Hot answers tagged

25

I disagree that dishwashers, compared to hand washing, will not save energy. First of all, as with almost anything, it depends how it's done. If you run your dishwasher half full, that's going to be bad for energy and water use. Similarly, if you hand wash, with the hot water running the whole time, that's bad. So, either technique requires tuning the ...


20

Take a look at a passive solar heat collector. They work on the principle of thermosiphoning. The design in the link and the picture below has an additional top vent exposed to the outside so you can close the top interior vent and draw air out of the building during the summer. I've seen more advanced designs that include doors that automatically close at ...


20

General principles The important thing here is to realise what these heaters heat. Radiative heaters radiate infra-red light which strikes objects and heats them directly, heating the intervening air less. Fan heaters primarily heat the air in the room by forced convection. Oil filled radiators, work like ordinary central heating radiators, primarily ...


18

Water takes energy to pump, filter and treat (and the treatment chemicals require energy to make), so it's likely a substantial part of the water cost goes to energy anyway. Given that in your case you can save a massive proportion of water for very little extra electricity, I'd go with the water saving. Secondly, it's often possible to run a lower ...


18

Perhaps this article is what you are looking for? It's a study by the US Department of Energy on the life-cycle environmental and resource costs in the manufacturing, transport, use, and disposal of light-emitting diode (LED) lighting products in relation to comparable traditional lighting technologies. There is a similar study done by manufacturer ...


17

TLDR; don't use them for lighting. Given that you could keep your incandescent bulbs for when your current energy-efficient (I will assume CCFL) bulbs need replacing, your choice boils down to: buy a new CCFL; or use an incandescent that has already been manufactured. This helpful analysis gives the embodied energy in a CCFL as 1.7 kWh. Let's assume that ...


16

From http://www.treehugger.com/green-food/meat-eaters-guide-get-to-know-the-carbon-footprint-of-your-diet-lamb-beef-cheese-are-the-worst.html we have which I find pretty fascinating — certainly I would have put pork much closer to beef than either salmon or Turkey... really interesting stuff. I'd like to see as well the same graph but per calorie rather ...


16

Use the kettle if you have one, and if you're nearby, switch it off as soon as it boils. Here's some evidence to prove it's the best option: Method: Measure 252g of cold tap water into Frog Mug using electronic kitchen scales, being the amount I'd use to make a cup of tea. Temperature according to my thermometer is 18 degrees C. Plug microwave in through ...


15

I'll take a slightly different line to Mark Booth's excellent answer. fan heater: If you've got a lot of still air, and / or if you only want the heater on for short bursts, then the fan heater is probably best, because it will get the warm air circulating in the room, and it will respond quickly to being turned on and off. However, dust can settle on the ...


14

TLDR; cadmium telluride panels have the highest EROI of the mentioned PV panels (around 34.2) EROI estimates vary widely. This is because of differences in the method of calculation, scope of the study, installation location, assumed lifespan of a panel, etc. This also makes it relatively easy to manipulate EROI calculations. Pessimistic The most ...


13

i signed up just so i could make this comment. THelper♦ provided a good link to a DOE report on this topic, which i was researching because my roommate is skeptical about the advantages of efficient bulbs. the report THelper♦ cited has the following bar graph that pretty much answers the question:


12

Someone has done it. A majority of the electricity I buy comes from geothermal energy †. Of course, I live in the Pacific Northwest of North America, which puts me close to a tectonic plate boundary. This presents good conditions for extracting geothermal heat (since the earth's crust is thinner at such boundaries ... making shallower wells productive). ...


12

No. With nothing plugged in there is no circuit, so no current can flow. An exception to this is if the socket or the switch has an indicator light - usually a neon one - that is illuminated when the switch is on. In that case the light will use a (very small) amount of power.


11

I use them in garden/indoor. Something like this... (source : google search)


11

I live off-grid, so I did a lot of study on this topic. All used coffee grounds make good fertilizer. Drip machines seem to use a lot of energy, and they seem to use it for a lot of time. They also use disposable filters. Drip machines are kind of on the off-grid "blacklist". Percolators waste a lot of energy because they have to keep the water boiling ...


10

Water loss is not the issue, because you need a lot of water to make it work at all. Even if your dams lose 30% of their water every year, that's about 0.1% per day. System losses in the best large-scale systems are about 20%. In other words, 70-80% efficiency of large scale systems (wikipedia). The big issue, though, is likely to be making it work at all. ...


10

No, you cannot get more energy out than you put in. No, you cannot invent a perpetual motion machine.


9

If you have the property, and resources, make sure your house is tight. Then, dig a four foot trench that zigzags across a suitable part of your yard, taking care to call Mis Dig for location of underwater electrical, water, and gas lines. Lay PVC pipe into the trench, making sure it's water tight. Bring one end up from the ground, above the maximum snow ...


9

The answer you are looking for would be contained in a Life Cycle Assessment (LCA). For an LCA you first want to determine the boundaries that are important to your question. Are you considering cradle to grave (disposal)? Cradle to cradle (recycling after use)? What are the boundaries for recycled source materials if used to make the light bulbs? The ...


9

Well, I'm by no means an expert on giving this answer, and yet I'll take a go at providing something reasonable. Assuming a 1ha biodiverse, properly hydrated, young stage forest with optimal leaf coverage that gives us a solar catchment area of 10,000 square metres. Subtract say 20% to account for immature trees amongst the larger growth, another 20% for ...


9

I disagree with the answers that say not to use it. It may in fact be an excellent idea to use it if: you live somewhere that requires your home to be heated in the winter you currently heat with electricity or with something less efficient than electricity The "wasted" energy from an incandescent bulb is wasted as heat. In the summer, this is really bad ...


9

Sort of. Consider the pay back time. high efficiency lights are expensive. Expense is, at least in part, a measure of the resources used to make it.* Replacing the fixtures in the kitchen where the lights are on 8-10 hours a day is probably a good idea. Replacing the lights in the hall closet that runs 20 minutes a week is not. Example: Our kitchen has ...


8

Generally, no they're not. For a combination of several reasons the tracking system itself has a high capital cost. static PV systems are extremely low maintenance. Tracking PV systems are not. adding a tracker means bigger spacing between groups of panels, so that they don't shadow each other The net additional energy yield isn't that high: for PV, ...


8

Constraints There are several aspects to energy storage, that can make one form better than another for a given set of circumstances. Cost is usually the biggest driver. Energy can be stored at pretty much any scale you like, and cost is typically the constrainer. There are additional constraints for within-household energy storage: in particular, safety, ...


8

tl;dr: Yes, lowering the room thermostat at night will generally help save energy, assuming we are in the heating season (winter), rather than the cooling season (summer). Let's take two points in time, one before the night, one after it. Let's choose them so that the dwelling has the same amount of heat energy contained within it at each point, so all the ...


8

Air is much more energy intensive. Gucwa and Schaefer looked at the impact of scale on energy intensity in freight transportation, and the chart below is taken from that paper. They looked at varying loads, across four modes - the line in the lower left is trucks, the cluster above it is air, the long spread-out light grey dots in the bottom-right is ships, ...


8

Electronically they're the same and will waste as much energy as a conventional adaptor. Depending on your electrical regulations they may be forced to be at the good end of adaptor efficiency, or they may be at the very cheap end. This will be a matter of safety regulations, but the cheapest designs fall down on safety and efficiency. I hunted for one ...


8

It is common knowledge that hot air rises and cold air sinks. Inside a fridge the coldest air will be in the bottom of the fridge. As soon as the fridge door is opened cold air from the bottom of the fridge drops out onto the floor of the room where the fridge is located. This air is replaced by room temperature air entering the top of the fridge space. ...


8

To determine the power used when the computer is in sleep mode you can acquire a power meter that plugs into a power outlet & measures the electricity used by devices that are connected to the power meter. This has been done by one person who posted the results online. The summary states: The standby mode power consumption is just a bit more than ...


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