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sustainable construction world
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Brick buildings
Addressing all the basics for affordable quality
living, with safety and security a given, clay brick
in construction has demonstrated the flexibility to
work well with all design styles to bring authenticity
and appealing human scale to buildings. But it goes
much further than that to afford opportunity for
lowest heating and cooling energy requirements that
translate into low total (embodied + HVAC energy)
Greenhouse Gas emissions over a 50 year lifecycle.
To this end, the world’s consuming focus on energy
efficiency has led the clay brick industry to research
how designers may simply and cost effectively
better work with nature to take the wonderful
thermal properties of clay brick in construction to
new levels of thermal comfort and lower heating and
cooling energy usage in all six major climatic zones
of South Africa.
The net conclusion from all the research is that
clay brick walling can be specified to deal with the
peculiarities of the different climatic zones in ways
that insulated lightweight walling cannot. This
provides brick walling options that will outperform
insulated lightweight walled buildings specified
in compliance with SANS 204 Energy Efficiency
Standards and SANS 517 required for Light Steel
Frame building.
In that process and following deemed to satisfy
requirements, clay brick walling can be specified
to offer the highest levels of thermal performance
this facilitating lowest lifecycle energy costs and
low total lifecycle carbon footprints. This can be
provided using insulation with a lower R-value than
for a better world
BRICK BUILDINGS
Simple clay brick construction,
the long-time benchmark for all
that is good about housing and
social infrastructure buildings in
South Africa, goes beyond the
important fundamentals of durable,
low maintenance structures with
enduring aesthetic integrity to afford
comfortable thermally efficient
accommodation in which South
Africans live, work and play.
required for lightweight to ensure best returns for the
cost of any insulation applied.
The thermal mass inherent in clay bricks is
what brings the ‘X’ factor to the thermal efficiency
equation as shown in Figure 1.
The net benefit of the slow transfer of heat (6
to 8 hours) to the inside is that the hottest part of
the day will have passed before the heat impacts on
the inside. This facilitates superior day-time thermal
comfort conditions and lowest cooling energy usage
compared to insulated lightweight walls that have no
propensity to self-regulate. In the case of insulated
lightweight the outside heat impacts on the inside in
approximately one hour, the heat flux on the inside
coinciding with the hottest part of the day outside
leading to comparative discomfort and greater need
for cooling energy.
Clay bricks on the inside add further function
to slowly absorbing and storing heat from the
internal air as day time temperatures rise this further
moderating internal temperatures, helping keeping
the house comfortable for longer, requiring less
cooling energy.
In winter the energy from lower angled sun
radiates in through the windows, the internal thermal
mass then functions to slowly absorb and store
radiant heat during the day that is then released in
the evening as the cold night air impacts on internal
conditions, helping keep the house warmer for
Figure 1 represents the heat flux through a double skin cavity
brick windowless wall in summer. Of the 700 to
900 W/m² that impacts on the outer surface just 5 to 6 W/m²
finally passes through the wall to the inside. The thermal lag
played a key role in limiting the magnitude of the maximum
and minimum internal temperatures. The study showed
that cavity brick reduces the heat transfer by absorbing and
storing the heat in the external brick leaf, then radiating it
back to the outside environment, thereby reducing the net
heat flux across the wall.