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MATERIAL HYSTERESIS
Comparative Thermal Analysis of Sahelian Masonry
Comparative Thermal Analysis of Sahelian Masonry
STATUS
Baseline Analysis / Model Development
STATUS
Baseline Analysis / Model Development
REGION
Northern Nigeria / Sahelian climatic conditions
REGION
Northern Nigeria / Sahelian climatic conditions
SUBJECT
Earthen masonry, thermal mass, and comparative wall performance
SUBJECT
Earthen masonry, thermal mass, and comparative wall performance
THE QUESTION
THE QUESTION
How does a documented high-mass earthen wall system behave under the strong day–night temperature cycle of the Sahel, and how does that behavior compare with selected contemporary masonry assemblies?
How does a documented high-mass earthen wall system behave under the strong day–night temperature cycle of the Sahel, and how does that behavior compare with selected contemporary masonry assemblies?
A|WA approaches this as a comparative building-physics question rather than an assumption that one material is inherently superior.
A|WA approaches this as a comparative building-physics question rather than an assumption that one material is inherently superior.
THE ARCHITECTURAL SYSTEM
THE ARCHITECTURAL SYSTEM
The investigation focuses on Tubali masonry and related earthen construction systems documented in northern Nigeria.
The investigation focuses on Tubali masonry and related earthen construction systems documented in northern Nigeria.
The study considers:
The study considers:
Wall thickness
Material composition
Unit geometry
Mortar and joint configuration
Surface conditions
Openings
Orientation
Solar exposure
Interior and exterior environmental conditions
Wall thickness
Material composition
Unit geometry
Mortar and joint configuration
Surface conditions
Openings
Orientation
Solar exposure
Interior and exterior environmental conditions
The architectural reconstruction is based on the available evidence and records uncertainty where evidence is incomplete.
The architectural reconstruction is based on the available evidence and records uncertainty where evidence is incomplete.
THE HYPOTHESIS
THE HYPOTHESIS
High-mass earthen construction may delay and moderate heat transfer through its combination of material properties, wall thickness, geometry, and thermal storage capacity.
High-mass earthen construction may delay and moderate heat transfer through its combination of material properties, wall thickness, geometry, and thermal storage capacity.
The magnitude of that effect must be demonstrated through documented modeling or measurement.
The magnitude of that effect must be demonstrated through documented modeling or measurement.
THE METHOD
THE METHOD
A|WA develops a comparative model of the selected earthen assembly and one or more contemporary reference assemblies.
A|WA develops a comparative model of the selected earthen assembly and one or more contemporary reference assemblies.
The model should document:
The model should document:
Geometry
Wall thickness
Material density
Thermal conductivity
Specific heat
Surface properties
Solar exposure
Climate data
Boundary conditions
Simulation period
Software / analytical method
Geometry
Wall thickness
Material density
Thermal conductivity
Specific heat
Surface properties
Solar exposure
Climate data
Boundary conditions
Simulation period
Software / analytical method
Where field measurements become available, modeled behavior can be compared against observed conditions.
Where field measurements become available, modeled behavior can be compared against observed conditions.
CURRENT FINDINGS
CURRENT FINDINGS
The current investigation is being developed as a baseline environmental analysis.
The current investigation is being developed as a baseline environmental analysis.
Previously proposed values for thermal lag and temperature differential are retained as model outputs requiring documented assumptions and verification, rather than presented here as universal properties of Tubali construction.
Previously proposed values for thermal lag and temperature differential are retained as model outputs requiring documented assumptions and verification, rather than presented here as universal properties of Tubali construction.
Future publication of numerical findings will include the model inputs, source data, comparison assembly, and validation procedure required to interpret those values.
Future publication of numerical findings will include the model inputs, source data, comparison assembly, and validation procedure required to interpret those values.
FIGURE 01: DIURNAL THERMAL RESPONSE
FIGURE 01: DIURNAL THERMAL RESPONSE
FIGURE 01
DIURNAL THERMAL RESPONSE
Comparative representation of temperature and heat-transfer behavior over a 24-hour cycle.
Documentation to accompany figure:
Climate file / simulation conditions / material properties / wall dimensions / model source
FIGURE 03: CROSS-SECTIONAL THERMAL RESPONSE
FIGURE 03: CROSS-SECTIONAL THERMAL RESPONSE
Comparative section showing modeled thermal conditions during peak solar loading.
Comparative section showing modeled thermal conditions during peak solar loading.
Documentation to accompany figure:
Time stamp / exterior conditions / interior conditions / material properties / boundary conditions
Documentation to accompany figure:
Time stamp / exterior conditions / interior conditions / material properties / boundary conditions
FIGURE 02: MODULAR MASONRY ASSEMBLY
FIGURE 02: MODULAR MASONRY ASSEMBLY
Exploded reconstruction of the selected earthen masonry system.
Documentation to accompany figure:
Source drawing / historical reference / reconstruction status / inferred elements
WHAT WE KNOW
WHAT WE KNOW
The study can document the architectural characteristics of the selected wall system.
The study can document the architectural characteristics of the selected wall system.
WHAT WE ARE TESTING
WHAT WE ARE TESTING
How those characteristics influence thermal response.
How those characteristics influence thermal response.
WHAT WE DO NOT YET CLAIM
WHAT WE DO NOT YET CLAIM
That the historical system universally outperforms contemporary construction, or that a single simulation represents all buildings constructed in the tradition.
That the historical system universally outperforms contemporary construction, or that a single simulation represents all buildings constructed in the tradition.
Fig 01. Thermal simulation data over a 24-hour cycle in Kano, Nigeria. The high thermal mass of the Tubali wall creates a 6-hour hysteresis, delaying heat transfer until evening when ambient temperatures drop.
Fig 02. Structural analysis of the Tubali unit. Unlike standard brick, the pear-shaped geometry creates a non-linear mortar interface, increasing shear resistance. The high-density laterite core functions as a thermal battery, regulating interior temperature fluctuations through material mass rather than insulation.
Fig 03. Cross-sectional thermal mapping at peak solar intensity (2:00 PM). The standard hollow concrete block (left) offers negligible thermal resistance, allowing interior temperatures to reach 38°C. The Tubali assembly (right) dissipates heat through its solid laterite core, maintaining a 10°C differential (ΔT) and stabilizing the interior environment.
NEXT STEP
NEXT STEP
NEXT STEP
NEXT STEP
Complete the comparative model, document the assumptions, test sensitivity to key variables, and compare modeled behavior with field measurements where available.
Complete the comparative model, document the assumptions, test sensitivity to key variables, and compare modeled behavior with field measurements where available.
CASE FILE STATUS: IN DEVELOPMENT
CASE FILE STATUS: IN DEVELOPMENT
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