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What is an energy efficient way to get fresh air indoors during winter?
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46 votes

Good ventilation needs a strategy of its own accord. It doesn't just happen. It will depend on what climate zone you're in, and what your building is, but from your question, I'm going to assume that ...

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Why am I offered a 5 kW inverter with a 6.6 kW solar installation?
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31 votes

It could be that the system will spend such little time providing above 5 kW, once shading and losses are taken into account, that it's not worth the cost of getting the next-largest inverter. ...

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What are the pros and cons of electric motors vs. internal combustion engines?
24 votes

Electric motors generally: are easier to maintain are very efficient (80-90% compared to 20-30% for ICEs) have a very wide range of operating speed, so need no gears, or fewer gears, to move through ...

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Is there a difference in insulation to keep heat in or out?
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24 votes

In reality, yes, it probably does matter. In each case, it will depend on a lot of detail, so I'll discuss the theoretical concepts, rather than any one particular application. How heat is lost Heat ...

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Are electric cars as environmentally friendly as we think they are?
23 votes

EVs offer some definite advantages, and lots of advantages that depend on the specifics. short answer: yes, it's better than driving a fossil-fuel car. Long answer: it may seem to make less sense if ...

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How many kilowatt hours of electricity does it take to heat 180 litres of water from 15 to 60 degrees C?
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19 votes

Let's look at how much electricity and money can be saved by using solar thermal to heat a cylinder of hot water, rather than by using an electrical resistance heater. Assuming a 100% efficient ...

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Which type of portable electric heater is better?
15 votes

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 ...

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How can I get my landlord to install better insulation?
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15 votes

This is the classic agency-dilemma,or principal agent problem. THe one who should bear the cost, the landlord, doesn't see any immediate benefit; and any indirect benefit may be, or be believed to be ...

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Biodegradable cleaners to remove mold?
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15 votes

There are plenty of biodegradable anti-fungals. For example, cetrimide is water-soluble, anti-fungal, anti-bacterial and biodegradable. White vinegar also has anti-fungal and anti-bacterial ...

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Wind turbine vs. solar panel or both?
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13 votes

A specific answer to your very narrow question wouldn't be much use to anyone else; and you haven't given us enough information to give you a specific answer anyway. But what we can do, is give you ...

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Do "100% renewable" electricity plans increase renewable electricity production?
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13 votes

Do “100% renewable” electricity plans increase renewable electricity production? Well, it will depend on how the specific scheme is implemented, what the renewable suppliers are, and what timescale ...

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How can I add thermal mass to a woodstove, without a lot of weight?
13 votes

There are various ways to include thermal mass with a lower weight. Different substances have different specific specific heat. So, for a given weight, a material with twice the specific heat, will ...

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Is creating hydrogen fuel for the fuel cell from the solar panel worth considering?
12 votes

Yes, if you want electricity, it's much cheaper and more efficient to just use the electricity directly from a solar panel, than to do any transformation of that electricity into any other form, then ...

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Potential health risks with keeping temperature in a house low?
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12 votes

Humidity is a funny thing. The warmer that air gets, the more water it can hold as vapour. When that air cools down, it can no longer hold as much water vapour; if its humidity was high, then some of ...

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What advantages (any?) has water heating via photovoltaic system over solar thermal system?
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12 votes

Exergy PV is generally superior to solar thermal because it produces a higher-quality energy: electricity rather than low-grade heat: 1kWh of electricity has more exergy than 1kWh of low-grade heat. ...

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Long-term sustainability concerns of compact flourescent vs incandescent light bulbs
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12 votes

Both incandescent and fluorescent are quite old technologies, and have been bettered in terms of efficiency and lifecycle impact. Furthermore, compact fluorescents aren't the only type of fluorescents....

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What can I do as a developer for the environment?
11 votes

Professional The low-carbon sector employees a lot of software developers. For example, wind farm operators use SCADA systems to provide data on performance and to inform proactive maintenance regimes;...

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Transmit solar over multiple time-zones?
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11 votes

Yes, we can. Estimates vary of the losses in long-distance HVDC (high-voltage direct current) transmission, but they're around 3-4% per 1000 km. Now, those operate at far higher voltages than you've ...

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Why are Fresnel lenses not widely used in the production of solar electricity?
11 votes

This is built on, and directly quotes from, my answer and user26165's answer to a similar question over on Physics.SE. No, fresnel lenses are not widely used for solar power. Occasionally, but rarely. ...

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Is Using Blankets to Insulate Doors and Windows Effective?
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11 votes

Yes, heavy blankets can be effective insulation over draughty windows; or in open doorways to shut off an unused space: over both, they will hinder heat loss through convection (air currents), and ...

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Is it true that if you have a thermostat, then there is no such thing as 'waste heat'
11 votes

No, it is not true if you have a themostat, then there is no such thing as 'waste heat'. If you have a thermostat, there can still be such a thing as waste heat. Space The positioning and timing of ...

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Propane vs. Electric vs. Heat Pump
11 votes

There isn't a single reliable way that fits all circumstances. What we can do, is look at some of the factors that influence the pros and cons. Uncertainties within the green electricity tariff If ...

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Getting power from an innovative new mechanism
10 votes

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

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What causes photovoltaic (solar) cells to degrade?
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10 votes

The rate and types of degradation differ a bit depending on the panels. Common to all types is water ingress within the panel itself, causing corrosion of the wiring. Monocrystalline silicon (aka ...

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Is concrete a sustainable material?
10 votes

Concrete is made from sand, grit and (portland) cement; portland cement is made primarily of clinker. Almost all concrete at the time of writing is unsustainable. The extractive industries that ...

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Which gases increase the greenhouse effect more than carbon dioxide?
10 votes

Yes, anthropogenic emissions of CO2 are a real threat: the scientific evidence for this is overwhelming. The IPCC summaries provide, every 6 or 7 years, an overview of all the science. The most recent ...

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Are there projects that use renewable energy sources to create renewable energy sources?
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10 votes

While such a project is technically possible, I have to wonder: why bother? There already exists a huge energy infrastructure, warehouses full of photovoltaic (PV) waiting to be bought, electricity ...

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Alternative to Toilet Paper?
10 votes

Yes, there are plenty of suppliers, at least in the UK, that use recycled materials to make their toilet paper. You could also look for accreditation for sustainable sourcing: there are schemes such ...

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Is it possible to convert rain drops to energy?
9 votes

It's possible, but the best way to do it was devised over a century ago: hydro power. Let the high land collect and channel lots of rain, and then put a turbine on the channel. The problem is that ...

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Is gasoline or Diesel refining less sustainable, per energy output?
9 votes

tl;dr There really isn't a sustainability argument for switching either way between them: there is only an argument for switching away from both. It's akin to asking whether we should switch from coal ...

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