‘Baby, it's cold outside’ as the song goes, but it’s colder inside in my house, and I would bet most people in Portugal are at the point of going outside to get warm during the day and huddling around the fireplace in the evenings, or scuttling off to bed early just to get warm!

A roaring log fire fills the entire house with a lovely smell – and enthusiasts get obsessive over which wood creates the best result – including olive wood if you can get it, a really dense wood that burns long and slow. A fireplace is a good focal point in a room, and some would say a home isn’t complete without one, but despite coming out on top for ambience, they are an inefficient method of heating, with uncontrolled airflow drawing air from the rest of the house up the chimney at the same time as – crucially - the heat from the fire.

Log burners

An efficient alternative is a log burner – the cast iron they are made from will give a constant radiant heat, and you are able to control the heat and the rate at which the wood burns for maximum efficiency very easily. They can be left to burn without supervision provided the flue is checked regularly, but are far less formal than an impressive open fire, so can be added to the corner of a room if there is no fireplace, provided there is somewhere for a chimney to be added, or can be fixed in an existing fireplace, provided all chimney and flue legalities are met. It would be wise to have a professional install one, and there are numerous websites where you can find out what size burner your room will need by just typing in a few measurements before you choose one. Another advantage is you won’t get a room filled with smoke if the wind changes, and the ash residue can be removed easily.

Now the downside – it is still a big investment, and it still burns trees, something we shouldn’t be so keen to do, although most wood burned here has been responsibly sourced, and you can add pruning offcuts yourself from your own garden to help.

Pellet burners

So, what about pellet burners? On the good side, they are efficient and they are clean – pellets are sold neatly in plastic bags (convenient, but not environmentally friendly), and are easy to store. The pellets are made from compressed materials such as wood chips, bark, sawdust, brush and other byproducts of lumber milling and the manufacture of wood products. Corn stalks, straw and other unusable agricultural materials can also be used to make pellets, meaning nothing gets wasted. However, the stoves themselves are noisy, are dependent on an electricity supply, and need regular maintenance, which is something that is sometimes overlooked.

A study by the Northeast States for Coordinated Air Use Management (NESCAUM) noted that the combustion of wood pellets “produces atmospheric emissions of particulate matter, carbon monoxide, nitrogen oxides, volatile organic compounds, mineral residues, and to a lesser extent sulfur oxides.” Probably pretty much the same as your logs, I would say.

Pellets, however, are assumed to be cleaner than other kinds of wood combustion, largely on the assumption that pellets are relatively uniform in content and low in moisture, and their combustion in automated pellet stoves is more controlled than that of log-burning stoves. However, emissions can still vary significantly depending upon what kind of pellet stove is used, how it is operated and what kind of pellets are used. They are said to be more convenient to operate than ordinary wood stoves or fireplaces, and some have much higher combustion and heating efficiencies. As a consequence of this, they apparently produce less air pollution. In fact, pellet stoves are supposed to be the cleanest solid fuel, residential heating appliance.

I am not saying either one is more efficient or practical than the other - they are both users of solid fuel, and trees are renewable at the end of the day, but some serious thought should be given if you are in the market for buying either.