Green Building Forum - Green fridge DIY Mon, 20 Apr 2026 15:18:11 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 Green fridge DIY https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60435#Comment_60435 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60435#Comment_60435 Mon, 17 Aug 2009 17:15:45 +0100 betterroof
http://www.homedesignfind.com/appliances/green-fridge-invention-uses-almost-no-electricity/

why we can't buy at this level I don't know - it would be interesting to see if there are any food storage safety implications...]]> Green fridge DIY https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60437#Comment_60437 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60437#Comment_60437 Mon, 17 Aug 2009 17:29:43 +0100 Julian Green fridge DIY https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60440#Comment_60440 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60440#Comment_60440 Mon, 17 Aug 2009 18:11:20 +0100 jon
0.001297 J/(cm3·K) x 1000 x 300 litres (half full fridge)= 387 J/C
Maintain at 30K differential & assume complete flush:
11170 Joules = 11170 watts.seconds
= 3.1 watt.hours = 0.003 kwh

Opened 10 times a day: 0.03 KWh

Total due to opening my fridge door 10 times a day in summer: 1 kWh per month (not the 30 claimed)

So the 30 kWh/month seems a bit of an overestimate. And our temp differential in the UK isn't that high. And we don't generally have 600 litre Westinghouse fridges in the UK

Looks to me as if the inventor multiplied by 30 days twice. Anyone see an error in above?]]> Green fridge DIY https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60446#Comment_60446 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60446#Comment_60446 Mon, 17 Aug 2009 18:52:10 +0100 DaveOxford
Can you set out the assumptions you have used in your calculation? I'm not sure I understand your method, but it looks as though you have assumed that no heat is lost between door opening episodes, and also that no new 'hot' objects are added to the freezer. Are you saying that it takes 387 joules to re-cool your 300 litres of air, or have I got the wrong end of the stick.

Bosch claim (and they are boasting) that one of their modestly sized upright freezers uses just over 200 kWh per year. If you are running a giant freezer on 1kWh per month, I want to know your secret, please.

D]]> Green fridge DIY https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60447#Comment_60447 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60447#Comment_60447 Mon, 17 Aug 2009 19:49:38 +0100 CWatters
Posted By: DaveOxfordJon,

Can you set out the assumptions you have used in your calculation? I'm not sure I understand your method, but it looks as though you have assumed that no heat is lost between door opening episodes..


Jon has calculated the energy cost of loosing the cold air and shown that that alone doesn't account for the claimed energy saving.

My guess is that chest _freezers_ are better insulated than upright _fridges_ and that this is where the real saving comes from.

Chest fridges aren't common because not everyone likes having to move all the baskets to get to things at the bottom. Chest freezers also take up more floor space in the kitchen.]]> Green fridge DIY https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60448#Comment_60448 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60448#Comment_60448 Mon, 17 Aug 2009 20:00:31 +0100 betterroof
I'm afraid my science/maths interface is in for repair ... :tongue:]]> Green fridge DIY https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60452#Comment_60452 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60452#Comment_60452 Mon, 17 Aug 2009 20:32:47 +0100 Julian Posted By: betterroofso is it good or not? and would the same technique work on an upright?
>

Well the originator claims that some of the saving comes from gravity - i.e. the cold air stays in the chest type freezer when it would fall out of an upright fridge or freezer. He does accept in his description of the process that the insulation in a chest freezer is probably better than in many fridges. But that can't be the whole story. Overall, if you were prepared to have the less convenient footprint that a top loading model would give, it does seem an improvment.
The originator may have exaggerated the effect as Jon suggests above but that doesn't mean it isn't an improvment.]]> Green fridge DIY https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60455#Comment_60455 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60455#Comment_60455 Mon, 17 Aug 2009 20:41:54 +0100 betterroof ]]> Green fridge DIY https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60481#Comment_60481 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60481#Comment_60481 Tue, 18 Aug 2009 09:58:32 +0100 jon
Yes, as CWatters says, all I did is look at my fridge to see if opening the door 10 times a day in mid summer really made that much difference:

I would guess freezers are much better insulated and it's the better insulation of the freezer (that he's using as a fridge) that cuts his costs down.

So the summary of it all seems to be that your fridge could be constructed like a chest freezer but that doing that won't make a huge difference (unless you have an empty fridge that you open 40 times a day and there happens to be a fan next to the fridge to flush out all the air): OTOH, the better insulated the fridge is, even if upright, the better the energy savings will be.

A better idea might be to have upright fridges with compartments and internal compartment doors?]]> Green fridge DIY https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60492#Comment_60492 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60492#Comment_60492 Tue, 18 Aug 2009 10:55:50 +0100 CWatters Green fridge DIY https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60513#Comment_60513 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60513#Comment_60513 Tue, 18 Aug 2009 12:47:58 +0100 djh http://www.rmi.org/sitepages/pid399.php]]> Green fridge DIY https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60517#Comment_60517 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60517#Comment_60517 Tue, 18 Aug 2009 13:04:54 +0100 DaveOxford
Thanks both for explaining that.

The internal compartment doors idea is interesting. The problem is that the air has to circulate (yes?) so that heat can be transferred efficiently. We already have open-topped trays that can be pulled out in our upright freezer. But, I notice my feet still get chilled when I open the thing, and this must be because there are gaps built into the design for the air to circulate above and around the food. A really clever design would block these gaps as the door opens, but open them again when the door is closed. I can imagine levers attached to the door that slide sheets over the vents to close them off when the door opens. Could the James Dyson among us comment on the trade-off between added complexity/cost and the savings? And would those savings be surpassed by adding more/better insulation?

D]]> Green fridge DIY https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60614#Comment_60614 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60614#Comment_60614 Wed, 19 Aug 2009 22:06:21 +0100 Terry see www.adande.com]]> Green fridge DIY https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60626#Comment_60626 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60626#Comment_60626 Thu, 20 Aug 2009 07:54:53 +0100 brig001 Green fridge DIY https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60645#Comment_60645 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60645#Comment_60645 Thu, 20 Aug 2009 13:18:11 +0100 DaveOxford
D]]> Green fridge DIY https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60696#Comment_60696 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60696#Comment_60696 Thu, 20 Aug 2009 22:19:45 +0100 Terry Green fridge DIY https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60731#Comment_60731 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=60731#Comment_60731 Fri, 21 Aug 2009 17:56:29 +0100 scott have been about for years , powered by pv panel]]> Green fridge DIY https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=61019#Comment_61019 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4432&Focus=61019#Comment_61019 Wed, 26 Aug 2009 18:36:37 +0100 CWatters