5×4 Hayes Lane

The 5×4 Hayes Lane project is a unique inner city dwelling located in the heart of Melbourne. The house is situated on a tiny plot measuring 5×4 meters. Project manager and owner, Ralph Alfonso wanted to demonstrate and encourage debate around sustainable living, a healthy form of densification in the city of Melbourne and how to achieve it through best practice design and living. Using the One Planet Living principles as a guide, Ralph incorporated many sustainable features into the design, including calculating its embodied energy using eTool LCA. Ralph plans to move into the 5×4 house on completion.

Results Summary

Impact AreaTotal CO2e / Year / occupant (kg CO2e)% Saved Against BenchmarkeTool Medal
Embodied Carbon  1,563-27 % increase 

no rating

Operational Carbon– 4,683273 % 


Total Carbon– 3,120177 %   

Project features

Design life

Increased design life – 65 years, when comparing to standard detached houses due to the use of small block space (5m x 4m), and very high quality custom architectural design. The estimated occupancy for this one bedroom design is 1.33 occupants over the life of the building.

Renewable energy generation

Although the building itself has a limited roof space, the design team looked for innovative approach to use adjacent roof space for the solar capacity. A total 8 kW solar PV system was included in the LCA and it is by far the biggest contribution to carbon savings. Solar PV has a high embodied carbon component and without it the design would have achieved a better “Embodied Energy” rating. 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 solar PV system produces more energy than the house needs, so the excess power is fed back into the grid, offsetting even more carbon. The main advantage of a solar system is that it offsets carbon intensive grid electricity.

Geothermal Heat Pump

Hot water will be coming from a ground coupled heat pump with a super insulated thermal store, electric emersion top up and a solar thermal charge that recharges the ground during winter. The overall system efficiency assumed (COP) is 3.6 including all system loss and an electric emersion of 86% efficiency.


The life cycle assessment highlighted the high energy demand from the spa in regards to hot water, pumping and filtration. Specific considerations for the hot water and on site electricity generation were implemented into the design to minimize the overall impacts while providing the required service.


Increased ventilation to the fridge space to improve the efficiency of the condenser by providing additional airflow to the base of the rear of the fridge through a vent in the adjacent kickboard cabinetry and ensuring the overhead cupboard above the fridge has a large gap between the wall and the rear of the cupboard.

Additional Features

Detailed analysis of embodied energy and low carbon materials

LED lighting

Induction cooktop

Energy monitoring system

This assessment was conducted by Henrique.