Author Topic: Why does refrigerator/light efficiency matter?  (Read 862 times)

Seadog

  • Stubble
  • **
  • Posts: 159
  • Age: 35
  • Location: Halifax, NS
Why does refrigerator/light efficiency matter?
« on: January 27, 2019, 12:11:00 AM »
I see everywhere "high efficiency refrigerator!, low power LED" etc etc. I've always sort of felt: who cares? Whether the power to heat your home comes from heating up a tungsten element(with added light) or compressing R134a (with added cooling to keep food cold/prevent spoiling) or convention slowing down electrons in an element or burning oil, isn't heat heat?

Provided you're in a climate where the predominant climate control is heating, why does efficiency in these appliances matter? Isn't every Joule of energy emitted from a light bulb or fridge due to "inefficiency" is one less Joule that comes from a conventional heating source? By their logic it seem that electrical space heaters are the least efficient of all!  Mind the hyperbole, but it seems they've pegged the value of not freezing to death at zero.

Goldielocks

  • Walrus Stache
  • *******
  • Posts: 5988
  • Location: BC
Re: Why does refrigerator/light efficiency matter?
« Reply #1 on: January 27, 2019, 01:46:48 AM »
Well, I am in a heating climate, but heat has for the furnace is currently 7x cheaper per btu than efficient electric heat.   I have the same logic as you do, however, about not worrying too much about wasted hot water tank heat...  Ok and the halogen lights.

Truth is, I want the heat in the living room, not the kitchen which I don't sit in, and has the oven heat anyway.  So the fridge not running efficiently is a loss for me.

ETA:   WTF with my lack of typing skills?!   I have now corrected.   I should not try to type on my phone.
« Last Edit: January 27, 2019, 11:32:56 PM by Goldielocks »

deborah

  • Walrus Stache
  • *******
  • Posts: 8190
  • Location: At Home
Re: Why does refrigerator/light efficiency matter?
« Reply #2 on: January 27, 2019, 03:43:28 AM »
The last time I bought a refrigerator, it used half the energy of the previous one (my measurements), and therefore I am paying half as much for the electricity as I was before. In fact, I went through my house, and did things here and there, and halved my entire electricity, gas and water bills. Saves my money if nothing else.

Ecky

  • Stubble
  • **
  • Posts: 166
Re: Why does refrigerator/light efficiency matter?
« Reply #3 on: January 27, 2019, 05:58:15 AM »
the furnace is currently 7x cheaper per btu than efficient electric heat.

This.

Plus in Vermont (one of the colder states in the continental US) I only have heat running maybe 5 months out of the year. The rest of the time the extra energy is just lost.

In hot climates every extra BTU you dump in your house costs you twice, since you not only have to pay to get that heat but also pay again to remove it from the house.

pecunia

  • Pencil Stache
  • ****
  • Posts: 820
Re: Why does refrigerator/light efficiency matter?
« Reply #4 on: January 27, 2019, 08:27:27 AM »
These are modern times.  We face a problem today not seen in human history.  Folks, I'm talking climate change here.  Appliances that gobble unnecessary energy cost you more money and also cause the use of more coal or natural gas.  Both if it is burned or unburned natural gas is a greenhouse gas. 

I guess eventually with global warming your heating costs will be less, but there will be a cost.

You can figure your energy comes from nukes, windmills or hydro and this won't do the greenhouse thing, but most of us still get our electricity from burning stuff to turn a turbine.

I am not one of these people that go environment crazy, but it's something to think about.

BudgetSlasher

  • Pencil Stache
  • ****
  • Posts: 603
Re: Why does refrigerator/light efficiency matter?
« Reply #5 on: January 27, 2019, 08:42:12 AM »
I see everywhere "high efficiency refrigerator!, low power LED" etc etc. I've always sort of felt: who cares? Whether the power to heat your home comes from heating up a tungsten element(with added light) or compressing R134a (with added cooling to keep food cold/prevent spoiling) or convention slowing down electrons in an element or burning oil, isn't heat heat?

Yes heat is heat, but . . .

Quote
Provided you're in a climate where the predominant climate control is heating, why does efficiency in these appliances matter?

Because even in most heating dominant climates there is a season where you do not want heat. Here in Maine we (as in my family) only heat roughly 5-6 months and many people run some sort of air conditioning in the Aug-Sep range (most years we don't). Many summer days are spent with the blinds closed during the middle of the day and the windows open at night to let in the cool air for the next day. The last thing I want to do is add heating load when I am already debating whether to bring the window unit up to the master bedroom.

Quote
Isn't every Joule of energy emitted from a light bulb or fridge due to "inefficiency" is one less Joule that comes from a conventional heating source? By their logic it seem that electrical space heaters are the least efficient of all!  Mind the hyperbole, but it seems they've pegged the value of not freezing to death at zero.

Here the cost per BTU looks like (excluding cost to install):

heat pump (when it isn't too cold) =< natural gas < purchased wood < pellets < high efficiency fuel oil < propane < electric resistive heating.

The waste from inefficient appliances falls in the electric resistive heating (the most expensive option).

TLDR: In short electric resistive is the most expensive form of heating in many location and even in heating dominant locations there are considerable parts of the year where additional heating BTUs are unwanted.

« Last Edit: January 28, 2019, 05:07:15 AM by BudgetSlasher »

maizeman

  • Magnum Stache
  • ******
  • Posts: 3288
Re: Why does refrigerator/light efficiency matter?
« Reply #6 on: January 27, 2019, 08:54:57 AM »
To be really simplify, let's assume that you live in a climate where it is always cold enough you need to heat your house and you have exactly two options to generate that heat:

A) Buy natural gas from your local utility to burn for heat.
B) Buy electricity from your local utility (generated using a natural gas power plant, because those are some of the cheapest to build and operate at the moment) to run an electric appliance where all the energy consumption ultimately ends up as waste heat.

For option A, to provide yourself with 10,000 BTUs of heat you can use 11.7 cubic feet of natural gas. (One cubic foot of gas = ~ 1,000 BTUs, you've got a non-high efficiency furnace where 85% of fuel is converted to heat in your house and 15% is wasted, if you wanted you could buy a 95% efficient furnace and need even less natural gas to produce the same amount of heat inside your house it'd just cost a bit more).

For option B, we burn the same natural gas in a power plant to create heat which is then converted to electricity. Under ideal conditions in a conventional natural gas power plan 38% of the energy in the natural gas makes it to the form of electrical energy (the rest ends up as heat at the power plant). You lose another 4% off the top from transmission losses (heating up power lines) and distribution losses (heating up transformers), so .38 * .96 * . 96 = ~35% of the energy in the natural gas makes it into your house. Once it is in your house you use it to run toasters and refrigerators and incandescent light bulbs until you've generated 10,000 BTUs of heat energy. In order to provide enough electricity for you to do so, your utility has now burned 10/.38 = 26.3 cubic feet of natural gas.

Prairie Stash

  • Handlebar Stache
  • *****
  • Posts: 1688
Re: Why does refrigerator/light efficiency matter?
« Reply #7 on: February 01, 2019, 08:21:42 AM »
In the winter natural gas is about 10-15% of the cost of electric heat.

In the summer if you ever run AC, you are paying to produce the heat and remove it. Even without AC, your house will have extra heat, in the summer that sucks. The greatest savings from high efficiency appliances comes from the avoidance of AC.

https://www.nspower.ca/en/home/about-us/environmental-commitment/air-emissions-reporting/total-system-emissions-all-plants.aspx
From an environmental perspective, each kWh of electricity in Nova Scotia emits 656.5 grams CO2 in 2017. If you use electric heat, your carbon footprint is massive. You can achieve the same heating of your house at a fraction of the emissions with natural gas.

You can also see massive savings by avoiding AC in the summer; lower heat from appliances in the summer means its less likely your AC will turn on if you have one, and if you don't it just means you house won't get as hot/uncomfortable. Remember, those inefficient appliances work year round, whatever you gain in the winter you lose in the summer.

The last reason is comfort; high efficiency appliances tend to be quieter and run less. I would also add that LED bulbs don't get as hot, they're awesome for nightlights and bedside lamps (I can't be the only one who's accidentally touched an incandesent bulb).

So that's three reasons; cost savings, reduced environmental impact and comfort.

Prairie Moustache

  • Stubble
  • **
  • Posts: 141
  • Location: Somewhere Flat
Re: Why does refrigerator/light efficiency matter?
« Reply #8 on: February 13, 2019, 12:51:17 PM »
Pretty similar numbers in Saskatchewan, I got data straight from the horses mouth and for us it's about 631 g CO2/kWh.