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Northlake Rd Residence

Heating Type: Underfloor
Heat Source: Ground Source HP
Other: Rotex


This brand new 250sq/m home houses one of our most exciting, environmentally-friendly heating solutions. Our clients came to us with a plan: they wanted to install a system that could provide ambient, comfortable heat throughout the entire house, without the high electricity bills that came with their last home (running an air-to-air heat pump). Given their goal, our clients had researched and chosen a remarkably efficient and sustainable geothermal heating system called ground source heating, and we were super excited to help them bring the project to life.

Ground-source (geothermal) heating works by water flowing through a series of pipes run below ground (called slinkys). The natural ground temperature heats the water which then passes through a heat pump to increase the temperature to a point it can be used for the central heating. As the earth temperature remains at a constant, the ground source heat pump is not affected by extremely cold temperatures. Due to the high efficiency of the system and lack of fossil fuels used to heat the water, a ground source system is considered to be one of the most environmentally friendly forms of heating.

Now that we knew what our clients wanted, it was our job to bring their vision to life, so we got to work. We organised the specific system design, performed all of the necessary heating calculations, and designed the house with passive heating principles and good insulation to ensure maximum system efficiency.

“The Optum team were really great when we were planning our new home and clearly understood the reasons we wanted a ground Source/underfloor solution. They worked well with both our designer and builder, and we’re really stoked with the result. The house is warm and comfortable, and the system works as promised. It’s low-cost to run and environmentally-friendly too!”

“We love how the rooms and floors are always a comfortable temperature. It’s very low-cost to run, and we barely think about it. We used to be concerned about running the air source heat pump in our old house, as it used a lot of power, but now we don’t have to worry about it.”


The system we designed divided the house into seven underfloor heating zones to provide efficiency and flexibility. Each zone is controlled by a programmable thermostat, and when the air temperature in a zone drops below the set temperature on the thermostat, that section of underfloor heating will turn on.

In addition to the highly effective central heating system, we also installed a thermostat-controlled radiator in the laundry room and a wood fire for ambience in the lounge. These two installations allow a final level of flexibility in the heating system, however, our client hasn’t bought any new wood in over two years! In winter, they occasionally light the fire if they want a direct heat source, or ‘top up’.


To give you a realistic running cost estimate, our clients’ largest electricity bill was around $400 for the month of June. The heat pump is a highly efficient method of water heating, making the system comparatively very low-cost to run with a higher capital cost.


To keep the system running at its best, it is important to maintain it well. The maintenance of this system simply requires an annual service by a certified technician and occasional client maintenance.

• Technician maintenance – all central heating systems should be serviced annually to maintain efficiency. An average heat pump service costs $250 + GST.

• Client maintenance – the pressure in the system needs to be kept topped up for the system to operate. Occasionally, this may drop and need to be topped up. This is a 10-minute task, and we provide our clients with a manual specific to their system with instructions on how to do this.


If you’re interested in any of the systems described in this case study, reach out and we can discuss options to help you heat your own home!

Northlake Road

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