SuitabilityandConstructionofSelfInsulationWallsint
Suitability and Construction of Self-Insulation Walls in the Hot Summer and Cold Winter Zone of Southern Shaanxi
LI Xueping
(School of Architectural and Civil Engineering, Xi’an University of Science and Technology, Xi’an, Shaanxi 710054, China)
Abstract In this paper, the suitability and construction technology of self-insulation walls were studied
under the specific climatic conditions and regional resources of Hanzhong and Ankang in the hot summer
and cold winter zone of Southern Shaanxi. Through the calculation of heat transfer coefficient and
thermal inertia index, combined with the specifications of the shale hollow brick and aerated concrete
block of Hanzhong and Ankang in southern Shaanxi, the thermal performance and suitable thickness
of the external wall using self-insulation materials that meet the Design Standard for Energy Efficiency
of Residential Buildings (DBJ61-65-2011) in Shaanxi Province were obtained. The results showed that
the self-insulation wall had technical suitability in the hot summer and cold winter zone. The research
results provide not only a theoretical basis for the external wall insulation design of urban residential
buildings in the hot summer and cold winter zone of southern Shaanxi, but also a reference for designers
to carry out energy-saving design of external walls of residential buildings in other similar climate zones.
Keywords Self-insulation wall, Southern Shaanxi, Hot summer and cold winter zone, Suitability,
Construction technology
DOI10.16785/j.issn 1943-989x.2019.1.004
1 Self-insulation status of ex-ternal walls of urban residential buildings in Hanzhong and Ankang According to the research, the self-insulation materials for the external wall used in Hanzhong City and Ankang City are sintered shale porous bricks, shale hollow bricks, and aerated concrete blocks, mainly shale porous bricks and shale hollow bricks. Southern Shaanxi is rich in shale resources. The shale bricks are ideal materials for replacing solid clay bricks. With numerous small holes, the shale porous bricks, whose specifications are 240 × 115 × 53 mm and 240 × 115 × 90 mm, are mainly used for load-bearing external walls of buildings of six stories and below six stories. The shale hollow bricks, which are formed by vacuum and high pressure extrusion molding, and are sintered at high temperature above 1,000 °C, have a small dry shrinkage rate, high porosity, and regular geometrical specifications, and are light-weight. With good physical properties and process performances, these bricks are principally used for infilled walls of high-rise residential frame structures, with the specifications of 240 × 115 × 170 mm, 240 × 115 × 240 mm, and 240 × 115 × 200 mm[1]. The aerated concrete blocks in Hanzhong and Ankang are mainly used for infilled walls with frames. The specifications are 600 × 100 × 200 mm, 600 × 150 × 200 mm, 600 × 180 × 200 mm, 600 × 200 × 200 mm, 600 × 240 × 200 mm, 600 × 250 × 200 mm, and 600 × 300 × 200 mm.
2 Thermal performance indexes of
self-insulation walls in Hanzhong
and Ankang
The structure level of the self-insulation
wall is from the outside to the inside: outer
plaster layer (20-mm-thick cement mortar),
self-insulation material layer, inner plaster layer
(20-mm-thick mixed mortar), and their thermal
performance indexes are as follows:
2.1 Thermal resistance (R0) of the self-
insulation wall
The thermal resistance of the wall is
represented by the symbol R0, whose unit is
(m2·K)/W, which is calculated as follows:
R0= R i + ∑ + R e
d
λ(1),
where R i is internal surface thermal resistance
[(m2·K)/W], generally taken 0.11; R e is the
external surface thermal resistance [(m2·K)/W],
generally taken 0.04; d is the thickness of the
self-insulation material layer (m); and λ is the
thermal conductivity of the self-insulation
material [W/(m·K)].
2.2 Heat transfer coefficient (K) of the
self-insulation wall
K= = 1
1
R0R
i
+ ∑ +R e
d
λ
(2).
2.3 Thermal inertia index (D)
D = R . S(3),
where R is the thermal resistance of the material
layer [(m2·K)/W]; and S is the heat storage
coefficient of the material [W/( m2·K)].
2.4 Required thickness of the wall
material layer
According to Formula 1 and Formula 2,
the thickness of cement mortar is 0.02 m, the
thermal conductivity is 0.93 W/(m·K); the
thickness of mixed mortar is 0.02 m, the thermal
conductivity is 0.87 W/(m·K). Numerical values
were substituted into the formulas, and the
thickness required for the self-insulation wall
material layer was obtained[2]:
d= λ ( - 0.915)
1
k
(4).
According to the limit of heat transfer
coefficient of external wall in the Design
Standard for Energy Efficiency of Residential
Buildings (DBJ61-65-2011), Formula 4 was used
to calculate the minimum thickness required
for the self-insulation walls to use sintered shale
perforated bricks, sintered shale hollow bricks,
and aerated concrete blocks, respectively, when
the heat transfer coefficient of the external wall
meets the limit[3].
The specification Sintered Porous Bricks
and Porous Blocks (GB13544-2011) stipulates
the elimination of circular hole-shaped bricks
and other hole-shaped brocks, and the use of
rectangular hole-shaped or rectangular strip
hole-shaped bricks. According to the research,
at present, the sintered shale porous bricks in
Received: October 29, 2018 Accepted: January 20, 2019
Journal of Landscape Research 2019, 11(1): 15–19
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