Blog entries from October, 2023

Continuing my thoughts on the cost of heating I have been running through different ways of thinking about what my house is and what I would want in regard to heating and cooling.

So what is my home?

• A two bedroom unit that was built in 1970.
• Insulation in the ceiling, but not in the best condition and should be replaced. No insulation in the walls or floor.
• No windows facing east so don’t get any morning sun.
• My lounge has north facing windows, but no significant heat comes from those.
• Both bedrooms have west facing windows (so they get the hot afternoon sun)
• The bedroom I use as my study had a north facing brick wall that heats up in summer.

What do I have for heating and cooling?

• Gas central heating.
• One bedroom has an ancient in-wall air conditioner that I never use.
• Ceiling fans in the bedrooms and lounge.
• Venetian blinds on all the windows.
• External blinds on the west facing windows.

What is a day like in winter?

• It is cold and dark outside.
• Central heating warms everything up quickly.
• I have the heating first set to 16°C to help me wake up, then warmer for the remainder of the day.
• It is comfortable to work in my study or be in other rooms.
• The afternoon the sun might hit my study window enough that I will close the venetian blinds.
• Once the heating turns off it looses head fairly quickly, but I am asleep by then.

What about in the peak of summer?

• It is more variable, often overnight in the teens and mid to high twenties during the day, but then periods of hot weather were is is above 30°C at night and over 40°C during the day.
• Most of the time it can be comfortable with the external blinds to blocking the sun and then the ceiling fans circulating air.
• When it gets hot then everything starts to heat up and then stays hot for a day once the cool change eventually comes through. It did get to 40°C in my study once, but it is hard to work in anything above 30°C

For now I am setting aside the issue of insulation and keeping my focus on active heating/cooling as that has a much more tangible impact in the form of bills. I would like to insulate the walls and re-insulate the ceiling, but that will be long term.

Something I have tried when the house is hot and a cool change has arrived is to open up doors and windows to try and get a draught, but that has never worked very well. The idea of a whole house fan has intrigued me, but while a thing in places like the US, it is rare in Australia. A couple of companies do install them, but none I have found in Melbourne.

So what I am after is a way to make things comfortable throughout winter (such as heating the study to 20ish degrees while I am working), and then make the extremes in summer tolerable (getting from the high 30s to the mid to high 20s).

While ducted air conditioning would be nice as it would be unobtrusive (unlike the the indoor head of a split system), the additional cost (double, quadruple, or more…) is not as appealing. It would also be heating/cooling rooms that I am not spending time in, so without better insulation that would be a wasted running cost.

This line of thought is taking me to split systems which would have the advantage of being able to cool the specific rooms that need it AND the room that I wish to use at the time. While there is more it learn about these specifically, it is also bringing me back to electricity, when does it get used, how efficiently is it being used, and where does it come from?

More electricity used during the day means that solar panels will be more beneficial…

Procrastination had its hand in it, but as previously indicated I have gone through my gas bills to produce this masterpiece of an Excel 2003 chart:

For 2018 and 2019 I was commuting to the city for work so the heating would only run on weekday afternoons and evenings and then all day on the weekends. There is a noticeable step up in usage for 2020 onwards when I was working from home because now the heating was running during the day on weekdays as well.

It was also interesting to see that the usage over summer didn’t drop to zero like it used to. I put this down to there still being cold mornings fairly late in spring and early in autumn. Previously I would have gotten up and left for work without running the heating, but when working from home the heating would run to eliminate the morning chill even though by lunchtime it had warmed up outside.

Also note the constant blue line that is the daily charge. This is just under $1 per day, so $365 per year and I could only expect that to go up.

Looking at these numbers from a yearly perspective:

It is appealing to think that I could get rid of this ongoing cost. But what is the upfront cost of a replacement system and what is the ongoing cost of that new system?

I’m pretty sure that a replacement system would be a form of reverse cycle air conditioning. A drop in replacement that used the existing ductwork would be convenient, but that does not exist. It does look like there are options for a ducted system that would be installed in the roof with an exterior unit, but that seems rare and expensive. The cheapest and most varied option appears to be split systems (though I would prefer not to have something sticking out of the wall), with multi-split systems (one exterior unit running multiple indoor units) somewhere in between.

What would this cost to heat my house (or just the single room I am in) over winter? How much of that could be covered by the output of solar panels on those dark and cold days? As usual I have answered some questions but raised more…

I have been thinking about changing some things around in regard to my credit card so I decided that I should look up what the options are with my current card. It has been a while since I compared the value between types of points or the difference between how the points are redeemed, so I was pleasantly surprised to find that I might already be on the best option for my use case.

I learned that with my current main credit card there are three ways to get cash value for the points:

1. Cashback to the card
2. Purchase gift cards to use for regular shopping
3. Transfer to another loyalty program, then in that program use the points in some way

Before I checked the numbers I would have assumed that cashback to the card should have been the best. There are no third parties involved so the costs should be minimized, however (spoiler alert) that is not the case.

The rate at which points are awarded is between 1 and 3 points per $1 depending on the type of transaction and/or who the transaction is with (eg some large retailers), but for comparison purposes I am going to use the rate of 1 point per $1. So $1000 will result in 1000 points.

• 12,500 points gives a $50 cashback directly to the card
• 10,210 points can be redeemed for a $50 Coles/Woolworths gift card
• 10,000 points can be converted into $50 Flybuys dollars

My card is currently covered by the $8/month fee for my home loan, that is $96/year or essentially the same as the $95 annual fee for existing customers. I will also round it up to $100 to keep the calculations simpler.

So what is the minimum spend to cover the annual fee?

• $25,000/year or $2083/month if getting cashback to the card
• $20,420/year or $1701/month if getting gift cards
• $20,000/year or $1666/month if getting flybuys dollars

The cashback option might be the most convenient to the consumer as there is zero involvement once it is set up (there is no actions needed to get gift cards and then remember to use them), but it is also the least cost for the bank to offer.

But what other benefits does the bank get from the other options? Converting the points to Flybuys is best for me, but does this mean the bank then has access to all the data Flybuys has collected about my purchase history? Does Flybuys also get information about my credit card activity?

Is the $5000/year difference between cashback and Flybuys dollars the value of my data?

It has been almost ten years since I started monitoring my home power usage from my smart meter. Since then I have improved how I do that and I also track the usage of my computers via a UPS.

Also hooked into Home Assistant is the control of my central heating, this has been working well and I have been comfortable (especially while working from home) but recent price increases have highlighted that it would be a good idea for things to change.

I get a gas bill every two months with the last one being $580 and the one before that $520. These are over winter when the heating is used the most, so I expect the next bill should be around $550. I checked my bills from last year and while the gas consumption is similar, they were around $180 cheaper. That is a big increase that I don’t like. I need to dig into things further, looking back over all my bills for the last couple of years, including from before I started working from home.

Once I have the information what am I going to do with it? There won’t be much I can do about the increasing prices so what can I do to reduce consumption? Getting around to replacing/upgrading insulation and similar changes could reduce the consumption, but what about eliminating my gas connection completely? Is it finally time to get reverse cycle air conditioning and use that for heating? That heating is during the day, so it is also time to get solar panels? What about my hot water, where are we up to with using heat pumps for hot water?

Lots of questions… as I get answers I will try to write them up.