TN#29 UP Thermal performance comparison of walling materials

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This Management Summary and consolidation report of the LCA study by the University of Pretoria compares the electricity use of 6 different types of walling common in South Africa. The measurements were based on the electricity used in heating and cooling a home or office in order to maintain  reasonable “thermal comfort” which is between 19 and 25˚C.

The low density walling systems (timber and steel frame) show a trend towards higher annual energy use, while the three high density walling systems (clay brick) consistently result in lower annual energy use.

There is a 30% to 70% energy saving if clay brick is used, relative to other typical building materials. In terms of climate change impact, this is equivalent to taking between 3 and 7 passenger cars off the road for a month for every year the building is in use. Even higher savings are evident in the hotter regions of South Africa and in non-residential buildings, where electricity use for air conditioning is much higher.

Methodology

The results can be summarised as follows:

Best (lowest) Energy Use

  1. Residential Buildings (all climate zones):thermally insulated 280mm clay brick cavity walling
  2. Non-residential building (climate zone 1): 140mm hollow concrete block walling
  3. Non-residential building (climate zones 2-6):220mm solid clay brick walling

Worst (highest) Energy Use

  1. Residential Buildings (all climate zones): 140mm hollow concrete block walling
  2. Non-residential building (climate zone 1): timber frame walling
  3. Non-residential building (climate zones 2-6):light steel frame walling

Methodology

“A thermal performance comparison between six walling construction materials frequently used in South Africa”

University of Pretoria
Published: November 2016

Six wall types were analysed

  1. Double (internal and external) clay brick solid wall (nominally 220 thick, plastered)
  2. Double clay brick cavity wall with air cavity (nominally 270 mm thick with an uninsulated 50mm air cavity)
  3. Insulated double clay brick wall (nominally 280mm thick, with 30mm extruded polystyrene insulation in the 50mm cavity)
  4. 140mm hollow core concrete block (150mm thick with a single external layer of plaster, and bagged internally)
  5. Light steel frame, externally clad with 9mm fibre cement board to SANS 517 (nominally 145 mm thick with 0.2mm polymer vapour membrane, 20mm orientated strand board and 0.8mm steel studs. Internal wall of 15mm gypsum board with 75/100mm fibre sound insulation.)
  6. Timber frame to SANS 10 082 clad with external ship-lapped tiles or weatherboard (nominally 145mm thick with 20mm orientated strand board and internal cladding of 15mm gypsum plasterboard.)

Click here to download the full University of Pretoria study

This study forms part of the Life Cycle Assessment of Clay Brick.

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