalized by an Act of Congress in 1866,

but was not made obligatory.

On December 23, 1975, Public Law 94-168, "The Metric Conversion Act of 1975," was signed by

President Ford, declaring a national policy of coordinating the increasing use of the metric

system in the United States, and establishing a United States Metric Board to coordinate the

voluntary conversion to the metric system. The Act specifically defines the metric system of

measurement as " the International System of Units as established by the General Conference

of Weights and Measures in 1960, and as interpreted or modified for the United States by the

Secretary of Commerce."

There have been some refinements of the system since 1960, and the United States has a special

opportunity to change from the outdated customary system to the most up-to-date international

system in one single step.

In the building design and construction community the application of SI units, together with

preferred numerical values, is certain to simplify and speed up calculations and facilitate

all measurement intensive activities. Because SI is a coherent system of units with only one

unit for any physical quantity, there is no need to convert within the system- from one unit

to another, as with feet and inches, ounces and pounds, or gallons and cubic feet. With the

change to SI, the U.S. construction community can become a leader in the metric building world.

This document has been prepared to provide the technical basis for a single, comprehensive,

and authoritative standard for SI units to be used in building design, product manufacture,

or construction applications.

vi
1. SCOPE

1.1 This document outlines a selection of SI units, with multiples and submultiples , for

general use in building design and construction.

1.2 In addition, rules and recommendations are given for the presentation of SI units and

symbols, and for numerical values shown in conjunction with SI.

1.3 A selection of conversion factors appropriate for use within the construction community

is given in Appendix A.

1.4 The SI units included in this document comply with and augment the "American National

Standard Metric Practice " ANSI Z 210.1- 1976 (also identified as ASTM E 380 -76 or

IEEE Std 268-1976 ), and are generally consistent with ISO 1000- 1973 (E) "SI Units and

Recommendations for the Use of Their Multiples and Certain Other Units."

1.5 The official metric (SI) system of measurement for use in the United States is described

in the Notice "THE METRIC SYSTEM OF MEASUREMENT - Interpretation and Modification of the

International System of Units for the United States," issued in the Federal Register

(Vol. 41, No. 239, pages 54 018-19) on Friday, December 10, 1976.

2. DEFINITIONS

2.1 SI_ - the International System of Units (abbreviation for " le j>ysteme International

d'Unitds) as defined by the General Conference of Weights and Measures (CGPM)- based

upon seven (7) base units, two (2) supplementary units, and derived units, which

together form a coherent system.

2.2 Quantity - measurable attribute of a physical phenomenon. There are base units for

seven (7) quantities and supplementary units for two (2) quantities upon which units

for all other quantities are founded.

2.3 Unit - reference value of a given quantity as defined by CGPM Resolution or set out

in ISO standards. There is only one unit for each quantity in SI.

2.4 Coherent unit system - system in which relations between units contain as numerical

factor only the number one (1) or unity, because all derived units have a unity

relationship to the constituent base and supplementary units.

2.5 Numerical value of a quantity - magnitude of a quantity expressed by the product of a

number and the unit in which the quantity is measured.
3. THE CONCEPT OF SI

3.1 The International System of Units CSI) represents a universal, coherent, and preferred

system of measurement for worldwide use and appropriate to the needs of modern science

and technology. SI is a live measurement system, under constant review and development by CGPM in line with practical developments and scientific advancement.

3.2 The principal features of SI are:

a. There is only one recognized unit for each physical quantity.

b. The system is fully coherent; this means that all units in the system relate to each other on a unity (one-to-one) basis.

c. A set of internationally agreed prefixes can be attached to units to form preferred

multiples and submultiples in powers of 1000. This provides for convenient numerical

values when the magnitude of a quantity is stated.

3.3 Because of their practical significance, the use of a specific group of non-SI units in

conjunction with SI is permitted for some quantities.

3.4 SI units, permissible non-SI units, and prefixes are discussed in Sections 4, 5, and 6.

3.5 The diagram below shows graphically the types of units within SI or associated with SI.

SI - THE INTERNATIONAL SYSTEM OF UNITS

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I OTHER UNITS

PERMITTED

FOR USE

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4. SI UNITS

4.1 The International System of Units (SI) has three classes of units:

a. Base Units (7) - for independent quantities

b. Supplementary Units (2) - for plane angle and solid angle

c. Derived Units

4.2 The seven base units and two supplementary units are unique units which, except for the

kilogram, are defined in terms of reproducible phenomena.

4.3 Derived units can all be defined in terms of their derivation from base units and

supplementary units. They fall into two categories:

a. Derived units with special names and symbols

b. Derived units with generic or complex names, expressed in terms of

i. one base unit

ii. two or more base units

iii. base units and/or derived units with special names

iv. supplementary units and base and/or derived units

4.4 Table A, on page 4, contains SI base, supplementary, and derived units of significance

in design and construction, listing the following:

a. Quantity

b. Unit name

c. Unit symbol

d. Unit formula

e. Unit derivation ( in terms of base and supplementary units )

f

.

Remarks

4.5 A. chart, showing the relationship between the base units, supplementary units and

derived units that have been given special names is set out in Appendix B,

5. NON-SI UNITS FOR USE WITH SI

5.1 There is an additional group of acceptable, but noncoherent, traditional units retained

for use with SI because of their significance in general application.

1 The ptumcuiy itandand faon man, U> the "tntejtnationat prototype kJJLoqKam mcu.ntcu.ned andeA Apecifited concUJtionA at the IntexnatlonaL BuAeau o£ WesLghtA and MeaiWieA (BZPM)

neat Vafta,, Vnance.
5.2 Non-SI units of significance to design and construction are shown in Table B, under two

categories:

a. Units for general use

b. Units for limited application only

TABLE B: OTHER UNITS WHOSE USE IS PERMITTED WITH SI

QUANTITY UNIT NAME SYMBOL RELATIONSHIP TO SI UNIT REMARKS

UNITS FOR GENERAL USI

Volume

(1) liter

(2) metric ton

L 1 L = 0.001 m

3 = 106 mm3 An alternate spelling is 'litre'

.

The liter can be used with

the SI prefix 'milli'. Mass t 1 t = 1 Mg = 1000 kg Time minute min 1 min = 60 s See also Section 9,6, hour h 1 h = 3600 s = (60 min) page 26 day (mean solar) d 1 d = 86 400 s = (24 h) year (calendar) a 1 a = 31 536 000 s = (365 d) Temperature Interval degree Celsius °C 1 °C = IK The Celsius temperature °C corresponds to 273.15 K

exactly. (t„ c = Tr - 273.15)

Plane Angle degree (of arc) 1° = 0.017 453 rad

= 17.453 mrad 1° = (ti/180) rad Velocity kilometer per hour km/h 1 km/h = 0.278 m/s 1 m/s = 3.6 km/h

UNITS ACCEPTED FOR L"IMITED APPLICATION C NLY:

Area hectare ha 1 ha = 10 000 m

2 For use in land measurement. Energy kilowatthour kUh 1 kWh = 3.6 MJ For measurement of electrical energy consumption only. Speed of Rotation revolution per minute r/min 1 r/min = - r/s = ?! rad/s

60 60

To measure rotational speed

in slow moving equipment only.

(1) The international symbol for liter is the lowercase "l'\ which can be easily confused with the numeral "1" Several English speaking countries have adopted the script "t" as symbol for liter in order to avoid any misinterpretation. The symbol " L" (capital ell) is recommended for United States use to prevent confusion.

(2) The international name for metric ton is "tonne". The metric ton is equal to the "megagram" (Mg).

5.3 Appendix C, on page 40, shows a group of superseded metric units not recommended for

use with SI in design and construction applications.

6. SI UNIT PREFIXES

6.1 SI is based on the decimal system of multiples and submultiples, and therefore the use

of common fractions is minimized. Multiples are formed by attaching standard prefixes

to SI units.
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JNITS IN THE INTERNATIONAL SYSTEM - SI

UNIT 1 ! GROUP QUANTITY UNIT NAME SYMBOL FORMULA UNIT DERIVATION REMARKS S

BASE UNITS

Length meter . An alternative spelling is "metre". Mass kilogram kg Time second s Already in common use. Electric Current ampere A Already in common use. Thermodynamic Temperature kelvin K The customary unit for temperature is the degree Celsius (°C)

.

Amount of Substance mole mol The mol has no application in construction.

Luminous Intensity candela cd Already in common use.

SUPPLEMENTARY UNITS

radian steradian

rad

sr

Already in common use. Already in common use. Plane Angle

Solid Anple

DERIVED UNITS WITH SPECIAL NAMES

hertz Hz 1/s kg-m/s 2 s-1 The hertz replaces "cycle per second". Frequency (of a periodic phenomenon)

Force newton N m.kg-s" 2 m-'.kg.s"2 m

2 -kg.s-2 Pressure, Stress, Elastic Modulus pascal Pa N/m2

Energy, Work, Quantity of Heat joule J N-m

Power, Radiant Flux watt W J/b m

2 -kg-s-3 Already in common use. Quantity of Electricity, Electric

Charge coulomb C A-s s-A Already in common use. Electric Potential, Potential Difference, Electromotive Force volt V J/C or W/A m

2 -kg.s- 3 -A-' Already In common use.

j Electric Capacitance farad F C/V m-2 -kg- 1 -s'*.A2 Already in common use.

j Electric Resistance ohm a V/A m

2 -kg.s- 3 -A"2 Already in common use. Electric Conductance Siemens s A/V or i/n m- 2 -kg->-G 3 .A* The Siemens was formerly referred

to as "mho". Magnetic Flux weber Wb V-s ra 2. kg . s -2. A

-l Already in common use. Magnetic Flux Density tesla T Wb/m2 kg-s- 2 -A-' m

2 -kg.s- 2 -A-2 Already in common use. Electric Inductance henry H Wb/A Already in common use. Luminous Flux lumen lm cd-sr cd-sr Already in common use. Illuminance lux lx lm/m2 cT 2 -cd-sr Activity (of radionuclides) becquerel Bq 1/s s-1 No application in construction.

Absorbed Dose gray Gy J/kg m

2 -s" 2 (*) (*) kg is cancelled out. No application in construction.

DERIVED UNITS WITH GENERIC NAMES

BASE UNIT

m

2 m

2

a. UNITS EXPRESSED IN TERMS OF ONE

Arta square meter

Volume, Capacity cubic meter m3 m

3

( lm3 *= 1000 L ) Section Modulus meter to third power m

3 m

3 Second Moment of Area meter to fourth power m

1* m

4 Curvature reciprocal (of) meter 1/m Rotational Frequency reciprocal (of) second 1/s s- 1 Revolution per second (r/s) is used in specifications for rotating machinery. Coefficient of Linear Thermal

Expansion reciprocal (of) kelvin 1/K K" 1

b. UNITS EXPRESSED IN TERMS OF ' WO OR MORE BASE UNITS

Linear Velocity meter per second m/s m.s-1

Linear Acceleration meter per second squared m/s 2 m.s"2 Kinematic Viscosity square meter per second m

2 /s m

2 -s_1

Volume Rate of Flow cubic meter per second m

3 /s m^s" 1 Specific Volume cubic meter per kilogram m

3 /kg m3 -kg" 1 Mass per Unit Length kilogram per meter kg/m m->.kg

Mass per Unit Area kilogram per square meter kg/m2 m" 2 -kg Density (Mass per Unit Volume) kilogram per cubic meter kg/m3 nr 3 -kg In this SI form, mass density is con- veniently 1000 times specific gravity. Moment of Inertia kilogram meter squared kg-m2 m

2 -kg Mass Flow Rate kilogram per second kg/s kg-s- 1 Momentum kilogram meter per second kg-m/s m-kg-3- 1 Angular Momentum kilogram meter squared per second kg-m2 /s m

2 -kg's" 1 Magnetic Field Strength ampere per meter A/m m-'*-A Current Density ampere per square meter A/m2 m"2 -A Luminance candela per square meter cd/m 2 m"2 -cd

c. UNITS EXPRESSED IN TERMS OF BASE UNITS AND / OR DERI /ED UNIT S WITH SPEC IAL NAMES

Moment of Force, Torque newton meter N-m n^-kg-s"2 Flexural Rigidity newton square meter N-m2 m

3 -kg-s~2 Force per Unit Length, Surface Tension newton per meter N/m kg-s"2 (1) (1) m is cancelled out Dynamic Viscosity pascal second Pa-s m-'-kg-s" 1 kg-s-2 Impact Ductility jouJe per square meter J/m (2) 2 (2) m

2 Is cancelled out

Combustion Heat (per Unit Volume) joule per cubic meter J/m3 m-'-kg-s-2 Combustion Heat (per Unit Mass), Specific Energy , Specific Latent joulfc per kilogram J/kg m

2 -s- 2 (3) (3) kg ia cancelled out

Heat Capacity, Entropy jo-lie per kelvin J/K m

2 -kg-s- 2 -K

_1 Specific Heat Capacity, Specific 1 Entropy Joule per kilogram kelvin J/(kg-K) m

z -s2 -K- 1 (4) (4) kg is cancelled out

Heat Flux Density, Irradiance,

Sound Intensity watt per square meter W/m2 kg-s" 3 (5) (5) m

2 is cancelled out Thermal Conductivity watt per meter kelvin W/(m-K) m.kg-s- 3 -^1 Coefficient of Heat Transfer watt per square meter

kelvin W/(m2 -K) kg.s- 3 -K-' (6) (6) m

2 is cancelled out

Thermal Resistance, Thermal Insulance square meter kelvin per watt m

2 -K/W kg-'-s 3 -K (7) (7) m

2 Is cancelled out Electric Field Strength volt per meter V/m m-kg-s- 3 -A- 1 Electric Flux Density coulomb per square meter C/m2 m" 2 -s-A Electric Charge Density coulomb per cubic meter C/m3 m3 -s-A Electric Permittivity farad per meter F/m m3 -kg- 1 -s''-A 2 Electric Permeability henry per meter H/m m-kg-s- 2 -A- 2 m

3 -kg-s" 3 -A-2 Electric Resistivity ohm meter fl-m Electric Conductivity Siemens per meter S/n m- 3 -kg-'-s 3 -A 2 Light Exposure lux second lx-S m" 2 -s-cd-sr Luminous Efficacy lumen per watt lm/W m

-2 -kg-1

-s

3 -cd-sr

d. UNITS EXPRESSED IN TERMS OF SU 'PLEMENTARY UNITS AND BAS I AND/OR DERIVED UNI rs

Angular Velocity radian per second rad/s s-'-rad

Angular Acceleration radian per second squared rad/s2 s2 -rad Radiant Intensity watt per steradian W/sr m

2 -kg-s- 3 -sr-1 Radiance watt per square meter

(8) m

2 is cancelled out steradian W/(m2 -sr) kg-s- 3 -sr- 1 (8)

6.3

Preferred multiples range in geometric steps of 1000 ( 10 3

) up to 10 , submultiples

range in geometric steps of iqOO ( 10~ 3

) down to 10-18 .

PREFERRED MULTIPLES AND SUBMULTIPLES: The following preferred prefixes, shown

in Table C, are relevant in building design and construction. Prefixes outside the

range 10° (micro) to 10° (mega) will only occur in rare instances.

TABLE C: PREFERRED MULTIPLES AND SUBMULTIPLES AND THEIR PREFIXES

PREFIX

MULTIPLICATION FACTOR NAME SYMBOL PRONUNCIATION

10 12 or 1 000 000 000 000 tera T as in terrace

10 9 or 1 000 000 000 giga G jig 'a 10 6 or 1 000 000 mega M as in megaphone

10 3 or 1 000 kilo k as in "kilowatt

10" 3 or 0.001 milli m as in military

10~ e 0.000 001 micro y as in microphone

10- 9 or 0.000 000 001 nano n nan 'oh 10"12 or . 000 000 000 001 pico P peek 'oh

6.4 OTHER MULTIPLES FOR LIMITED APPLICATION: SI includes a number of additional

historically used multiples and submultiples, shown in Table D, but these should be

avoided as far as possible.

TABLE D: OTHER NON-PREFERRED MULTIPLES AND THEIR PREFIXES

MULTIPLICATION FACTOR PREFIX NAME PREFIX

SYMBOL

PRONUNCIATION

102 or 100

10 1 or 10 10-1 or 0.1

10-2

or 0.01

hecto

deka

deci

centi

h

da

d

c

heck 'toe deck 'a as in decimal

as in sentiment

7. RULES AND RECOMMENDATIONS FOR THE USE OF SI

7.1 Two tables of rules and recommendations have been prepared in order to facilitate

the correct application of SI units and symbols; and the correct presentation of units,

symbols, and numerical values shown in conjunction with units and symbols.

7.2 Table E, on pages 8 and 9, gives "Rules and Recommendations for the Presentation of SI

Units and Symbols."

7.3 Table F, on pages 10 and 11, gives guidance on "Presentation of Numerical Values with SI."

7.4 The tables provide a convenient reference guide for the editorial checking of metric

documents to ensure that the presentation of data is in line with accepted practice.

5
TABLE E RULES AND RECOMMENDATIONS FOR THE PRESENTATION OF SI UNITS AND SYMBOLS

A. GENERAL

All unit names should either be denoted by correct

symbols or be written in full. In the interest of simplification and to reduce the amount of writing

use unit symbols rather than fully written forms.

DO NOT USE mixtures of names and symbols.

B. SYMBOLS FOR UNIT QUANTITIES AND PREFIXES

1. SI symbols are internationally agreed and there is only one symbol for each unit quantity. Multiples

and submultiples are formed by using the unit

symbol and attaching a prefix symbol in front of it.

2. All unit symbols are shown in upright letters, and can be produced by a normal typewriter keyboard with the exceptions of the symbols for the SI unit ohm and the prefix micro which are represented

by Greek letters Q and u respectively.

3. Unit symbols are NEVER followed by a period (full

stop) except at the end of a sentence.

4. Unit symbols are normally written in lowercase, except for unit names derived from a proper name,

in which case the initial is capitalized. Some units have symbols consisting of two letters from

a proper name, of which only the first letter is capitalized. (The symbol for the unit name "ohm"

is the capital Greek letter SI ) .

5. Prefixes for magnitudes from 106 to 10 18 have

capital upright letter symbols.

6. Prefixes for magnitudes from 10_1 ° through to 10 3 have lowercase upright letter symbols. (The symbol for 10 or micro is the lowercase Greek

letter u ) .

7. Prefix symbols are directly attached to the unit

symbol, without a space between them.

8. DO NOT USE compound prefixes to form a multiple

or submultiple of a unit (e.g. USE nanometer,

DO NOT USE micromillimeter o£ millimicrometer)

.

9. In the case of the base unit kilogram, prefixes

are attached to the 'gram' (e.g. milligram NOT microkilogram)

.

10. USE ONLY ONE PREFIX when forming a multiple or a submultiple of a compound unit. Normally, the prefix should be attached to a unit in the numerator. An exception from this rule is made

for the base unit kilogram.

C. AREAS OF POSSIBLE CONFUSION REQUIRING SPECIAL CARE

1. The symbols for SI units and the conventions that govern their use should be STRICTLY followed. A number of prefix and unit symbols use the same

letter, but in different form. EXERCISE CARE to present the correct symbol for each quantity.

2. All prefix and unit symbols retain their prescribed

form regardless of the surrounding typography.

In printouts from limited character sets ( telex, computer printers) special considerations apply

to symbols for mega, micro, ohm and Siemens. Where

confusion is likely to arise, WRITE UNITS IN FULL.

TYPICAL EXAMPLES REMARKS

USE: J/kg or NOT: joule per kg

joule per kilogram NOT: J/kilogram

m, kg, s, A, cd, K

See also B5 - B7

EXCEPTIONS: Q, u

60 kg/m NOT: 60 kg./m.

m, kg, s, mol, cd etc. EXCEPTION: L

A, K, N, J, W, V etc.

Pa, Hz, Wb, etc.

M, G, T etc. See also CI

p, n, u, m, k etc. See also CI

mm, kW, MN, etc. NOT: m m, kW, M N

nm NOT: umm or mum

mg NOT: ukg

km/s; mV/m NOT: mm/us; uV/mm

EXCEPTION

MJ/kg NOT kJ/g

g (gram) ; G (giga) OTHERS

k (kilo); K (kelvin) c (centi) ; C (coulomb) m (milli) ; „ ( , m (meter)

;

°C (degree Celsius)

s (second); S (Siemens) n (nano) ; N (newton) t (metric ton) ; T (tera)
TABLE E (CONTINUED)

D. UNIT NAMES WRITTEN OUT IN FULL

1. Unit names, including prefixes are treated as common names and are not capitalized , except

at the beginning of sentences or in titles.

(The only exception is "Celsius" in "degree

Celsius," where degree is considered as the unit name and is shown in lowercase, while

Celsius represents an adjective and is capitalized)

.

2. Where a prefix is attached to an SI unit to form a multiple or submultiple, the combination

is written as one word. (There are three cases where the final vowel of the prefix is omitted

in the combination: megohm, kilohm.and hectare.)

3. Where a compound unit is formed by multiplication

of two units, the use of a space between units

is preferred, but a hyphen is acceptable and in some situations more appropriate, to avoid any risk of misinterpretation.

4. Where a compound unit is formed by division of two units, this is expressed by inserting per between the numerator and the denominator.

5. Where the numerical value of a unit is written in full, the unit should also be written in full.

E. PLURALS

1. Units written in full are subject to the normal

rules of grammar. For any unit with a numerical

value greater than one (1) , an "s" is added to the written unit to denote the plural.

2. The following units have the same plural as singular when written out in full: hertz, lux, Siemens.

3. Symbols NEVER change in the plural.

COMPOUND UNIT SYMBOLS - PRODUCTS AND QUOTIENTS

1. The product of two units is indicated by a dot

placed at mid-height between the unit symbols.

2. To express a derived unit formed by division,

any one of the following methods may be used:

a. a solidus ( slash, / )

b. a horizontal line between numerator and denominator

c. a negative index (or negative power)

3. Only one solidus may be used in any combination.

4. DO NOT USE the abbreviation "p" for per in the expression of a division.

5. Where the denominator is a product, this should

be shown in parentheses.

TYPICAL EXAMPLES REMARKS

meter, newton, etc. NOT: Meter, Newton

EXCEPTION

degree Celsius

millimeter

;

NOT: milli-meter

kilowatt NOT: kilo watt

newton meter or NOT: newtonmeter

newton-meter

meter per second NOT: meter /second joule per kelvin NOT: joule/kelvin

seven meters NOT : seven m

1.2 meters;

2.3 newtons; BUT: 0.8 meter

33.2 kilograms

350 kilohertz

12.5 lux

2.3 N; 33.2 kg NOT: 2.3 Ns_; 33.2 kgs

kN-m; Pa-s NOT: kNm; Pas

NOT: kN m; Pa s

See also F3 and F5

kg/m3

; W/(m-K) See also F3 and F5

kg ; _w_

nw m-K

kg-rn" 3

; W-m-^K-1

m/s 2

; m-kg/(s 3 -A) NOT: m/s/s

NOT: m-kg/s 3 /A

km/h NOT: kph or k.p.h.

W/(m2 -K)
TABLE F

PRESENTATION OF NUMERICAL VALUES

A. DECIMAL MARKER

1. Whereas most European countries use the comma on

the line as the decimal marker and this practice

is advocated by ISO, a special exception is made

for documents in the English language which have

traditionally used the point (dot) on the line,

or period, as decimal marker.

2. The recommended decimal marker for use in the United States is the point on the line (period), and the comma should not be used.

In handwritten documents the decimal marker may

be shown slightly above the line for clear identification

.

3; Always show a zero before the decimal point for all numbers smaller than 1.0 (one).

B. SPACING

1. Always leave a gap between the numerical value

associated with a symbol and the symbol, of at least half a space in width.

In the case of the symbol for the "degree Celsius' this space is optional, but the degree symbol

must always be attached to Celsius.

2. In non-SI expressions of plane angle (°, ', "), DO NOT LEAVE A SPACE between the numerical value

and the symbol.

3. Always leave a space on each side of signs for multiplication, division, addition, and sub- traction

FRACTIONS

IN CONJUNCTION WITH SI

1. Avoid common fractions in connection with

SI units.

2. Always use decimal notation to express fractions

of any number larger than 1.0 (one).

3. While the most common fractions such as half,

third, quarter, and fifth will remain in speech, always show decimal notation in written, typed, or printed material.

POWERS OF UNITS AND EXPONENTIAL NOTATION

1. When writing unit names with a modifier 'squared'

or 'cubed', the following rules should be applied:

a. In the case of area and volume, the modifier is written before the unit name

as "square" and "cubic".

b. In all other cases, the modifier is shown

after the unit name as "squared", "cubed",

"to the fourth power", etc.

c. The abbreviations "sq." for square, and "cu." for cubic should not be used.

2. For unit symbols with modifiers (such as square,

cubic, fourth power etc.) always show the superscript immediately after the symbol.

TYPICAL EXAMPLES REMARKS

See also under G.

9.9 ; 15.375 NOT: 9,9 ; 15,375

9f ; 'S-37S

0.1 ; 0.725 NOT: .1 ; .725

900 MHz ; 200 mg ; 10 6 mm2 or 10 6 mm2 NOT:

NOT:

900MHz ; 200mg

10 6mm2

20°C or 20 °C NOT: 20° C

27°30' (of arc) NOT: 27 ° 30 '

100 mm x 100 mm ; 36 MPa + 8 MPaNOT:

NOT: 100 mmxlOO mm

36 MPa+ 8 MPa

WRITE: 0.5 kPa NOT: 1/2 kPa

1.5 ; 16.375 NOT: 1-1/2 ; 16-3/8

0.5 ; 0.33 ; 0.25 ; 0.2NOT: 1/2 ; 1/3 ; 1/4 ; 1/5

cubic meter ; square millimeterNOT: meter cubed ; millimeter squared

meter per second squaredNOT: meter per square

second; (or 'meter per second per second')

NOT: NOT:sq. millimeter

cu. meter

2 3 4 m' ; mnr ; s NOT: 2 3 4 m '; mm ; s
TABLE F (CONTINUED)

4.

Show the superscript as a reduced size numeral

raised half a line space. Where a typewriter without superscript numerals is used, the full

size numeral should be raised half a line space, provided that this does not encroach on print

in the line above.

Where an exponent is attached to a prefixed symbol,

it indicates that that multiple (or submultiple)

is raised to the power expressed by the exponent. RATIOS

Do not mix units in expressing

unit quantities.

a ratio of like

2. Wherever possible, use a nonquantitative

expression (ratio or percentage) to indicate measurement of slopes, deflections, etc.

F. RANGE

1. The choice of the appropriate prefix to indicate

a multiple or submultiple of an SI unit is governed by convenience to obtain numerical values within a practical range and to eliminate nonsignificant digits.

2. In preference, use prefixes representing ternary

powers of 10 (10 raised to a power which is a multiple of 3)

.

3. Select prefixes so that the numerical value or values occur in a common range between 0.1 and

1000.

4. Compatibility with the general range must be

a consideration; e. g. , if all dimensions on

a drawing are shown in millimeters (mm) , a range from 1 to 99 999 (a maximum of five numerals) would

be acceptable to avoid mixing of units.

G. PRESENTATION AND TABULATION OF NUMBERS

1. In numbers with many digits it has been common practice in the United State to separate digits

into groups of three by means of commas. This practice must not be used with SI, to avoid

confusion. It is recommended international

practice to arrange digits in long numbers in groups of three from the decimal marker, with

a gap of not less than half a space, and not more than a full space, separating each group.

2. For individual numbers with four digits before

(or after) the decimal marker this space is not necessary.

3. In all tabulations of numbers with five or more

digits before and/or after the decimal marker,

group digits into groups of three:

e.g., 12.5255; 5735; 98 300; 0.425 75

H. USE OF UNPREFIXED UNITS IN CALCULATIONS

Errors in calculations involving compound units

can be minimized if all prefixed units are reverted back to coherent base or derived units, with numerical values expressed in powers-of-ten notation.

TYPICAL EXAMPLES REMARKS

mm3

, m/s 2 PERMITTED: mm , m/s

1 mm3 = (10_3 m) 3 = 10- 9 m

3 NOT; 1 mm3 = 10" 3 m

3

1 km2 = (10 3 m) 2 = 10 6 m

2

0.01 m/m NOT: 10 mm/m

0.03 m

2 /m2 NOT: 30 000 mm2 /m2

PREFERRED:

1:100; 0.01; 1% 1:33; 0.03; 3%

milli, kilo, mega AVOID: centi, deci,

deka, hecto

120 kN

3.94 mm

14.5 MPa

IN LIEU OF: 120 000 N 0.003 94 m

14 500 kPa

NOTE: Drawings should show

"All dimensions in millimeters".

54 375.260 55 NOT: 54,375.260,55

54 375.260 55 NOT: 53475.26055

4500; 0.0355

12.525 5 5 735 98 3000.425 75 104 047.951 25

PREFERRED

ALSO ACCEPTABLE:

136 kJ = 136 x 10 3 J (or 1.36 x 10 5 J) 20 MPa = 20 x 10 6 Pa (or 2 x 10 7 Pa) 1.5 t (Mg) = 1.5 xlO3 kg
8. SI UNITS FOR USE IN DESIGN AND CONSTRUCTION

8.1 Correct selection of units for use in building design calculations and in documentation

is essential to minimize errors and to optimize the coordination between the various

sectors and groups within the construction community.

8.2 The following tables list SI units, and other units acceptable with SI as recommended , for

use in building design and construction related activities. Where appropriate, working

ranges are indicated for selected units, and typical examples provided of their field (s)

of application. In addition, explanatory remarks are added to briefly deal with any

special considerations. A subdivision, similar to that used for ISO 1000, has been

adopted:

Table G: Pages 13-15 SPACE AND TIME: GEOMETRY, KINEMATICS,

AND PERIODIC PHENOMENA

Table H: Pages 16-17 MECHANICS: STATICS AND DYNAMICS

Table J: Pages 18-19 HEAT: THERMAL EFFECTS, HEAT TRANSFER

Table K: Pages 20-21 ELECTRICITY AND MAGNETISM

Table L: Page 22 LIGHTING

Table M: Page 23 ACOUSTICS

8.3 PREFERRED RANGES OF VALUES

The use of an appropriate unit or multiple of a unit depends upon the context in which

it is used.

8.4.1 In printed or typed material it is preferable to use numbers between 1 and 1000,

wherever possible, by selecting the appropriate prefix. For example:

• 725 m is preferred to 0.725 km or 725 000 mm.

8.4.2 If the numerical quantity is part of a group of numbers in a different range, select the prefix which most adequately covers the range, without unduly large

or small numbers. For example:

• If 725 m is part of a group of numbers shown in kilometers, show it as 0.725 km.

8.4.3 Although physical data generally should be presented in the most condensed form

possible -by using appropriate prefixes - it may be advantageous in calculations

to use exponential notation, in lieu of prefixes. For example:

• 900 mm2 = 0.9 x 10~ 3 m

2

; 36 MPa = 36 x 10 6 Pa = 36 x 10 6 N/m2

8.4.4 In drawings it will be of advantage to show one measurement unit throughout,

so that numerical values can be represented by numbers only, and the unit symbol

can be deleted.

For example, in a drawing in which all dimensions are shown in millimeters,

5-digit numbers (indicating millimeters) are quite acceptable.

10
SPACE AND TIME:

TABLE G

GEOMETRY, KINEMATICS AND PERIODIC PHENOMENA

QUANTITY PREFERRED OTHER

AND SI UNIT SYMBOL

UNITS

(SYMBOLS) ACCEPTABLEUNITS UNIT NAME TYPICAL APPLICATIONS REMARKS

LENGTH m meter ARCHITECTURE AW GENERAL ENGINEERING

Levels, overall dimensions, spans, USE meters on all drawings with scale

(m) column heights, etc., in engineering

computations. ESTIMATING ANP SPECIFICATION

Trenches, curbs, fences, lumber

lengths, pipes and conduits; lengths

of building materials generally.

LANP SURVEYING

Boundary and cadastral surveys; survey

plans; heights, geodetic surveys,

contours. HVV1WL1C ENGINEERING

Pipe and channel lengths, depth of storage tanks or reservoirs, height of potentiometric head, hydraulic head,

piezometric head.

ratios between 1:200

and 1:2000. Where required for purposes of accuracy,

show dimensions to three decimal places.

An alternative spelling is "metre".

ram millimeter ARCHITECTURE ANP GENERAL ENGINEERING USE millimeters on Spans, dimensions in buildings, dimen- drawings with scale

sions of building products; depth and width of sections; displacement, settlement, deflection, elongation; slump

of concrete, size of aggregate; radius

of gyration, eccentricity; detailed

ratios between 1:1 and 1:200. AVOID the use of centimeters (cm) . dimensions generally; rainfall. ESTIMATING ANP SPECIFICATION

Where 'cm' is shown

in documents, such Lumber cross sections; thicknesses, as for snow depth,

diameters, sheet metal gages, body dimensions, or fasteners; all other building product

dimensions. HWRAULIC ENGINEERING

carpet sizes, etc. CONVERT to 'mm' or

'm' . Pipe diameters; radii of ground water

wells; height of capillary rise; precipitation, evaporation.

km kilometer Distances for transportation purposes

geographical or statistical applications in surveying; long pipes and

channels.

pm micrometer Thickness of coatings (paint, galvanizing etc.), thin sheet materials, size

of fine aggregate.

AREA m

2 square meter GENERAL APPLICATIONS

Small land areas; area of cross-section

(1 m

2 = 10 6 mm2

)

(m2

) of earthworks, channels and larger

pipes; surface area of tanks and small reservoirs; areas in general. ESTIMATING ANP SPECIFICATION

Site clearing; floor areas; paving, masonry construction, roofing, wall and floor finishes, plastering, paintwork,

glass areas, membranes, lining materials, insulation, reinforcing mesh, formwork; areas of all building com- ponents.

Replaces sq.ft.;

sq.yd. aniT square. SPECIFY masonry con- struction by wall

area x wall thickness.

mm2 square millimeter Area of cross section for structural

and other sections, bars, pipes, rolled and pressed shapes, etc.

AVOID the use of cm2 (square centimeter)

by conversion to mm2. (1 cm2 = 10 2 mm2 = 100 mm2

) km2 square kilometer Large catchment areas or land areas.

ha hectare Land areas; irrigation areas; areas on boundary and other survey plans.

( 1 ha = (10 2 m) 2 = 10" m

2

, = 10 000 m

2
TABLE G (CONTINUED)

QUANTITY

AND SI UNIT

SYMBOL

PREFERRED

UNITS

(SYMBOLS)

OTHER

ACCEPTABLE

UNITS UNIT NAME TYPICAL APPLICATIONS REMARKS

VOLUME, CAPACITY

(m3

)

m3 cubic meter

GENERAL APPLICATIONS

Volume, capacity (large quantities); volume of earthworks, excavations,

filling, waste removal; concrete, sand, all bulk materials supplied by volume,

and large quantities of lumber. HVVRAULIC ENGINEERING

Water distribution, irrigation,

diversions, sewage, storage capacity,

underground basins.

1 m3 = 1000 L

As far as possible, USE the cubic meter

as the preferred unit

of volume for all

engineering purposes.

3 ram cubic millimeter Volume, capacity (small quantities)

L liter Volume of fluids and containers for

fluids; liquid materials, domestic

water supply, consumption;

volume/capacity of fuel tanks

The liter and its multiples or submultiples may be used

for domestic and industrial supplies

of liquids

11= 1 dm 3 = 1000 cm3 1 mL = 1 cm3

See Section 9. 3,p. 25/26

mL milliliter Volume of fluids and containers for fluids (limited application only)

3 cm3 cubic centimeter Limited application only (small quantities)

1 cm3 = 1000 mm3 = 10"6 m

3

MODULUS OF SECTION

(m 3

)

3 mm" millimeter to third power Geometric properties of structural

sections, such as plastic section

modulus, elastic section modulus, etc. See Section 9.4, p. 26 m

3 meter to third power

SECOND MOMENT

OF AREA

(V*)

ii mnr millimeter to fourth power Geometric properties of structural

sections, such as moment of inertia

of a section, torsional constant of

a cross section.

See Section 9.4, p. 26 m" meter to fourth

power

PLANE ANGLE

(rad)

rad radian Generally used in calculations only

to preserve coherence. Slopes and gradients may be expressed as

a ratio or as a percentage:

26.57° =1:2

= 50%

= 0.4637 rad

( lrad = 57.2958°)

See also Section 9.5, on pages 26 and 27

mrad milliradian

(_°) degree (of arc) GENERAL APPLICATIONS

Angular measurement in construction

(generally using decimalized degrees);

angle of rotation, torsion, shear re- sistance, friction, internal friction,

etc. LAND SURVEYING

Bearings shown on boundary and cadastral survey plans; geodetic surveying

TIME, TIME

INTERVAL

(s)

s second Time used in methods of test; all cal- culations involving derived units with

a time component, in order to preserve

coherence.

AVOID the use of minute (min) as far

as possible

h hour Time used in methods of test; all cal- culations involving labor time, plant

hire, maintenance periods, etc.

( 1 h = 3600 s ) (Id = 86 400 s ) = 86.4 ks ) d day

a annum (year)

FREQUENCY

(Hz)

Hz hertz Frequency of sound, vibration, shock; frequency of electro-magnetic waves

( 1Hz = 1/s = s _1

) Replaces cycle (s) per second (c/s or cps) kHz kilohertz

MHz megahertz

12
TABLE G (CONTINUED)

QUANTITY

AND SI UNIT

SYMBOL

PREFERRED

UNITS

(SYMBOLS)

OTHER

ACCEPTABLE

UNITS UNIT NAME TYPICAL APPLICATIONS REMARKS

ROTATIONAL FREQUENCY, SPEED OF ROTATION

(s" 1 )

r/s revolution per

second Widely used in the specification of rotational speed of machinery; Use r/min (revolutions per minute) only

for slow moving machinery

( 1 r/s = 2 tt rad/s ) = 60 r/min )

VELOCITY,

SPEED

(m/s)

m/s meter per second Calculations involving rectilinear

motion, velocity and speed in general; wind velocity; velocity of fluids; pipe

flow velocity

( 1 m/s =3.6 km/h )

km/h kilometer per hour

Wind speed; speed used in transportation;

speed limits mm/h millimeter per hour

Rainfall intensity

ANGULAR

VELOCITY

(rad/s)

rad/s radian per second Calculations involving rotational motion

LINEAR ACCELERATION

(m/s 2

)

m/s 2 meter per second squared

Kinematics, and calculation of dynamic

forces Recommended value of acceleration of gra- vity for use in U.S: 9Us = 9.8 m/s 2 See page 28

VOLUME RATE

OF FLOW

(m 3 /s)

m

3 /s cubic meter per second Volumetric flow in general; flow in

pipes, ducts, channels, rivers; irrigation spray demand

( 1 m3 /s = 1000 L/s )

See also Section m 9.6.3 on page 27 3 /h cubic meter per hour

m

3 /d cubic meter per day

L/s liter per second Volumetric flow of fluids only

' L/d liter per day

13
TABLE H MECHANICS: STATICS AND DYNAMICS

QUANTITY

AND SI UNIT

SYMBOL

PREFERRED

UNITS

(SYMBOLS)

OTHER ACCEPTABLE

UNITS UNIT NAME TYPICAL APPLICATIONS REMARKS

MASS

(kg)

kg kilogram Mass of materials in general, mass of structural elements and machinery

USE kilograms (kg) in calculations and specifications

g gram Mass of samples of material for testing Masses greater than

lO1* kg (10 000 kg) may be conveniently

expressed in metric

tons (t)

1 t = 10 3 kg = 1 Mg

= 1000 kg

t metric ton Mass of large quantities of materials,

such as structural steel, reinforcement, aggregates, concrete, etc.; ratings of lifting equipment.

MASS PER UNIT LENGTH -

(kg/m)

kg/m kilogram per meter Mass per unit length of sections, bars,

and similar items of uniform cross section

Also known as "Linear Density"

g/m gram per meter Mass per unit length of wire and similar material of uniform cross section

MASS PER UNIT AREA

(kg/m2

)

kg/m2 kilogram per square meter

Mass per unit area of slabs, plates, and similar items of uniform thickness or depth; rating for load-carrying capacities on floors (display on notices only)*

*D0 NOT USE

in stress calculations

g/m2 gram per square meterMass per unit area of thin sheet materials, coatings, etc.

MASS DENSITY, CONCENTRATION

(kg/m 3

)

kg/m3 kilogram per cubic meter

Density of materials in general; mass

per unit volume of materials in a con- crete mix; evaluation of masses of structures and materials

Also known as "Mass per Unit Volume"

( 1 kg/m 3 = 1 g/L )

( 1 g/m 3 = 1 mg/L ) g/m3 gram per cubic meter

Mass per unit volume (concentration) in pollution control ug/m3 microgram per cubic meter

MOMENTUM

(kg-m/s)

kg-m/s kilogram meter

per second

Used in applied mechanics; evaluation

of impact and dynamic forces

MOMENT OF INERTIA

(kg-m2

)

kg-m2 kilogram square meter Rotational dynamics. Evaluation of the retraining forces required for propellers, windmills, etc.See also Section

9.11 on pages 29/30

MASS PER

UNIT TIME

(kg/s)

kg/s kilogram per second Rate of transport of material on con- veyors and other materials handling

equipment

1 kg/s = 3.6 t/h

t/h metric ton per

hour

FORCE

(N)

N newton Unit of force for use in calculations 1 N = 1 kg-m/s2

See also Section 9.8

on page 28

kN kilonewton Forces in structural elements, such as columns, piles, ties, pre-stressing

tendons, etc.; concentrated forces; axial forces; reactions; shear force; gravitational force

FORCE PER

UNIT LENGTH

(N/m)

N/m newton per meter Unit for use in calculations kN/m kilonewton per meter Transverse force per unit length on a beam, column, etc.; force distribution

in a linear direction

MOMENT OF FORCE TORSIONAL OR

BENDING MOMENT,

(N-m)

N-m newton meter Bending moments (in structural sections), torsional moment; overturning moment; tightening tension for high strength

bolts; torque in engine drive shafts,

axles, etc.

See also Sections

9.10.4 and 9. 11 on pages 29 and 30 kN-m kilonewton meter

MN-m meganewton meter

14
TABLE H (CONTINUED)

QUANTITY AND SI UNIT

SYMBOL

PREFERRED

UNITS

(SYMBOLS)

OTHER ACCEPTABLE

UNITS UNIT NAME TYPICAL APPLICATIONS REMARKS

PRESSURE,

STRESS, MODULUS OF ELASTICITY

(Pa)

Pa pascal Unit for use in calculations; low differential pressure in fluids

(1 Pa = 1 N/m2

)

kPa kilopascal Uniformly distributed pressure (loads)

on floors; soil bearing pressure; wind

pressure (loads), snow loads, dead and

live loads; pressure in fluids; differen- tial pressure (e.g., in ventilating

systems)

Where wind pressure,

snow loads , dead and

live loads are shown

in kN/m2 CHANGE

units to kPa

MPa megapascal Modulus of elasticity; stress (ultimate,

proof, yield, permissible, calculated,

etc.) in structural materials; concrete

and steel strength grades

1 MPa = 1 MN/m2 = 1 N/mm2

GPa gigapascal Modulus of elasticity in high strength materials

UPa micropascal Sound pressure (20 yPa is the reference, quantity for sound pressure level)

COMPRESSIBILITY

(Pa J

)

1/Pa reciprocal (of ) pascal

Settlement analysis, (coefficient of compressibility), bulk compressibility

(1/Pa = 1 m

2 /N)

1/kPa reciprocal (of ) kilopascal

DYNAMIC VISCOSITY

(Pa's)

Pa-s pascal second Shear stresses in fluids (1 Pa.s = 1 Ns/m2

) The centipoise (cP) = 10" 3 Pa-s WILL

mPa-s NOT BE USED millipascal second

KINEMATIC

VISCOSITY

(m2 /s)

m

2 /s square meter per second . The centistokes(cSt)

= 10" 6 m

2 /s WILL NOT

BE USED

1 cSt = 1 mm2 mm /s square millimeter /s per second Computation of Reynold's number settlement analysis (coeff. of consolidation)

WORK, ENERGY

(J)

J j oule Energy absorbed in impact testing of materials; energy in general; calculations involving mechanical and electrical

energy

kJ kilojoule

MJ megajoule

kWh kilowatthour Electrical energy applications only 1 kWh = 3.6 MJ

IMPACT STRENGTH

(J/m2

)

J/m2 joule per square meter

Impact strength; impact ductility

kJ/m2 kilojoule per

square meter

POWER

(W)

W watt Power in general (mechanical, electrical,

kW kilowatt

thermal) ; input/output rating, etc. of motors, engines, heating and ventilating

plant and other equipment in general

MW megawatt Power input/output rating etc. of heavy

power plant

pW picowatt Sound power level (1 pW is the reference quantity for sound power level)

15
TABLE J

HEAT: THERMAL EFFECTS, HEAT TRANSFER

QUANTITY AND SI UNIT

SYMBOL

FREFERRED

UNITS

(SYMBOLS)

OTHER ACCEPTABLE

UNITS UNIT NAME TYPICAL APPLICATIONS REMARKS

TEMPERATURE

VALUE

(K)

K kelvin Expression of thermodynamic temperature; calculations involving units of temperature

(t.

c

= TR

- 273.15)

Temperature values will normally be measured in C (degrees Celsius)

°C degree Celsius Common temperature scale for use in meteorology and general applications;

ambient temperature values

TEMPERATURE

INTERVAL

(K)

K kelvin Heat transfer calculations; temperature

intervals in test methods, etc.

(1 K = 1°C) The use of K (kelvin)

in compound units is

°C degree Celsius recommended

COEFFICIENT OF LINEAR THERMAL

EXPANSION

(1/K)

1/K reciprocal (of ) kelvinExpansion of materials subject to a change in temperature (generally

expressed as a ratio per kelvin or 1/°C reciprocal (of ) degree Celsius)

degree Celsius

HEAT, QUANTITY OF HEAT

(J)

J joule Thermal energy calculations. Enthalpy,

latent heat, sensible heat

kJ kilojoule

MJ megajoule

SPECIFIC ENERGY, SPECIFIC LATENT

HEAT; COMBUSTION HEAT

(mass basis)

(J/kg)

J/kg joule per kilogram

Heat of transition; heat and energy con- tained in materials; combustion heat

per unit mass; calorific value of fuels

(mass basis); specific sensible heat, specific latent heat in psychrometric

calculations

kJ/kg kilojoule per kilogram

MJ/kg megajoule per kilogram

ENERGY DENSITY,

COMBUSTION HEAT

(Volume basis)

(J/m3

)

J/m3 joule per cubic meterCombustion heat per unit volume

Calorific value of fuels (volume basis)

(lkJ/m 3 = 1 J/L)

(1 MJ/m3 = 1 kJ/L)

kJ/m3 kilojoule per

cubic meter

MJ/m3 megajoule per

cubic meter

HEAT CAPACITY, ENTROPY

(J/K)

J/K joule per kelvin Thermal behavior of materials, heat transmission calculations, entropy kJ/K kilojoule per

kelvin

SPECIFIC HEAT

CAPACITY , SPECIFIC ENTROPY

(J/(kg-K) )

J/(kg-K) joule per kilogram kelvin Thermal behavior of materials, heat

transmission calculations

kJ/(kg-K) kilojoule per kilogram kelvin

HEAT FLOW

RATE

(W)

W watt Heat flow rate through walls , windows -, ecc. ; heat demand (111=1 J/s) kW kilowatt

POWER DENSITY, HEAT FLUX

DENSITY, IRRADIANCE

(W/m2

)

W/m2 watt per square meter

Density of power or heat flow through

building walls and other heat transfer

surfaces; heat transmission calcula- kW/m tions 2 kilowatt per

square meter

16
TABLE J (CONTINUED)

QUANTITY AND SI UNIT

SYMBOL

PREFERRED

UNITS

(SYMBOLS)

OTHER ACCEPTABLE

UNITS UNIT NAME TYPICAL APPLICATIONS REMARKS

HEAT RELEASE RATE

(W/m3

)

W/m3 watt per cubic meter

Rate of heat release per unit volume

over time (for gases and liquids)

(W/m 3 = J/(m3 -s)

kW/m3 kilowatt per

cubic meter

THERMAL

CONDUCTIVITY,

( W/(m-K) )

W/(m-K) watt per meter

kelvin Estimation of thermal behavior of materials and systems; heat transmission

calculations

Thermal conductivity of structural and building materials in fire-resistance

testing, insulation, etc.

1 W/(m-K) =

1 W/(m.°C)

( k value)

COEFFICIENT OF HEAT TRANSFER,

(THERMAL CONDUCTANCE)

( W/(m2 -K) )

W/(m2 -K) watt per square meter kelvin

Heat transfer calculations for buildings,

building components and equipment. Transmittance of construction elements

( U value)

kW/(m2 -K) kilowatt per square meter kelvin

THERMAL

RESISTIVITY

(m-K)/W

(m-K)/W meter kelvin per

watt Heat transmission calculations (reciprocal of thermal conductivity)

THERMAL INSULANCE, (THERMAL RESISTANCE)

(m2 -K)/W

(m2 -K) /W square meter kelvin per watt

Heat transmission calcuations (reciprocal of thermal conductance)

( R value)

17
TABLE K

ELECTRICITY AND MAGNETISM

QUANTITY PREFERRED OTHER

AND SI UNIT UNITS ACCEPTABLE UNIT NAME TYPICAL APPLICATIONS REMARKS SYMBOL (SYMBOLS) UNITS

ELECTRIC CURRENT A ampere Maintenance rating of an electrical

installation. Leakage current

(A) kAmA

uA

kiloampere

milliampere

microampere

MAGNETOMOTIVE Used in the calculations involved in FORCE, MAGNETIC magnetic circuits POTENTIAL

DIFFERENCE

(A)

MAGNETIC FIELD

STRENGTH, A/m ampere per meter Magnetic field strength used in calculation of magnetic circuitry such as

(1 kA/m = 1 A/mm)

MAGNETIZATION kA/m kiloampere per

meter

transformers, magnetic amplifiers, and general cores

(A/m)

CURRENT A/m2 ampere per square Design of cross-sectional area of DENSITY

(A/m2

)

meter electrical conductor

kA/m2 kiloampere per

square meter

(1 A/mm2 = 1 MA/m2 A/mm ) 2 ampere per square millimeter

ELECTRIC CHARGE, QUANTITY OF

C coulomb Ihe voltage on a unit with capacitive

type characteristics may be related to

1 C = 1 A-s

ELECTRICITY kC kilocoulomb the amount of charge present (e.g. DO NOT USE ampere

uC microcoulomb electrostatic precipitators). Storage hour:

(C) nC

pC nanocoulombpicocoulomb

battery capacities 1 A-h = 3.6 kC

ELECTRIC

POTENTIAL,

V volt 1 V = 1 W/A

POTENTIAL MV megavolt DIFFERENCE , kV kilovolt

ELECTROMOTIVE mV millivolt

FORCE UV microvolt

(V)

ELECTRIC FIELD STRENGTH V/m volt per meter Ihe electric field strength gives the potential gradient at points in space. MV/m megavolt per meter This may be used to calculate or test

(V/m) kV/m kilovolt per meter electrical parameters such as dielectric mV/m millivolt per meter strength. uV/m microvolt per meter

ACTIVE POWER W watt The useful power of an electrical 1 W = 1 V-A

(W)

circuit is expressed in 'watts' (W) . GW gigawatt (The apparent power in an electrical MW megawatt circuit is expressed in 'volt-amperes', kW kilowatt (V-A) ). mW milliwatt

yW microwatt

CAPACITANCE F farad Electronic components. Electrical 1 F = 1 C/V (F)

design and performance calculators.

mF millifarad

yF microfarad

nF nanofarad

PF picofarad .

18
TABLE K (CONTINUED)

QUANTITY AND SI UNIT SYMBOL

PREFERRED

UNITS

(SYMBOLS)

OTHER ACCEPTABLE

UNITS UNIT NAME TYPICAL APPLICATIONS REMARKS

RESISTANCE

(S3)

a ohm The design of electrical devices with resistance, such as motors,

generators, heaters, electrical distribution svstems , etc.

12=1 V/A

Mfi

kfi mf!

gigaohm

megohm

kilohm milliohm

CONDUCTANCE , ADMITTANCE

SUSCEPTANCE

(S)

S

MS

kS

mS

us

Siemens

megasiemens

kilosiemens

mi His iemens micros iemens

The Siemens (S) was formerly kn

as mho

3wn

RESISTIVITY n-m ohm meter

(a-m) G£2-m MfJ-m

kfl-m mfi-m

ufl-m nfi-m

gigaohm meter megohm meter kilohm meter milliohm meter microohm meter

nanoohra meter

(ELECTRICAL) CONDUCTIVITY

S/m Siemens per meter A parameter for measuring water quality.

(S/m) MS/m

kS/m

uS/m

megasiemens per meter

kilosiemens per meter microsiemens per meter

MAGNETIC FLUX, FLUX OF MAGNETIC

INDUCTION

mWb milliweber Used in the calculations involved in magnetic circuits.

1 Wb = 1 V-s

(Wb)

MAGNETIC FLUX

DENSITY, MAGNETIC

INDUCTION

(T)

T

mT

nT

tesla

millitesla

microtesla

nanotesla

Used in the calculations involved in magnetic circuits.

1 T = 1 Wb/m2

MAGNETIC VECTOR POTENTIAL kWb/m2 kiloweber per square meter

Used in the calculations involved in magnetic circuits.

(Wb/m2

)

SELF INDUCTANCE, MUTUAL

INDUCTANCE

,

PERMEANCE

(H)

H

mH

uHnH

pH

henry

millihenry

microhenry : nanohenry

picohenry

Used in analysis and calculations involving transformers.1 H = 1 Wb/A

RELUCTANCE

(1/H)

1/H reciprocal of henry

Design of motors and generators

PERMEABILITY

(H/m)

H/m

uH/m

nH/m

henry per meter

microhenry per

meter nanohenry per

meter

Permeability gives the relationship

between the magnetic flux density and

the magnetic field strength.

19
TABLE L

LIGHTING

QUANTITY AND SI UNIT

SYMBOL

PREFERRED

UNITS

(SYMBOLS)

OTHER ACCEPTABLE

UNITS UNIT NAME TYPICAL APPLICATIONS REMARKS

LUMINOUS INTENSITY

(cd)

cd candela

SOLID ANGLE

(sr)

sr steradian

LUMINOUS FLUX dm)lm

klm

lumen

kilolumen

Luminous flux of light sources, lamps and light bulbs

1 lm = 1 cd-sr Already in general

use

QUANTITY OF LIGHT

(lm-s)

lm- s

lm-h

lumen second

lumen hour

1 lm-h = 3600 Im/s

LUMINANCE

(cd/m2

)

cd/m2

kcd/m2

cd/mm2

candela per square meter

kilocandela per

square meter

candela per square millimeter

Assessment of surface brightness;

luminance of light sources, lamps and

light bulbs; calculation of glare in lighting layouts

Replaces stilb

(1 sb = 101* cd/m2

) and apostilb

(1 apostilb =

cd/irm2

)

ILLUMINANCE

(lx)

lx

klx

lux

kilolux

Luminous flux per unit area used in determination of illumination levels and design/evaluation of interior lighting

Layouts. (Outdoor daylight illumination

on a horizontal plane ranges up to

100 klx)

a) Formerly referred

to as illumination

1 lx = 1 lm/m2 b) Replaces

(1 ph = 101* lx)

c) Luminous exitance is described

in lm/m2

LIGHT EXPOSURE

(lx-s)

lx's

klx's

lux second

kilolux second

LUMINOUS EFFICACY

(lm/W)

lm/W lumen per watt Rating of luminous efficacy of artificial

light sources

20
TABLE M

ACOUSTICS

QUANTITY AND SI UNIT

SYMBOL

PREFERRED

UNITS

(SYMBOLS)

OTHER ACCEPTABLE

UNITS UNIT NAME TYPICAL APPLICATIONS REMARKS

WAVE LENGTH

(m)

m

mm

meter

millimeter

Definition of sound wave pitch

AREA OF ABSORPTIVE

SURFACE

(m2

)

m

2 square meter Calculations of room absorption

PERIOD, PERIODIC TIME

(s)

s

ms

second

millisecond

Measurement of time and reverberation

time

FREQUENCY

(Hz)

Hz

kHz

hertz

kilohertz

Frequency ranges in sound absorption

calculations and sound pressure measurement

1 Hz = 1 cycle per second (cps)

(INSTANTANEOUS) SOUND PRESSURE

(Pa)

Pa

mPa

uPa

pascal

millipascal

micropascal

Measurement of sound pressure; reference

level for sound pressure is 20 uPa, but sound pressure is shown in decibels (dB) based upon a logarithmic scale

Sound pressure level L v P = 20 log actual pressure (Pa)

10 20 x 10"6 (p a )

Do NOT USE dyne

(1 dyn = 10 pPa)

SOUND POWER, SOUND ENERGY

FLUX

(W)

W

mW

pW

pW

watt

milliwatt

microwatt

picowatt

Measurement of sound power; reference

level for sound power is 1 pW

Sound power level, L =

= 10 log actual power (W)

10 io- 12 (w)

SOUND INTENSITY

(W/m2

)

W/m2

pW/m2

watt per square meter

picowatt per

square meter

Measurement of sound intensity; reference level for sound intensity is

1 pW/m2

Sound intensity level L =

= 10 log actual intensity (W/m2

) ^g

10-12 (W/m2

)

SPECIFIC ACOUSTIC

IMPEDANCE

(Pa-s/m)

Pa-s/m pascal second per meterSound impedance measurement (1 Pa-s/m = 1 N s/m3

)

ACOUSTIC

IMPEDANCE, RESISTANCE

(Pa-s/m3

)

Pa-s/m 3 pascal second

per cubic meter

Sound impedance measurement

21
9. SPECIAL CONSIDERATIONS IN THE USE OF SI UNITS IN BUILDING DESIGN AND CONSTRUCTION

9.1 LINEAR MEASUREMENT (LENGTH)

9.1.1 The preferred units for measurement of length in building design, construction,

and production are the millimeter (mm) and the meter (m)

.

9.1.2 In special applications, the kilometer (km) is used for the measurement of long

distances, and the micrometer (um) is used for precision measurements.

9.1.3 The centimeter (cm) is to be avoided in all building design and construction

applications.

9.1.4 The arguments for the deletion of the centimeter are:

a. the centimeter is not consistent with the preferred use of multiples which

represent ternary powers of 10 ;

b. the order of magnitude between the millimeter and centimeter is only 10, and

the use of both units would lead to confusion ;

c. the millimeter (mm) provides integers within appropriate tolerances for all building dimensions and nearly all building product dimensions, so that

decimal fractions are almost entirely eliminated from documents. In contrast,

acceptance of the centimeter would inevitably lead to extensive use of decimal fractions, which is undesirable.

9.1.5 On drawings, unit symbols may be deleted if the following rules are applied:

a. the drawing is designated "all dimensions shown in millimeters," or "all

dimensions shown in meters;"

b. whole numbers always indicate millimeters: e.g. 3600 ; 300 ; 25

i. any length up to 328 feet can be shown by a simple 5-digit number;

for example:

32? , _ 1Q 11/16 „ ^^ gg ^

ii. similarly, any length up to 32 feet and 9 inches can be shown by a 4-digit number ;

iii. any length up to 3 feet and 3 /l 6 inches can be shown by a 3-digit

number.

c. decimalized expressions, taken to three decimal places, always indicate

"meters"; for example: 3.600; 0.300; 0.025

9.1.6 The use of millimeters and meters, as recommended, saves both space and time in

drawing, typing, and computer applications. It also improves clarity in

drawings with a lot of dimensions.

9.1.7 SURVEY MEASUREMENT

The change to SI units will also eliminate the discrepancies between the units

22
"international foot" and U.S. survey foot," "international mile" and "U.S. survey

mile" (the survey mile is approximately 3 millimeters longer) , and corresponding

derived units for area measurement. ' '

9.2 AREA

9.2.1 The preferred unit for area measurement is the square meter ( m

2

) . Very large

areas can be expressed in square kilometers ( km ) , and small areas will be

expressed in square millimeters (mm2 ), or in square meters using exponential

notation (e.g. 10""° m ) .

9.2.2 The hectare (ha), is used for surface measurement of land and water only

( 1 ha =(100m) 2 = 10 000 m

2 = 10 4 m2 = 0.01 km2 ).

9.2.3 The square centimeter (cm2

) is to be avoided to minimize confusion. Any

measurement of area given in square centimeters should be converted to square

millimeters or square meters ( 1 cm2 = 100 mm2 = 10

-1

* m

2

) .

9.2.4 At times, it will be more appropriate to indicate the surface or cross-sectional

area of building products by linear dimensions ; e.g., 40mm x 90mm ; 300 x 600 .

It is preferred practice to indicate the width dimension first and height second.

9.3 VOLUME AND FLUID CAPACITY

9.3.1 The preferred unit for measurement of volume in construction and for large

storage tank capacities is the cubic meter (

m

3

) .

9.3.2 The preferred units for measurement of fluid capacity (liquid volume) are the

liter (L) and the milliliter (mL) .

9.3.3 By international definition, in 1964, the liter is equal to one thousandth of

a cubic meter, or equal to one cubic decimeter (dm ) .

9.3.4 Because the cubic meter contains one billion (10 3

) cubic millimeters, the

cubic decimeter ( dm3

) and the cubic centimeter ( cm3) may find limited

application in some industries, particularly as they represent preferred steps

Since 7 §93, the U.S. baAlA o{ length mzoAUXement haA be.e.n dexivzd ^Aom metxlc

itand.aA.cU>. In 1959, the, dzfilnltlon ojj Length ofi the. "fioot" woa changed {Aom

1200/3937 m to 0-304& m exactly, which KZAulteA In the. new value being ihontex

by two paAtA In a million.

At the. t>ame. time, IX woa dtclde.d that any data dexlved ^nom and publlihed oa a AeAult o{ ge.odetA.ci tiUh.ve.yi, within the. UnlXed States would Aemaln with the, old

itandaAd. ThuA alt land me.aAuAeme.ntA In U.S. cuAtomaxy unlXA axe baAzd upon the

"U.S. iuAve.y hoot," which convextA to 0.304 BOO 6 m [1200/3937 m)

.

The. change, to SI will eliminate, thlA dual itandaxd.

23
of 1000 in volume measurement. However, it is recommended that any such cases

be converted to the preferred units for volume measurement in building design

and construction applications, shown in Table N.

TABLE N: UNITS FOR VOLUME AND FLUID CAPACITY AND THEIR RELATIONSHIPS

PREFERRED UNITS LIMITED APPLICATION RELATIONSHIPS ALL VOLUMES

FLUID

VOLUME ONLY

m

3 1 m

3 = 1000 L = 1000 dm3

L dm3 , 10- 3 m3 1 L = 1 dm3 = 106 ^3

= 1000 mL

mL cm3 i t i 3 10~ 6 m

3 1 mL«= 1 cm 3 =

3

, 10° mm3

mm 1 mm3 = 10-9 m

3

9.4 GEOMETRICAL CROSS- SECTIONAL PROPERTIES

9.4.1 The expression of geometrical cross-sectional properties of structural sections

involves raising the unit of length to the third, fourth or sixth power. Values

can be shown either in mm 3

, mm , or mm >with exponential notation, or else in m,

m , or m , with exponential notation.

9.4.2 The following measurement units are suitable:

a. Modulus of Section

Second Moment of Area

Torsional Constant

c. Warping Constant

3

- mm° or nr

) mm

1* or nr

6 6 mmD or mc

( 1 mm3 = 10"9 m

3

)

( 1 mm,+ = 10-12 m

k

)

( 1 mm6 = 10" 18 m

6

)

9.4.3 Thus, the cross-sectional properties of a wide flange beam, 460 mm deep, and

82 kg/m mass per unit length, could be expressed as follows:

a. Plastic Modulus Zx

b. Second Moment of Area Ix_x

c. Torsional Constant J

d. Warping Constant Cw

1.835 x 106 mm3 or 1.835 x 10"3 m3

0.371 x 109 mm

1* or 0.371 x 10" 3 m

k

0.691 x 10 6 mm4 or 0.691 x 10~6 m

k

0.924 x 1012 mm6 or 0.924 x 10"6 m

6

9.5 PLANE ANGLE

9.5.1 While the SI unit for plane angle, the radian ( rad ), should be used in calculations for reasons of its coherence, the customary units of angular measure,

degree (°), minute ('), and second (") of arc will continue to be used in

24
many applications in cartography and surveying.

9.5.2 The degree (°), with parts denoted by decimals (as in 27.25° ), will continue

to be utilized in engineering and in construction.

9.6 TIME INTERVAL

9.6.1 In general applications, the day (d), hour (h) , and minute ( min ) are permitted non-SI alternatives to the SI base unit for time, the second (s)

.

9.6.2 It is recommended that the minute (min) be avoided as far as possible to minimize the number of units in which time is a dimension.

9.6.3 For instance, flow rates should be expressed in cubic meters per second, liters

per second, or cubic meters per hour, rather than in cubic meters per minute or

in liters per minute, so that the variety of units is reduced. For example:

1 m

3 /s = 1000 L/s (DO NOT USE 60 m3 /min )

1 L/s = 3.6 m

3 /h ( DO NOT USE 60 L /min )

1 m

3 /h = 1000 L/h (DO NOT USE 16.67 L/min)

9.6.4 Because of its variability, the month should not be used to indicate a time

dimension, unless a specific calendar month is referred to.

9.6.5 Where the calendar year (symbol "a" for annum) is used as a measurement for

time interval, it represents 365 days, or 31536 000 seconds.

9-7 TEMPERATURE AND TEMPERATURE INTERVAL

9.7.1 The SI base unit of (thermodynamic) temperature is the kelvin (K),and this unit

is used for expressing both thermodynamic temperature and temperature interval.

9.7.2 Wide use is also made of the degree Celsius (°C), for the expression of ambient

temperature levels in Celsius temperature, and for temperature intervals.

9.7.3 The temperature interval of one kelvin equals exactly one degree Celsius. For

this reason, the degree Celsius may be used in lieu of kelvin in calculations

involving temperature interval, although the kelvin (K) is preferred.

9.7.4 A temperature expressed in degrees Celsius is equal to the temperature expressed

in kelvins less 273.15 . There are no negative (minus) temperature values in

the kelvin scale.

9.7.5 It is recommended that the kelvin (K) be used in compound units involving

temperature or temperature interval.

25
9.8 MASS, WEIGHT, AND FORCE

9.8.1 The significant difference between SI and traditional metric or other

measurement systems is the use of explicit and distinctly separate units

for "mass" and for "force".

9.8.2 The SI base unit kilogram (kg) denotes the base unit of mass (the quantity

of matter of an object which is constant and independent of gravitational

attraction)

.

9.8.3 The derived SI unit newton (N) denotes the absolute derived unit of force

(mass times acceleration : kg-m/s 2

)

.

9.8.4 The general use of the term "weight" should be avoided in technical practice for two reasons:

a. in common parlance "weight" is confused with "mass" ; b. weight describes only a particular force that is related solely to gravitational acceleration, which varies on the surface of the earth.

9.8.5 As servicable as the customary gravitational system may seem in the area of

"statics", the absolute and more universally useful concepts of the clear SI distinction between "mass" and "force" will become increasingly significant as engineering and construction become more and more involved in "dynamic"

considerations

.

9.8.6 In dynamic calculations, the value of a mass in kilograms (kg) is used directly

with the appropriate acceleration. Thus the customary (frequently mystifying)

expression m = W/g is not applicable, and is indeed inconsistent with SI. Hence SI simplifies and clarifies dynamics.

9.8.7 For engineering design purposes, in United States locations (except perhaps

Alaska), the following value is recommended for acceleration of gravity:

g = 9.8 m/s 2

. (The standard international value is 9.806 65 m/s 2

).

9.8.8 The use of the factor 9.8 (m/s 2

) is recommended for g because it:

a. provides adequate accuracy in nearly all instances ; b. gives fewer decimal places than the use of 9.81, or even 9.806 65, which

was advocated in Britain ; c. provides a different number in the product than would be obtained with the use of a factor of 10 (advocated by some) , which can be easily overlooked

and cause errors, as well as introducing overdesign by 2% .

9.8.9. The newton extends through to derived quantities for pressure and stress;

energy, work, and quantity of heat; power; and many of the electrical units.

26
9.8.10 The unit kilogram-force (kgf) is inconsistent with SI, and is in the process

of being dropped and replaced by the newton in traditionally metric countries.

The kilogram-force (kgf) SHOULD NOT BE USED in the United States.

9-9 PRESSURE, STRESS, AND ELASTIC MODULUS

9.9.1 The SI unit for both pressure and stress (force per unit area) is the

pascal (Pa), which replaces a large number of customary units, and also supersedes a few traditional but non-SI metric units.

9.9.2 While it may be useful in some applications to read out test results in N/mm2

(which is identical with MN/m2

) , or in kN/m , it is preferable and recommended

to always show computations and results in megapascals (MPa) or kilopascals (kPa)

.

9.9.3 The non-SI units, the "bar" (which equals 100 kPa or 0.1 MPa), and the

"mill ibar

(which equals 100 Pa or 0.1 kPa ), should not be used with SI

in design or construction applications.

9-10 ENERGY, WORK, AND QUANTITY OF HEAT

9.10.1 The SI unit of energy, work, and quantity of heat is the joule (J), which is

equal to a newton meter (N-m), and to a watt second (W-s).

9.10.2 The joule provides one coherent unit to supersede a large number of traditional

units: Btu, therm, calorie, kilocalorie, foot pound-force, etc.

9.10.3 For many years, and since long before the joule was named, the kilowatthour (kWh)*

has been used extensively as the unit of energy in electrical energy consumption.

Most existing electricity meters show kWh, and recalibration in the SI unit

megajoule ( MJ ) would be needlessly costly. For this reason, the kWh (kilowatthour) will be permitted as an alternative unit in electrical applications, but it

should not be introduced in new areas. ( * The accepted symbol in the United

States is "kWh" , but the correct SI symbol would be kW-h ) .

9.10.4 The joule should never be used for torque, which is widely designated as newton

meter ( N-m ) .

9.11 ROTATIONAL DYNAMICS

For dimensional consistency in calculations involving rotational dynamics, the

units shown in Table 0, on page 29, are recommended, because they contain the SI

unit for angular displacement, the radian (rad) , and thus provide dimensional

integrity in equations.

27
TABLE 0: UMTS RECOMMENDED FOR ROTATIONAL DYNAMICS

QUANTITY RECOMMENDED SI UNIT

ALTERNATIVE UNIT

WHICH DISREGARDS

ANGULAR DISPLACEMENT

Torque

Moment of Inertia

Moment of Momentum

N • m / rad

kg • m / rad 2 kg • m

2 /(rad -s)

N • m

kg . m

2

kg • m

2

/ s

9.12 POWER AND HEAT FLOW RATE

9.12.1 The SI unit for power and heat flow rate is the watt (W), which is already

in worldwide use as the general unit for electrical power,

9.12.2 The watt, and its multiples, will now replace a number of traditional units of

power and heat flow rate:

a. for general power: the horsepower (electric, boiler), and the foot

pound-force per hour ( or minute / or second ) b. for heat flow rate: the Btu per hour, the calorie per minute (or second ), the kilocalorie per minute ( or second ) , and the

ton of refrigeration

9.13 ELECTRICAL UNITS

There are no changes in units used in electrical engineering, except:

a. the renaming of the unit of conductance to Siemens (S) from "mho" ;

b. the use of the SI unit for frequency, hertz (Hz), in lieu of cycles per

second ( cps ) .

9.14 LIGHTING UNITS

9.14.1 The SI units for luminous intensity, candela ( cd ) , and for luminous

flux, lumen ( lm ) , are already in common use.

9.14.2 The candela ( cd ) directly replaces the former units "candle" and "candlepower".

9.14.3 Illuminance will be expressed in the SI unit lux ( Ix ), which is equal to the

lumen per square meter ( lm/m2

), and replaces lumen per square foot and the

f ootcandle

.

9.14.4 Luminance will be expressed in the SI unit candela per square meter (cd/m2

)

,

which replaces candela per square foot, footlambert, and lambert.

28
9.15 DIMENSIONLESS QUANTITIES

Dimensionless quantities, or ratios, such as relative humidity, specific gravity,

decibel (dB) , pH, etc., remain unchanged when converting to SI.

9-16 CONSTANTS FOR USE IN BUILDING DESIGN CALCULATIONS

Table P shows a selection of internationally agreed values and empirical constants

for use in design calculations.

TABLE P: DESIGN CONSTANTS (NAME. SYMBOL. VALUE AND UNIT)

NAME SYMBOL VALUE UNIT

Standard atmosphere pressure

(international value)

P

o 101.325 kPa

Absolute (zero) temperature T

0.0

(-273.15) K(°C)

Velocity of sound in air

(P , 20°C, 50% R.H.)

M 344 m/s

Specific volume of perfect gas

(P , 20° C) Vo 22.414 m

3 /kmol

(L/mol)

Characteristic gas constant for air Ra

287.045 J/(kg-K)

Characteristic gas constant for water vapor

Rv 461.52 J/(kg.K)

Natural logarithms e 2.718 28

Pi (it) ir 3.141 59

29

10. APPENDIXES

APPENDIX A: Pages 34-37

CONVERSION FACTORS FOR THE MOST COMMON UNITS USED IN BUILDING

DESIGN AND CONSTRUCTION (shown to six significant places)

METRIC TO CUSTOMARY CUSTOMARY TO METRIC

APPENDIX B: Page 38

SI UNITS AND RELATIONSHIPS CHART: CHART AND EXPLANATIONS

APPENDIX C: Page 40

SUPERSEDED METRIC UNITS NOT RECOMMENDED FOR USE WITH SI

31
APPENDIX A

CONVERSION FACTORS FOR THE MOST COMMON

UNITS USED IN BUILDING DESIGN AND CONSTRUCTION

Conversion factors are taken to six significant figures, where

appropriate. Underlined values denote exact conversions.

METRIC TO CUSTOMARY CUSTOMARY TO METRIC

LENGTH

1 km = 0.621 371 mile

= 49.7096 chai

1 m. = 1.093 61 yd

= 3.280 84 ft

1 mm = 0.039 370 1 in

1 mile (international)

1 chain

1 yd

1 ft

1 in

(1 US. survey foot

* Section 9.1.7 on page 27 deals with US survey measurement

= 1.609 344 km

= 20.1168 m

= 0.9144 m

= 0.3048 m

= 304.8 mm

= 25.4

= 0.304 800 6 m)*

AREA

1 km 2 = 0.386 101 mile 2 (US survey) 1 mile 2

(US. survey) = 2.590 00 km2 1 ha = 2.471 04 acre (US. survey) 1 acre (US. survey) = 0.404 687 ha

1 m

2 = 1.195 99 y< = 4046.87 m

2 = 10.7639 ft 2

1 yd 2 = 0.836 127 m

2

1 mm = 0.001 550 in21 ft 2 1 in 2 = 0.092 903

= 645.16 m

2

2 mm

VOLUME, MODULUS OF SECTION

1 m

3 = 0.810 709 xlO- 3 acre feet 1 acre ft _ 1233.49 m3 = 1.307 95 yd 3 1 yd 3 = 0.764 555 m3 = 35.3147 ft 3 100 board ft = 0.235 974 m

3 = 423.776 board ft 1 ft 3 = 0.028 316 8 m3 1 mm3 = 61.0237 xlO-6 in 3 = 28.3168 L (dm 3

) 1 in 3 =

16 387.1

16.3871 mm 3 mL (cm 3

(FLUID) CAPACITY

1 L = 0.035 314 7 ft 3 1 gal (US liquid)** = 3.785 41 L

= 0.264 172 gal (US) 1 qt (US. liquid) = 946.353 mL

= 1.056 69 qt (US) 1 pt (US liquid) = 473.177 mL

1 mL = 0.061023 7 = 0.033 814

in 3 fl oz (US.)

1 fl oz (US) = 29.5735 mL

** i gal (UK) approx. 1 2 gal (US) SECOND MOMENT OF AREA

1 mm^ 1 in1* 416 231 mm

1

* 0.416 231 xlO-6 m* PLANE A.NGLE

1 rad = 57° 17' 45" (degree)

= 57.2958° (degree)

= 3437.75' (minute)

= 206 265" (second)

VELOCITY, SPEED

1 m/s = 3.280 84 ft/s

= 2.236 94 mile/h

1 km/h = 0.621 371 mile/h

1° (degree) = 0.017 453 3 rad

= 17.4533 mrad

1' (minute) = 290.888 urad

1" (second) = 4.848 14 urad

1 ft/s

1 mile/h

= 0.3048 m/s

= 1.609 344 km/h

= 0.447 04 m/s

32
APPENDIX A (CONTINUED)

METRIC TO CUSTOMARY CUSTOMARY TO METRIC

ACCELERATION

1 m/ S 2 3.280 84 ft/s 2 1 ft/s 2 = 0.3048 m/s 2

VOLUME RATE OF FLOW

1 m

3 /s = 35.3147

= 22.8245

= 0.810 709 xlO-3

1 L/s = 2.118 88

= 15.850 3 = 951.022

£t 3 /s million gal/d

acre ft/s

ft 3 /min

gal/min

gal/h

1 ft 3 /s

1 ft 3 /min

1 gal/min

1 gal/h

1 million gal/d

1 acre ft/s

0.028 316 8 m

3 /s 0.471947 L/s

0.063 090 2 L/s

1.051 50 mL/s 43.8126 L/s 1233.49 m

3 /s

TEMPERATURE INTERVAL

1 "C 1 K 1.8 °F 1 °F 0.555 556 5/9 °C°C or K

5/9 K

EQUIVALENT TEMPERATURE VALUE ( t £ = TR

- 273.15 )

to

c = 5/9 ( tF

- 32 ) tF 9/5 t»r + 32 MASS

1 kg

1 metric

ton

1 g

= 2.204 62

= 35.2740

= 1.102 31 = 2204.62

= 0.035 274

= 0.643 015

lb (avoirdup

oz (avoirdup

ton (short,

lbozpennyweight

ois)

ois) 2000

1

lb) 1

1

1

***( i

ton (short)***

lbozpennyweight

long ton (2240 lb)

= 0.907 185 = 907.185

= 0.453 592

= 28.3495

= 1.555 17

= 1016.05

metric ton kg

kg

gg

kg ) MASS PER UNIT LENCTH

1 kg/m

1 g/m

= 0.671969 - . = 3.547 99 lb/ft

lb/mile

1 lb/ft

1 lb/mile

= 1.488 16

= 0.281 849 kg/m

g/m

MASS PER UNIT AREA

1 kg/m2

1 g/m2 = 0.204 816

= 0.029 494

= 3.277 06 xlO-3

lb/ft2

oz/yd

oz/ft 2

1

11

lb/ft 2 oz/yd

oz/ft 2

= 4.882 43

= 33.9057

= 305.152

kg/m2 g/m2 g/m2

DENSITY ( MASS PER UNIT VOLUME )

1 kg/m3

1 t/m 3

= 0.062 428

= 1.685 56

= 0.842 778

lb/ft 3 lb /yd 3 ton/yd 311

1

lb/ft 3 lb/yd 3 ton/yd 3

= 16.0185

= 0.593 276

= 1.186 55

kg/ra 3 kg/m3 t/m3

MOMENT OF INERTIA

1 kg.m2 = 23.7304 =3417.17

lb- ft2 lb- in 2 11 lb. ft 2 lb. in2 = 0.042 1401

= 292.640 kg«m

kg" mm

MASS PER UNIT TIME

1 kg/s

1 t/h

= 2.204 62

= 0.984 207 lb/s

ton/h

11 lb/s

ton/h

= 0.453 592

= 1.016 05 kg/s

t/h

33
APPENDIX A (CONTINUED)

METRIC TO CUSTOMARY CUSTOMARY TO METRIC

FORCE

1 MN = 112.404 tonf (ton-force)

1 kN = 0.112 404 tonf

= 224.809 lbf (pound-force)

1 N = 0.224 809 lbf

MOMENT OF FORCE, TORQUE

1 N-m = 0.737 562 lbf -ft = 8.850 75 lbf -in

1 kN-m = 0.368 781 tonf -ft = 0.737 562 kip- ft

FORCE PER UNIT LENGTH

1 N/m = 0.068 5218 lbf/ft

1 kN/m = 0.034 260 9 tonf/ft

1 tonf (ton-force)

1 kip (1000 lbf)

1 lbf (pound-force)

1 lbf -ft

1 lbf -in

1 tonf -ft

1 kip-ft

1 lbf/ft

1 lbf/in

1 tonf/ft

= 8.896 44

= 4.448 22 = 4.448 22

kN

kN

N

= 1.355 82 N-m

= 0.112 985 N-m

- 2.71164 kN-m

= 1.355 82 kN-m

= 14.5939 N/m

= 175.127 N/m

= 29.187 8 kN/m

PRESSURE, STRESS, MODULUS OF ELASTICITY (FORCE PER UNIT AREA) (1 Pa = 1 N/m2

)

1 MPa

1 kPa

= 0.072 518 8 = 10.4427

= 145.038

= 20.8854

tonf /in 2 tonf/ft 2 lbf/in2 lbf/ft 2

1 tonf/in 2 1 tonf/ft 2 1 kip/in 2 1 lbf/in2 1 lbf/ft 2

= 13.7895 MPa

= 95.7605 kPa

= 6.894 76 MPa

= 6.894 76 kPa

= 47.8803 Pa

WORK, ENERGY, HEAT

1 MJ

1 kJ

1 J

= 0.277 778

= 0.947 817

= 0.737 562

( 1 J 1 N.m

kWh

Btu ft-lbf

1 W.s )

1 kWh (550 ft-lbf/s) = 3.6 MJ

1 Btu (Int. Table) = 1.055 06 kJ

= 1055.06 J

1 ft-lbf = 1.355 82 J

POWER, HEAT FLOW RATE

1 kW

1 W

= 1.341 02 = 3.412 14

= 0.737 562

hp (horsepower)

Btu/h

ft-lbf/s

1 hp

1 Btu/h

1 ft-lbf/s

0.745 700 kW 745.700 W

0.293 071 W

1.355 82 W

HEAT FLUX DENSITY

1 W/m 2 0.316 998 Btu/(ft 2 -h) 1 Btu/(ft 2 -h) = 3.154 59 W/m2

COEFFICIENT OF HEAT TRANSFER

1 W/(m2 -K) = 0.176 110 Btu/(ft 2 -h-°F) 1 Btu/(ft 2 -h-°F) 5.678 26 W/(m2 -K)

THERMAL CONDUCTIVITY

1 W/(m-K) - 0.577 11 Btu/(ft-h-°F) 1 Btu/(ft-h-°F) = 1.730 73 W/(m-K)

34
APPENDIX A (CONTINUED)

METRIC TO CUSTOMARY CUSTOMARY TO METRIC

CALORIFIC VALUE (MASS AND VOLUME BASIS)

1 kJ/kg

( x j/|) = 0.429 923 Btu/lb

1 kJ/m3 =0.026 839 2 Btu/ft 3

1 Btu/lb

1 Btu/ft 3

2.326

2.32b 37.2589

kJ/kg

(J/g)

kJ/m 3

THERMAL CAPACITY (MASS AND VOLUME BASIS)

1 kJ/(kg-K) = 0.238 846

1 kJ/(m3 -K) = 0.014 910 7

Btu/(lb>°F)

Btu/(ft 3 .°F)

1 Btu/(lb-°F)

1 Btu/(ft 3 -°F)

= 4.1868

= 67.0661

kJ/(kg-K)

kJ/(m 3 -K)

ILLUMINANCE

1 lx (lux) = 0.092 903 lm/ft 2 (footcandle) 1 lm/ft 2 (footcandle) = 10.7639 lx (lux)

LUMINANCE

1 cd/m2 = 0.092 903

= 0.291864

1 kcd/m2 = 0.314 159

cd/ft 2

1 cd/ft 2 = 10.7639 cd/m 2

f ootlambert . 1 footlambert = 3.426 26 cd/m2 lambert 1 lambert = 3.183 01 kcd/m2

35
APPENDIX B

SI UNITS AND RELATIONSHIP CHART EXPLANATIONS

The SI CHART on page 38 shows graphically how the seventeen (17) derived SI units with

special names are formed in a coherent manner from the hase and supplementary units.

Unit symbols are shown in rectangles for base units and supplementary units, and in

circles for derived units. The unit name is spelled out in full toward the upper left,

and the derivation is shown in parentheses toward the upper right. The name of the

quantity (the measurable attribute) is stated in capital letters.

In the chart the derivation of each unit is indicated by arrows in the following manner:

a. solid lines represent a relationship in which the derived unit is a product

of the constituent units (J = N-m;Wb = V-s; C = A- s ) b. a single broken line indicates that the derived unit is the reciprocal of

the originating unit ( Hz = 1/s ; Bq = 1/s ; S = 1/fi )

c. solid and broken lines indicate that the derived unit has both a numerator

factor (solid line) and a denominator factor (broken line) , as shown by the

following examples : Pa = N/m2

; W=J/s ; Q = V / A ; H = Wb/A ; lx=lm/m2

The progressive linking of coherent SI units is illustrated by the two reduced size extracts from the SI Chart:

LENGTH

MASS

TIME

LENGTH

MASS

TIME

03

iFv3®r

nf

fysJT

'Mm

5®rEXAMPLE B

Three base units - meter (m) , kilogram (kg) and second (s) combine to form the derived

unit of FORCE (kg.m/s2 ), which has been

given the special name "newton" (N) .

The newton (N) combines with the base unit meter (m) to form the derived unit of ENERGY, or WORK or QUANTITY OF HEAT (N-m) , which has been

given the special name "joule" (J).

There are a total of twenty-six (26) SI units with special names and symbols of the

Chart. Of these:

a. thirteen (13), one-half of the total, are already in general use now:

s, A, cd, Hz, W, V, C, F, H, Q, lm, rad , and sr

b. one (1), the Siemens (S) , was previously referred to as "mho", so that

its adoption involves a change in name only

c. three (3) have almost no application in design and construction:

mole (mol) - base unit for amount of substance

becquerel (Bq) - derived unit for activity (of radionuclides)

gray (Gy) - derived unit for absorbed dose

Thus, a maximum of nine (9) new units in SI will need to be learned:

m, kg, K, N, Pa, J, Wb, T, and lx

The "degree Celsius" (°C) is a special name for the base unit kelvin (K) , for use in

expressing temperature interval or Celsius temperature, and is therefore shown directly

related to kelvin.

36
37
APPENDIX C

SUPERSEDED METRIC UNITS NOT RECOMMENDED FOR USE WITH SI

It is strongly recommended that the traditional and "cgs" metric (non-SI)

units listed in Table P be avoided in building design or construction

applications. Any data showing these units should be converted to the

appropriate SI units that supersede them.

TABLE P: UNITS OUTSIDE SI NOT RECOMMENDED FOR USE

Unit Name Symbol Value in SI Units

dyne dyn 10" 5 N (or 10 uN)

bar bar 10 5 Pa (or 100 kPa)

erg erg 10" 7 J (or 100 nJ)

poise P 10- 1 Pa-s (or 100 mPa-s)

stokes St 10

_l+ m

2 /s (or 100 mm 2 /s)

gauss Gs,(G) 10" k T (or 100 uT)

maxwell Mx 10" 8 Wb (or 10 nWb)

stilb sb 10 4 cd/m 2 (or 10 kcd/m 2

)

phot ph 10 k lx (or 10 klx)

kilogram-force kgf 9.806 65 N

calorie (int.) cal 4.1868 J

kilocalorie (int.) kcal 4.1868 kJ

torr torr 133.322 Pa

oersted Oe 79.5775 A/m
REFERENCES (AND THEIR AVAILABILITY)

1. American National Standard ANSI Z 210.1- 1976 / ASTM E 380- 76 / IEEE Std 268-1976 METRIC PRACTICE (1976 Revised Edition ) Availablz {.nam:

- (ANSI 1 210.1) - kmzn.-ic.an Nat-tonal Standahds I ns titutz

,

1430 Bhoadway, New Yolk, N.Y. 10018

- (ASTM E 3S0) - Amzhican Soc.-lz.tij fioh. Testing and Matzhials

1916 Race Sthzzt, Philadelphia, Pa. 19013

- (IEEE Std 268) - Institutz o $ Elzcth.ic.al and Elzcthonic

EnginzzhS

,

345 Bait 47th Sthzzt, Nzw Yolk, N.Y. 10017

2. ANMC METRIC EDITORIAL GUIDE , 2nd Edition, 1975

Availablz &hom: Amzh.ic.an National \KztKic Council,

7625 Massachusetts Avenue, N.W.

Washington, V.C. 20036

3. U.S. Department of Commerce /National Bureau of Standards

NBS Special Publication 330, THE INTERNATIONAL SYSTEM OF UNITS (SI) , 1974 Revised Edition

Available fthom: U.S. Govzhnmznt Phinting Ofi&icz,

Washington, V.C. 20402

4. U.S. Federal Register - The National Archives of the United States,

Vol. 41, Number 239, pages 54018-19, THE METRIC SYSTEM OF MEASUREMEN T

( Interpretation and Modification of the International System of

Units for the United States) - Issued December 10, 1976

Availablz ^hom: Ofi&icz oh Tzchnical Publications

,

National Buh.zau o & Standards , Washington, V.C. 20234

5. Public Law 94 -168, METRIC CONVERSION ACT OF 1975 (December 23, 1975)

Availablz ^hom: U.S. Govzfinmznt Ph.inting O^icz,

Washington, V.C. 20402

6. International Standard ISO 1000 - 1973 (E) SI UNITS AND RECOMMENDATIONS

FOR THE USE OF THEIR MULTIPLES AND CERTAIN OTHER UNITS (1973 Edition)

7. International Standard ISO 31/0- 1974(E), General Introduction to ISO 31 - GENERAL PRINCIPLES CONCERNING QUANTITIES, UNITS AND SYMBOLS

6. and 7. availablz through: Amzhican National Standahds Institutz,

1430 Bhoaduiay, New Vohk, N.Y. 10018

39
NBS-114A (REV. 7-73)

U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO. NBS TN 9382. Gov't Accession

No.

3. Recipient's Accession No.

4. TITLE AND SUBTITLE

RECOMMENDED PRACTICE FOR THE USE OF METRIC (SI) UNITS

IN BUILDING DESIGN AND CONSTRUCTION

5. Publication Date April 1977

6. Performing Organization Code

7. AUTHOR(S)

Hans J. Milton

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No.

11. Contract/Grant No.

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP)

Same as 9.

13. Type of Report & Period Covered Interim

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here.)

This Technical Note contains a comprehensive set of recommendations for the use of

metric (SI) units in building design and construction.

It includes descriptive material dealing with the structure of the International

System of Units (SI); rules and recommendations for the presentation of SI units

and symbols, and of numerical values associated with SI; a set of tables showing

working units and typical applications for SI units in building design and con- struction; and a section dealing with special considerations in the selection and use of SI units in design and construction. Appendixes show conversion factors

for the most common units; superseded metric units not recommended for use with

SI; an SI units and relationships chart; and appropriate references.

This document was prepared to provide the technical basis for an ASTM reference

standard on recommended practice for the use of metric (SI) units in building

design and construction.

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons)

International System of Units (SI); metric design and construction; recommended

SI practice

18. AVAILABILITY fc

-1 Unlimited

_j For Official Distribution. Do Not Release to NTIS

I -^ Order From Sup. of Doc, U.S. Government Printine Office Washington, D.C. 20402, SD Cat. No. C13. 46:938

_j Order From National Technical Information Service (NTIS)

Springfield, Virginia 22151

19. SECURITY CLASS

(THIS REPORT)

UNCLASSIFIED

20. SECURITY CLASS

(THIS PAGE)

UNCLASSIFIED

21. NO. OF PAGES

47

22. Price $1.60

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DIMENSIONS/NBS (formerly Technical News Bulletin) —This monthly magazine is published to inform

scientists, engineers, businessmen, industry, teachers,

students, and consumers of the latest advances in science and technology, with primary emphasis on the work at NBS. The magazine highlights and reviews

such issues as energy research, fire protection, building

technology, metric conversion, pollution abatement,

health and safety, and consumer product performance.

In addition, it reports the results of Bureau programs

in measurement standards and techniques, properties of matter and materials, engineering standards and services, instrumentation, and automatic data processing.

Annual subscription: Domestic, $12.50; Foreign, $15. 65.

NONPERIODICALS

Monographs—Major contributions to the technical liter- ature on various subjects related to the Bureau's scientific and technical activities. Handbooks—Recommended codes of engineering and

industrial practice (including safety codes) developed

in cooperation with interested industries, professional

organizations, and regulatory bodies. Special Publications—Include proceedings of conferences

sponsored by NBS, NBS annual reports, and other

special publications appropriate to this grouping such

as wall charts, pocket cards, and bibliographies.

Applied Mathematics Series—Mathematical tables, manuals, and studies of special interest to physicists, engineers, chemists, biologists, mathematicians, computer programmers, and others engaged in scientific and technical work.

National Standard Reference Data Series—Provides

quantitative data on the physical and chemical properties of materials, compiled from the world's literature and critically evaluated. Developed under a world-wide

program coordinated by NBS. Program under authority

of National Standard Data Act (Public Law 90-396).

NOTE: At present the principal publication outlet for these data is the Journal of Physical and Chemical

Reference Data (JPCRD) published quarterly for NBS

by the American Chemical Society (ACS) and the American Institute of Physics (AIP). Subscriptions, reprints,

and supplements available from ACS, 1155 Sixteenth

St. N.W., Wash. D. C. 20056. Building Science Series—-Disseminates technical infor- mation developed at the Bureau on building materials,

components, systems, and whole structures. The series presents research results, test methods, and performance criteria related to the structural and environmental

functions and the durability and safety characteristics of building elements and systems.

Technical Notes—Studies or reports which are complete

in themselves but restrictive in their treatment of a

subject. Analogous to monographs but not so comprehensive in scope or definitive in treatment of the subject area. Often serve as a vehicle for final reports of work performed at NBS under the sponsorship of other government agencies.

Voluntary Product Standards—Developed under proce- dures published by the Department of Commerce in Part

10, Title 15, of the Code of Federal Regulations. The

purpose of the standards is to establish nationally rec- ognized requirements for products, and to provide all concerned interests with a basis for common understanding of the characteristics of the products. NBS

•administers this program as a supplement to the activities of the private sector standardizing organizations.

Consumer Information Series—Practical information,

based on NBS research and experience, covering areas

of interest to the consumer. Easily understandable language and illustrations provide useful background knowledge for shopping in today's technological marketplace.

Order above NBS publications from: Superintendent

of Documents, Government Printing Office, Washington,

D.C. 20U02. Order following NBS publications—NBSIR's and FIPS

from the National Technical Information Services,

Springfield, Va. 22161. Federal Information Processing Standards Publications

(FIPS PUBS)—Publications in this series collectively constitute the Federal Information Processing Standards Register. Register serves as the official source of information in the Federal Government regarding stand- ards issued by NBS pursuant to the Federal Property

and Administrative Services Act of 1949 as amended,

Public Law 89-306 (79 Stat. 1127), and as implemented

by Executive Order 11717 (38 FR 12315, dated May 11, 1973) and Part 6 of Title 15 CFR (Code of Federal

Regulations).

NBS Interagency Reports (NBSIR)—A special series of interim or final reports on work performed by NBS for

outside sponsors (both government and non-govern- ment). In general, initial distribution is handled by the sponsor; public distribution is by the National Technical Information Services (Springfield, Va. 22161) in paper copy or microfiche form.

BIBLIOGRAPHIC SUBSCRIPTION SERVICES

The following current-awareness and literature-survey

bibliographies are issued periodically by the Bureau:

Cryogenic Data Center Current Awareness Service. A

literature survey issued biweekly. Annual subscription: Domestic, $20.00; Foreign, $25.00.

Liquified Natural Gas. A literature survey issued quarterly. Annual subscription: $20.00.

Superconducting Devices and Materials. A literature survey issued quarterly. Annual subscription: $20.00.

Send subscription orders and remittances for the pre- ceding bibliographic services to National Bureau of Standards, Cryogenic Data Center (275.02) Boulder,

Colorado 80302.
U.S. OEPARTMENT OF COMMERCE

National Buraau of Standards

Washington. D.C. S0S34

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