Split System Heating and Cooling

As I mentioned in my previous post, we have now created a heating and cooling zone in our main room by rebuilding a wall and fitting a door. If we’re inside during the day we spend most of our time either in this room or in our study, so converting our heating in this space to zero emissions sources will put a significant dent in the emissions generated in our home.

The heating unit that we decided to go with is a heat pump, alternatively known as a split system or a reverse cycle air conditioner. Switching to this technology is ranked #42 on Project Drawdown. In traditional heating, you can convert one unit of energy into one unit of heat. With a heat pump you aren’t creating heat so much as moving it from one place to another, which means the heat output can be significantly higher than the energy input. This is the same concept used in refrigeration.

Heat pump heating and coolingEfficiency varied considerably across the units that we looked at. We decided to go with the most efficient unit that we could afford, and were quite surprised by how many units cost more with lower efficiency. We went with a 5-star Mitsubishi unit that we bought at Bunnings. Heating is rated at 3.2kW output for 0.65kW input, and cooling is rated at 2.5kW for 0.51kW input. Our unit is considered too small for the space, but we wanted to size it against our solar panels instead of our room size.

Our hope is that installing this unit will mean that we no longer run the gas ducted heating at all in a best case scenario, or only on the coldest days in a worst case scenario. In either case, we expect our heating bills to be slashed. By switching to electricity we generate ourselves instead of using natural gas, the unit will potentially pay for itself in fuel savings before it is out of warranty.

If you’re playing along at home…

…how much could you increase the energy efficiency of your home by switching to a heat pump for heating and cooling? If you already have a system for cooling, how much gas could you save by also using it to heat? Please share your experience in the comments below.

Budget For Change

On the political scale, as soon as talk turns to climate action it quickly takes a detour through accounts. The general argument seems to be “we could do x things, but they cost $y, so that will never happen.” Happily, as a family, we have the ability to question our budget overall and not just individual line items.

We wanted to divert enough money in our budget to cover the cost of changing our emissions. We’ve got a long list of projects that we want to complete, and they all cost money. I have our budget in a fairly detailed spreadsheet, so I can make small changes and immediately see the impact on our bottom line. The most recent change was adding in the repayments for our Solar Victoria loan to buy our PV system:

3 Lines of Budget

At first, we weren’t sure where we were going to pull $556.20 per year from – that’s a lot of money. We started by looking at the electricity line – the feed in tariff on offer from our retailer is 11c/kW, and our system should produce a minimum of 5kW per day. If we feed in all of that energy, our daily cost drops from $2.10 to $1.55, for an annual reduction of $200.75. In reality we would be using some of that energy instead of exporting it, and generation will be higher in summer, so the practical savings should be higher. When we take that from the loan amount, the additional expense for the system drops to $355.45. Expressed as a weekly amount, the loan will cost us $6.84. We could cover that by working from home one day a week instead of taking the train, by walking to the supermarket instead of taking the car, or by borrowing a book from the library instead of buying something new.

The important thing to note with this change is that the loan will not be there for nearly as long as the panels will be. After four years we stop paying for that loan, so we’ll have those funds available in our budget for other projects, and $556.20 per year is still a lot of money.

If you’re playing along at home…

…how much could you divert in your budget towards actions that will reduce your footprint? Please share in the comments below what you’re budgeting to change.

Mowing The Lawn

When we first moved to this house, the biggest job in the garden was keeping the lawns mowed. It was winter, so the grass was long and lush, and it seemed as if my partner was out there every weekend trying to keep it under control. We didn’t own a mower at that point, so we had borrowed an old one from relatives. It had a pull cord to start it, two stroke to fuel it, broke down more than it worked, and my partner seemed to spend more time violently swearing at it than he did mowing the lawn. The edge trimmer was even worse.

Standing on the deck holding the baby and watching this was hilarious.

After a few weeks of this, he finally reached the snapping point and wanted a new mower and trimmer. We had barely any money in our budget, but new tools were probably going to be cheaper than the required counselling sessions if I made him keep using the old ones.

Once the decision was made, we had to decide what type of mower and trimmer to buy. At the time I had been flipping through a book in the library that recommended getting rid of lawns around the home to improve your environmental impact. This seemed counter intuitive to me, but the book went on to explain that the amount of energy used to maintain them more than outweighed any environmental benefit to having them. With two young children we didn’t want to convert their play area into a hard surface or cover it with plastic grass, so it was time for better alternatives.

Initially we were looking at an electric lawn mower and an electric trimmer. These options seemed better than the petrol ones, because we wouldn’t have the hassle of jerrycans and trips to the petrol station to fill them. When we got to the store, we discovered that not only did they have electric mowers, they also had push mowers. The push mower was tiny compared to the mower we had been using, and the lack of an engine meant that it was light weight and easier to move.

I’d like to claim that it was environmental diligence that inspired us to buy the push mower, but it was our budget. At less than half the price of the mowers we were initially looking at, a push mower and electric trimmer combination meant that we could afford both, while staying with the more common petrol equivalents would have meant we could only afford one.

Push mower and electric trimmer
It came with a grass catcher, but catching grass is too much work on any mower.

The reaction from friends and family when they heard that we had bought a push mower was pure astonishment. We were told by many people that we’d be back to a regular mower within weeks. Strangers have stopped on the footpath to watch my partner, amazed that our pathetic little mower works so well. Thanks to our push mower, we got to know some of our neighbours, and we’ve built a reputation of being amazing gardeners as a result. One guy said our lawn looked so good that he wanted a bit of grass to try growing it at his place, so we switched from the edge trimmer that weekend to a shovel and he happily took home some of the grass roots that had grown out over the footpath.

Despite its many benefits, there are a few disadvantages to the push mower. Obviously the power that we get out of it is the power that we literally push into it. If we let the grass grow too long then it doesn’t cut as well as it does with more frequent cutting. Weeds can also be a problem if they are supple enough to flex around the blades, and if we push over something long it can wrap around the cutting bits and they get stuck.

We made that purchase about a year ago now, and we have no intention of going back to a petrol mower or trimmer. The drawbacks are negligible or easily solved, and the switch to something that gives us healthy exercise while being quieter and cleaner more than outweighs the negatives.

If you’re playing along at home…

…have you found any techniques to reduce the amount of fossil fuels that you use to maintain your garden? Please share what worked and didn’t work for you in the comments below.