Technical Note #29 UP Thermal performance comparison of walling materials
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.
The results can be summarised as follows:
Best (lowest) Energy Use
- Residential Buildings (all climate zones):thermally insulated 280 mm clay brick cavity walling
- Non-residential building (climate zone 1): 140 mm hollow concrete block walling
- Non-residential building (climate zones 2-6):220 mm solid clay brick walling
Worst (highest) Energy Use
- Residential Buildings (all climate zones): 140mm hollow concrete block walling
- Non-residential building (climate zone 1): timber frame walling
- Non-residential building (climate zones 2-6):light steel frame walling
“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
- Double (internal and external) clay brick solid wall (nominally 220 mm thick, plastered)
- Double clay brick cavity wall with air cavity (nominally 270 mm thick with an uninsulated 50 mm air cavity)
- Insulated double clay brick wall (nominally 280 mm thick, with 30 mm extruded polystyrene insulation in the 50 mm cavity)
- 140 mm hollow core concrete block (150 mm thick with a single external layer of plaster, and bagged internally)
- Light steel frame, externally clad with 9 mm fibre cement board to SANS 517 (nominally 145 mm thick with 0.2 mm polymer vapour membrane, 20mm orientated strand board and 0.8 mm steel studs. Internal wall of 15 mm gypsum board with 75/100 mm fibre sound insulation.)
- Timber frame to SANS 10 082 clad with external ship-lapped tiles or weatherboard (nominally 145 mm thick with 20 mm orientated strand board and internal cladding of 15 mm gypsum plasterboard.)
This study forms part of the Life Cycle Assessment of Clay Brick.