Construction World October 2015

Thermal modelling of verdant and sirocco house plans:

-e) emissions over 50 years,

average HVAC green house gas (kg co 2

extracted from Energetics Full Life Cycle Assessment Uninsulated Insulated double Insulated

Insulated timber Insulated timber

Location Orientations double brick brick (R1.3)

timber frame more/(less) GHG more/(less) GHG than double brick than double brick insulated R1.3

Newcastle Climatic Zone Melbourne Climatic Zone Brisbane Climatic

N,S,E & W 54 137

51 236

60 457

11,67%

18,00%

N,S,E & W 73 050

63 641

72 570

-0,66%

14,03%

N,S,E & W 64 924

65 010

72 554

11,75%

11,60%

Zone Average GHG N,S,E & W 64 037

59 962

68 527

7,01%

14,28%

Summary of operational energy greenhouse gas emissions over 50 years.

longer. Should heaters be required the clay bricks continue to function, absorbing and storing this heat that is then released to counter the inroads of the cold, extending the thermal comfort conditions for longer. Research further shows that clay brick partition walls, used in lieu of lightweight, further enhances a buildings thermal performance no matter the external wall construction type. It was a conclusion of the University of Pretoria study that “there is a significant cost premium associated with the use of lightweight partitioning systems in all three building typologies modelled”. The University of Newcastle, Australia, empirical study found that clay brick internal partition walls improved the energy efficiency of the insulated lightweight external walled building by 20%. With regard to facilitating a low lifecycle carbon footprint the substantive thermal modelling done as part of a Full Life Cycle Assessment (LCA) by Energetics in Australia highlighted the contribution of thermal mass to greater thermal efficiency, lowest operational energy usage that in turn translated into low to lowest total (embodied energy and operational energy) Greenhouse Gas emissions over a 50 year cycle. Cavity brick walls (R0.65) provided lowest total GHG emissions in most situations modelled while insulated cavity brick walls (R1.30) provided lowest total emissions in all situations. As shown in the table above, the energy savings provided by double skin cavity walled house translated into 7% less GHG (kg CO 2 -e) emissions and the cavity brick with insulation into 14% less GHG emissions In South Africa, the University of Pretoria study modelling of a 130 m² house produced similar findings. Notably, cavity brick walls outperformed SANS 517 compliant lightweight in most situations while cavity brick with insulation R1 applied in the cavity, to give a wall R-value of 1.3, well outperformed insulated lightweight R1.9 and R2.2. The University of Pretoria study reported the following key findings:

• The most efficient South African walling system for residential buildings is a 280 mm insulated cavity brick masonry wall. • The most efficient South African walling system for a commercial or institutional building is a 220 mm solid clay brick masonry wall (or for Climate Zone 4: a 270 mm clay brick cavity wall, as is the norm for the Southern Cape condensation problem areas) • Light steel frame wall construction specified SANS 517 is not as thermally efficient and use more heating and cooling energy compared to clay brick masonry cavity walls in all climate regions. • That there is a significant energy cost premium associated with the use of lightweight partitioning systems in all three building typologies modelled. When all is said and done, clay brick in construction has so much more to offer than lightweight IBTs for achieving sustainable, energy efficient buildings. This sustainability extends to clay bricks having mineral properties that meet all necessary requirements for healthy living and to clay brick being one of a few building material that is both reusable and recyclable. On top of that of course, are the enduring maintenance free attributes as a face brick that help mitigate future carbon debt associated with replacement, refurbishment and painting associated with less durable lightweight walling materials. As was highlighted in Energetics full Life Cycle Assessment, today’s environmental paradigm requires we build buildings able to endure with little maintenance, and definitely no materials’ replacement, way beyond the 50 year life cycle. Clay brick buildings in all their forms have proven themselves over the centuries to be more than up to this task. In retrospect, it may be considered most fortunate that South African building has been founded on a masonry tradition that endures to this day; a simple building methodology that science now proves so relevant for achieving a more sustainable future and keeping our world a better place. ∞

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