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Clay brick proves best for low cost housing
The Minister of Human Settlements clearly defined that housing must function to restore dignity among the communities occupying low cost houses. WSP Green by Design has extensively researched how the different materials in this segment stacked up.
Various lightweight building systems are being recommended to government as a panacea to the limitations of through-the-wall concrete block construction. Many claim lower environmental impacts.
"WSP's brief was to evaluate which building methodology provided a 'best fit' for South African low cost housing in terms of initial cost, lifecycle cost, lifecycle energy cost and upliftment in disadvantaged communities." reports Clay Brick Associaiton Chairman Dirk Meyer.
The WSP research validates clay face brick walling as a 'best fit both economically and environmentally appropriate for sustainable low cost housing in South Africa'.
The study based on a 40 sq. m. house used computational modelling and simulation. Comparing through the wall concrete block which is typically used in low cost house construction, clay brick in two leaf and cavity wall formats and the light steel frame building (LSFB) insulated walling, the latter walling building system being chosen for its potential representative of other systems/technologies that use insulated lightweight panel type external walling.
Since completing the study, SASFA has confirmed to WSP that the specification information as provided by its industry members and used in the study was not necessarily 100% SANS 517:2009 compliant. WSP is re-running their LSFB calculations using assumptions based on SANS 517:2009 compliance but does not anticipate a material change to the results of their study.
The study found in each of the six climate zones. the clay brick masonry house required the lowest heating energy per annum in comparison to both concrete block walled and LSFB insulated lightweight walled houses. In each of the six climatic zones the tile clay brick masonry house was found to experience less time that occupants might experience significant thermal discomfort compared to both concrete block and the LSFB insulated lightweight walled alternatives.
Notwithstanding the higher capital cost of clay brick walling versus concrete block walling, the lifecycle costs and lifecycle embodied energy are considerably less for clay brick homes compared to both concrete block and the LSFB lightweight walled alternatives.
Conventional clay brick walling with a face brick external skin has a 15,8% lower first built cost than the LSFB insulated lightweight walled alternative and afforded both a lower lifecycle cost and lifecycle embodied energy cost. Clay brick construction, unlike LSFB, has a well established record in South Africa of maximising the long term value of properties. 'A real brick' house is also the benchmark in South Africa to which persons living in poor communities most aspire.
When it came to the bigger picture for South Africa, the research high-lighted the importance of considering lifecycle impacts when making walling material choices in this segment.
Should the targeted 500 000 homes be constructed every year over 10 years in the Johannesburg region [Climate Zone 1]. assuming no inflation, it could cost South Africa anything from about R9,6 billion more to build these homes using clay brick (two leaf) compared to concrete block. If LSFB construction is used this figure would increase to approximately R46,4 billion more to build.
These costs are based on a house with an insulated ceiling. Over 10 years, however, the additional winter peak power requirement that would augment the South African national grid by these 500 000 homes being constructed each yea r in concrete block rather than two leaf clay brick could cost the country anything from R45 billion in increased power plant capacity, This R45 billion might be considered negligible against the capital cost of R9.6 billion.