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Technical Notes on Brick Construction INTRODUCTION
Brick masonry can be used most advantageously as
the thermal storage media in direct gain systems, thermal
storage wall systems and attached sunspaces. The gen-
eral concepts, empirical procedures for sizing systems
and performance calculations are discussed in Parts I
through III of this
Technical Notes Series. This Technical
Notes provides information and references regarding the
material properties of the basic components of passive
solar energy systems. This information includes the prop-
erties of brick masonry when used for thermal storage,
with major emphasis on the effective thermal storage of
brick masonry and a general discussion of the properties
of glazing materials when used as collectors.
BRICK MASONRY
General
Most of the design requirements and performance of
brick masonry as a general building material are discussed
in other
Technical Notes. The inherent properties of brick
masonry offer many design advantages in addition to those
required for use as a thermal storage material.
Structural
Brick masonry has many applications as a structural
element in buildings. Brick masonry is commonly used as
loadbearing elements in commercial and residential struc-
tures. Brick masonry when considered as a thermal stor-
age media for passive solar energy systems may also be
considered as a structural element. Information on load-
bearing brick masonry is provided in
Technical Notes 24
Series.
One of the reasons brick masonry is less frequently
considered as a structural element in one and two-family
construction is because of the difficulties in insulating solid
masonry walls to meet prescriptive energy code require-
ments for the reduction of heat loss. This can be over-
come by using loadbearing insulated cavity walls which
provide a durable facade, sufficient space for insulation
and interior brick masonry which may be used as thermal
storage in direct gain systems. Cavity wall construction is
addressed in
Technical Notes 21 Series.
The structural design may require reinforced brick
masonry. Reinforcement in brick masonry usually has lit-
tle if any effect on the thermal performance of the wall.
This is because the reinforcement is usually horizontal
and/or vertical in the plane of the wall, and occurs at or
near the center of the wall section resulting in very little
increase of thermal transmission through the wall.
Information regarding reinforced brick masonry is provid-
ed in
Technical Notes 17 Series.
Durability
Brick masonry is an extremely durable building mater-
ial requiring little or no maintenance. It does not require
coatings or coverings which could reduce its thermal per-
formance as a storage media. Coatings and coverings
may decrease the emissivity and thermal conductivity of
the brick masonry. This is not desired when trying to opti-
mize on the available thermal storage and thermal energy
retrieval. Since coatings and coverings are not required,
brick masonry may be exposed to enhance the aesthetics
of the building. The use of coating applied to exterior
brick masonry is discussed in
Technical Notes 6A.
Aesthetics
Brick masonry is normally used as an exterior facade,
not only because of its durability but also because it pro-
vides architectural freedom. Brick masonry offers many
bond patterns, colors and textures. As elements of the
building, brick masonry provides options for architectural
freedom that no other building material can offer. For
instance, not only the texture of the brick itself is available
in many varieties, but brick allows variation in wall texture,
Reissued*
September
1988
43D
Technical Notes
on Brick Construction
Brick Industry Association 11490 Commerce Park Drive, Reston, Virginia 20191
BRICK PASSIVE SOLAR HEATING SYSTEMS
MATERIAL PROPERTIES--PART IV
Abstract
:
The inherent properties of brick masonry make it one of the most advantageous storage media mate-
rials for passive solar energy systems. Brick masonry may be used to provide an aesthetic effect, structural
capacity and other design considerations in addition to thermal storage. Most of these inherent properties of
brick masonry are already well understood for conventional applications. However, in order to properly use brick
masonry as a thermal storage media for passive solar energy systems additional information may be needed by
the designer. This additional information has to do with the effective thermal storage of brick masonry.
Key Words:
absorptivity, brick, density, emissivity, energy heat transfer, masonry, material properties, pas-
sive solar energy systems, reflectance, solar radiation, specific heat, temperature, effective thermal storage,
thermal conductivity, thermal diffusivity.
*Originally published in Sept/Oct 1980, this
Technical Notes has been reviewed and reissued. also. The texture of the wall may be varied by using project-
ed or recessed brick or even sculptured brickwork. The typi-
cal modular sizes of brick masonry are given in
Te c h n i c a l
Notes 10B and common bond patterns are given in
Technical Notes 30. Brick masonry used as paving is dis-
cussed in Technical Notes 14 Series. Information on the
use of brick masonry sills and soffits is provided in
Te c h n i c a l
Notes 36 Series. The use of brick masonry arches and rein-
forced brick masonry lintels are discussed in
Te c h n i c a l
Notes 31 Series and 17H, respectively.
Fire Resistance
Depending upon the specific application of brick
masonry in passive solar energy systems, brick masonry
may be designed and placed to offer fire protection. The
fire resistance of brick masonry is discussed in
Technical
Notes 16 Series.
Sound Transmission Resistance
Brick masonry, because of its inherent properties
offers considerable reduction in sound transmission.
Thus, depending on specific design applications, strategi-
cally placed thermal storage elements may be used to
reduce sound transmission from one area of the building
to another or from the exterior to the interior of the build-
ing. Information on the sound transmission classification
of brick masonry is provided in
Technical Notes 5A.
Effective Thermal Storage
The overall performance of the brick masonry as a
passive solar energy system thermal storage component
is dependent on its absorptivity, emissivity, and ability to
store heat. The ability of a material to store heat is usual-
ly referred to as heat capacity which is a function of the
specific heat and density of a material. In addition to the
heat capacity, the way the wave of thermal energy pene-
trates the material being used to store heat should also
be considered. The performance as a thermal storage
media may be estimated using the value of the thermal
diffusivity of the material. Thermal diffusivity is not only a
good value for assisting in the selection of materials but is
also useful in simplified heat flow calculations to deter-
mine the amount of heat penetrating a material and the
number of hours it takes for the heat transmission to
occur. This information is useful for selecting the thick-
ness of thermal storage. The thermal diffusivity is a func-
tion of the specific heat, density and thermal conductance
of a material.
Specific Heat. The specific heat, c, of material is the
amount of heat required to increase the temperature of a
unit weight of material one degree. The specific heat, c,
in Btu per pound per degree Fahrenheit, for brick may
vary from 0.20 to 0.26. Typically this variation is due to
the impurities in the clay used to manufacture the brick.
The greater the percentage of metallic oxides in the clay,
usually the greater the specific heat. Building brick which
usually have a low percentage of metallic oxides by
weight have low specific heats usually between 0.20 to
0.22 Btu/lb/F, whereas face brick which contain larger
amounts of metallic oxides, typically up to 35%, have spe-
cific heats ranging between 0.22 to 0.26 Btu/lb/F. A value
of specific heat of face brick which may be used when the
actual specific heat is not known is 0.24 Btu/lb/F.
For building brick or brick containing a low percentage
of metallic oxides, a value of 0.22 Btu/lb/F may be used.
Generally red, brown and blue brick contain high amounts
of metallic compounds.
The value of the specific heat for brick may be
assumed for brick masonry. The specific heat of grouted
hollow brick may be approximated by determining the per-
cent of the brick masonry which is to be grouted, and
averaging the specific heat, accordingly. This may be
done by adding the product of the specific heat of face
brick times the fraction of the brick which is solid, at least
0.60, and the specific heat of grout times the fraction of
the brick which is cored, less than or equal to 0.40. For
grouted hollow walls, the specific heat for the masonry
wall may be modified for the grout by using Equation 1:
c
w
= [(t
b1
X c
b1
) + (t
b2
X c
b2
) +
(t
g
X c
g
)] / (t
b1
+ t
b2
+ t
g
)
(1)
where:
c
w
= Average specific heat of a grouted brick