Housing in Southern Africa October-November 2016

In total, two rounds of inspections were carried out on unoccupied IBT show houses at Eric Molobi Housing Innovation Hub before the tool was piloted on a list of IBT houses in provinces in which beneficiaries lived.

Scoring differed from the literature in that the extent and intensity were five-point scales with one being criti- cal and five or six minor. The impor- tance of the elements (component type) was weighted in terms of the defects that can directly harm the function of the building component. Once all the elements were evalu- ated the scores were carried over to be weighted again in terms of the key components that are a high risk to the NHBRC mandate, which focuses on the structural strength and stability. The overall score was indicated as a percentage and categorised in grades of A, B and C. A good score would preferably be accepted as an A Grade. The theoretical expectationwould be that IBT homes with certification should be able to attain these scores. Those scores that were on the borderline were given an additional opportunity to qualify by adding percentages of between 1% and 5% to the total end score. This resorted to 1% extra for a house 0-5 years old; 2%extra for house 6-10 years old; 3% extra for a house 11-15 years old and 5% extra for a house 16-20 years old. The decision to add a score related to age depended on the superstruc- ture’s wall element score. If the wall element score was 75% or more the system would qualify for an addi- tional percentage to possibly get a qualifying score. The older the system was, of which the superstructure was still functioning well, the higher the additional score. The tool was piloted through preliminary inspections and its uni- form application. The purpose of the testing of the tool was to determine the outcome of the scores inspected by five inspectors in terms of the de- gree of convergence of the scores to preferably bewithin at least 10 points and whether the tool reflected the Grades Percentages A B C ≥81% 61% - 80% ≤ 60% Table 1 – Performance grades

severity of the defect in terms of health, safety and the environment. The tool was calibrated for the first two rounds by means of changing the weighting of the components. In this context the structural safety was weighted higher than the other components. The tool however, did not exclude the minimum energy efficiency requirements, which was included in terms of checking the roof insulation, and whether there were air leaks around openings. In total, two rounds of inspections were carried out on unoccupied IBT show houses at Eric Molobi Hous- ing Innovation Hub before the tool was piloted on a list of IBT houses in provinces inwhichbeneficiaries lived. These houses were taken from a list of IBT system owners interested in getting on the database. From the information received 12 houses were inspected for the piloting stage in four provinces. Discussion The description of the dataset for the pilot study suggests that there are questions as to the true central tendency. Further investigation is required by extending the study to draw inferences froma larger sample size that is a better representation to make generalisations. Not only should the sample size be increased, but IBT homes should be monitored at a relevant frequency to compare the results of the same homes that can establish possible degradation over time. Future investigations could also provide more insight as to whether the IBT database is really necessary and could shed light on the compo- nents of a home that will requiremore scrutiny during general inspections of IBT systems. The full results will be made available on the NHBRC web- site when the regulatory body imple- ments its dynamic IBT Database. Extracts from ‘Assessing the condition of ‘as built’ innova- tive building technology homes against theorectical expectations’ by Jeff Mahachi and Dominique Geszler, NHBRC. ■

11