FIRE Tips for a Comfortable, Energy-Efficient Home
On the path to FIRE it’s great to find little hacks that can boost your journey. Based on outgoings the home is a logical place to start to look at making more comfortable and sustainable (economical and environmental). Not only with some really good ROIs to boost your FIRE journey, once implemented it brings your cost of living down and protects against inflation (energy costs). We also find we use the ACs in the summer much more as we know it is FREE than we usually would if we were consumer grid electricity. Disclaimer: I (Cam) is an energy nerd with a honours degree in Environmental Mechanical Engineering and currently a Sustainability Manager for a large multinational company.
There are some really easy wins in this order:
1. Draft-Proofing: Check for cold drafts on winter nights—fireplaces (most) can reveal these quickly as they suck air from the living space to burn.
A FLIR thermal camera borrowed from the library can also be helpful and fun!
2. Insulation: Start with easy fixes like ceiling insulation, then move to walls, floors, and window coverings (honeycomb). Any windows that are replaced during renovations are done with double glazed, however the ROI to replace windows for efficiency only will have a much higher ROI.
3. Solar & Battery: Our 11.5kW solar ($12k) system and Tesla battery ($14k) cost a total of $26k but reduced our electricity costs to nearly zero, with a payback period of about six years.
This is a reduced payback due to the OVO 3 plan to freely charge our battery between 11am – 2pm each day and heat/cool the house during this time. Feel free to search their plans with this OVO referral code which will give you $10 off per month for the first year. After you have done steps 1 & 2 above, the house then becomes your thermal battery storing energy. The relatively good payback is supported by the liberal use of our 7 ACs, pool and largish family trying to be comfortable. We want to get an EV in the next few years too.
There are over 3.6 Million homes with solar in Australia which is one of the highest uptakes across the world. When we first got our 1kW solar installed we had a FIT of 66 cents. Now most areas limit or don’t allow feed in at all due the over supply and infrastructure limitations. If you can get a FIT it is now only around 3 to 4 cents per kWh. Hence with the above plans or looking at Amber (wholesale) it now makes more financial sense look at the numbers to store your own energy. The old method of getting as much solar as possible and batteries don’t make sense is changing. The other thing with a combination of solar and batteries you can run off grid during blackouts or emergencies. As we are in a Fire Zone this was another consideration for us.
4. Water Efficiency: Install efficient showerheads, dual-flush toilets, water restrictors, install rain tanks and run to your toilets and laundry (we run seperate lines and it’s not connected to the mains water to avoid cross contamination. As a family of 5 at our last home we went from 600 lt per day down to 145 lt per day by doing the above. Not only do you save on water usage but as your sewage is calculated on water usage you save there too. It was about $5 per 1000 lts when I calculated a few years back.
5. Gas-Free Living: We’ve replaced gas appliances with energy-efficient electric alternatives, such as heat pumps and induction cooktops, which we power using solar energy. Our old gas pool heater was only every used it once! It worked great, but cost us over $40 for a day’s use! We installed a Heat Pump (17kW was $5k installed, apparently usually $10k but they wanted a sale!) which we have automated to run for free off solar (Shelly EM switch) and our 3 Free electricity plan. The pool temp in Melbourne runs at about 28-31 degrees in the warmer months and heated all for free! We have replaced our gas heater with 2 additional ACs ($4k) and an induction cooktop for the gas cooktop (Ikea $400 and installed for free as part of the AC installation). We are about to have our last gas appliance replaced next week which is a hot water heat pump ($1300). After this removal we can disconnect from gas saving a supply charge of nearly $300 pa + usage costs which used to cost over $1200 per year.
Types of Heating and Cooling
Modern Air Conditioners
New air conditioners have a Coefficient of Performance (COP) of around 4, meaning they’re approximately 400% efficient. For every 1kWh of electricity used, you get 4kWh of thermal energy in return. This remarkable efficiency is thanks to the refrigeration cycle, where a compressor adjusts the refrigerant pressure, transferring heat between the evaporator (inside unit) and the condenser (outside unit). They can heat and cool which is great. At our beach house where the outside unit rust I installed a multi-head AC (5 indoor units and one outdoor unit). If the outside unit rusts out again I only replace one unit. They work well too but they all need to be on the same function i.e. All heat or all cool (you can’t heat and cool different rooms which is fine).
Resistive Heating
Resistive heating systems (electric element), on the other hand, are far less efficient, providing just 1kWh of heat for every 1kWh of electricity consumed. The technology essentially relies on electrical resistance to generate heat—similar to a car battery shorting out and heating the wires. We replaced and sold all our resistive wall-mounted heaters, though we’ve kept a small portable one for short bathroom use (about 10 minutes on cold winter mornings).
Evaporative Cooling
Evaporative coolers operate by lowering air temperature through the addition of moisture (increasing humidity), making them particularly effective in dry climates like Melbourne. They draw in outside air and add some water, which can reduce the indoor temperature by around 10°C. These systems use electricity to run fans and water pumps and require a steady water supply for cooling. However, their performance drops considerably during humid days or extreme heat, especially when temperatures soar into the high 30s or 40s, limiting their effectiveness in such conditions. They work well in large factories which are hard to insulate well and have a large area to cool.
Gas Heating
While gas heating provides instant warmth, the rising cost of gas (aka a double in the last few years) has made it increasingly hard to justify as a viable option. There are also health concerns and safety risks associated with burning gas indoors. Furthermore, gas can only be used for heating, offering no relief on hot days. For these reasons, we’ve made the decision to remove all gas appliances from our home.
The Best Choice for Efficiency
In a well-insulated, draft-proof home, efficient air conditioners are generally the best option. They provide reliable heating and cooling across a wider range of temperatures and are far more cost-effective over time compared to other systems.
Us again! It’s uncanny; but the efficient electric home has been our thing as well ever since we got back from Singapore and started freezing our butts off in Winter!
This year we finally went for it and:
1. Installed R5 insulation on top of the the existing R2.5? insulation.
2. New honeycomb blinds throughout the whole house
3. Touched up our draft-proofing (did most of that the previous year).
Fortunately the house already had two decent sized splits in the living & kitchen areas. We also started on the OVO “3 hours of power” plan as I like to call it and went completely nuts in Winter taking advantage of it!
The house has a gas log heater on bottled gas; got the bill for that the first year we were here (btw just celebrated our 3 years in Aus last week) – and after that first bill never ran it again and sent the bottles back to Elgas for a refund! The gas log heater itself will be removed in the next few months, along with the ducated Evap cooler.
At the same time as they remove that junk we are going to get another couple of multi-splits installed in our Master&Study, and the two other bedrooms for the boys.
It’s already been a night and day difference this year with the insulation and honeycomb blind upgrades. The new multi-splits will just be the icing on the cake. Forgot the mention the house already came with 6KW solar & heatpump hot-water systems which has been great. Next in line will be the EV at some stage as well, but thinking of adding some more solar for that purpose.
Anyway it’s an unreal journey and we couldn’t agree more how in line it is with FIRE principals. Our energy bills are so minuscule now and our comfort levels are almost second to none. (I also got carried away as I usually do and started researching on studying to get certified for home energy assessments – but so many other things to do; so little time, even with loads of time up our sleeve!)
Keep up the great work!
Matt & Grace
Haha love it Matt & Grace!!! Thanks for sharing. Which honeycomb blinds did you install? We have these on our list too. I love OVO – especially in winter! Our gas log heater in the holiday house was using up to $500 in 3 weeks (the highest bill)! I put a Shelly EM with a countdown timer so guests can used but it goes off after 3 hours. I think most guests were just leaving it on which I’m sure I would have done in a previous life. Now the gas lasts over 3 months but I would like to remove but it does create a nice ambience when overlooking the ocean. I’ve also installed IR blasters (broadlink) to turn off the ACs once the guests leave. During lockdown the last guests left a couple of resistive heaters (now ripped out) and it cost $1200 for the quarter with no one being allowed to stay there.
If you get certified I might need to get your services 😉
Cheers Cam (& Trish)
Ouch on the resistive heater bill! Although we were glad we had one recently in our camper when we stayed in Melbourne over this Christmas break 🙂 Cold, Hot, Wet – Melbourne gave us a bit of everything!
I’ve recently also taken delivery of a Shelly Pro EM-50 for better power monitoring. Previously had the PowerPal+SolaX, but wasn’t quite cutting it. I also plug these things into Home Assistant – https://www.home-assistant.io/ – so we can automate a few things like AC’s to come on and off when we need.
For the blinds we went with Veneta and they’ve been good. There are cheaper ones out there, but Veneta had the range and the Australia presence + warranty that convinced us. Just wait for their regular discount cycles; can be quite okay then. (They’re still way cheaper than a so called premium brand that will make your eyes water!). We went with double honeycomb blackout blinds for the bedrooms, study, & south-west facing Windows. For the rest we went with light filtering and a few vertical blinds for the sliding doors that we have.
Anyway maybe if you guys make it up this way you can come check it out anytime (I heard rumours of a Grampians FIRE meet-up early March which would be great!).
Matt (& Grace).