1^ 1 1

^^^BH United States Department of Commerce

I I^^^ I Technology Administration ^^"^^

National Institute of Standards and Technology

NATL INST. OF ^^^^nn ||M'|||f11 III 11 NiST

llllllilllll^ PUBLICATSONS

NIST Special Publication 853

MOIST

A PC Program for Predicting

Heat and Moisture Transfer

in Building Envelopes

Release 2.0

Douglas M. Burch and William C. Thomas

-QG—

100

.U57

#853

1993
7he National Institute of Standards and Technology was established in 1988 by Congress to "assist industry in the development of technology . . . needed to improve product quality, to modernize

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'At Boulder, CO 80303. ^Some elements at Boulder, CO 80303.
NIST Special Publication 853

MOIST

A PC Program for Predicting

Heat and Moisture Transfer

in Building Envelopes

Release 2.0

Douglas M. Burch

Building and Fire Research Laboratoray

National Institute of Standards and Technology

Gaithersburg, MD 20899 William C. Thomas

Department of Mechanical Engineering

Virginia Polytechnic Institute and State University Blacksburg, VA 24061 September 1993

U.S. Department of Commerce

Ronald H. Brown, Secretary

Technology Administration

Mary L. Good, Under Secretary for Technology

National Institute of Standards and Technology

Arati Prabhakar, Director
National Institute of Standards and Technology Special Publication 853

Natl. Inst. Stand. Technol. Spec. Publ. 853, 75 pages (September 1993)

CODEN: NSPUE2

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 1993

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402-9325
CONTENTS

Page

Disclaimer and Conditions v System Requirements vi

Preface vi

Warning vi

Chapter 1. Introduction 1 Brief Description of MOIST 1 Limitations of MOIST 2

Getting Help 3

Chapter 2. Getting Started 4

Installing MOIST 4

Installing Weather Data Files

Separately 5

Running the Sample Problem 7

Explanation of Files in

Directory MOIST 12

Chapter 3. Getting Hard Copy

Documentation for a Computer Run 16

Chapter 4. Getting a Plot for a Report 17

iii
Page

Chapter 5. Modifying the Input Data for a Computer Run 19

Modifying Property Data 19

Modifying Input Parameters 24

Modifying Building Construction ... 29

Modifying Analysis Intervals 34

Modifying Output Files 38

Running the Revised Sample

Problem 42

Chapter 6. Including Convection

in a Problem 43

Chapter 7. Creating a New Building

Construction 46

Chapter 8. Achieving Convergence for

Mathematical Solution 50

Choosing Number of Nodes 51

Choosing Convergence Criteria

and Maximum Iterations 53

Chapter 9. Comments 56

Chapter 10. Acknowledgements 57

References 58

Appendix A - Technical Information on the Model 59

Appendix B - Listing of File RUNl.OUT 63

Appendix C - Listing of File RUNl.MC 68

iv
DISCLAIMER AND CONDITIONS

The authors have made a concerted effort to find and

remove errors in the coding of program MOIST.

However, we make no guarantee that the program is free

from errors or that the results produced with it will be

free of errors. We assume no responsibility or liability

for the accuracy of the program or for the results which

may come from its use. The American Society of Heating, Refrigerating and AirConditioning Engineers, Inc. (ASHRAE) has consented

to permit NIST to use their WYEC hourly weather data

for six U.S. cities with MOIST. These weather data will

permit you to learn how to use the program and perform

a limited amount of analysis. You may obtain WYEC

hourly weather data for forty other U.S. cities and five

Canadian cities from ASHRAE located at 1791 TuUie

Circle, NE, Atlanta, GA 30329-2305.

MOIST was compiled in Microsoft FORTRAN (Release

5.0).

Some copies of this publication are being disseminated

without the diskette containing the program software.

For more information or to request the diskette, contact

the Heat Transfer Group, NIST, Building 226, Room

B320, Gaithersburg, MD 20899, telephone 301-975-

5648.

V
SYSTEM REQUIREMENTS

Your computer needs to be equipped with the following

hardware: a 286, 386, or 486 processor; 512 kilobytes of

memory or more; a math co-processor; and a hard drive

with at least 2 megabytes and preferably 5 megabytes

available for program and data storage. The monitor

must have either EGA or VGA graphics capability. The

operating system must be MS-DOS 3.1 or higher.

PREFACE

The authors would like to thank the National Institute of

Standards and Technology and the Department of Energy

(through the Oak Ridge National Laboratory) for funding

the development of MOIST. In addition, the authors

would like to thank ASHRAE for agreeing to permit us

to release WYEC hourly weather data for six U.S. cities. WARNING

For demonstration purposes, the program is loaded with

values for two parameters (convergence criteria and

maximum iteration) which make the program run faster. When you run a problem for analysis, it is essential that

you use appropriate values for these parameters (see

Chapter 8 - Achieving Convergence for Mathematical

Solution).

vi
Introduction

Chapter 1. Introduction

Brief Description of MOIST

MOIST is a user-friendly, personal computer program

that predicts the one-dimensional transfer of heat and

moisture. With MOIST, you will be able to easily define

a wall, cathedral ceiling, or low-slope roof construction.

You will subsequently be able to investigate the effect of

various parameters on the moisture accumulation within

layers of construction. For example, you will be able to conduct computer runs for different U.S. and Canadian

cities, thereby investigating the effect of climate on

moisture accumulation. You will be able to determine if a vapor retarder is needed, and if needed, where it should be placed relative to the other materials. MOIST

allows the user to vary easily the building materials and

their relative placement and predicts the resulting

moisture accumulation within each as a function of time

for the selected climate. MOIST permits the evaluation

of the effect of the water-vapor resistance offered by

paint layers, wallpaper, and vapor retarders. Finally,

MOIST can be used to produce moisture control

guidelines.

The algorithms in the program can predict moisture

transfer for the diffusion regime through the capillary

flow regime. The program has a provision to account

for convective moisture transfer by including embedded

cavities which may be coupled to indoor or outdoor air. The program generates a plot on the computer screen of

1
Introduction

the average moisture content of the construction layers versus time as the program executes. The program

generates output files which may be imported into

plotting programs for preparing reports.

The American Society of Heating, Refrigerating and AirConditioning Engineers, Inc. (ASHRAE) has consented

to permit NIST to release their Weather Year for Energy

Calculations (WYEC) weather data for the following six

U.S. cities: a cold climate (Madison, WI), intermediate

winter climates (Boston, MA and Washington, DC), a mild winter climate (Atlanta, GA), a Pacific northwest

climate (Portland, OR), and a hot and humid climate

(Lake Charles, LA). These weather data will permit you

to learn how to use the program and perform a limited

amount of analysis. You may obtain WYEC hourly

weather data for 40 other U.S. cities and five Canadian

cities from ASHRAE located at 1791 Tullie Circle, NE,

Atlanta, GA 30329-2305.

Information on the theory and validation of MOIST is given in Appendix A.

Limitations of MOIST

One of the most significant limitations of MOIST is that

the model is one dimensional. This means that it does

not include the effect of framing members and the two

and three dimensional effects associated with infiltration.

However, the authors believe that the model is

2
Getting Started

and the third layer (plywood) is displayed in green

(upper curve). In the sample problem, we treated the

glass-fiber insulation as a non-storage layer (i.e., a layer

with negligible moisture storage). For this reason, the

moisture content of the glass-fiber insulation (layer 2) is not shown.

In the graph on the computer screen, the vertical axis

displays the relative moisture content of the construction

layers. The term "relative moisture content" is defined

as the moisture content of the material divided by

moisture content of the material at maximum sorption^

.

The dashed horizontal line in the center of the graph

depicts a relative moisture content of 1 . This is the

critical moisture content above which liquid water

appears in the pore structure of the material. Relative

time is displayed on the horizontal axis. A relative time

of 0 corresponds to the start of a simulation and a value

of 1 corresponds to the end of the simulation.

At this point, you may want to take a brief break and

allow the computer simulation to finish executing. Some

benchmark times for MOIST to complete this sample

problem are given in the following table.

Maxunum sorption is the moisture content of a material in

equilibrium with air saturated with water vapor.

11
Getting Started

CPU Speed, Mhz Time, min

286 6 154

386 16 26

486 66 2.25

(You can interrupt execution by either a < ctrl-break >

command or rebooting. When the < ctrl-break > is entered, the DOS prompt will eventually appear and you

then need to issue < MODE CO80 > to reset the screen

to text mode.)

After Program MOIST completes the simulation, it displays a

" © " icon at the lower-right comer of the

computer screen. You may return to MAIN MENU by

pressing the Enter key. To exit the program, select 7

from the MAIN MENU by:

Enter: 7

Press: < Enter >.

Explanation of Files in Directory MOIST

After exiting Program MOIST, your computer screen should display C:\MOIST. You may examine the files in

Directory MOIST by:

Enter: DIR

12
Getting Started

Press: < Enter >.

The following listing of files should appear on your

computer screen. An explanation of each file is given

below.

Volume in drive C is C DRIVE Volume Seric3l Hmber is 3A38-11EF Directory of C:\MOIST

<DIR> 07-23-93 5:01p

<DIR> 07-23-93 5:01p

MOIST EXE 387978 06-16-93 4:38p

PDATA DAT 4708 07-23-93 4:20p

DEFSET DAT 293 07-23-93 4:21p

CONST DAT 233 07-23-93 4:21p

PEROD DAT 62 06-22-93 4:18p

OUT DAT 112 07-23-93 4:22p

WYBOSMA 718320 11-17-92 1:52p WYWASDC 718320 11-17-92 2:19p

WYPOROR 718320 11-17-92 11:30a WYMADWI 718320 11-17-92 1:39p WYATLGA 718320 11-17-92 9:48a WYKCLA 718320 11-17-92 10:19a CHECK DAT 4691 07-27-93 1:23p

RUN1 OUT 33050 07-27-93 1:23p

RUN1 MC 1144 07-27-93 1:23p

17 file(s) 4742191 bytes

8366080 bytes free MOIST.EXE: This is Program MOIST.

PDATA.DAT: This file contains the property data for

the materials.

DEFSET.DAT: This file contains the input parameters.

CONST.DAT: This file contains the construction

parameters.

13
Getting Started

PEROD.DAT: This file contains the analysis intervals.

OUT. DAT: This file contains the selection of output and

plot files which will be generated during the execution of

MOIST.

WYBOSMA: This file contains weather data for Boston,

MA.

WYWASDC: This file contains weather data for

Washington, DC.

WYPOROR: This file contains weather data for

Portland, OR.

WYMADWI: This file contains weather data for

Madison, WI.

WYATLGA: This file contains weather data for Atlanta,

GA.

WYLKCLA: This file contains weather data for Lake

Charles, LA.

CHECK.DAT: This file contains diagnostic parameters

used by the authors to debug the program.

The remaining files are output files for the sample

problem which you just ran on your computer.

14
Getting Started

RUN1. OUT: This file contains data that summarizes the

property data, input parameters, and construction

parameters for your simulation. It also contains the

unprocessed simulation results. We recommend that you

print out this file to document your computer run. RUNl.MC : This file contains the average moisture

content of the layers of the construction displayed in

column format FIO.2^. Program MOIST sends a set of

values to this file at the print interval specified in

ANALYSIS INTERVALS.

If you installed only one weather data file, then the other

weather files will not appear in Directory MOIST.

^A column format of F10.2 indicates that the column width

is 10, and the numerical values are displayed with two

digits given to the right of the decimal point.

15
Getting Hard Copy

Documentation for a Computer Run

Chapter 3. Getting Hard Copy

Documentation for a Computer

Run

If you would like a hard copy documenting your

computer run, you may send RUNLOUT to a printer

attached to your computer. You may accomplish this

from Directory MOIST by:

Enter: PRINT RUNLOUT

Press: < Enter >.

Several pages of this file are given in Appendix B. File

RUNLOUT is very long. Therefore, you may want to modify the output file options (see Chapter 5) and print

only the abbreviated hard copy documentation and omit

unprocessed output results.

16
Getting a Plot for a Report

Chapter 4. Getting a Plot for a Report

If you would like a "hard copy" of a plot for a report,

then you can import one of the plotting output files (e.g.,

RUNl.MC) to a commercially available spread-sheet

program with plotting capability (e.g., LOTUS 123^).

Let's examine how you would obtain a report plot for the

moisture content of the construction layers for the sample

problem. The data are contained in file RUNLMC and

are printed out in Appendix C. The first and second

columns are the weekly moisture contents (expressed in

percent) for the gypsum board and plywood siding,

respectively. The rows correspond to sequential sets of

weekly values. Each of the moisture contents is averaged over the thickness of the layer. You can

import file RUNLMC into a spread-sheet program with

plotting capability and obtain the following line plot in

just a few minutes.

^Reference here to Lotus 123 is only for illustration

purposes and does not constitute an endorsement of this

program by the Government.

17
Getting a Plot for a Report

ELAPSED TIME (WEEKS)

Note: Each division on the horizontal axis corresponds

to 1 week.

18
Getting Started

and the third layer (plywood) is displayed in green

(upper curve). In the sample problem, we treated the

glass-fiber insulation as a non-storage layer (i.e., a layer

with negligible moisture storage). For this reason, the

moisture content of the glass-fiber insulation (layer 2) is not shown.

In the graph on the computer screen, the vertical axis

displays the relative moisture content of the construction

layers. The term "relative moisture content" is defined

as the moisture content of the material divided by

moisture content of the material at maximum sorption^

.

The dashed horizontal line in the center of the graph

depicts a relative moisture content of 1 . This is the

critical moisture content above which liquid water

appears in the pore structure of the material. Relative

time is displayed on the horizontal axis. A relative time

of 0 corresponds to the start of a simulation and a value

of 1 corresponds to the end of the simulation.

At this point, you may want to take a brief break and

allow the computer simulation to finish executing. Some

benchmark times for MOIST to complete this sample

problem are given in the following table.

Maximum sorption is the moisture content of a material in

equilibrium with air saturated with water vapor.

11
Getting Started

GPU Speed, Mhz Time, min

286 6 154

386 16 26

486 66 2.25

(You can interrupt execution by either a < ctrl-break >

command or rebooting. When the < ctrl-break > is entered, the DOS prompt will eventually appear and you

then need to issue < MODE CO80 > to reset the screen

to text mode.)

After Program MOIST completes the simulation, it displays a

" © " icon at the lower-right comer of the

computer screen. You may return to MAIN MENU by

pressing the Enter key. To exit the program, select 7

from the MAIN MENU by:

Enter: 7

Press: < Enter >.

Explanation of Files in Directory MOIST

After exiting Program MOIST, your computer screen should display C:\MOIST. You may examine the files in

Directory MOIST by:

Enter: DIR

12
Getting Started

Press: < Enter >.

The following listing of files should appear on your

computer screen. An explanation of each file is given

below.

Volume in drive C is C DRIVE Volume Serial Number is 3A3B-11EF Directory of C:\MOIST

<DIR> 07-23-93 5:01p

<DIR> 07-23-93 5:01p

MOIST EXE 387978 06-16-93 4:38p

PDATA DAT 4708 07-23-93 4:20p

DEFSET DAT 293 07-23-93 4:2 p CONST DAT 233 07-23-93 4:21p

PEROD DAT 62 06-22-93 4:18p

OUT DAT 112 07-23-93 4:22p

718320 11-17-92 1:52p 718320 11-17-92 2:19p

718320 11-17-92 11:30a 718320 11-17-92 1:39p WYATLGA 718320 11-17-92 9:48a WYLKCLA 718320 11-17-92 10:19a CHECK DAT 4691 07-27-93 :23p

RUN1 OUT 33050 07-27-93 1:23p

RUN1 MC 1144 07-27-93 1:23p

17 fiLe<s) 4742191 bytes 8366080 bytes free

WYBOSMA

WYWASDC

WYPOROR

WYMADWI

MOIST.EXE: This is Program MOIST.

PDATA.DAT: This file contains the property data for

the materials.

DEFSET.DAT: This file contains the input parameters,

CONST.DAT: This file contains the construction

parameters.

13
Getting Started

PEROD.DAT: This file contains the analysis intervals.

OUT. DAT: This file contains the selection of output and

plot files which will be generated during the execution of

MOIST.

WYBOSMA: This file contains weather data for Boston,

MA.

WYWASDC: This file contains weather data for

Washington, DC.

WYPOROR: This file contains weather data for

Portland, OR.

WYMADWI: This file contains weather data for

Madison, WI.

WYATLGA: This file contains weather data for Atlanta,

GA.

WYLKCLA: This file contains weather data for Lake

Charles, LA.

CHECK.DAT: This file contains diagnostic parameters

used by the authors to debug the program.

The remaining files are output files for the sample

problem which you just ran on your computer.

14
Getting Started

RUN1. OUT: This file contains data that summarizes the

property data, input parameters, and construction

parameters for your simulation. It also contains the

unprocessed simulation results. We recommend that you

print out this file to document your computer run. RUNl.MC : This file contains the average moisture

content of the layers of the construction displayed in

column format FIO.2^. Program MOIST sends a set of

values to this file at the print interval specified in

ANALYSIS INTERVALS.

If you installed only one weather data file, then the other

weather files will not appear in Directory MOIST.

^A column format of F10.2 indicates that the column width

is 10, and the numerical values are displayed with two

digits given to the right of the decimal point.

15
Getting Hard Copy

Documentation for a Computer Run

Chapter 3. Getting Hard Copy

Documentation for a Computer

Run

If you would like a hard copy documenting your

computer run, you may send RUNLOUT to a printer

attached to your computer. You may accomplish this

from Directory MOIST by:

Enter: PRINT RUNl. OUT

Press: < Enter >.

Several pages of this file are given in Appendix B. File

RUNLOUT is very long. Therefore, you may want to modify the output file options (see Chapter 5) and print

only the abbreviated hard copy documentation and omit

unprocessed output results.

16
Getting a Plot for a Report

Chapter 4. Getting a Plot for a Report

If you would like a "hard copy" of a plot for a report,

then you can import one of the plotting output files (e.g.,

RUNl.MC) to a commercially available spread-sheet

program with plotting capability (e.g., LOTUS 123^).

Let's examine how you would obtain a report plot for the

moisture content of the construction layers for the sample

problem. The data are contained in file RUNLMC and

are printed out in Appendix C. The first and second

columns are the weekly moisture contents (expressed in

percent) for the gypsum board and plywood siding,

respectively. The rows correspond to sequential sets of

weekly values. Each of the moisture contents is averaged over the thickness of the layer. You can

import file RUNLMC into a spread-sheet program with

plotting capability and obtain the following line plot in

just a few minutes.

Reference here to Lotus 123 is only for illustration

purposes and does not constitute an endorsement of this

program by the Government.

17
Getting a Plot for a Report

ELAPSED TIME (WEEKS)

Note: Each division on the horizontal axis corresponds

to 1 week.

18
Modifying the Input Data for a Computer Run

Chapter 5. Modifying the Input Data for a

Computer Run

In this chapter, we show you how to modify the property

data for a material, the input parameters, the building

construction, the analysis intervals, and the output files for a computer run. We use the sample problem as an

example.

Modifying Property Data

Go to the MAIN MENU in MOIST and select

PROPERTY DATA by:

Enter: 1

Press: < Enter >.

The resulting screen display is given below. The four

options discussed below are permitted.

MAKE APPROPRIATE SELECTION

1 CREATE A NEW PROPERTY DATA FILE

2 EDIT AN EXISTING PROPERTY DATA FILE 3 ADD A NEW MATERIAL

4 RETURN TO MAIN MENU

ENTER SELECTION <1-4)

19
Modifying the Input Data for a Computer Run

If you select option 1 , you will be prompted to enter all the properties for each of the materials. This option is used by the authors of the program to generate the

property data file (PDATA.DAT). You generally will

not use this option. If you inadvertently enter this

option, then you may exit the program by performing a "warm" boot (i.e., press the keys <Ctrl>, <Alt>,

<Del> simultaneously). Specifying zero materials after

the prompt: HOW MANY MATERIALS DO YOU

WANT TO ENTER? will cause all data in the property

data file to be deleted.

The selection of option 2 allows you to change one of the

properties for a particular material. This option is discussed in the section below.

The selection of option 3 permits you to add a new

material to the catalog of property data. If you select

this option, then you will be prompted to enter

appropriate property data for the new material.

Selection of option 4 causes the computer to return to the

MAIN MENU of Program MOIST.

To modify one of the property data for a material, select

option 2 for PROPERTY DATA by:

Enter: 2

Press: < Enter >.

Your computer screen now displays the following listing

of materials. Let's modify item 4 (exterior grade

plywood). This is accomplished by:

20
Modifying the Input Data for a Computer Run

WHICH MATERIAL TO YOU WANT TO EDIT?

1 GYPSUM BOARD 2 SUGAR PINE

3 FIBER BOARD SHEATHING 4 EXTERIOR GRADE PLYWOOD

5 ORIENTED STRAND BOARD 6 MICROFINE PARTICLE BOARD

7 WAFER BOARD SIDING 8 STURDY BRACE BOARD

9 CELLULOSE INSULATION 10 FOAM CORE SHEATHING

11 GLASS FIBER INSULATION 12 KRAFT PAPER

13 ROOFING SHINGLES 14 PERMEABLE BOARD

15 BRICK 16 CONCRETE BLOCK

17 GLASS FIBER BOARD 18 CONCRETE

19 BUILT-UP ROOFING 20 GRAVEL

21 6-MIL POLYETHYLENE 22 BUILDING PAPER

23 EXTRUDED POLYSTYRENE 24 EXPANDED POLYSTYRENE

25 CEMENT PARGE COAT 26 STUCCO FINISH 27 ALUMINUM SIDING 28 AIR BARRIER ENTER MATERIAL NUMBER (ENTER 0 TO QUIT)

Enter: 4

Press: < Enter >.

The table of coefficients given below is now displayed on

your computer screen.

EXTERIOR GRADE PLYWOOD SORPTION COEFFICIENTS

1 A1 3441E+00

2 A2 6177E+01

3 A3 .8283E+00 CAPILLARY COEFFICIENTS

4 LIQUID PERMEABILITY 2787E-19

5 DRY POROSITY 6360E+00

HEAT TRANSFER PROPERTIES

6 DRY DENSITY .5094E+03

7 SPECIFIC HEAT 1214E+04

8 DRY THERMAL CONDUCTIVITY 1154E+00 PERMEABILITY PROPERTIES

9 1ST FIT COEFFICIENT -.2666E+02

10 2ND FIT COEFFICIENT -.6368E+01

11 3RD FIT COEFFICIENT 8889E+01

ENTER NUMBER OF PROPERTY (ENTER 0 TO QUIT)

21
Modifying the Input Data for a Computer Run

The coefficients are:

Items 1, 2, and 3 . These are the moisture storage

coefficients for the material. They are the coefficients

for the relation between moisture content (7) and relative

humidity (</>), or

In the above equation, both 7 and 0 are expressed as a

fraction. This equation is called the sorption isotherm

function. Many of the moisture storage coefficients

provided to you in the PROPDAT.DAT file are based on

NIST measurements by R.F. Richards, D.M. Burch, and

W.C. Thomas (1992)1

Item 4 . This is the liquid permeability of the saturated

porous media expressed in m^ (ft^).

Item 5 . This is dry porosity (e^j) of the porous media

defined as the ratio of the pore volume to total volume.

It may be expressed in terms of dry density (p^) and

density of the solid material (p^) that comprises the

porous media, or:

7

=

Al-</>

(1)

(1 + A2-(?!>)(1 - A3-0)

(2)

^References are cited at the end of the text. 22
Modifying the Input Data for a Computer Run

Item 6 . This the dry density (p^) of the material

expressed in kg/m^ (Ib/ft^).

Item 7 . This is the dry specific heat of the material

expressed in J/kg-°C (Btu/lb-°F).

Item 8 . This is the thermal conductivity of the material

expressed in W/m-^C (Btu/h-ft-°F).

Items 9, 10, and 11 . These are the water vapor

permeability coefficients. They are the coefficients for

the empirical permeability equation expressed as a function of relative humidity (0), or:

IJL = exp(al + a2-(/) + aS-c^)^)

In the above equation, permeability is expressed in

kg/s-m-Pa (grains/h-ft-inHg), and relative humidity (</>) is expressed as a fraction. Many of the water-vapor

permeability coefficients provided on the

PROPDAT.DAT file are based on NIST measurements

by D.M. Burch, W.C. Thomas, and A.H. Fanney

(1992).

Now let's change the thermal conductivity of the

plywood to 0.12 W/m-°C. This is accomplished by

selecting Item 8 or:

Enter: 8

Press: < Enter >.

23
Modifying the Input Data for a Computer Run

When you see the message on the screen prompting you

to enter the new value:

Enter: 0.12

Press: < Enter >.

The computer screen now displays the revised table of

coefficients. Check to make sure you entered the correct

value. At this point, you may either revise another value or select 0 to exit this sheet of the program. Let's select

0. You should next see the options for PROPERTY

DATA. By selecting 4, the computer program returns to MAIN MENU.

Modifying Input Parameters

From MAIN MENU, let's select INPUT

PARAMETERS by:

Enter: 2

Press: < Enter >.

Your computer screen should now display the options for

the INPUT PARAMETERS.

24
Modifying the Input Data for a Computer Run

MAKE APPROPRIATE SELECTION

1 CREATE A NEW INPUT PARAMETER FILE

2 REVISE EXISTING INPUT PARAMETER FILE

3 RETURN TO MAIN MENU ENTER SELECTION (1-3)

Select 2 to revise the existing Input Parameter File.

Your computer screen should now display the following

input parameters.

1 TYPE SOLUTION? ( IS0THERMAL=1 N0NIS0THERMAL=2) 2

2 CONVECTION COEF AT INSIDE SURFACE 3.600

3 CONVECTION COEF AT OUTSIDE SURFACE 12.400

4 CONVERGENCE CRITERIA FOR MOISTURE SOLUTION .1000E-02

5 MAXIMUM ITERATIONS IN MOISTURE LOOP 20 6 SOLAR ABSORPTANCE OF EXTERIOR SURFACE .700 7 SURFACE TILT (DEGREES) 90.

8 SURFACE AZIMUTH (DEGREES) 0. 9 INDOOR TEMPERATURE 21.000

10 INDOOR RELATIVE HUMIDITY, PERCENT 35.000

11 BOUNDARY FILE TYPE (WYEC=1, SPECIAL=2) 1 12 BOUNDARY FILE NAME WYMADWI

13 INSIDE SURF PAINT PERMEANCE 575.000

14 OUTSIDE SURF PAINT PERMEANCE 115.000 ENTER ITEM NUMBER (ENTER 0 TO QUIT)

The input parameters are explained below:

Item 1 . This is the type of solution. For type = l, an

isothermal solution is obtained (i.e., the temperature of

the layers are set equal to the initial temperatures of the

layers and held constant thereafter). For type =2, the

temperatures of the layers are calculated at each time

step of the analysis.

25
Modifying the Input Data for a Computer Run

Items 2 and 3 . These are the convection coefficients at the inside and outside surfaces of the construction,

respectively, expressed in W/m^-°C (Btu/h-ft^-°F).

They do not include the radiation heat transfer

coefficient. We suggest that you obtain appropriate

coefficients for your particular application from the

ASHRAE 1993 Handbook of Fundamentals . However,

the simulation results will often not be significantly

affected by the particular coefficients that you use. Item 4 . This is the convergence criteria (e) for the

moisture solution. When the condition given below is satisfied at all locations within the building construction,

then the iterative calculation proceeds to the next time

step.

'^prev

where y^^^^ is the newly calculated moisture content and

7prg^ is the previously calculated moisture content. In

the sample problem, a value of 0.1 x 10"-^ is used to make the problem run faster for demonstration purposes.

When you run a problem for analysis, we recommend

you use a value of 0.1 x 10"^ when liquid water is not

present and 0.1 x 10"^ when model MOIST determines

that liquid water is present in the pore structure. Smaller

e values require more computer time. The selection of an appropriate value for this parameter to achieve

convergence is discussed later.

26
Modifying the Input Data for a Computer Run

Item 5 . This is the maximum number of iterations that

the program will attempt to satisfy the convergence

criteria given in eq (4). In the sample problem a value

of 20 is used to make the problem run faster for

demonstration purposes. When you run a problem for

analysis, we recommend a value of 50 when program

MOIST determines that liquid water is not present and a value of 500 when liquid water is present. The selection

of an appropriate value for this parameter to achieve

convergence is discussed later. Item 6 . This is the solar absorptance of the exterior

surface. The sample problem uses a solar absorptance of

0.7. We recommend a value of 0.3 for light-colored

surfaces, 0.6 for medium-colored surfaces, and 0.8 for

dark-colored surfaces.

Item 7 . This is the surface tilt expressed in angular

degrees. Select 90° for vertical surfaces and 0° for

horizontal surfaces.

Item 8 . This is the surface azimuth expressed in angular

degrees. A north azimuth is 0°.

Item 9 . This is the indoor dry-bulb temperature

expressed in °C (°F).

Item 10 . This is the indoor relative humidity expressed

as a percent.

Item 11 . This is the boundary file type. For Type = l,

the program expects the WYEC weather data. For

27
Modifying the Input Data for a Computer Run

Type =2, the program expects special weather data with

indoor temperature, indoor relative humidity, outdoor

temperature, and outdoor relative humidity presented in a column format of 4F12.4. This option permits you to enter your own weather data files from laboratory or

field experiments.

Item 12 . This is the file name for the weather data to be

analyzed. For example, if you want MOIST to use Madison, WI weather data, then Item 12 must be

WYMADWI. It is imperative that vou use the exact

ASHRAE file name, so that the program can identify the

longitude, latitude, and time zone for the location. For

MOIST to run successfully, you must install the specified

weather data file in Directory MOIST (see Chapter 2).

Items 13 and 14 . These are the permeances of the inside

and outside surfaces coverings, respectively, expressed in

ng/s-m^-Pa (permjp)^.

Now let's change the indoor relative humidity to 50%.

This is accomplished by selecting Item 10 by:

Enter: 10

Press: < Enter >.

When you see the message on the screen prompting you

to enter the new value:

^1 permjp = 1 grain/(h-ft^-inHg)

28
Modifying the Input Data for a Computer Run

Enter: 50

Press: < Enter >.

It is imperative to enter a realistic indoor relative

humidity value (i.e., 0 < rh < 100). A relative

humidity outside this range will produce invalid results. The computer screen displays the revised table of input

parameters. Check to make sure you entered the correct

value, as no check on the validity of the value is provided by MOIST.

At this point, you may either revise another input

parameter or select 0 to exit this sheet of the program.

Select 0 and exit. You should next see the options for

INPUT PARAMETERS. By selecting 3, the computer

program returns to MAIN MENU.

Modifying Building Construction

From MAIN MENU, let's select BUILDING

CONSTRUCTION by:

Enter: 3

Press: < Enter >.

The resulting screen display follows. The three options

discussed below are permitted.

29
Modifying the Input Data for a Computer Run

MAKE APPROPRIATE SELECTION

1 CREATE A NEW BUILDING CONSTRUCTION FILE

2 REVISE EXISTING BUILDING CONSTRUCTION FILE

3 RETURN TO MAIN MENU

ENTER SELECTION (1-3)

If you select option 1 , you will be prompted to enter all the data for a new building construction file. The

procedure for carrying this out is given in Chapter 7. The selection of option 2 permits you to alter one of the

parameters for the existing building construction file. The procedure for carrying this out is given below.

The selection of option 3 causes the program to return to the MAIN MENU of Program MOIST.

In this section, we show you how to modify an existing

building construction. To carry this out, select option 2. The computer screen now displays the following

parameters for the building construction.

30
Modifying the Input Data for a Computer Run

1 GYPSUM BOARD 2 SUGAR PINE

3 FIBER BOARD SHEATHING 4 EXTERIOR GRADE PLYWOOD

5 ORIENTED STRAND BOARD 6 MICROFINE PARTICLE BOARD

7 WAFER BOARD SIDING 8 STURDY BRACE BOARD

9 CELLULOSE INSULATION 10 FOAM CORE SHEATHING

11 GLASS FIBER INSULATION 12 KRAFT PAPER

13 ROOFING SHINGLES 14 PERMEABLE BOARD

15 BRIC< 16 CONCRETE BLOCK

17 GLASS FIBER BOARD 18 CONCRETE

19 BUILT-UP ROOFING 20 GRAVEL

21 6-MIL POLYETHYLENE 22 BUILDING PAPER

23 EXTRUDED POLYSTYRENE 24 EXPANDED POLYSTYRENE

25 CEMENT PARGE COAT 26 STUCCO FINISH 27 ALUMINUM SIDING 28 AIR BARRIER

LAY DES L T MC NX R M VEI VEO SIDE

1 1 1.300 21.0 .5 2

2 1.9 1900.0 .000 .000 0 3 4 1.300 21.0 7.0 2 ENTER WHICH LAYER DO YOU WANT TO CHANGE <0 TO QUIT)

A list of building storage materials and corresponding

identification numbers is given at the top. A table

summarizing the parameters for the construction layers is given below this list. Each row corresponds to a particular layer of the construction. If the layer is a storage layer (i.e., it stores both heat and moisture), then

the parameters for the layer are given in subsequent

columns at the left side of the table. These are:

description (DES)^

thickness (L) expressed in cm (in),

^The column headings are for the Building Construction

Table displayed on your computer screen. 31
Modifying the Input Data for a Computer Run

initial temperature (T) expressed in °C (°F),

initial moisture content (MC) expressed as a percent, and

number of finite-difference nodes in the layer

(NX)

On the other hand, if the layer is a non-storage layer

(e.g., air space, glass-fiber insulation, or vapor retarder),

the parameters are:

thermal resistance (R) expressed in m^-^C/W

(h-ft^-°F/Btu),

permeance (M) expressed in ng/s*m^*Pa (permjp)

air exfiltration flux at the inside surface (VEI)

expressed in m^/h per m^ (ft^/h per ft^),

air infiltration flux at the outside surface (VEO)

expressed in m^/h per m^ (fi^/h per ft^), and

convective layer "node" location (SIDE)

are given in consecutive columns at the right side of the

table. The inclusion of convective fluxes in computer

simulations is discussed later in Chapter 6.

32
Modifying the Input Data for a Computer Run

Let's include a vapor retarder in the sample problem.

This may be accomplished by changing the permeance of

the non-storage layer (LAY =2) from M =

1900 ng/s-m^-Pa (33.1 permjp) to M = 57.5

ng/s-m^-Pa (LO permjp). You can select layer 2 by:

Enter: 2

Press: < Enter >.

Your computer screen now displays the following.

SELECT PARAMETER

1 R

2 M

3 VEI

4 VEO

5 SIDE ENTER ITEM NUMBER

Enter 2 to modify the permeance (M). The program

next prompts you to enter the new value. Enter 57.5

ng/s-m^-Pa (1.0 permjp). The computer screen displays

the revised wall construction. Check that you entered

the correct value.

At this point, you may either revise another wall

construction parameter or select 0 to exit this sheet of the

program. Let's select 0 and exit. You should next see

the options for WALL CONSTRUCTIONS. By

selecting 3 , the computer program returns you to the

MAIN MENU for Program MOIST.

33
Modifying the Input Data for a Computer Run

Modifying Analysis Intervals

From MAIN MENU, let's select ANALYSIS

INTERVALS by:

Enter: 4

Press: < Enter >.

The program now displays options for ANALYSIS

INTERVALS (see below).

MAKE APPROPRIATE SELECTION

1 CREATE A NEW ANALYSIS INTERVAL FILE

2 REVISE EXISTING ANALYSIS INTERVAL FILE

3 RETURN TO MAIN MENU ENTER SELECTION (1-3)

As in the previous example, you may select option 1 to create a new analysis interval file, select option 2 to revise an existing analysis interval file, or select option 3

to return to the MAIN MENU of Program MOIST.

Select revise existing analysis interval file by:

Enter: 2

Press: < Enter >.

The program now displays the parameters for

ANALYSIS INTERVALS for the sample problem (see

below). These parameters are: 34
Modifying the Input Data for a Computer Run

COMPUTER ANALYSIS

1 FIRST DAY 182

2 LAST DAY 546 PRINTING AND PLOTTING

3 FIRST DAY 182

4 LAST DAY 546

5 INTERVAL (HOURS) 168 ENTER ITEM NUMBER <ENTER 0 TO QUIT)

Items 1 and 2 . These are pointers that instruct MOIST

to carry out an analysis starting with the first Julian^

calendar day and ending with the last Julian day for the

period of analysis. Program MOIST is set up to execute

the number of consecutive calendar years specified by the

user. The first day of the first year is designated 1. The

last day of the first year is designated 365. The first day

of the second year is designated 366, etc.

Items 3 and 4 . These are pointers that instruct MOIST

to send print and plot data to the output files starting

with the first Julian day and ending with the last Julian

day. These pointers may be different from those for the

computer analysis. This makes it possible to include a pre-conditioning period in the computer analysis when

print and plot data are not sent to output files. Here, the

term "pre-conditioning" denotes a period of time, placed

in front of the period of analysis, which serves to

initialize the simulation results so that they are

In the Julian calendar, the days of the year are numbered

and referred to consecutively. For example, Julian day 45

refers to February 14.

35
Modifying the Input Data for a Computer Run

independent of assumed initial moisture content and

temperature.

Item 5 . This is how often print and plot data are sent to output files. If Item 5 is 168, print and plot data are sent

to the output file every 168 hours (or once a week) of

simulation time.

The Julian days at the end of the months covering a 2-

year period are given in the following table. This table

will assist you in choosing appropriate values for the

Julian day pointers.

Let's add a 6-month pre-conditioning period to the

computer analysis. This will cause the 1-year simulation

results sent to the print and plot output files to be less dependent on the selection of the initial temperature (T)

and moisture content (MC) of the layers in BUILDING

CONSTRUCTION. You can accomplish this by

selecting Item 1 by:

Enter: 1

Press: < Enter >.

36
Modifying the Input Data for a Computer Run

Year

Julian Day^

January 31 February 59 March 90

April 120 May 151 June 1 O 1 181

July 212

Aiio^ii^t 243

September 273

October 304

November 334

December 365

'at end of month.

Mnnth Year

Julian

January 2 396

February 2 424 March 2 455

April 2 485

May 2 516

June 2 546

July 2 577

2 608 September 2 638

October 2 669

November 2 699

December 2 730

^at end of month

When the program prompts you for a new value, enter 1 instead of 182. This causes the program to start the

analysis 182 days sooner, thereby pre-conditioning the

previous 1-year results with 182 days.

From the ANALYSIS INTERVAL screen, enter 0 to

quit. This will take you back to a menu options screen where you will enter 3 to return to the MAIN MENU of

Program MOIST.

37
Modifying the Input Data for a Computer Run

Modifying Output Files

From MAIN MENU, select OUTPUT FILES by:

Enter: 5

Press: < Enter >.

The program now displays options for OUTPUT FILES.

As in the previous example, you may select option 1 to create a new list of output files, select option 2 to revise an existing list of output files, or select option 3 to return

to MAIN MENU. Let's select revise existing list of

output files by entering 2.

The computer screen now displays a menu of files that

you can select for output and plotting (see below).

Program MOIST sends a set of certain parameters to selected files at the print interval specified in ANALYSIS

INTERVALS. If a "Y" appears to the right of an item,

then a file for this item will be generated by the

program. On the other hand, an "N" indicates that no

file for this item will be generated by the program. The

file options are:

1 BOUNDARY CONDITIONS N

2 AVERAGE MOISTURE CONTENT OF LAYERS Y 3 SURFACE MOISTURE CONTENT OF LAYERS N

4 SURFACE RELATIVE HUMIDITY OF LAYERS N

5 WEEKLY AVG SURFACE RELATIVE HUMIDITY OF LAYERS N

6 ABBREVIATED HARDCOPY DOCUMENTATION N

7 FULL HARDCOPY DOCUMENTATION Y 8 TIME AVG SURFACE HEAT FLUXES N

9 SURFACE MOISTURE FLUXES N ENTER ITEM NUMBER (ENTER 0 TO QUIT)

38
Modifying the Input Data for a Computer Run

1 BOUNDARY CONDITIONS. This item causes a file to be generated that contains the boundary conditions

(indoor temperature and water-vapor pressure and

outdoor dry-bulb temperature, water-vapor pressure, solair temperature, and dew-point temperature) displayed in a column format of F10.4. All quantities are timeaveraged between the print intervals. Temperatures are expressed in °C for SI units and °F for English units.

Vapor pressures are expressed in Pa for SI units and

in Hg for English units. File name is run-name plus

extension "BND" (e.g., RUNl.BND).

2 AVERAGE MOISTURE CONTENT OF LAYERS. This item causes a file to be generated that contains the

spatial-average moisture content of the layers of the

construction to be displayed in a column format of F7.2.

Moisture content is expressed as a percent. File name is run-name plus extension "MC" (e.g., RUNl.MC).

3 SURFACE MOISTURE CONTENT OF LAYERS. This item causes a file to be generated that contains the

moisture content at the inside surface, interfaces between

layers, and outside surface displayed in column format

F7.2. Moisture content is expressed as a percent. File

name is run-name plus extension "SMC" (e.g.,

RUNl.SMC).

4 SURFACE RELATIVE HUMIDITY OF LAYERS. This item causes a file to be generated that contains the

instantaneous relative humidity at the inside surface,

interfaces between layers, and outside surface displayed

in column format F7.2. Relative humidity is expressed

39
Modifying the Input Data for a Computer Run

as a percent. File name is run-name plus extension

"SRH" (e.g., RUNl.SRH).

5 WEEKLY AVG SURFACE RELATIVE HUMIDITY

OF LAYERS. This item causes a file to be generated

that contains the time-average relative humidity at the

inside surface, interface between layers, and outside

surface displayed in a column format of F7.2. The

relative humidity is time-averaged between the print

intervals. Relative humidity is expressed as a percent.

File name is the run-name plus extension "ARH" (e.g.,

RUNLARH).

6 ABBREVIATED HARD COPY DOCUMENTATION. This item causes a file to be generated that contains

PROPERTY DATA, INPUT PARAMETERS, WALL

CONSTRUCTION, ANALYSIS INTERVALS, and

OUTPUT FILES. The unprocessed output results for the

computer simulation will not appear at the end of the

file. File name is run-name plus extension "OUT" (e.g.,

RUNLOUT).

7 FULL HARDCOPY DOCUMENTATION. This item

causes a file to be generated that is the same as Item 6,

except the unprocessed output results for the computer

simulation will appear at the end of the file. Full hard

copy documentation for the sample problem is given in

Appendix B. File name is run-name plus extension

"OUT" (e.g., RUNLOUT).

40
Modifying the Input Data for a Computer Run

8 TIME AVG SURFACE HEAT FLUXES. This item

causes a file to be generated that contains the timeaveraged heat fluxes at the inside and outside surfaces of

the construction displayed in a column format of F7.4.

The fluxes are time-averaged between the print intervals.

The units are W/m^ for SI units and Btu/h-ft^ for

English units. File name is run-name plus extension

"AQ" (e.g., RUNl.AQ).

9 SURFACE MOISTURE FLUXES. This item causes a

file to be generated that contains the instantaneous

moisture fluxes at the inside and outside surfaces of the

construction displayed in a column format of El 5. 6. The

"E" indicates that the results are displayed in engineering

(or scientific) format (e.g., 1.3 E-3 or 1.3 x 10 "^). The

units are ng/s-m^ for SI units and grains/h-ft^ for

English units. File name is run-name plus extension

"MF" (e.g., RUNl.MF).

To change the selection status of a file for printing and

plotting, enter the item number after the prompt ENTER

ITEM NUMBER (ENTER 0 TO QUIT). Then, at the

prompt ENTER REVISION (Y OR N) enter a "Y" if you want this file generated or a "N" if you do not want

this file generated. After each selection, the program

will redisplay the OUTPUT FILE MENU. Continue in

this fashion until you are ready to quit this menu, then

type "0" to return to the MAIN MENU of Program

MOIST.

41

i
Modifying the Input Data for a Computer Run

Running the Revised Sample Problem

You may now run the revised sample problem by

selecting 6 from the MAIN MENU. You should name

your revised sample problem RUN2, so that new output

files will be generated by the program. If you name the

revised sample problem RUNl, then the output files generated by the program will write over the existing

RUNl output files. The revised sample problem takes

somewhat longer to run because of the addition of a preconditioning period to the problem.

After running the revised sample problem, the computer

screen will display the following graph. The moisture

content of the plywood is considerably lower due to the

presence of the vapor retarder in the construction.

2

1

Rel

n C

e

B .2 .4 .6 Relative Tine

8 l.B

Lager

:

1 3 0

42
Including Convection in a Problem

Chapter 6. Including Convection in a

Problem

The program has a provision for including a convective

"node" at either the inside surface (I) or outside surface

(O) of an adjacent layer. This convection node may be

coupled to either the indoor or outdoor air. The

procedure for including a convective node is explained

by way of an example.

Consider the following wall construction. This wall has

a 19 mm (3/4 in) thick air cavity between the wall

insulation and the plywood siding. Let's assume that this

cavity is ventilated continuously with outdoor air at a rate of 6 air changes per hour (ACH). This air change rate may be multiplied by the volume of a 1 m^ (ft^) section

of air cavity to give 0.114 rn^/h per m^ (0.375 ft^/h per

ft^). Generally, the node location [SIDE = I (inside) or O (outside)] should be the bounding surface of the cavity

where the highest moisture concentration is expected to occur. For the present wall configuration, the node will

be located at the outside surface (O) for winter analysis.

For moisture accumulation in hot & humid climates, this

node should be placed at the inside surface (I).

Let's reload the sample problem. You may accomplish

this by implementing again the installation procedures for

Program MOIST and the input files for the sample

problem. This is accomplished by inserting the MOIST

disk into your floppy drive, making this floppy drive the

default directory, and then entering the command

43
Including Convection in a Problem

INSTALL MOIST followed by the letter designating

your hard drive. This will cause the original input files for the sample problem to overwrite the revised input

files. During the installation process, ignore the

warnings indicating that the MOIST program and input

files are being overwritten.

Next go to building construction sheet. It should be the

same as that given on page 32. Following the procedure

given in the previous chapter, change the outdoor air flux

44
Including Convection in a Problem

(VEO) to be equal to 0.114 mVh per (0.375 ft^/h per

ft^). In addition, increase the thermal resistance (R) to 2.1 m^-°C/W (12 h-ft2-°F/Btu) for the non-storage

layer to account for the additional thermal resistance of

the air cavity. The parameter SIDE should already be O

specifying an outside surface node. The Building

Construction Parameter Sheet should now appear as that

given below.

1 GYPSUM BOARD 2 SUGAR PINE

3 FIBER BOARD SHEATHING 4 EXTERIOR GRADE PLYWOOD

5 ORIENTED STRAND BOARD 6 MICROFINE PARTICLE BOARD

7 WAFER BOARD SIDING 8 STURDY BRACE BOARD

9 CELLULOSE INSULATION 10 FOAM CORE SHEATHING

11 GLASS FIBER INSULATION 12 KRAFT PAPER

13 ROOFING SHINGLES 14 PERMEABLE BOARD

15 BRICK 16 CONCRETE BLOCK

17 GLASS FIBER BOARD 18 CONCRETE

19 BUILT-UP ROOFING 20 GRAVEL

21 6-MIL POLYETHYLENE 22 BUILDING PAPER

23 EXTRUDED POLYSTYRENE 24 EXPANDED POLYSTYRENE

25 CEMENT PARGE COAT 26 STUCCO FINISH 27 ALUMINUM SIDING 28 AIR BARRIER

LAY DES L T MC NX R M VEI VEO SIDE

1 1 1.300 21.0 .5 2 2 2.1 1900.0 .000 .114 0 3 4 1.300 21.0 7.0 2 ENTER WHICH LAYER DO YOU WANT TO CHANGE <0 TO QUIT)

As an exercise, you may run this sample problem.

45
Creating a New Building Construction

Chapter 7. Creating a New Building

Construction

In this chapter, we will show you how to create a new

building construction file for the wall construction given

below.

From the MAIN MENU of Program MOIST, select

option 3 to obtain BUILDING CONSTRUCTION. Then

at the options menu for BUILDING CONSTRUCTION,

46
Creating a New Building Construction

select option 1 to CREATE A NEW BUILDING FILE.

When the program prompts you for the number of layers

in the construction, enter 4. A maximum of 10 layers can be simulated with MOIST. The program will next

prompt you to enter parameters for each of the layers.

MOIST can treat a layer of the construction as either a "storage" or a "non-storage layer." The first and last layers must be storage layers.

In a storage layer, both the storage of heat and moisture

are considered. The program subdivides a storage layer

into equal-size subvolumes. The program performs a

transient calculation of the heat and moisture transfer

within each of the subelements. An initial temperature

and moisture content must be specified to get the

simulation started.

In a non-storage layer (e.g., air space), the storage of

heat and moisture is neglected. The transfer of heat and

moisture is assumed to be steady. Since the calculations

are steady state, it is unnecessary to specify an initial temperature and moisture content. A non-storage layer

may be convectively coupled to either the indoor or outdoor air. For layer 1, when prompted to enter the type of layer, enter S for storage layer. When prompted to enter the

material index, enter 1 for gypsum board. When

prompted for the layer thickness, enter L 3 cm (0.5 in).

For initial temperature, enter 21 °C (70 °F). For initial moisture content, enter 0.5%. Lastly, enter the number

47
Creating a New Building Construction

of finite-difference nodes, which must be 2 or greater.

However, the total number of nodes for all the layers

must be less than 500. Since very little variation in

moisture content is expected in the gypsum board, we

can select the minimum number of nodes (2).

For layer 2, when the program asks for type, enter N for

non-storage layer. For thermal resistance, enter 1.9

m^-°C/W (11 h-ft^-°F/Btu). For permeance, enter

1900 ng/s-m^-Pa (33.1 permjp). For both convection

coefficients, enter 0. For side, enter O to indicate an

outside node.

For layers 3 and 4, enter the parameters given below:

Parameter Layer

3 4 Type S S

Material Index 3 2

Thickness, cm (in) 1.3 (0.51) 1.3 (0.51)

Initial Temperature, C(F) 21 (70) 21 (70)

Initial Moisture Content, % 7 7 Nodes 4 7

After you enter the last parameter, the program will

display the following table of parameters for the new

construction. Check this table and make sure you

entered the correct values. If you made a mistake, use

48
Creating a New Building Construction

the procedures discussed in Chapter 5 to correct an

invalid entry.

1 GYPSUM BOARD 2 SUGAR PINE

3 FIBER BOARD SHEATHING 4 EXTERIOR GRADE PLYWOOD

5 ORIENTED STRAND BOARD 6 MICROFINE PARTICLE BOARD

7 WAFER BOARD SIDING 8 STURDY BRACE BOARD

9 CELLULOSE INSULATION 10 FOAM CORE SHEATHING

11 GLASS FIBER INSULATION 12 KRAFT PAPER

13 ROOFING SHINGLES 14 PERMEABLE BOARD

15 BRICK 16 CONCRETE BLOCK

17 GLASS FIBER BOARD 18 CONCRETE

19 BUILT-UP ROOFING 20 GRAVEL

21 6-MIL POLYETHYLENE 22 BUILDING PAPER

23 EXTRUDED POLYSTYRENE 24 EXPANDED POLYSTYRENE

25 CEMENT PARGE COAT 26 STUCCO FINISH 27 ALUMINUM SIDING 28 AIR BARRIER

LAY DES L T MC NX R M VEI VEO SIDE

1 1 1.300 21.0 .5 2 2 1.9 1900.0 .000 .000 0 3 3 1.300 21,0 7.0 4 4 2 1.300 21.0 7.0 7 ENTER WHICH LAYER DO YOU WAfiT TO CHANGE (0 TO QUIT)

49
Achieving Convergence for Mathematical Solution

Chapter 8. Achieving Convergence for

Mathematical Solution

For each building construction that you simulate with

Program MOIST, it is essential for you to carry out the

procedures described below to insure convergence of the

mathematical solution. Otherwise, the computer

predictions may be in error. We will illustrate the procedure using the sample

problem (see page 7) using Washington, DC weather

conditions. The easiest way to reload the original sample

problem is to carry out the following steps: insert the

MOIST program disk into your floppy disk drive, make

this floppy drive the default drive, and enter the

conmiand INSTALL MOIST followed by the letter designating your hard drive.

After the above steps, the BUILDING CONSTRUCTION should be those given on page 3 1 . The INPUT

PARAMETERS should be the same as those given on

page 25, except that the boundary file name should be

changed to WYWASDC (Washington, DC) and the

convergence criteria and the maximum iterations should

be changed to the values recommended for applications

without liquid in the pore structure of the materials (i.e.,

0.1 X 10"^ and 50, respectively). The revised INPUT

PARAMETERS are:

50
Achieving Convergence for Mathematical Solution

1 TYPE SOLUTION? C

I

S0THEkMAL=1 N0NIS0THEkMAL=2) 2

2 CONVECTION COEF AT INSIDE SURFACE 3 .600

6 LUNVtLllUN LUtr Al UUlaiUt csUKrALh 1 "5 /on

k CONVERGENCE CRITERIA PGR MOISTURE SOLUTION , HJUuE-03 MAXlMUn lltKAliUNo IN nUlolUKt LUUr

6 SOLAR ABSOfiPTANCE OF EXTERIOR SURFACE .700 7 SURFACE TILT (DEGREES) 90. 8 SURFACE AZIMUTH (DEGREES) 0. 9 INDOOR TEMPERATURE 21.000

10 INDOOR RELATIVE HUMIDITY, PERCENT 35.000

11 BOUNDARY FILE TYPE (WYEC=1, SPECIAL=2) 1 12 BOUNDARY FILE NAME WYWASDC

13 INSIDE SURF PAINT PERMEANCE 575 . 000

14 OUTSIDE SURF PAINT PERMEANCE 115.000 EMTER ITEM NUMBER (ENTER 0 TO QUIT)

Choosing Number of Nodes

MOIST predicts the temperature and moisture content of

the layers of the construction as a function of time of

year using a finite-difference model. In this finite- difference model, each layer of the construction is subdivided into equal-size subvolumes. A heat and

moisture balance is performed on the nodes at the center

of these subvolumes. The heat and moisture fluxes

between nodes are predicted by linear approximations.

As the number of nodes is increased, the approximate

solution approaches the "exact" solution.

In materials with very little difference in moisture

content across the layer, two nodes are sufficient to achieve convergence of the mathematical solution. Since

very little difference in moisture content occurs across

the gypsum board, two nodes are adequate. The number

51
Achieving Convergence for Mathematical Solution

of nodes for the storage layers are given in the

BUILDING CONSTRUCTION menu.

In the original sample problem, a large difference in

moisture content is expected to occur across the

plywood, and it is therefore necessary to determine a

sufficient number of nodes for the plywood. This can be

accomplished by carrying out computer simulations with an increasing number of nodes and comparing the

predicted moisture content in the plywood. An adequate

number of nodes is deemed to exist when the predicted

moisture content of the plywood is nearly the same as a simulation with twice as many nodes. This process is illustrated in the following figure. Note that the moisture

content in the plywood is very nearly the same for cases with 10 and 20 nodes. Therefore, 10 nodes is sufficient.

52
Achieving Convergence for Mathematical Solution

Choosing the Convergence Criteria and Maximum

Iterations

First carry out a computer run with the recommended

convergence criteria = 0.1 X lO'-^ and maximum

iterations = 50 for the case of liquid water not present in

the construction layers. Then carry out another

computer run with the convergence criteria decreased by

a factor of two and maximum iterations increased by a factor of two. If the predicted moisture contents of the

53
Achieving Convergence for Mathematical Solution

layers are nearly the same, then the recommended

parameter values provide convergence. This process is illustrated in the figure below. Note that there is little or no difference between the moisture contents for the two

simulations, thereby indicating that the recommended

parameter values are adequate. In the event that the two

simulations had produced different results, then you

would continue to decrease the convergence criteria and

increase the maximum iterations until there is very little difference between consecutive simulation results.

54
Creating a New Building Construction

select option 1 to CREATE A NEW BUILDING FILE.

When the program prompts you for the number of layers

in the construction, enter 4. A maximum of 10 layers can be simulated with MOIST. The program will next

prompt you to enter parameters for each of the layers.

MOIST can treat a layer of the construction as either a "storage" or a "non-storage layer." The first and last layers must be storage layers.

In a storage layer, both the storage of heat and moisture

are considered. The program subdivides a storage layer

into equal-size subvolumes. The program performs a

transient calculation of the heat and moisture transfer

within each of the subelements. An initial temperature

and moisture content must be specified to get the

simulation started.

In a non-storage layer (e.g., air space), the storage of

heat and moisture is neglected. The transfer of heat and

moisture is assumed to be steady. Since the calculations are steady state, it is unnecessary to specify an initial temperature and moisture content. A non-storage layer

may be convectively coupled to either the indoor or outdoor air. For layer 1 , when prompted to enter the type of layer,

enter S for storage layer. When prompted to enter the

material index, enter 1 for gypsum board. When

prompted for the layer thickness, enter L 3 cm (0.5 in).

For initial temperature, enter 21 °C (70 °F). For initial moisture content, enter 0.5%. Lastly, enter the number

47
Creating a New Building Construction

of finite-difference nodes, which must be 2 or greater.

However, the total number of nodes for all the layers

must be less than 500. Since very little variation in

moisture content is expected in the gypsum board, we

can select the minimum number of nodes (2).

For layer 2, when the program asks for type, enter N for

non-storage layer. For thermal resistance, enter 1.9

m^-°C/W (11 h-ft^-°F/Btu). For permeance, enter

1900 ng/s-m^-Pa (33.1 permjp). For both convection

coefficients, enter 0. For side, enter O to indicate an

outside node.

For layers 3 and 4, enter the parameters given below:

Parameter Layer

3 4

Type S S

Material Index 3 2

Thickness, cm (in) 1.3 (0.51) 1.3 (0.51)

Initial Temperature, C(F) 21 (70) 21 (70)

Initial Moisture Content, % 7 7 Nodes 4 7

After you enter the last parameter, the program will

display the following table of parameters for the new

construction. Check this table and make sure you

entered the correct values. If you made a mistake, use

48
Creating a New Building Construction

the procedures discussed in Chapter 5 to correct an

invalid entry.

1 GYPSUM BOARD 2 SUGAR PINE

7

Jl rlDtK dUAKi/ ontAlniNu CVTCDTHD /*DAr\r m VI irtr»r> CA 1 tKlUK uKAUt rLYwUUU

5 ORIENTED STRAND BOARD 6 MICROFINE PARTICLE BOARD

f WAFER BOARU SluING 0 SIURUT BRACE BOARD

0y

nci 1 III ncc T 11 CI II a t t r*ii LcLLULUbt INbULAI lUN 1 ucriAM fnoc cue A T u T kir- rUAM LUKE SnEAIHiNG

1

1

1

1

^1 A ec CTOcn tmciii atiaw GLASS rlBcR INSULATION \RArl PAPER

t J KUUr I Nu Sn I NuLco 1 / rEKMEABLb BOARD

15 BRICK 16 CONCRETE BLOCK

17 GLASS FIBER BOARD 18 CONCRETE

19 BUILT-UP ROOFING 20 GRAVEL

21 6-MIL POLYETHYLENE 22 BUILDING PAPER

23 EXTRUDED POLYSTYRENE 24 EXPANDED POLYSTYRENE

25 CEMENT PARGE COAT 26 STUCCO FINISH 27 ALUMINUM SIDING 28 AIR BARRIER

LAY DES L T MC NX R M VEI VEO SIDE

1 1 1.300 21.0 .5 2 2 1.9 1900.0 .000 .000 0 3 3 1.300 21.0 7.0 4 4 2 1.300 21.0 7.0 7 ENTER WHICH LAYER DO YOU WANT TO CHANGE (0 TO QUIT)

49
Achieving Convergence for Mathematical Solution

Chapter 8. Achieving Convergence for

Mathematical Solution

For each building construction that you simulate with

Program MOIST, it is essential for you to carry out the

procedures described below to insure convergence of the

mathematical solution. Otherwise, the computer

predictions may be in error. We will illustrate the procedure using the sample

problem (see page 7) using Washington, DC weather

conditions. The easiest way to reload the original sample

problem is to carry out the following steps: insert the

MOIST program disk into your floppy disk drive, make

this floppy drive the default drive, and enter the

command INSTALL MOIST followed by the letter designating your hard drive.

After the above steps, the BUILDING CONSTRUCTION should be those given on page 31. The INPUT

PARAMETERS should be the same as those given on

page 25, except that the boundary file name should be

changed to WYWASDC (Washington, DC) and the

convergence criteria and the maximum iterations should

be changed to the values recommended for applications

without liquid in the pore structure of the materials (i.e.,

0.1 X 10-^ and 50, respectively). The revised INPUT

PARAMETERS are:

50
Achieving Convergence for Mathematical Solution

1 TYPE SOLUTION? (IS0THERMAL=^1 N0NIS0THERMAL=2) 2

2 CONVECTION COEF AT INSIDE SURFACE 3.600

3 CONVECTION COEF AT OUTSIDE SURFACE 12,400

4 CONVERGENCE CRITERIA FOR MOISTURE SOLUTION .1000E-03

5 MAXIMUM ITERATIONS IN MOISTURE LOOP 50

o <;ni AR AR<;ORPTANCE OF EXTERIOR SLJRFAPF .700 7 SURFACE TILT (DEGREES) 90. 8 SURFACE AZIMUTH (DEGREES) Q 9 INDOOR TEMPERATURE 21.000

10 INDOOR RELATIVE HUMIDITY, PERCENT 35.000

11 BOUNDARY FILE TYPE (WYEC=1, SPECIAL=2) 1 12 BOUNDARY FILE NAME WYWASDC

13 INSIDE SURF PAINT PERMEANCE 575.000

14 OUTSIDE SURF PAINT PERMEANCE 115.000 ENTER ITEM NUMBER (ENTER 0 TO QUIT)

Choosing Number of Nodes

MOIST predicts the temperature and moisture content of

the layers of the construction as a function of time of

year using a finite-difference model. In this finitedifference model, each layer of the construction is subdivided into equal-size subvolumes. A heat and

moisture balance is performed on the nodes at the center

of these subvolumes. The heat and moisture fluxes

between nodes are predicted by linear approximations.

As the number of nodes is increased, the approximate

solution approaches the "exact" solution.

In materials with very little difference in moisture

content across the layer, two nodes are sufficient to achieve convergence of the mathematical solution. Since

very little difference in moisture content occurs across

the gypsum board, two nodes are adequate. The number

51
Achieving Convergence for Mathematical Solution

of nodes for the storage layers are given in the

BUILDING CONSTRUCTION menu.

In the original sample problem, a large difference in

moisture content is expected to occur across the

plywood, and it is therefore necessary to determine a

sufficient number of nodes for the plywood. This can be

accomplished by carrying out computer simulations with an increasing number of nodes and comparing the

predicted moisture content in the plywood. An adequate

number of nodes is deemed to exist when the predicted

moisture content of the plywood is nearly the same as a simulation with twice as many nodes. This process is illustrated in the following figure. Note that the moisture

content in the plywood is very nearly the same for cases with 10 and 20 nodes. Therefore, 10 nodes is sufficient.

52
Achieving Convergence for Mathematical Solution

Choosing the Convergence Criteria and Maximum

Iterations

First carry out a computer run with the recommended

convergence criteria = 0.1 X 10"^ and maximum

iterations = 50 for the case of liquid water not present in

the construction layers. Then carry out another

computer run with the convergence criteria decreased by

a factor of two and maximum iterations increased by a factor of two. If the predicted moisture contents of the

53
Achieving Convergence for Mathematical Solution

layers are nearly the same, then the recommended

parameter values provide convergence. This process is illustrated in the figure below. Note that there is little or no difference between the moisture contents for the two

simulations, thereby indicating that the recommended

parameter values are adequate. In the event that the two

simulations had produced different results, then you

would continue to decrease the convergence criteria and

increase the maximum iterations until there is very little difference between consecutive simulation results.

54
Appendix B

Appendix B

Listing of File RUNl.OUT

RUN1PROPERTY DATA

1 GYPSUM BOARD

.2465E-01 .9075E+01 .1089E+04 .1603E+00

2 SUGAR PINE .1951E+00 .2116E+01 .1633E+04 .9692E-01

3 FIBER BOARD SHE .3369E+00 .6488E+01 .1298E+04 .5469E-01

4 EXTERIOR GRADE

.3441E+00 .6177E+01 .1214E+04 .1154E+00

5 ORIENTED STRAND

.2121E+00 .3427E+01 .1298E+04 .1177E+00

6 MICROFINE PARTI .2564E+00 .4860E+01 .1298E+04 .1360E+00

7 WAFER BOARD SID .4601E+00 .1218E+02

.1214E+04 .9086E-01

8 STURDY BRACE BO

.1139E+01 .5060E+02

.1298E+04 .7961E-01

9 CELLULOSE INSUL .5420E-01 -.3201E+00

.1382E+04 .4327E-01

10 FOAM CORE SHEAT

.3636E+00 .1455E+02

.1298E+04 .4846E-01

11 GLASS FIBER INS .1009E+00 .5356E+02

.7118E+03 .4327E-01

12 KRAFT PAPER

.5190E+02 .2538E+04

.1256E+04 .1592E+00

13 ROOFING SHINGLE

.5190E+02 .2538E+04

.1256E+04 .1038E+00

14 PERMEABLE BOARD

.3360E+00 .6488E+01

.9354E+00 -.2347E+02.1115E-13

-.1480E+01

.5000E+00

.1082E+01 .6696E+03

.7674E+00 -.2868E+02

.2787E-18 -.9198E+00

.7560E+00

.4576E+01 .3652E+03

.8467E+00 -.2262E+02.1301E-13

-.4562E+01 .7650E+00

.2953E+01 .2659E+03

.8283E+00 -.2666E+02.2787E-19

-.6368E+01 .6360E+00

.8889E+01 .5094E+03

.8106E+00 -.2768E+02.2787E-19

-.1468E+01 .5720E+00

.3418E+01 .6407E+03

.8216E+00 -.2552E+02.1022E-14

-.3298E+01 .4910E+00

.3817E+01 .7625E+03

.8630E+00 -.2804E+02

.2787E-19

-.5720E+01

.5280E+00

.9367E+01 .7064E+03

9232E+00

-.2452E+02

.1301E-13

.2399E+01 .7340E+00

-.2539E+01 3988E+03

.9275E+00 -.2398E+02

.2044E-10

.1440E+01 .9470E+00 .OOOOE+00

.8009E+02

.9023E+00 -.2585E+02

.4645E-14

-.2782E+01 .7000E+00.2884E+01 .9691E+02

.9312E+00 -.2404E+02

.4645E-14

.2572E+01 .9960E+00

.OOOOE+00 .1147E+02

.9020E+00 -.3224E+02.2787E-19

-.1168E+01 .9000E+00

.3058E+01 .8393E+03

.9020E+00 -.3224E+02

.2787E-19

-.1168E+01

.9000E+00

.3058E+01 .1121E+04

.8467E+00 .1301E-13 .7650E+00 .2659E+03 63
Appendix B

.1298E+04 .5469E-01 - .2449E+02 .OOOOE+00 .OOOOE+00

15 BRICK

.7880E-02 .3771E+01 .8142E+00 .1626E-15 .5000E+00 .1922E+04 .7955E+03 .7494E+00 -.2623E+02 .OOOOE+00 .OOOOE+00

16 CONCRETE BLOCK

.1021E+00 .1010E+02 .7745E+00 .1626E-15 .5000E+00 .8490E+03 .9211E+03 .1113E+01 - .2578E+02 .2538E+01 .OOOOE+00

17 GLASS FIBER BOA

.1009E+00 .5356E+02 .9312E+00 .D295E- 14 .9900E+00 . 2643E+03

.7955E+03 .4898E-01 - .2382E+02 AAAAf AA .OOOOE+00 AAAAr* AA .OOOOE+00

18 CONCRETE

.1253E+00 .1432E+02 .o2/yE+U0 .8082E-17 OAAAr AA .8000E+00 .2243E+04 .9211E+03 .2163E+01 - . 2664E+02 - .4404E+01 .5888E+01

19 BUILT-UP ROOF IN .5190E+02 .2538E+04 .9020E+00 .2787E-19 ^AAA^ • AA .9000E+00 . 1 121E+04 .1465E+04 .1627E+00 - .3224E+02 - .1168E+01 .3058E+01

20 GRAVEL

.1253E+00 .1432E+02 .8279E+00 .1301E-13 .7650E+00 .1442E+04 .8374E+03 .1731E+01 - .2334E+02 AAAA^ AA .OOOOE+00 AAAAr" . AA .OOOOE+00

21 6-MIL POLYETHYL

.5190E+02 .2538E+04 .9020E+00 .2787E-19 ^AAAr AA .9000E+00 .8393E+03 .1256E+04 .1592E+00 - .3518E+02 AAAA^ • AA .OOOOE+00 AAAA^ . .OOOOE+00

22 BUILDING PAPER

.5190E+02 .2538E+04 .9020E+00 .2787E-19 I^AAA^ 1 AA .9000E+00 .8393E+03 .1256E+04 .1592E+00 - .2936E+U2 .OOOOE+00 .OOuOE+00

23 EXTRUDED POLYST

.4194E+00 .1293E+02 .^/^orc- 19 .9U00E+00 .424DE+U2 .1214E+04 .2890E-01 - .2707E+02 AAAAr* 1 AA .OOOOE+00 AAAA^ AA .OOOOE+00

24 EXPANDED POLYST

.4194E+00 .1293E+02 r O / AA .5247E+00 .2787E-19 />AAAr I AA .9000E+00 1 ^ A A^ I A

A

. 1602E+02 .1214E+04 .3756E-01 -.2589E+02 AAAAr" AA .OOOOE+00 AAAA^ • AA .OOOOE+00

25 CEMENT PARGE CO

.6580E-01 .2815E+01 .7062E+00 .2322E-16 PAAAr • AA .5000E+00 . 1922E+04

.8374E+03 .1118E+01 -.2584E+02 -.2451E+00 .1019E+01 26 STUCCO FINISH

.2465E-01 .9075E+01 .9354E+00 .1115E-13 .5000E+00 .6696E+03 .1089E+04 .1603E+00 -.2564E+02 .OOOOE+00 .OOOOE+00 27 ALUMINUM SIDING

.1009E+00 .5356E+02 .9312E+00 .2787E-19 .9000E+00 .8393E+03 .1256E+04 .1160E+00 -.2495E+02 .OOOOE+00 .OOOOE+00

28 AIR BARR][ER .5190E+02 .2538E+04 .9020E+00 .2787E-19 .9000E+00 .8393E+03 .1256E+04 .1592E+00 -.2778E+02 .OOOOE+00 .OOOOE+00

INPUT PARAMETERS

1 TYPE SOLUTION? ( IS0THERMAL=1 N0NIS0THERMAL=2) 2

2 CONVECTION COEF AT INSIDE SURFACE 3.600

3 CONVECTION COEF AT OUTSIDE SURFACE 12.400

64
Appendix B

4 CONVERGENCE CRITERIA FOR MOISTURE SOLUTION .1000E-02

5 MAXIMUM ITERATIONS IN MOISTURE LOOP 20

6 SOLAR ABSORPTANCE OF EXTERIOR SURFACE .700 7 SURFACE TILT (DEGREES) 90. 8 SURFACE ORIENTATION (DEGREES) 0. 9 INDOOR TEMPERATURE 21.000

10 INDOOR RELATIVE HUMIDITY, PERCENT 35.000

11 FILE TYPE (WYEC=1, SPECIAL=2) 1 12 BOUNDARY FILE NAME WYMADWI

13 INSIDE SURF PAINT PERMEANCE 575.000

14 OUTSIDE SURF PAINT PERMEANCE 115.000

WALL CONSTRUCTION

LAY

123

DES L T

1 1.300 21.0

MC

.5 NX2

R M 1.9 1900.0 1.300 21.0 7.0VEI .000VEO SIDE

.000 0

ANALYSIS INTERVALS COMPUTER ANALYSIS

1 FIRST DAY 182

2 LAST DAY 546 PRINTING AND PLOTTING

3 FIRST DAY 182

4 LAST DAY 546

5 INTERVAL (HOURS) 168

ITEMS SENT TO OUTPUT FILES

1 BOUNDARY CONDITIONS N 2 AVERAGE MOISTURE CONTENT OF LAYERS Y

3 SURFACE MOISTURE CONTENT OF LAYERS N 4 SURFACE RELATIVE HUMIDITY OF LAYERS N

5 WEEKLY AVG SURFACE RELATIVE HUMIDITY OF LAYERS N 6 ABBREVIATED HARDCOPY DOCUMENTATION N 7 FULL HARDCOPY DOCUMENTATION Y

8 TIME AVG SURFACE HEAT FLUXES N 9 SURFACE MOISTURE FLUXES N DAY=188.00 TTIAV= 21.0 TTOAV= 20.1 TTSAV= 23.7

PPIAV= .868E+03 PPOAV= .162E+04

NODAL TEMPS 20.62178 20.55762 20.42251 20.35052

13.47190 13.36887 13.00912 12.74954

65
Appendix B

NODAL MOISTURE CONTENTS

.344 .346 .347 .348 8.824 6.245 6.865 8.180

NODAL VAPOR PRESSURES

.9829E+03 .9832E+03 .9815E+03 .9793E+03

.9326E+03 .6523E+03 .7112E+03 .8334E+03

QI= .31636E+01 WI= -.64586E+05 Q0= .92202E+01 W0= -.39631E+05

DAY=195.00 TTIAV= 21.0 TTOAV= 20.6 TTSAV= 24.1 PPIAV= .868E+03 PPOAV= .164E+04 NODAL TEMPS 20.90529 20.89123 20.86059 20.84365

19.22558 19.20079 19.10641 19.03681 NODAL MOISTURE CONTENTS

.335 .336 .337 .337 6.276 5.664 6.603 7.792

NODAL VAPOR PRESSURES

.9663E+03 .9679E+03 .9697E+03 .9699E+03

.9534E+03 .8356E+03 .1005E+04 .1191E+04 QI= .69330E+00 WI= -.55310E+05 Q0= .24719E+01 W0= -.58319E+05

DAY=202.00 TTIAV= 21.0 TTOAV= 21.2 TTSAV= 24.5 PPIAV= .868E+03 PPOAV= .195E+04 NODAL TEMPS 20.94782 20.94037 20.92473 20.91644

20.12472 20.11201 20.07764 20.05701 NODAL MOISTURE CONTENTS

.325 .325 .326 .326 5.859 5.497 6.595 8.565

NODAL VAPOR PRESSURES

.9331E+03 .9342E+03 .9354E+03 .9356E+03 .9250E+03 .8494E+03 .1066E+04 .1382E+04 QI= .36724E+00 WI= -.36696E+05 Q0= .73289E+00 W0= -.10878E+06

DAY=209.00 TTIAV= 21.0 TTOAV= 22.3 TTSAV= 25.4 PPIAV= .868E+03 PPOAV= .215E+04

66
Appendix B

NODAL TEMPS 21.0U13 21.01963 21.02813 21.03080

21.28483 21.28788 21.24995 21.20872

NODAL MOISTURE CONTENTS

.334 .334 .335 .335 5.721 5.346 6.634 8.472

NODAL VAPOR PRESSURES

.9695E+03 .9714E+03 .9741E+03 .9748E+03

.9631E+03 .8791E+03 .1153E+04 .1470E+04

QI= -.27109E+00 WI= -.57067E+05 Q0= .14644E+01 W0= -.10805E+06

67
Appendix C

Appendix C

Listing of fileRUNl.MC

.35 7.04 • .34 6.36 • .33 6.34 • .33 6.27 .29 19.28

.32 6.41 dl .\ f .32 6.43 dW.5i* .32 6.53 - .do dd.of

.33 6.50 .do .33 6.63 .dy .32 6.81 .24 24.86

.30 7.12 .dd .30 7.68 .5\ 2b. 16 .30 7.95 .5d oc / c ^b .h3

.31 8.02 .32 25 . 10 .33 7.21 .55 .27 8.63 .42 22.28

.29 9.04 .40 21.76

.27 9.90 .34 20.21 .27 10.53 .35 17.98

.28 10.99 .48 16.48

.27 12.43 .37 13.99

.30 12.40 .41 12.08

.24 14.75 .40 10.84

.25 15.29 .37 9.39

.26 16.89 .37 8.12

.27 17.45 .36 7.26

.25 18.58 .34 6.54

• .35 6.08
NIST 114 U.S. DEPARTMENT OF COMMERCE

mcv. 9 921 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY

AOMAN 4.09MANUSCRIPT REVIEW AND APPROVAL

(ERB USE ONLY!

FOB CONTROL NUMBER DIVISION 863

PUBLICATION REPORT NUMBER CATEOORY CODE

INSTRUCTIONS: ATTACH ORIGINAL OF TtHS FORM TO ONE HI COPY Of MAMUSCRWf AND SEND TO: THE SECRETARY. APPROPRIATE EDITORIAL REVIEW BOARD

PUIllC«ridll OAIE NUMBER PRlNieb PACES 7^r

TniE AND SUBTITLE (CITE m FULL) MOIST: A PC Program for Predicting Heat and Moisture Transfer in Building Envelopes, Version 2.0 CONTRACT OR GRANT NUMBER TYPE OF REPORT AND/OR PERIOD COVERED

Special Publications AUTHORISI (LAST NAME. FIRST INITIAL. SECOND MITIALI

BuTcli, D. M., and Thomas, W. C.

PEFIFORM XUNO ORGANIZAIION (CHECK (X( ONE BOX) NIST/GAmiERSBURO

NIST/BOUIOER

JILA/BOUIOER LABORATORY AND DIVISION NAMES (FIRST NIST AUTHOR ONIYI

Building and Fire Research Laboratory. BuiHing Environment Division SPONSORING ORGANIZAIION NAME AND COMPLETE ADDRESS ISTREET. CITY. STATE. Z\P) NIST. Gaithersburg, MD 20899 and U.S. Department of Energy, Washington. D.C. 20585

RECOMMENDED FOR NISI PUBUCATIOM JOURNAL OF RESEARCH (NIST JRESI

J. PHYS. A CHEM. REF. DATA (JPCROI HANDBOOK (NIST HB( SPECIAL PUBLICATION (NIST SP) TECHNICAL NOTE (NIST TN)

MONOGRAPH (NUT MNI

NATL. STO. REF. DATA SERIES (NIST NSROSI

FEDERAL WF. PROCESS. STOS. (NIST FrS|

LIST OF PUBLICATIONS (NIST IPI NIST MTERAGENCY/MTERNAL REPORT INISTIRI

LETTER CIRCULAR

BUN-DING SCIENCE SERIES PRODUCT STANDARDS

OTHER RECOMMENDED FOR NON NIST PUBLICATION (CITE FUUY) FOREIGN PUBUSHWO MEDIUM

PAPER

DISKETTE (SPECIFYI OTHEB (SPECffYI

I I CO ROM

3-1/2- SUPPLEMENTARY NOTES

ABSTRACT (A 1 500-CHARACTEB OH LESS FACTVAL SUMMARY OF MOST SIGNIFICANT INFORMATION, DOCUMENT ftClUDES A SIGNIFICANT BIBLIOGRAPHY OR LITERATURE SURVEY. CTTE IT HERE. SPELL OUT ACRONYMS ON FWST REFERENCE I (CONIINUE ON SEPARATE PAGE, If NECESSARY ) lllis report is a users manual for a computer program called MOIS I". MOIS 1' is a tiser- friendly personal computer program that predicts the one-dimensional transfer of heat and moisture in multi-layer walLs, cathedral ceilings, and low-sloped roofs. The

algorithms in the program predict moisture transfer in the diffusion through the capillary flow regimes. Tlie program has a provi.sion to account for convective moisture transfer by including embedded cavities which may be coupled to indoor and/or outdoor air. The

user can readily include the water-vapor resistance offered by paint layers, wallpaper, and vapor retarders in simulations. Hie program generates a plot on the computer

screen of the average moisture content of the construction layers versus lime of year as

the program executes. 1 he program generates output files which may be imported into

plotting programs for preparing reports.

KEY WORDS (MAXIMUM 9 KEY WORDS: 28 CHARACTERS AND SPACES EACH: ALPHABETICAL ORDER: CAPIIAIIZE ONLY PROPER NAMESI

building (echnology. heal and moisture Iransfer, moi<:ture control, moisture transfer, wall perfonnance

AV ULAB X

X

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LITY UNLIMITED 1

1 FOR OFFICIAl DISTRIBUTION. DO NOT RELEASE TO NHS. ORDER FROM SUPERINTENDENT OF DOCUMENTS. U.S. OPO. WASHINGTON. DC 20402 ORDER FROM NTIS. SPRINGFIELD. VA 22181

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