Another Low Impact Earth Building

The Earth Building Association (EBAA) of Australia recently commissioned eTool to perform another LCA on one of their existing mud brick homes. EBAA demonstrated a conscientious approach to the original design and construction of the building which was evident from the LCA results. The LCA results for the mud brick home pointed to notable carbon savings compared to the benchmark and showcased a number of impressive sustainable design features.

  • Date: April 2014
  • Builder: Peter Hickson – Earth Building Solutions
  • Location: NSW

Results Summary

Impact AreaTotal CO2e / Year / occupant (kg CO2e)% Saved Against BenchmarkeTool Medal
Embodied Carbon88441%Silver_medal
Operational Carbon-1,444152%Platinum_medal
Total Carbon-559113%

Project Features

Low Carbon Structure

Mud bricks are inherently low carbon, particularly in this instance where they were constructed by hand onsite using mud found onsite. You cant get much lower impact on the environment than that! The initial embodied impacts of the mud brick walls are virtually zero. Further superior material choices include solid oregon beams which were recovered from a nearby beach house. The beams will no doubt outlast this house as well given their structural strength. The house has been constructed in traditional post, beam and rafter which means a higher chance of end-of-life recovery as opposed to modern framing which tends to use shorter nailed gangs and glue.

Renewable Heat Sources

The bulk of the thermal load is a heating requirement. This is managed with a slow combustion wood heater. The hot water is provided by a bank of 30 evacuated tubes which can be more efficient than the standard flat plates.  The tubes have not yet been installed with a backup heat source (gas or electric is common) as it has not yet been required. The hope is that the system will provide 100% of the hot water throughout the year.

Low Carbon Finishes

The finishes inside and out are excellent in this design. Plasterboard is kept to a minimum with pine lining boards to all ceiling and wall linings. Externally, an earth based paint was applied to the mud bricks. Although woollen carpets have been used in the living area which are typically very high in embodied carbon, the carpets have been reused and are predicted to last much longer than the 10 year standard life expectancy of a carpet. When they are replaced, eTool is assured it will be with a low carbon alternative such as Jute.  Vanity and laundry cabinets are made from recycled oregan as are the hardwood benchtops.

Photovoltaic System

The building has a 4.9kW PV system, which, renders the building truly carbon neutral (including both embodied and operational emissions). The extra PV generation above what the average occupant would use is fed into the grid and offsets all embodied carbon as well as the electricity that is consumed from the grid when the sun is not shining.

This assessment was conducted by  Pat.

Pat Hermon