SUSTAINABLE AND AFFORDABLE RAMMED EARTH HOUSES IN KALGOORLIE, WESTERN AUSTRALIA: DEVELOPMENT OF THERMAL MONITORING TECHNIQUES
C BECKETT, D CIANCIO, C HUEBNER & R CARDELL-OLIVER
FACULTY OF ENGINEERING, COMPUTING AND MATHEMATICS
The University of Western Australia
Remote housing in WA – Current practice
• In 2008, the Australian Government dedicated $5.5bn over 10 years to the NPARIH project.
• Current “transportable” building solutions:
• Advantages: • Reduced road traffic • Short construction time
• Disadvantages: • High cost: average $450,000 • High running costs
– Difficult/expensive to maintain – Thermally unsuitable (without
HVAC)
The University of Western Australia
Remote housing in WA – Rammed earth
• Rammed earth (RE) construction is the compaction of moist soil into formwork – “soil fill in the form of a building”.
• Technique traditionally used in arid to semi-arid regions worldwide.
• Load-bearing walls typically 300mm thick, granting high thermal mass.
• Presence of clay enables moisture exchange with atmosphere.
• Common practice in Australia to add cement to the raw soil (5-15%) to improve material strength and durability.
• Potential for RE construction to excel in remote areas is self evident.
The University of Western Australia
Remote housing in WA – Benefits of rammed earth
• Advantages • Majority of material available
on site • Does not require skilled
labour • Lower construction costs • Highly robust product • Significantly reduced
embodied energy • Disadvantages
• Poorly-understood thermal performance
• Lack of familiarity/confidence
The University of Western Australia
Thermal resistance vs thermal mass
• Building Code of Australia requires houses to achieve a minimum energy efficiency.
• Construction using highly insulating materials is therefore encouraged to reduce energy loss to the environment.
• RE has low thermal resistance. However, thick walls grant RE a high thermal mass: the ability of a body to absorb, store and release heat:
𝜕𝜕𝑇𝑇𝜕𝜕𝑡𝑡
=𝑘𝑘𝜌𝜌𝐶𝐶𝑝𝑝
𝜕𝜕2𝑇𝑇𝜕𝜕𝑥𝑥2
• Dynamic process – accommodates, rather than resists, thermal fluctuations.
The University of Western Australia
Kalgoorlie RE project
[Bwh]
The University of Western Australia
Thermal monitoring
The University of Western Australia
Laboratory programme
• Testing: • survivability of embedded
sensors; • rapid exposure to simulate high
diurnal load; • long-term guarded exposure to
simulate internal conditions.
The University of Western Australia
Laboratory programme – rapid exposure
The University of Western Australia
Laboratory programme – long-term exposure
The University of Western Australia
Current status – June/July 2014
The University of Western Australia
Conclusions
• RE potentially viable as remote construction solution • Performance likely to be underestimated by current regulations – thermal
monitoring warranted • Sensor design and installation successful, providing a versatile technique
that can easily be applied to other sites. • Results gathered so far indicate good ability for RE materials to buffer
thermal fluctuations • Monitoring programme to begin in August/September 2014.
The University of Western Australia
Acknowledgements
LINKAGE PROJECT LP110100251
www.ecm.edu.au/research/icrec2015
