Using permaculture ethics & design principles to transform an old energy guzzling bungalow into a showcase of sustainable design. It's about energy cycling, building community, self-reliance,creatively using & reusing materials... all without spending heaps of money.

Wednesday, April 24, 2013

The 'Super Fridge' (upright freezer conversion)

Principle 12: Creatively use and respond to change

I'm one for trying out different things, and I like to see what we can get away with before committing to something bigger and 'better'. Fridges and freezers are one of the biggest energy consumers in the household - usually behind heating / cooling and hot water systems.

Our upright freezer to fridge conversion in action

We've trialed a number of fridge systems here before settling on the upright freezer conversion.
  • First we used an old 150lt bar fridge that used around 670Wh per day
  • Then we bought a 150lt chest freezer (using around 466Wh per day) for preserving bulk food - with the idea of a possible conversion.
  • Our bar fridge died two weeks later so we used ice from our freezer to create a 'ice box bar fridge'
  • We then tried a smaller old Engel fridge (about 50lt) that I had in the Kombi that used about 420Wh per day.
After not being entirely satisfied with any of the above I finally decided to try out what I always wanted to and convert a freezer to a fridge. I first read about this in Renew magazine (I think) many years ago, along with this article about a chest fridge that captured my imagination. Freezers are super insulated compared to a fridge and the motor wouldn't work as hard, so it should (?) last longer - we will see. The chest fridge idea makes a lot of sense, as the cold air can't easily escape when opened, but after having bought one and used it for a while I found it was a pain, so I wanted to try an upright.

The things that I like about the upright are that they take up less floorspace and its much easier to access / stack goods. There are elements (if that's what they are called) on each shelf, so the air is cooled evenly throughout. The drawers are clear, and hold the cold air, even when the door is open. But they do come with drawbacks: they are less efficient that a chest design, water condenses on the elements and drips into the drawers - more of an issue in the top two shelves, so food should be stored in containers. They don't have a drainage plug, so the probe needs to break the door seal, and water removed manually. The plastic drawers are clunky, could break and be difficult to replace.

I didn't want to spend a lot of money on the freezer, as I wasn't sure that the system would work well. Not long ago Aldi had a 190lt upright freezer on offer for $299 and I jumped at the chance. Getting to the store on opening there was a crowd already lined up. I managed to get one of the four on offer, finding a large trolley in store to take it to the checkout. Thanks to the fella that gave me a hand with it! It's a bit of a mission taking a freezer through the checkout - and then getting it home.

The freezer I got is only a 2.5 star rated one, not great - but I figured that it would be fine for it's purpose. When used as a freezer it's expected to use 334 kWh per year - 915 Wh per day.

The Control Box

NOTE: I can't recommend that you attempt this yourself as there are high voltages involved in the conversion.

I asked a friend of mine, John - an electrical engineer, about the conversion. He had trialed one in the past and made a programmable controller for the purpose, that he kindly loaned to me. He suggested that I buy a digital thermostat controller on eBay, around $15 delivered - much cheaper than he could make one up for - and make the controller up myself (being the DIY kinda guy that I am).

The basic idea of it is that the temperature probe determines the range at which power is supplied to the freezer, so that it turns on at say 7º and turns off at 3º (these are the settings that I am currently using). I did have it set lower, but found that the temperature sensor has a delay, and so the air space continues to get colder after the power is shut off. You can also set a delay, which allows for fluctuations as the door is opened and closed - I set mine at 2 minutes.

I wanted to wire it up to a power point so that I could plug the freezer in, rather than cut the cable on it. It also means that you could use it for other devices easily. I ran my old bar fridge power cable to the controller (see wiring diagram), and then onto the power point (earth running directly). This was all fitted into a plastic box to keep everything together and looking neat. I extended the wire for the probe so that I could run it up the back of the freezer, along the top and into the back of the freezer compartment. I used white electrical tape to fix it, and used tape to reduce the air gap at the entry point where the wire breaks the door seal. I did this at the top of the door to reduce potential losses through the breaking of the seal.

Digital Temperature Controller - programmable and very flexible device.

Wiring diagram - the wire on the right (to #4) is negative, left (to #3) is positive - it wasn't clear here.

Controller fitted into a box with a power point, so not having to modify the freezer wiring.

Wire for probe extended and fed through top of freezer to be fitted at the back - see water condensing on 'elements'.

The Results

We've been running the 'super fridge' for a bit over a month now and here are the results from my testing:
  • 19/3/13 1:30pm began testing
  • first 29 hours 330 Wh = 273 Wh per day
  • 28/3/13 8:30pm (9 days 7 hours / 223 hours) 1.89 kWh = average 203 Wh per day
  • 12/4/13 10:00pm (24 days 8.5 hours / 584.5 hours) 4.39 kWh = average 180 Wh per day
  • 25/4/13 10:30am (approx 37 days) 6.12 kWh = average 165 Wh per day
Interesting to see that it's dropping - perhaps because we are entering a cooler time of year? Looking at the use between periods show more typical consumption once the system has settled in. 

28/3 - 12/4 (approx 15 days) 2.5 kWh = 167 Wh per day
12/4 - 25/4 (approx 12.5 days) 1.73 kWh = 138 Wh per day

More testing with a better quality device would ensure more accurate results - but these results indicate some great savings. It's not uncommon for similar size fridges to use five times more electricity. The 'super fridge' uses around 165Wh per day, as compared to the same unit used as a freezer which was rated at 915 Wh per day, about 80% less power.

As a side note - I think that cool cupboards should be built into every new home, which helps to reduce the size of the fridge needed - but more research really needs to be done on how to design them well. I am looking at fitting a fan inside ours with a digital temperature controller to help it draw air through when needed - to help regulate temperature. More later...

Monday, April 22, 2013

International Permaculture Day 2013

Principle 8: Integrate rather than segregate

Well, it's come around to that time of year again. Sunday May 5th is International Permaculture Day and we'll open the property up and happily show people around from 1pm till 4pm. You can see the details for our event here. If Seymour in Victoria (Australia) is too far out of your way, then check the above website for something closer.

I've asked Peter Lockyer, the builder / architect that I worked with on the construction, to join me - so if you've got any technical questions or are looking to build yourself then Pete's your man.

Our north facing deck with recently constructed trellis

I'm going to ask for a gold coin donation this year, all proceeds being donated to Permafund - supporting permaculture projects internationally. We'll have permaculture publications on offer on the day with net proceeds from sales tithed to Permafund. This is part of my new business venture, publishing, selling and distributing permaculture publications - mainly through my recently updated website Permaculture Principles.

We are right on the change of the seasons now with lots of summer veg on their last legs and winter veg seedlings on their way up. The place is looking pretty good, and I'll be working hard over the next week or so cleaning up to make the place look spic and span - well as good as it can be at least. I hope you can join us!

Saturday, April 6, 2013

Food Harvest - First Quarter of 2013

Principle 3: Obtain a yield and Principle 4: Apply self regulation and accept feedback

Life has been very busy lately. I've been flat out on redeveloping the Permaculture Principles website which is now online. As part of the rebuilding of the website I have been working with Charlie Mgee in integrating his interpretations of the permaculture principles into song with the website. He launched his album last night with his constantly evolving band at CERES (most appropriate) along with this video clip featuring the 'Obtain a yield' principle - which I love. I took the family down for the event and finally met Charlie in the flesh - the latest effervescent permaculture ambassador. A fantastic night that gave me hope for a resurgence of interest in permaculture.

While working on the new website I've been trying to keep the water up to the garden during this unrelenting dry season. In the last four months of the year I recorded just 72mm of rain, and in the first quarter of 2013 we had no rain in January, 50mm in Feb and 39mm in March - 89mm in total. Comparing to the previous season where we had 194mm in the last four months of 2011 and 313mm in the first quarter of 2012.

This has resulted in a rethink about how I manage our rainwater supply (31,000lt). My plan for previous seasons has been to use most of our rainwater supply for irrigating our gardens with the assumption (based on previous years) that we would get heavy summer rains at some point during the dry season. But this year we were left with a low rainwater supply for household use, as the rains didn't come. We ended up running a hose into the house to keep our washing machine going, saving the precious rainwater for more important uses. We used about 40,000lt from the mains during the first quarter to irrigate the garden and run our washing machine. The rainfalls in late Feb and late March ensured that we didn't run out of rainwater for the household.

I know that many people think that using mains water for watering the garden is wasteful, but as a comparison I thought that I'd point out that daily average water use in Melbourne during January reached up to 238lt per person per day. To compare, we used a total of 40,000lt, or about 111lt per person per day from the mains - primarily for irrigation.

Next season I plan to keep the rainwater tanks full leading into summer for household use, and if water restrictions come in during the dry then I may be able to afford to use some rainwater to keep the gardens alive. When the dry breaks (around April) then I can afford to use rainwater for irrigation once again until September.

Part of out 2012 summer vegie harvest
You may be aware of the previous annual missions that we have undertaken - the Binimum challange of 2011 and our Food purchase analysis of 2012. This year we've decided to record our food production for the year. The table below shows our first quarter results - an interesting exercise...

NOTE: I've recorded totals at the bottom of the tables as an indicator, but they are not that important - the value of food varies a lot. Some food weights are not accurate like strawberries that get eaten before making it to the scales. Leafy greens, and chive's sometime don't get included as they are picked and used straight away.

All weights are measured in grams (except for the eggs)
As vegies and fruit often come in an abundance we have been preserving and sharing excess amongst neighbours and friends - especially the zucchini. We also have recently bought some more chickens to try to increase our egg production, to chicks and two pullets, and are going to start sprouting grains before feeding them.

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