Questions tagged [energy-efficiency]

Questions about ways to measure and improve the ability to get useful work out of devices that consume energy. This includes coal, oil and gas as well as electricity.

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1 answer
97 views

Real world difference between a 0.18 W/m^2k U-value and 0.22 W/m^2k U-value

I'm currently choosing the thickness of the PIR insulation I will use for the ground floor (first floor US) in my house. It's a traditional (UK) suspended timber floor build with concrete foundations ...
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23 votes
4 answers
6k views

Why would a particular heat pump model be illegal in my state?

I am trying to replace an electricity-hungry whole-house electric furnace with something that will be more cost-effective. I live in a high-altitude part of New Mexico, where I don't need to use much ...
  • 897
0 votes
2 answers
42 views

Is there more to consider than the R-value when installing stucco in the Southwest?

I live in the Southwest and notice 90% of the homes in my area are stucco. Since I'm considering wrapping the house in an additional layer of insulation, then new siding, I am considering stucco. Many ...
  • 897
3 votes
4 answers
1k views

Are new aircons with less BTUs more efficient than the older ones?

I am trying to replace the air conditioning device at home but I am not sure how to compare my old Panasonic that was bought in 1999 (possibly model of 1997 or 1998). Some facts: I was not able to ...
1 vote
1 answer
72 views

Should the door be open or closed between two separate HVAC systems?

We recently built out an additional 600sqft theater room in our attic. It’s a big room with 14’ high vaulted ceiling. We live in Houston and room heat load is fairly high. We installed a 2-ton unit ...
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31 votes
11 answers
8k views

Why are so many radiators installed beneath a window (at least in Germany)?

I live in Germany and I always wondered why the radiators in most apartments are installed right beneath a window. The pictures below show an example (this is an older building, but you see similar ...
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0 votes
1 answer
64 views

Home energy monitoring in split floor with one compressor

I have an odd situation where I live on a floor split in two and I want to split the electricity bill fairly with my floormate. I am looking at the home energy monitoring systems that have all the ...
0 votes
0 answers
38 views

Radiant Barrier: with or without Insulation?

Researching an attic radiant barrier for my old home has yielded two general classes of radiant barrier: simple films and then sandwiches of film/insulation/film. Is there really much benefit to ...
2 votes
1 answer
123 views

increasing R-value for old vaulted ceiling

I have vaulted ceilings in the main living space. Internally there are 2x6 joists between the roof and the drywall and the insulation I am guessing is original from the 1960's so this section of roof ...
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3 votes
3 answers
831 views

Is it more efficient to heat a room using an air conditioner (heat pump) when the windows are open?

In general, using an air-conditioner for heating is more efficient than a standard electric heater or radiator. But in our home, we keep the windows open all the time, in order to decrease the chance ...
19 votes
7 answers
7k views

Why is my house energy efficient only in winter?

My electric utility company sent me a graph of my home's electricity usage over time as shown in the picture below. My home beats what the company considers as efficient homes in the neighborhood when ...
0 votes
1 answer
80 views

Using water cooler for CNC laser as residential heat pump

I want to save money on heating bills. Residential heat pump systems cost thousands of dollars, which I can't afford. I am considering using a heat pump marketed to chill water for cooling CNC lasers (...
2 votes
0 answers
39 views

Where can I find the efficiency of my heat pump with respect to temperature?

I can heat my house either with a standard gas heater, with a documented efficiency of 0.9, or with an heat pump, with a standardized coefficient of performance (Seasonal Coefficient of Performance) ...
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7 votes
2 answers
2k views

(When) Does room messiness affect water heater efficiency?

I have what I think of as a "standard US electric standby water heater." I will update this when I know the model; I am out of town right now. It is located in a cold, cluttered closet in a ...
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1 vote
2 answers
129 views

Most efficient heating system @ ~41° N

I'm researching building a home on a property I just bought. Water is plentiful but there is little or no chance of getting municipal services such as natural gas or electricity. However I have open ...
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5 votes
1 answer
182 views

How do the old and new (post-2021) EU energy labels for LED light bulbs compare?

One of my light bulbs recently failed, for the first time in a few years, and I had to go buy a replacement. Usually I try to look for the ones with the best EU energy label rating, since not only do ...
2 votes
2 answers
226 views

If I live in the US Southwest, would a heat pump or conventional dryer use less energy?

Suppose I live in Poway, CA (weather), where temperatures are roughly between 50 and 90 F throughout the year and relative humidity is generally between 40 and 60%. With climate change the highs have ...
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2 votes
0 answers
110 views

What is the optimal number of solar panels for my house?

Just had a solar power tech stop by. With the orientation of our house and the solar load, our property (house + workshop) can support roughly 41 panels. Each panel provides 370 W (max)...which ...
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3 votes
6 answers
11k views

120v vs 240v Mini Split Efficiency

I am under the impression that, as a general rule, 110v heating and cooling options are inherently not very efficient. So I was surprised to find a 120v mini split shopping around with a fairly decent ...
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1 vote
3 answers
169 views

Is there a low-e alternative to double-pane gas-filled window panes?

I spoke with a local glass retailer and he said instead of using double-pane gas filled windows, I could instead use a 3-layer sandwich of, say, 1/8", 1/4", 1/8" panes to achieve the ...
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24 votes
8 answers
6k views

How to find electric device(s) driving a high electric bill?

The cabin electric bill came and I gave it what I thought would be a cursory glance and it looked unusually high. Not just for this cabin, but in my experience with our houses. Our main house is a ...
1 vote
3 answers
451 views

Why is Condenser energy guide rating different from advertised?

I'm installing a Carrier 24APB6 which has advertised up to 17 SEER. The seller tells me it is a 16 SEER unit but the yellow Energy Guide sticker on the condenser gives it a SEER rating of 14 on a 13-...
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35 votes
9 answers
9k views

Can I gain AC efficiency by spraying condensate water on the outdoor coils?

Recently, I was working from the basement and I noticed tonnes of condensate water going down the drain, and thought I might re-use it to improve the efficiency of my home AC system. So I put a ...
-1 votes
1 answer
93 views

same-sized alternatives to F14T12 bulb

I have two bathroom light fixtures with very old magnetic ballasts and F14T12 fluorescent bulbs. These are, of course, a 1.5-inch diameter. I've been doing some bathroom renovations and I thought this ...
24 votes
13 answers
5k views

Do smart or programmable thermostats actually save money?

I am looking at replacing all the thermostats in my house. I have hot water baseboard heat and forced air A/C. Each room's baseboard heat is controlled by a thermostat in that room. I tend to prefer ...
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1 vote
0 answers
39 views

How can heat pump water heaters be more efficient when they just use heat from heated space? [duplicate]

I understand the principle of heat pumps, and it makes sense that a heat pump / AC split system is more efficient then for example resistive heating for heating a house. In this case, the heat pump ...
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3 votes
2 answers
139 views

How could I insulate a thin hot roof and bring it to current Southern CA code?

So we started an exterior remodel today, and found that our roof construction is way more mickey mouse than I thought it was. Our house has vaulted 2nd floor ceilings through most of the 2nd floor ...
2 votes
2 answers
79 views

Is there any considerable advantage to a forced air-to-air heat exchanger over just cleverly positioned positive pressure forced air intake?

This is from a typical North Western European housing perspective where most (older) buildings will not have forced air/AC/heat pumps etc. for various reasons, and most houses are only heated using ...
2 votes
2 answers
227 views

Replacing 2 hot water heaters with 1

I've recently purchased a home that has two hot water heaters - one at each end of the house. One in the garage, one in a closet. They're both showing their age, and both cost quite a bit to operate. ...
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2 votes
1 answer
59 views

Determine highest "carbon reduced per dollar spent" option for reducing pollution generated by home?

I've been talking with friends and coworkers about how I can reduce the amount of pollution generated by my house (heating the air, heating the water, cooking the food, etc.) Everybody has a ...
1 vote
1 answer
62 views

Would down-stuffed curtains stop heat loss through windows?

My home has some very big 6 ft by 8 ft windows likely a big source of heat loss and is contributing to high heat bills. It would be too expensive to replace them with modern vinyl windows and the ...
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0 votes
1 answer
653 views

Run mini-split heat pump heads at different temperatures

I vaguely remember the contractor who did maintenance on our ductless heat pumps two summers ago telling us not to set the thermostats of the two small heads that share an outdoor unit to different ...
0 votes
2 answers
349 views

Why does G23 energy-saving lamps need ballast, LED type as well?

IKEA Lival desktop lamp (like this) uses a huge adapter plugging into power-socket, which should be a ballast/transmitter. The lamp uses a G23 bulb from e.g. OSARAM DULUX S11 W. I feel it is very ...
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0 votes
3 answers
51 views

Letting a thermostat regulate temperature, or do it myself? [closed]

I always hear people say that it is more efficient to let a thermostat regulate the room temperature. Well, I do not have a thermostat, but I have an electric heater with on internal one. Not a exact ...
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0 votes
2 answers
288 views

California Title 24 implications for bypassing ballasts in my 4-pin (GX24Q) fixtures

I've gotten fed up with the recessed 4-pin GX24Q fixtures in my kitchen that were required by California Title 24, after removing a burned out (and relatively expensive) CFL, cracking it in the ...
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1 vote
2 answers
134 views

Removing excess HVAC ductwork for efficiency

I have central ac in my home and at some point the kitchen was redone, blocking an existing vent permanently. The flex HVAC ductwork leading to the vent (probably 8 feet of it) is still there. Should ...
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0 votes
3 answers
193 views

Do plugged in chargers always use up energy? [closed]

I always make sure that all chargers with no device attached (mostly laptop and phone chargers) are unplugged so that they don't use up electricity. I guess it used to be a reasonable approach. I was ...
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1 vote
0 answers
67 views

How best to capture and move the heat from oil furnace stove pipe more efficiently throughout room

In my basement the stove pipe that goes from the oil furnace to the chimney is always hot, so I feel like I should be capturing this extra heat and moving it about the basement. How do I keep this ...
0 votes
1 answer
61 views

How will a hybrid water heater perform in less than optimal conditions?

I'm thinking of getting a heat pump hybrid water heater (this one maybe); The operating conditions will be technically within the prescribed range but less than optimal. I'm wondering how I should ...
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0 votes
1 answer
46 views

Using radiant barrier to keep a room warm [closed]

I have been told (including in comments by awesome user Unslander Monica) that a foil sheet placed on the interior side of an air-sealed window can help prevent radiative heat loss through that window....
  • 461
0 votes
1 answer
55 views

Window film affixed to the wall around a window?

Useful related questions: here, here. I live in an apartment with a window that I want to insulate during the winter. I am currently using one of those shrink film kits and it seems to be working. ...
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1 vote
1 answer
230 views

Can I use two layers of window film to create a narrow, convection-reducing gap?

This is a follow-up to this question. The official answerer A.I. Breveleri writes: The ideal separation distance between film and glass is 1/2 inch. Even 1 inch is too thick as it allows the trapped ...
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0 votes
1 answer
58 views

To maximize heat in winter, should I remove my window quilt during the day?

Let's say it's -5 deg C outside and I'm inside a building with a moderately efficient window and a window quilt. Will I stay warmer if I take the window quilt down during the day and put it back up at ...
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0 votes
0 answers
21 views

Wool batting window quilt? [duplicate]

Would it make sense to use wool batting like this as a window quilt? Why or why not? What factors would affect its suitability? For context, I propose using this on the inside of one of those shrink ...
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0 votes
1 answer
70 views

Aerogel winter window quilt?

Would it possibly make sense for me to use aerogel as a seasonal window quilt? It may depend critically on some other factors; if so, what are they? In particular, I have heard that aerogel designed ...
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0 votes
0 answers
18 views

R-value of textiles

Does anyone know of any good sources of information about the R-value of various textiles, like blankets and quilts of various materials/thicknesses in various conditions?
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1 vote
3 answers
158 views

Help me test my electricity usage monitor?

I just got one of these; I love it and it seems accurate. But I would like to check its accuracy. Can anyone think of an appliance with very predictable constant power consumption that I could use to ...
  • 461
0 votes
1 answer
48 views

How does denim insulation perform at low ambient temperatures?

I am interested in how denim insulation like this performs at low ambient temperatures. Does anyone know? I am most interested in performance measures like R-value and what other factors affect this. ...
  • 461
-1 votes
1 answer
74 views

Insulate my window with water heater blankets?

I have some windows that I want to insulate at night during the winter. Would it make sense to use water heater blankets, doing something or other to secure the edges? I'm wondering whether you think ...
  • 461
2 votes
1 answer
779 views

How does the insulation value of multiple layers of insulation compare to a single layer of the same total thickness?

If I insulate a surface with two sheets of rigid foam insulation with thickness x, or with one sheet of otherwise identical rigid foam insulation with thickness 2x, how should I think about the ...
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