Results Summary

A Life Cycle Assessment has been carried out on the proposed design calculating the greenhouse gas emissions over the whole life of the project as per EN 15978 scope and system boundary. The benchmark chosen to compare against is the International Residential Benchmark Weighted (x10 Dwellings). The results are summarised below:

Impact AreaTotal CO2e / Year / occupant (kg CO2e)% Saved Against BenchmarkeTool Medal
Embodied Carbon1,11113 % increase
Operational Carbon-25101 %etool_plat_medal
Total Carbon1,08674 %etool_gold_medal

Project features

It is observed through the LCA modeling that the following areas have the greatest impact to the overall environmental footprint of the building:

Design Life

High quality design differentiates this project from surrounding residences and extends the lifespan to 80 years by reducing redevelopment pressure in the near future. Higher design life means that all initial impacts are diluted over a longer period of time therefore improving the performance on a per year basis.

Materials Selection

A careful selection of materials guaranteed higher durability, lower embodied impacts and lower maintenance requirements. The materials list included:

  • Polished concrete floors;
  • Concrete replacement – 50% fly-ash blend;
  • Timber cladding internal finishes;
  • Light construction in timber frame for walls and roof.

An increase in overall embodied carbon was mainly because of a large 5 kW solar PV system. It’s estimated the system will get replaced three times over the life of the building. However, the substantially reduced “Operational Impact” due to the renewable energy input offsets this increased “Embodied Impact” many times over during its design life. The main advantage of a solar system is that it offsets carbon intensive grid electricity.

Net Positive Operational Carbon

The project was designed for reduced energy demand and included:

  • Ceiling fans to reduce demand from split system;
  • High efficiency LED lighting;
  • Motion and lux sensors for outdoor lighting;
  • Induction cooktop;
  • Well ventilated fridge space;
  • Electric heat pump hot water system;
  • Energy monitoring;
  • Solar pool heating;
  • High efficiency pool water pumping and filtration;
  • 5kw Solar PV System.

Water efficiency features include low flow shower heads (5.5L/minute) and grey water diverters to garden helped reduce annual water consumption as well as greenhouse gas emissions associated with mains water supply and treatment.

After all energy efficiency measures were implemented, a large solar PV system of 5kW was installed. The system will produce excess clean electricity which will generate carbon credits to offset impacts associate with materials and recurring impacts, resulting in a whole of building whole of life performance of 1,086 kgCO2e/occupant/year, or a 74% savings in equivalent carbon emissions when compared to a residential benchmark.

This assessment was conducted by Fei Ngeow and certified by Rich Haynes from eTool in May 2015.