Environmental Implications
Hebel Supercrete is increasingly recognized as one of the most environmentally sustainable building materials available today. It combines lower materials and energy usage in manufacture with a range of environmental benefits in use. With Hebel Supercrete Autoclaved Aerated Concrete, the low energy consumption which starts with production continues throughout its life as a construction material in the completed building.
- Embodied energy
-
The total amount of energy consumed during the production of Hebel Supercrete AAC, including conditioning energy for raw materials, internal power consumption and energy content
contained in raw materials which are not produced in the AAC plant (e.g. lime, cement, aluminium powder), is found to be approximately 2.1 MJ/kg or 1005 MJ/m3 at a
density of 550 kg/m3. A comparison of Hebel Supercrete AAC with other common building materials reveals its relatively low embodied energy.
Embodied Energy Coefficients Material MJ/kg MJ/m3 Fibreglass Insulation 30.3 970 Wool insulation (recycled) 14.6 139 Polystyrene 117 2340 Softwood timber, kiln dried dressed 2.5 1380 Particle board 8.0 4400 Precast Concrete 2 2780 Clay Brick 2.5 5170 Cement mortar 2.0 3200 *Hebel Supercrete AAC 2.1 1005 Sources:
Centre for Building Performance Research
University of Victoria, Wellington, New Zealand
www.vuw.ac.nz/cbpr/*Aroni, S. et al Autoclaved Aerated Concrete: Properties, Testing & Design.
RILEM Technical Committees 78-MCA & 51-ALC.
E & FN Spon, London, 1993
- Operational energy
- The modest energy consumption for its production is payed back faster during the life of the building due to Hebel Supercrete's insulating capacity. Additionally, the energy needed for heating and cooling of buildings can be reduced with a subsequent reduction in environmental impact. Well designed and constructed Hebel Supercrete buildings - being low in embodied and operational energy have minimized life-cycle energy consumption.
- Heat capacity (Thermal mass)
- Hebel Supercrete AAC provides a useful thermal inertia, reducing the extremes of lighter framed structures, which have minimal thermal capacity, or heavy weight structures which provide less thermal insulation. This dynamic process which is a combination of heat capacity, thermal conductivity, and specific heat of the Hebel Supercrete building element, plays an important role in significantly increasing the effective R-value of Hebel Supercrete walls. A Hebel Supercrete building with this higher thermal inertia will have a lower temperature variance compared with a lighter, framed structure, meaning the inside temperatures will not fluctuate so much. While providing sufficient heat capacity for thermal benefit, Hebel Supercrete has very good thermal resistance qualities which means in many instances the use of supplementary insulation is unnecessary.
- Production emissions
- Emissions of gases such as CO2, CO and NOx which originate from steam generation in the production process are therefore relatively low compared, for example, with burning processes involved in brick making.
- Raw materials
- The finished Hebel Supercrete product has a pore content of approximately 80% meaning 5m3 of Hebel Supercrete material can be produced out of 1 m3 of raw materials. This cellular structure is what gives Hebel Supercrete its exceptional thermal, acoustic, and breathable properties. The low consumption of raw materials contributes to their conservation, compared to other construction materials.
- Product weight/volume
- Hebel Supercrete has a dry density of 550kg/m3, giving it a dry density approximately one-quarter that of normal high density concrete. Hebel Supercrete's low weight has advantages for transporting as a good ratio of volume to weight permits full utilisation of transport capacity, and means effectively 1 truck of materials entering the manufacturing plant, leaves as 5 trucks of Hebel Supercrete product.
- Recycling
- By-products of AAC production including condensate from the autoclaving, hardened AAC waste, and unhardened AAC mixture, are recycled back into the production process. Being highly durable a Hebel Supercrete building will perform over many generations and if it needs to be retired for some reason the building's structural materials are non-toxic and recyclable.
- Renewable energy
- With the right design, Hebel Supercrete AAC makes an ideal material for active and passive solar systems to provide energy needs. Hebel Supercrete's thermal properties make it a very effective heat insulator and a natural choice for sustainable houses. Hebel Supercrete houses take less energy to heat, and less energy to keep warm.
- Indoor air quality & moisture control
- Hebel Supercrete AAC is open to diffusion; it will naturally extract or add humidity to the air of a room helping to moderate moisture levels. This is vital for maintaining correct relative humidity and maintaining a comfortable and mold-free living space.
- Thermal bridging & infiltration
- Unlike frame construction, which leaves thermal gaps at every stud and lintel, Hebel Supercrete Blocks and Structural Panels provide structure and insulation in a single component. Hebel Supercrete's even insulating properties, and the whole wall coverage of all Hebel Supercrete building systems, prevents thermal bridging which provides a pathway between the cold outside surface of a building and the warm internal air of the room. Due to construction detailing Hebel Supercrete houses have lower air infiltration than conventional stud frame houses with vented cavities, while allowing the diffusion of moist air through the building envelope.
