g^att of standards
The program of research on building materials and structures, carried on by the

National Bureau of Standards, was imdertaken with the assistance of the Central

Housing Committee, an informal organization of governmental agencies concerned with

housing construction and finance, which is cooperating in the investigations through a committee of principal technicians.

CENTRAL HOUSING COMMITTEE

ON RESEARCH, DESIGN, AND CONSTRUCTION

A. C. Shire, Chairman, Howard P. Vermilya, Vice Chairman,

United States Housing Authority. Federal Housing Administration.

Sterling R. March, Secretary.

Pierre Blouke, John S. Donovan,

Federal Home Loan Bank Board. Farm Security Administration.

Hugh L. Dryden, George W. Trayer,

National Bxu'eau of Standards. Forest Service (F. P. Laboratory).

Louis A. Simon, Joseph M. DallaValle,

Public Buildings Administration. Public Health Service.

Luther M. Leisenring, George E. Knox,

Construction Division (War). Yards and Docks (Navy).

Edward A. Poynton, William R. Talbott,

Office of Indian Affairs. Veterans' Administration.

Wallace Ashby,

Bureau of Agricultural Chemistry and Engineering.

NATIONAL BUREAU OF STANDARDS

STAFF COMMITTEE ON ADMINISTRATION AND COORDINATION

Hugh L. Dryden, Chairman.

Mechanics and Sound.

Phaon H. Bates, Gustav E. F. Lundell,

Clay and Silicate Products. Chemistry.

Hobart C. Dickinson, Addams S. McAllister,

Heat and Power. Codes and Specifications.

Warren E. Emley, Henry S. Rawdon,

Organic and Fibrous Materials. Metallurgy.

The Forest Products Laboratory of the Forest Service is cooperating with both

committees on investigations of wood constructions.

[For list of BMS publications and directions for purchasing, see cover page III.
UNITED STATES DEPARTMENT OF COMMERCE • Jesse H. Jones, Secretary

NATIONAL BUREAU OF STANDARDS • Lyman J. Briggs, Director

BUILDING MATERIALS

and STRUCTURES

REPORT BMS56

A Survey of Humidities in Residences

by THOMAS D. PHILLIPS

ISSUED OCTOBER 9, 1940

The National Bureau of Standards is a fact-finding organization;

it does not "approve" any particular material or method of construction. The technical findings in this series of reports are to be construed accordingly.

UNITED STATES GOVERNMENT PRINTING OFFICE • WASHINGTON • I94O

FOR SALE BY THE SUPERINTENDENT OF DOCUMENTS, WASHINGTON, D. C. • PRICE lO CENTS
Foreword

As a part of the investigation of low-cost housing being conducted by the National

Bureau of Standards, data on the atmospheric conditions prevailing in occupied houses were needed. It was known that, in general, the relative humidity in heated houses

during cold weather was likely to be rather low, and many means of increasing the humidity have been devised and advocated. However, there has been a lack of specific information on the conditions actually prevailing, and such information could be obtained

only by a rather extensive survey. Such a survey can be made efficiently and economically by the cooperation of a considerable number of observers located in various parts

of the country. The Bureau was fortunate in obtaining the cooperation of the physics

faculties of a considerable number of colleges, who generously contributed to the success

of the project.

Lyman J. Briggs, Director.

[n]
A Survey ot Humidities in Residences

by THOMAS D. PHILLIPS

CONTENTS

Page

Foreword ii

I. Introduction 1 II. Source of data 2

III. Tabulation of data 2 IV. Graphs of relative humidities 2

Page

V. Distribution of vapor pressures 6

VI. Distribution of interior dew points 6

VII. Effect of continued cold weather or low

exterior absolute humidity 6

VIII. Conclusions 6

ABSTRACT

This report presents the results of a survey of the relative humidities prevailing in occupied houses during the

winter. The observations were made by students of colleges cooperating in the survey, working under the supervision of the physics departments of the colleges, and data were obtained from 26 localities in the northern part of the United States. In general, in the occupied houses, the moisture content of the air was sufficient to make the

interior condition from 10- to 15-percent relative humidity higher than would have resulted from heating outside

air to 70°F without change in moisture content.

I. INTRODUCTION

Problems which involve the effects of moisture or water vapor on either the occupants or

the structm'e of dwellings call for some definite

information as to the humidity conditions wliich

exist within the buildings under normal conditions of occupancy. Such information is not

generally available, as measm'ements of humidity in dwellings have been made only

sporadically and at isolated points. Such

observations do not well serve the purpose of estimating the inside humidities which may be

expected, on the average, over periods of either

winter or summer weather conditions in a

variety of dwellmgs.

During the winter, the outdoor air usualh^

has a fairly Mgh relative humidity, but because

the temperature is low, the moistiu-e content is also low. Wlien cold au* with its low moistm-e

content is brought into a house, and heated to 70^ F, for example, without adding or removing

moisture, its relative hinnidity becomes very

low, even though its moisture content is unchanged. The relative humidity that would

be expected in a house under various conditions

in winter, if the air in the house had the same

moisture content as the outdoor air, is shown,

in table 1.

Table 1.

Calculated indoor relative humidities at indoor

temperatures of 70° and 80° Ffor outdoor relative humidities cf 100 percent and 50 -percent

Outdoor temperature

Indoor temperature 70° F. Outdoor relative humidity

Indoor temperatare 80° F. Outdoor relative liumidity

100% 50% 100% 50%

o F % % % %

40 33 17 24 12

30 22 11 16 8

Jfi . 14 10 5

10 9 4 6 3

0 6 3 4 2 -10 3 2 2 1 -20 2 1 1 1

Relative humidities as low as those showm in table 1 are rather rare, because there are many

sources from which moisture may be supplied

to the air in a house, for example, the occupants

and their activities, plants, woodwork, furnishings, humidifying systems, etc. The extent to which the relative hiunidity in any house is raised above that indicated in table 1 will depend upon the amount of moisture added and

upon the ventilation, that is, upon the rate at which fresh air of low moisture content comes

into the house and air of higher moisture content escapes. Since such effects are not readih'

subject to calculation, the only way to determine

the relative humidities actually prevailing in occupied houses is by measurement.

2478Sl"-40 [1]
II. SOURCE OF DATA

To provide these measurements, a nmiiber of colleges located in the Northern States were

asked to cooperate. The data presented in this report are based on observations made by

students or by the physics faculties of the

following colleges:

Whitman College, Walla Walla, Wash.

Cornell College, Mt. Vernon, Iowa. Parsons College, Fairfield, Iowa. Doane College, Crete, Nebr.

Friends University, Wichita, Kans. Lake Forest College, Lake Forest, Iowa. Earlham College, Richmond, Ind. Western State Teachers College, Kalamazoo, Mich.

Findlay College, Findlay, Ohio. Marietta College, Marietta, Ohio. Bethany College, Bethany, W. Va. Allegheny College, Meadville, Pa. Haverford College, Harverford, Pa. Waynesburg College, Waynesbiirg, Pa. Alfred University, Alfred, N. Y. Hamilton College, Clinton, N. Y. Hobart College, Geneva, N. Y. Mount Holyoke College, South Hadley, Mass.

Wellesley College, Wellesley, Mass.

University of Vermont, Burlington, Vt. Ricker Classical Institute and .Itniior College,

Houlton, Maine.

Oregon State College, Corvallis, Oreg.

University of Idaho, Moscow, Idaho. Montana State College, Bozeman, Mont.

Milton College, Milton, Wis.

Ripon College, Ripon, Wis.

The instrument data consisted of wet- and

dry-bulb readings taken with sling psychrometers. Each observation included an outdoor

reading and one taken within the residence.

In all, 3,050 such observations were made,

involving 215 residences.

Owing to the fact that the convenience of

the observers and of the residents had to be

served, no fixed time of observation was set. In general, two observations per day were made, one between nine and eleven o'clock in the morning and another between thi'ee and

five o'clock in the afternoon. Also, in many

cases, observations were made in several rooms

in the house at one visit. In addition, the observers furnished a brief

description of the heating system and of any

provision for humidification. Also note was

taken of any readily observed characteristics

of the structure or conditions of occupancy

which might be expected to affect the interior

Immidity.

III. TABULATION OF DATA

The data have been tabulated with the

intent of putting them into forms in which they

may best be available for immediate use. No

causal relationship is assumed or implied in the

choice of method of grouping them.

The houses were divided into two groups on

the basis of their description. One group is called "unhumidified" and includes 73 houses.

The other group is called "humidified" and

includes 142 houses. The houses forming the

unhumidified group are those which have no

provision whatever in the heating system for adding moisture to the air. The houses in the

humidified group include those in which some

sort of humidifying appliance is included in the

heating system. Houses with such devices as water pans on radiators or water tank in a warm-air furnace were placed in this group as well as the very few houses provided with

humidification under instrument control. In

this group also were included houses in which

the heating system consisted of open, naturalgas stoves without flue connections, since such

a heating system is equivalent to one with

a humidifying appliance.

As the data given later show, the amount of humidification was not very great in some of the houses described as humidified. However,

no attempt has been made to evaluate the

various methods of humidification, since the

conditions imder which observations were made were not controlled.

IV. GRAPHS OF RELATIVE

HUMIDITIES

It is to be expected from the information

given in table 1, and it was at once apparent

from the data, that the outside dry-bulb

temperatures formed a convenient means of grouping the relative humidities of the interiors. The bar graphs in figure 1 show the

distribution of relative humidities for various

outside temperatures. The method of obtaining these graphs was as follows: The data were

separated into two groups as previously described, those for the humidified houses being

[2]
placed in one g-roup and those for the nnhumidified m the other. On the graphs tlie data

for the humidified are represented by solid

bars and those for the unhumidified by shaded

bars. In cases where observations were made

in more than one room of the house at the same time, only one value was chosen, that in the living room or other room most nearly

equivalent to the living room in method of use. Considering only the humidified houses, the

observations of relative humidity were grouped

according to the outside dry-bulb temperature.

For example, there were 45 observations of

interior relative humidities that were made

when the outside dry-bulb temperature was

60° F or higher. These 45 observations were

used as the data for plotting the solid bars of

the top graph of figure 1. For the other

brackets of outside temperature a similar

procedure was followed. The resulting groups

are listed in table 2.

Table 2.

Observations of interior humidities of humidified houses at various ranges of outside temperature

Number of observations Outside dry-bulb temperature of interior relative humidity

F

60° or hiETher _ 45

50° to 59° 109

40° to 49° 258

30° to 39° 337

20° to 29° 128

19° or l&wer_ . .... . . . 21

Considering, for example, those observations

made when the outside temperature lay between

30° and 39° F, figure 1 and table 2, there was a

total of 337 observations of interior relative

humidity. These 337 observations were then

divided into subgroups according to the interior

relative humidity. The number in each subgroup was counted and percentages computed.

The results are given in table 3. The dark bars in the part of figure 1 captioned

"Outside temperature 30°-39° F"—represent

the data in the last column of table 3.

Figure 1.

Distribution of interior relative humidities grouped according to outside dry-bulb temperatures. The height of a bar represents the percentage of the total number of

I observations in that temperature group which pave the indicated rela-

! five humidity. The data for the hum.idified houses are represented by

' solid bars and those for unhumidified houses by shaded bars.

20

10

O

20

10

0

30

20

10

<>

uj 30 m

° 20

ui OinOiOOioO inoio Oioo

10

0

40

30

20

10

0

40

30

20

10

0

OUTSIDE TEMPERATURE

*^ 0VER60°F.

OUTSIDE TEMPERATURE

50°-59°F

OUTSIDE TEMPERATURE

40°-49°F

^ OUTSIDE TEMPERATURE ^ ^ 30°-39°F.

7^ _ OUTSIDE TEMPERATURE

20°-29°F.

OUTSIDE TEMPERATURE

BELOW 20°

F

(ji — — (Mcjtoro^^inin (£)u3r~

I '''Oio'-''''oiooin0ir)0ir)0

INDOOR RELATIVE HUMIDITY - PERCENT

[3]
Table 3.

Distribution of interior relative humidities in

the humidified houses when the outside dry-hulh temperature was 30° to 39° F

Interior relative humidity (in groups)

(percent)

Number of observations

for which

this relative humidity was found

Percentage of observations

for which

this relative humidity was found

10 to 14 210

49

735965

38

25

1122

0

1

Percent

0. 6

3. 0

14. 5

21. 6

17. 5

19. 3

11. 3

7. 4 3.3

0. 6

. 6

. 0

.3

16 to 19 on i-r\ 04 zU to z4_ _ . ___ . 25 to 29

30 to 34

35 to 39 40 to 44

45 to 49

50 to 54

55 to 59

60 to 64 65 to 69

70 to 74

Total , 337 100

Following a similar procedure, the graphs for the other outside temj^eratiire ranges and also for the Tnihumidified houses were constructed,

completing the set shown in figure 1. At outside temperatures above 60° F, the graph is irregular, particularly for the humidified houses.

At outside temperatures below 60° F, the

graphs of the interior relative humidities are of a more definite pattei'n and have fairly well

defined maxima. Upon comparison of the

graphs of figure 1, it will be noted that the

position of the maximum shifts to lower values

of relative humidity in going to graphs of lower outside temperatures.

The average relative humidities in the humitlified houses are plotted against the outdoor

dry-bulb temperature in curve 1 of figure 2, using the data shown in figure 1, and curve 2 of figure 2 gives the corresponding data for the unhumidified houses. It may be seen from

these curves that the average relative humidities

fall to rather low values for outside temperatures

below 20° F. Figure 3 shows the differences between the

average relative humidities observed in the

20 I

1 r

1 1

1 1 1 1

0

' ' ' ' ' ' ' ' 10 15 20 25 30 35 40 45 50

OUTSIDE TEMPERATURE DEGREES F. Figure 3.

Effective humidijication of humidified and

unhumidified. houses shown by the difference between the averages of the observed relative humidities and the relative humidity which would have resulted if outdoor air of 70-percent relative humidity had been heated to 70° F

without change in moisture content. Curve 1, in humidified houses; curve 2, in unhumidified houses. survey and the relative humidity of outdoor

air of 70-percent relative humidity after heating

to 70° F without gain or loss of moisture.

Curve 1 is for the humidified houses and curve

2 for the unhumidified houses. It may be seen

that at outdoor temperatures below 35° F the

relative humidity in unhumidified houses ranged

from 10- to 13-percent relative humidity above

that corresponding to no addition of moisture,

while in the houses classed as humidified the

corresponding figure was about 15-percent

relative humidity. In other words, the average

eft'ect of all sources of additional moisture in the unhumidified houses was to raise the relative

humidity some 10-percent relative humidity

[4]
C)CT)SrE?,r>a)iot--E?inO)rO

OOOOOOOOqOoOO — — — cMCJrOtoro^^^in

OUTSIDE TEMPERATURE

50°-59°E

OUTSIDE TEMPERATURE

40»-49"'F.

OUTSIDE TEMPERATURE

1771

OUTSIDE TEMPERATURE

BELOW 20°F.

O) 01 in 01 o c

o ^

fj, 01 O) 01

2: in 01 to

CM iM CM ro o o

01 01

r-- — o

01 O) 01 in o> m

CO (M to

CvJ (M fO ro ro INTERIOR THOUSANDTHS

VAPOR PRESSURE

OF AN INCH OF MERCURY

'JtOITj-OI^OI^Ol^Ol ^ 01 — _c^ojrOrOTj-^»n,n(i>

o in o

30

20

10

0

40

30

20

I 0

0

30

20

10

0

30

20

10

0

omoinOinOinO cJCOrOro^^LnintD

OUTSIDE TEMPERATURE I

MIII

OUTSIDE TEMPERATURE

40°- 49''R

OUTSIDE TEMPERATURE

30''-39°F ^

OUTSIDE TEMPERATURE

BELOW 20°

F

30

20

10

0

40

30

20

10

0

30

20

10

0

30

20

A 10

0

40

30

20

10

0

01

<j- in

01 "i- in U3 O in O lO O

<a- 1- lo lO 10 INTERIOR DEWPOINT DEGREES FAHRENHEIT

A B

Figure 4.

Distribution of (A) interior vapor pressures and (B) interior dew points grouped according to outside dry-bidb temperature. The height of a bar represents the percentage of the total number of observations in that temperature group " hic^ foj fjmre 4 (. 0^^^^^ indicated vapor pressure or, for figure 4 (B) the indicated dew point. The data for the humidified houses are represented bj solid bars and those for unhumidifled houses by shaded bars.
above what it would be in a house which was

heated but not occupied. In the houses classed

as humidified there was a corresponding increase

of 15-percent relative humidity. This is a comparatively small dift'erence between the two

classes of houses, which is probably acco inted

for by the fact that most of the houses classed

as humidified had no really effective means of adding moisture to the air. In any use that is made of these data it should be noted that the outside temperatures were taken for the most part during the warmer

hours of the day, between 9 a. m. and 5 p. m.,

0 10 20 30 40 50 60

OUTSIDE TEMPERATURE, DEGREES F Figure 5.

Percentage of observations for which the interior dew point in unhumidijied houses was higher than the outside dry-bulb temperature. and in particular that they are not the minimum for the day which is the temperature most

frecj[uently mentioned in other publications.

The winter of 1937-38, when the observations were made, was a comparatively mild one, which accounts in part for the comparatively

small number of observations of outdoor temperatures below 20° F.

V. DISTKIBUTION OF VAPOR

PRESSURES

Figure 4 (^4) gives the distribution of interior

vapor pressures in the two groups of houses

with reference to the outside dry-bulb temperature. The bar graphs were constructed in a manner similar to that used for figure 1. It is again apparent that the maximum points of each

graph go to lower vapor pressures in progressing to graphs for lower outside temperatures.

VI. DISTRIBUTION OF INTERIOR DEW

POINTS

Figure 4 (5) gives the distribution of interior

dew points. The data are divided into five groups according to the outside dry-bulb temperature. The method of obtaining these

gi'aphs was similar to that used for the relative

humidities shown in figure 1. Figure 5 gives,

for the unhumidificd houses, the percentage of cases for which the interior dew point was higher

than the outside temperature.

VII. EFFECT OF CONTINUED COLD

WEATHER OR LOW EXTERIOR

ABSOLUTE HUMIDITY

Observations taken after an extended period

of cold weather or weather of low exterior

absolute humidity show much lower interior

vapor pressures than those on days similar at the time of observation but preceded by warmer

weather. This points to a large contribution

by the house and furniture to the interior

humidity by the absorption and release of water

vapor. The data are too scattered to permit

any estimate of the lag introduced in this way.

VIII. CONCLUSIONS

L The relative humidity in occupied houses

decreases as the outside air temperature

decreases.

2. The average effect of all sources of additional moisture in unhumidified houses is to raise the relative humidity some 10-pei-cent

relative humidity above what it would be in a house which was heated, but not occupied.

3. In houses with some provision for humidification, on the average the humidity was some

5-percent relative humidity higher than for unhumidified houses.

4. Conditions in individual houses ma}'

depart widely from the average.

This survey was made possible by the cooperation of a large number of observers who

supplied the basic data. Some of the preparation of the manuscript for publication was

undertaken by E. F. Mueller and H. V.

Cottony.

Washington, May 17, 1940.

[6]
BUILDING MATERIALS AND STRUCTURES REPORTS

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BMSl Research on Building Materials and Structures for Use in Low-Cost Housing 10j5 BMS2 Methods of Determining the Structural Properties of Low-Cost House Constructions- 10^ BMS3 Suitability of Fiber Insulating Lath as a Plaster Base 10^ BMS4 Accelerated Aging of Fiber Building Boards 10^ BMS5 Structural Properties of Six Masonry Wall Constructions 15^ BMS6 Survey of Roofing Materials in the Southeastern States 15jS BMS7 Water Permeability of Masonry Walls lOji BMS8 Methods of Investigation of Surface Treatment for Corrosion Protection of Steel 10^ BMS9 Structural Properties of the Insulated Steel Construction Co.'s "Frameless-Steel"

Constructions for Walls, Partitions, Floors, and Roofs lOjS BMSlO Structural Properties of One of the "Keystone Beam Steel Floor" Constructions Sponsored by the H. H. Robertson Co 10j5 BMSll Structural Properties of the Curren Fabrihome Corporation's "Fabrihome" Constructions for Walls and Partitions 10^ BMS12 Structural Properties of "Steelox" Constructions for Walls, Partitions, Floors, and Roofs

Sponsored by Steel Buildings, Inc 150 BMS13 Properties of Some Fiber Building Boards of Current Manufacture 10^ BMS14 Indentation and Recovery of Low-Cost Floor Coverings 10^ BMS15 Structural Properties of "Wheeling Long-Span Steel Floor" Construction Sponsored by

the Wheeling Corrugating Co 100 BMS16 Structural Properties of a "Tilecrete" Floor Construction Sponsored by Tilecrete Floors, Inc 10(4 BMS17 Sound Insulation of Wall and Floor Constructions 100 BMS18 Structural Properties of "Pre-Fab" Constructions for Walls, Partitions, and Floors Sponsored by the Harnischfeger Corporation 100 BMS19 Preparation and Revision of Building Codes 150 BMS20 Structural Properties of "Twachtman" Constructions for Walls and Floors Sponsored by

Connecticut Pre-Cast Buildings Corporation 100 BMS21 Structural Properties of a Concrete-Block Cavity-Wall Construction Sponsored by the National Concrete Masonry Association 100 BMS22 Structural Properties of "Dun-Ti-Stone" Wall Construction Sponsored by the W. E. Dunn Manufacturing Co 100 BMS23 Structural Properties of a Brick Cavity- Wall Construction Sponsored by the Brick Manufacturers Association of New York, Inc 100 BMS24 Structural Properties of a Reinforced-Brick Wall Construction and a Brick-Tile CavityWall Construction Sponsored by the Structural Clay Products Institute 100 BMS25 Structural Properties of Conventional Wood-Frame Constructions for Walls, Partitions,

Floors, and Roofs 150 BMS26 Structural Properties of "Nelson Pre-Cast Concrete Foundation" Wall Construction

Sponsored by the Nelson Cement Stone Co., Inc 100

[List continued on cover page IV]
BUILDING MATERIALS AND STRUCTURES REPORTS

[Continued from cover page III]

BMS27 Structural Properties of "Bender Steel Home" Wall Construction Sponsored by The

Bender Body Co 10«5 BMS28 Backrlow Prevention in Over-Rim Water Supplies 10* BMS29 Survey of Roofing Materials in the Northeastern States 10j§ BMS30 Structural Properties of a Wood-Frame Wall Construction Sponsored by the Douglas

Fir Plywood Association lOjS BMS31 Structural Properties of "Insulite" Wall and "Insulite" Partition Constructions Sponsored by The Insulite Co 15^ BMS32 Structiu-al Properties of Two Brick-Concrete-Block Wall Constructions and a Concrete- Block Wall Construction Sponsored by the National Concrete Masonry Association. 10^ BMS33 Plastic Calking Materials 10^ BMS34 Performance Test of Floor Coverings for Low-Coet Housing: Part 1 10^ BMS35 Stability of Sheathing Papers as Determined by Accelerated Aging 100 BMS36 Structural Properties of Wood-Frame Wall, Partition, Floor, and Roof Constructions with

"Red Stripe" Lath Sponsored by The Weston Paper and Manufacturing Co lOji BMS37 Structural Properties of "Palisade Homes" Constructions for Walls, Partitions, and

Floors, Sponsored by Palisade Homes 100 BMS38 Structural Properties of Two "Dunstone" Wall Constructions Sponsored by the W. E. Dunn Manufacturing Co 100 BMS39 Structural Properties of a Wall Construction of "Pfeifler Units" Sponsored by;the Wisconsin Units Co 100 BMS40 Structural Properties of a Wall Construction of "Knap Concrete Wall Units" Sponsored

by Knap America, Inc 100 BMS41 Effect of Heating and Cooling on the Permeability of Masonry Walls 100 BMS42 Structural Properties of Wood-Frame Wall and Partition Constructions With "Celotex"

Insulating Boards Sponsored by the Celotex Corporation 100 BMS43 Performance Test of Floor Coverings for Use in Low-Cost Housing: Part 2 100 BMS44 Surface Treatment of Steel Prior to Painting 100 BMS45 Air Infiltration Through Windows 100 BMS46 Structural Properties of "Scot-Bilt" Prefabricated Sheet-Steel Constructions for Walls,

Floors, and Roofs Sponsored by the Globe-Wernicke Co 100 BMS47 Structural Properties of Prefabricated Wood-Frame Constructions for Walls, Partitions,

and Floors Sponsored by American Houses, Inc 100 BMS48 Structural Properties of "Precision-Built" Frame Wall and Partition Constructions

Sponsored by the Homasote Co 100 BMS49 Metallic Roofing for Low-Cost House Construction 100 BMS50 Stability of Fiber Building Boards as Determined by Accelerated Aging 100 BMS51 Structural Properties of "Tilecrete Type A" Floor Construction Sponsored by the TilecreteCo 100 BMS52 Effect of CeiUng Insulation Upon Summer Comfort 100 BMS53 Structural Properties of a Wall Construction of "Munlock Dry Wall Brick" Sponsored

by the Munlock Engineering Co 100 BMS54 Effect of Soot on the Rating of an Oil-Fired Heating Boiler 100 BMS55 Effects of Wetting and Drying on the Permeability of Masonry Walls 100 BMS56 A Survey of Humidities in Residences 100