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I live in a relatively modern (built 1983) home, which has a fireplace in the living room. How should I decide if I should use the fireplace for heat, or strictly use use the natural-gas central heating system?

I have an open fireplace, situated roughly in the center of the living room, which in turn is in the center of the house. The fireplace will not completely replace the central heating system, but if it will help reduce my environmental footprint, I'd love to use it to reduce my NG usage.

And although I think it's slightly tangential, in response to some other comments/answers, I will only be using free firewood.

lemontwist
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Flimzy
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    Can you give more details on your fireplace? Is it an open fire, or not? Does it have a type approval (e.g. in the UK, DEFRA-approval) And ideally a photo - it will at least give us something to start on. – 410 gone Jan 29 '13 at 21:20
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    @EnergyNumbers: Question updated some... I'll try to include a photo when I return from my vacation. I don't know anything about a "type approval." – Flimzy Jan 30 '13 at 17:09
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    Fireplaces ought to be banned. They're extremely polluting and biomass burning in general is very deadly indeed. – gerrit Sep 07 '18 at 16:58

5 Answers5

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I tend to think renewables (like wood) are a more sustainable heat source than natural gas. There are tradeoffs of course. Most fireplaces are pretty inefficient and can result in a lot of particulates. A wood stove (sometimes mistaken for regular fireplaces) or a pellet stove ensure much more complete burning of the fuel (wood), but require an extra up front investment and represent some embodied energy. If you're not burning enough wood energy to make up for the embodied energy of the wood insert, that's probably not worth the investment.

Another thing to consider is the positioning of the fireplace. Is the fireplace in a central location? If it's off to one corner of the house, you may have more heat radiate outside the home than you actually benefit from inside the home.

Finally, do you have a source of good dry wood? If you're buying wood that gets shipped from somewhere other than your own property, the fuel required for transportation may offset the relative carbon savings of using a biofuel.

rethinkag
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  • As an alternative source of fuel, I recently saw an episode of 'Invention USA' where a man had modified a wood splitter to use as a leaf compacter, creating a log to burn, while retaining the splitting functions. I believe they set him up with DR Power Equipment to negotiate a manufacturing deal. This may allow the OP to clean the yard and provide fuel for the fire at the same time. – Prymaldark Feb 03 '13 at 14:09
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    Wood can be a renewable, but the way almost all wood is harvested, in practice, is not sustainable. The wood people tend to use is what's available, and hasn't been selected for its overall efficiency as a fuel. – Nate Apr 21 '13 at 22:19
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    From an environmental point of view, it's hard to do worse than burning wood. See this Guardian article. Burning wood kills 250,000 people per year. – gerrit Sep 07 '18 at 16:54
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    Re to yesterdays comment: you may be able to do less bad depending on the type of fireplace. – gerrit Sep 08 '18 at 21:02
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Open fireplaces provide minimal heat to a house, as the warm air heads out the chimney, while cool air is sucked in to the house to replace it. This is a great feature when cooking over wood in the summer, but it's not helpful for staying warm in the winter.

You can buy a woodstove insert that will improve the efficiency, keeping more of the heat in your house.

If you are interested in a major project, look at high thermal mass stoves, which can be extremely efficient when burning wood.

As rethinktag mentions, moisture content of wood is extremely important. All the latent moisture in wood must be evaporated before the wood can get hot enough to burn. Wetter wood means more heat devoted to drying the wood out, which means burning more wood. Wetter wood also means cooler fires, which means incomplete combustion, leading to increased air pollution.

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Jay Bazuzi
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  • Good design practices can make an efficient wood burning stove look like a fireplace. Those units are good to use. The fireplace built into your house, however, is probably a whole lot of work for a net negative effect on energy use. – OCDtech Feb 21 '13 at 16:29
  • Can you link some on the high thermal mass stoves? Typical wood burning is worse than a diesel truck and kills 250,000 people per year. Do high thermal mass stoves mitigate those problems? – gerrit Sep 07 '18 at 16:56
  • For example, https://en.wikipedia.org/wiki/Masonry_heater https://en.wikipedia.org/wiki/Russian_oven and https://en.wikipedia.org/wiki/Rocket_mass_heater (note Kenneth mentioned rocket mass heaters in his answer) – Jean-Paul Calderone Sep 07 '18 at 18:22
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A fire in a fireplace is pretty to look at but is probably the most inefficient way to heat a home. Not because wood is a poor fuel, which it really isn't, but rather that it is an incredibly poor design for a heating source. A huge amount of the heat goes straight up the chimney.

If you really want to use wood as a fuel source the most efficient way to burn it would probably be a rocket mass heater.

If your main concern is decreasing energy consumption you can accomplish this more easily by focusing on heating the people rather than the house. A blanket or a well placed heat lamp can decrease your heating bill far more than lighting up the fireplace.

Kenneth Cochran
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  • Do some reading on rocket mass heaters. They're not the wood stoves you're familiar with, nor the wood stoves discussed in the article you reference. – Jean-Paul Calderone Sep 07 '18 at 18:23
  • Agreed — it's all about the design. Ancient, open fireplaces are terrible. Old heaters with a single burn stage are generally poor. Modern heaters with multiple burn stages are quite good. Mass heaters are awesome. – Tim Sep 08 '18 at 07:47
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    @Jean-PaulCalderone Thank you, you're right. I have deleted my comment. – gerrit Sep 08 '18 at 21:04
  • You would be surprised how efficient modern chimneys got, as well as modern fireplaces. Natural gas heating also has a chimney. – Tomáš Zato Nov 15 '19 at 15:16
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There's two things to consider when looking at the efficiency of a wood stove:

  • Clean, complete burning - wood stove rely on natural convection to supply air to the fire. This usually means in practice that the stove is most efficient when it's burning "full throttle", meaning most of the wood in the fireplace is actually burning.

  • Form of the heat - in an open fire (with flames) most of the thermal energy is conained in the exhaust gases. In most cases, this will go up the chimney - though I don't know your setup.

This makes it hard to efficiently heat a home with fire - though pellet stoves (where a small fire is maintained automatically) or stoves with huge thermal mass (that evens out the heat output over time) are good ideas.

In your case, I would suggest conducting an experiment - assuming you can see and access your gas counter, you can monitor how much gas you use with and without using the stove to augment your heating, at the same time measureing (weighing) your wood consumption. One week with, one week without wood stove (given roughly the same weather and daily/weekly pattern of living) could give you some data to base your decision on.

mart
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Be careful with wood fireplaces — most emit A LOT of very bad particulate matter!

Burning wood in a common type of stove may result in more particulate matter than a diesel truck and may carry more carcinogens than a diesel or petrol exhaust. In the United Kingdom, where many people have such stoves or even open hearths, wood burning generates twice as much PM2.5 as all traffic combined. In many urban areas, burning wood is prohibited (I don't know if those bylaws make exceptions for modern, cleaner stoves). Globally, biomass is estimated to be responsible for 250,000 casualties per year, as the overwhelming majority of biomass burning takes place with open fire or primitive stoves.

From an environmental point of view, burning solid fuel at home may be much worse than you think, depending on the type of fireplace you have. Wood may be (at least potentially) be carbon neutral, that does not mean the exhaust is anywhere near healthy to breathe. Check the characteristics of your fireplace before you assume that wood is carbon neutral and therefore environmentally friendly.

See this article in The Guardian:

Wood smoke is thick with the tiny particulates, known as PM2.5, that are linked to heart attacks, strokes, cancer, dementia and various other ailments. What’s more, the claims about a climate benefit from wood use are questionable.

Cars and trucks get more attention but nationally, domestic wood burning is the largest single source of PM2.5. According to one analysis of government data, it produces more than twice as much as all road traffic. While concerns about diesel vehicles focus largely on the nitrogen dioxide they produce, the evidence tying particulates to death and disease is even more powerful.

According to Leigh Crilley, an atmospheric chemist at the University of Birmingham, wood smoke also carries more carcinogens than diesel or petrol exhaust.

The increasing popularity of wood fires, scientists warn, threatens to erase any progress big cities might achieve in reducing pollution from traffic. “It’s overtaking the gains we’re making,” Crilley said.

One study from 2014 found that wood smoke was adding more particle pollution to London’s air than the first two phases of the city’s low-emission zone were expected to remove. In London and Birmingham, King’s College researchers reported wood accounted for up to 31% of locally produced particulates. And across Europe, wood burning is worsening pollution in capitals such as Paris, Berlin and Lisbon.

Cities are moving toward it:

The mayor of London, Sadiq Khan, asked the Department for Environment, Food and Rural Affairs (Defra) in September for the power to ban solid fuel use (wood, coal and the like) in high-pollution areas of the city, starting in 2025, which would require amending the Clean Air Act.

If you live equatorward of 60°, there is in theory no need to actively heat your home. The most sustainable thing you can do, if you can afford it, is to upgrade your home to passive house standards and you can dispense with any sources of space heating altogether (you still need hot water, of course, but most wood fireplaces are impractical for this purpose).

There may exist specialised high pressure/temperature or perhaps heavily filtered wood fireplaces that exhaust much less or no particulate matter. If you insist on burning wood, investigate the particulate matter exhaust of your technological choice. Being carbon neutral is not enough; air quality must be part of your sustainability budget, in particular if you live in a populated area.

NB: This answer is focussing purely on what is best from a sustainability point of view. Of course, many people around the world cannot afford any other source of cooking or heating than wood fires, just like they cannot afford access to clean water, access to sewage, or the only vehicle they can afford is a very dirty scooter. Sustainable solutions often cost more out of pocket, which puts policy makers in a very difficult dilemma. Humanity must all work together to improve the economic situation of rural and urban people around the world such that we can all sustainably stay warm and cook. However, if you are purely asking from a sustainability point of view, there are far better alternatives than burning wood — in particular if your fireplace is typical.

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gerrit
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  • It seems that you are on a holy crusade against wood heaters. You are cherry-picking facts and making blanket statements that simply aren't true under average conditions. Do you think that is even remotely wise? Sure, in a small number of situations, wood heaters are sub-optimal, but for billions of people wood heat is so far ahead of any other option that it's not even funny. – Tim Sep 08 '18 at 06:10
  • @Tim Do you have any citation for "for billions of people wood heat is so far ahead of any other option"? Who are those people and what are their other options? – gerrit Sep 08 '18 at 09:57
  • A third of the planet (2.5 billion) lives off less than $2 a day. Unless you somehow think they are able to afford [fancy, feel-good heating option of your choice] then they have no option but to use wood for heating and cooking. If you outlaw fireplaces you kill them from exposure and starvation. Well played. – Tim Sep 08 '18 at 10:33
  • Please cite actual evidence that something like a Rocket Mass Heater produces more particulate emissions than a diesel truck. It burns wood, and your assertion is that burning wood produces more particulates than a diesel truck. Evidence please. – Tim Sep 08 '18 at 10:36
  • Also, even if the 250,000 deaths per year figure is accurate, given that at least 2,500,000,000 would die within a single year from not burning biomass, that makes "banning fireplaces" ~10,000x more lethal than leaving them in place. Have you really thought this through? – Tim Sep 08 '18 at 11:10
  • Oh, and finally, if the firewood is from a managed woodlot (i.e. the fuel is renewable), then all you are doing when you burn wood is returning carbon back to the same atmosphere that it came from in the first place. Over a 20–30 year time frame the whole process is carbon neutral. That's pretty-much the gold standard for environment friendliness. If you think "carbon neutral" is "the worst thing you can do" then I'm not sure we are living on the same planet. – Tim Sep 08 '18 at 11:28
  • @Tim I'm not talking about carbon (climate change), I'm talking about particulate matter (air quality), and there are people in central London who are burning wood because they think it's cozy or sustainable, while it isn't. I cited evidence for the effects on air quality. England is rich enough to upgrade their homes to never need any active heating. Yes, there are billions of people who are living in bad air quality because they are too poor to afford a healthy way of heating or cooking or transport. My final line clearly said alternatives are available. – gerrit Sep 08 '18 at 13:12
  • @Tim As for cooking in rural areas in 3rd world countries, charities are working to bring solar cookers to these communities, saving forests and improving health. The reality is that the wood being burned by poor people is not sustainably sourced in practice, so it's not even carbon neutral. Deforestation is a serious problem. In big polluted 3rd world cities, local government is aware that traffic and home wood fire cooking toxifies and they are working on providing alternatives. – gerrit Sep 08 '18 at 13:20
  • @Tim The people you're talking about primarily use wood fires for cooking, not for heating, as most live in warm climates such as in Africa, South-Asia, or South-East Asia. The question is about heating. The majority of the world lives in cities, this is even more true in cold climates. It is very important for the air quality in cities in cold climates (like in northern China or Mongolia) to move away from fires for domestic heating, but regrettably they cannot always afford the alternatives. My answer of course is about whether wood burning is sustainable: de facto, it is not. – gerrit Sep 08 '18 at 13:26
  • @Tim I have rephrased my answer to explain the context more. – gerrit Sep 08 '18 at 13:32
  • Thanks for editing your answer and toning down some of the wildly generalised and false statements. Facts: Managed woodlots are entirely renewable and sustainable. Large swaths of Af/SEA endure nightly freezing temperatures on a regular basis, so treating it all as "warm" is simply wrong. Most of the planet cannot afford fancy alternatives, so there are no other options. By admitting that low-emission heaters exist, you contradict your own assertion that "burning wood" causes the problem. The reality: Poorly designed heaters are the problem. Blaming the fuel is a mistake. I'm done. – Tim Sep 08 '18 at 14:18
  • @Tim Many people in the world cannot access clean drinking water, many people in the world who can just about afford a motorised vehicle can only afford one of the dirtiest type of scooters, etc.: often the cheap alternatives are dirty. Just because many people can only afford dirty solution does not mean we shouldn't thrive for a cleaner one. The question I'm answering is one of sustainability, not affordability. And I don't think your statement on freezing temperatures in SEA is accurate. – gerrit Sep 08 '18 at 20:53
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    @Tim I have rephrased my answer to not blame the fuel as such. – gerrit Sep 08 '18 at 21:02