How to work out energy used?

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ericmark
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How to work out energy used?

Post by ericmark » Wed Dec 27, 2017 12:57 pm

It seems easy until you place items in your house. So tumble drier, put an energy meter on the plug and you can measure the electric used. I can also use the washer/drier and also measure electric used. however with the tumble drier I am pumping air heated by the central heating out side as well.

This is just an example, there are many more where some part can't be easy measured. Be it a tungsten lamp which is heating as well as lighting. Or even the size of a dish washer when you use a tablet be it 10 or 20 placinģ.
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Re: How to work out energy used?

Post by big-all » Wed Dec 27, 2017 1:08 pm

with my old 1600 spin speed washing machine and moisture sensor tumble dryer
i worked out a cold fill 1hr cycle and full tumble dry cost about 30p total at around 12p a kwh so stopped worrying as micromanaging the situation would at best save perhaps 2p a wash or 1-£2 a year maximum so not worth any effort :lol:
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Re: How to work out energy used?

Post by Rorschach » Wed Dec 27, 2017 2:53 pm

Make a heat exchanger for the tumble drier and you can recover a large amount of the heat in the winter. Though to be honest for the effort involved it likely isn't worth it.
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Re: How to work out energy used?

Post by big-all » Wed Dec 27, 2017 3:19 pm

i recon total amount used to to dry a load about 1.25-1.5kw or 15-18p at 12p kwh
if you can recover say 20% thats 3-4p per load at 2 loads a week thats about £3-3.50p a year :dunno:
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Re: How to work out energy used?

Post by Rorschach » Wed Dec 27, 2017 3:53 pm

Made from salvaged/recycled materials you can build one in a couple of hours for just a few £'s in parts, whether that is worth it is another matter as you say big-all. Myself I probably would, not so much for the money savings but for the bonus of "free" heat and the fact I think it would be an interesting and useful project. Then again I also would like to build a heat exchange air vent if I am able to in a future house, partly because it would be useful, partly because it would be an interesting project.
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Re: How to work out energy used?

Post by big-all » Wed Dec 27, 2017 4:02 pm

i think the trouble is the airflow rate and relatively high temperatures mean a big bulky heat exchanger
then because you dont want to waste energy half the time you could use the heat recovered you dont use the tumble but hang the washing out
then then for 25% off the year you dont need the heat as its summer time :lol:
you also need to remember any fins or bends to control the airflow and recover heat may both clog up and overly restrict the airflow causing the machine to operate above temperature cutting out on the safety cutout rather than the normal thermal cutout :dunno:
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Re: How to work out energy used?

Post by kellys_eye » Wed Dec 27, 2017 5:12 pm

Is there a reason (point) to the exercise?

Any energy you can't recover is wasted energy and as daft as leaving the front door and all the windows wide open in winter. In theory you could calculate the u-value for all the walls, roof and floors and calculate the potential heat loss through them but given a lot of the heat comes for the occupants anyway are you prepared to measure the calorific input/output to take these into account for an overall figure?

As a mental exercise it may prove interesting to discuss the various methods required to achieve this measurement but it is a totally impractical actual task.

As ever, make savings in those areas where the largest power transfers occur and concentrate less on the lower powered systems. The energy loss attending to some 'power saving schemes' is probably greater than the value of any financial saving you can make.

Aim to have better 'personal' insulation - decent clothing.
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Re: How to work out energy used?

Post by ericmark » Thu Dec 28, 2017 4:35 pm

I think the idea of heat recovery with tumble drier air or a hob extractor has a problem with fluff or fat build up, however in general the idea of the heat recovery system is good.

As to how much heat is recovered is another thing, I have been supprised how much energy is used by devices which are not switched on, in the main older stuff pre-switch mode power supplies. However it is only a problem in the summer, in the winter all energy ends up as heat anyway.

However in the summer it's not so much wasted energy as over heating the house. But unless one knows how much heat is lost of gained you can't work out which items need extra control.

In a caravan I found a fan behind the fridge blowing the warm air outside really made a diffrence, the caravan stayed a lot cooler.

Tried using a remote switch to switch the TV and all connected items off, it was a failure, the recorder would clearly not record but times and dates also had to be reset and so it simply did not work. The same applies to many more items, either a date or time needs setting, or a button needs pressing for it to work, I had same problem with a battery charger why it is designed so you need to press a button I don't know, but that's how they are designed.
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Re: How to work out energy used?

Post by kellys_eye » Thu Dec 28, 2017 5:12 pm

This is what happens when you have a Government in thrall to green energy - you find yourself counting the most insignificant energy costs in order to cope when, under ordinary circumstances, they could be passed off as 'inevitabilities' ....
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How to work out energy used?

Post by ericmark » Tue Jul 16, 2019 9:16 pm

When changing our house we had energy surveys done. However they seem to be a tick the box exercise, I know my father-in-laws house was far better than mine, with triple glazing, well fitting doors, solar panels yet the survey showed one point better than mine, and since identical design, being next door but one, there is clearly no other factors.

As to poorly fitting doors or windows, not really sure how one could test them? But for existing houses there must be energy bills so although can't show if people have house warm or cool they can show where some thing is clearly wrong.

This house not a clue how last people heated it, it was clearly warm when we viewed it in February, but when we moved in late May, and after getting oil tank filled, we could not get radiators to warm up, some turned off, but those that did work seemed cool, looking further we found the pump for circulating radiator water was on a 13 amp plug, once plugged in, main house radiators worked.

So on further investigation found no thermostat in main house, there were only two wires between main house and flat under it where the boiler is located, and DHW is simple thermo syphon.

So DHW not much I can do, however there is the question, in summer, is it best to use the oil boiler, or the immersion heater? There is some waste using oil, the pipes between boiler and cistern are heated and cooled every time the boiler fires up, and that heat is lost, and only control I have is time, at the moment 1/2 hour 4 out of 7 days, use boost if the water does not feel hot enough in taps.

I have considered a timer on the immersion heater, so the oil will fire for 1/2 hour, then the electric for an hour, the latter to ensure water temp over 60 degs to kill legionnaires, as to if really needed not sure.

Rooms in the house have doors, so central heating could be programmed different for each room, as to if this saves energy, not so sure, insulation in internal walls is rather poor, so turning off office heating may make very little difference? However I have 4 electronic TRV heads paired to Nest so three down stairs rooms will all be same temperature as the Nest wall thermostat which controls the boiler. Upstairs using blue tooth heads, cheaper than the wifi, but still allow a program to be set, so bedrooms not heated in the day, and office and craft room not heated at night.

I have ordered 5 blue tooth heads, 4 I know where they are going, the fifth not so sure, I have down stairs kitchen and toilet/shower, and upstairs bathroom, the latter at moment has no TRV fitted, likely fifth will go in kitchen.

But then it's down how to program? With the 4 Energenie TRV heads linked to Nest, one can program in an over ride, so at night hall could be set to 16 deg C but dinning room and living room to 14 deg C. But in the day all at 20 deg C linked to Nest wall thermostat, clearly since Nest thermostat in the hall the hall TRV head will always be linked, but as to rest?

Pre the electronic head on the TRV we would not fit one in same room as wall thermostat, but with the ability to link wall thermostat to the TRV so all change together, the whole concept changes, they will not fight each other as linked. Also being able to program each room independent changes how central heating is run, and even maybe radiator sizes, where larger radiators are fitted to allow fast warm up of key rooms.

If I have been on holiday I will likely turn heating down to say 10 degrees while away, on return I want to walk into a warm house, three rooms I can set to warm up anywhere with mobile phone coverage, other 5 rooms must wait until I arrive home, however unlikely we will go straight to bed so there is time for other rooms to heat.

But will it work out that way? Would you consider closing down a rooms heating in winter? Is that getting rid of the whole idea of central heating, I have a open fire able to burn logs in centre of house, is that maybe the best central heating?
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