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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
≥81%
B
61% - 80%
C
≤ 60%
Table 1 – Performance grades
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.
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.
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