Phone COSI on 01227 787 587

or visit our show room at 58/60, Wincheap, Canterbury, CT1 3RS

COSI LOG PRICES all inc. VAT @ 5% Jan 2010

Type	Sold by	Cost inc. VAT	Cost per kW*
Bulk logs, barn stored 30 - 40% moisture, delivered 20mile rad. from CT4 8HN
Large builders bags (£5 deposit/bag)	Min 4 bags	£130.00	7p if dried
3.5 cubic meter load loose packed £ 65/Mt. cu.	1 delivery	£230.00	6.5p if dried
7 cubic meter, 2 deliveries £49/cu.Mt. loose	2 deliveries	£345.00	5p if dried
Loose collected	Cubic Mt.	£45.00	4.5p if dried
Hard wood briquettes in bags collected	20kg bags	£4.95	6p
1 tonnes delivered locally	50 bags	£247.50	6p
‘Certainly Wood’ kiln dried 20-25% moisture	Bags
Bags collected	Per bag	£5.95	14.5p
Delivered (28 bags/cu.Mt)	80bags = 2.86 cu Mt	£365.00	13.5p
Cheapest Loose collected, dried and burnt in Burley T3 with Thornhill Turbo Technology			3.5p

Firewood Facts and FAQ’s

Builders bag is about ½ cubic, 28 bags kiln dried is approx. 1 metre cubed loose loaded. 35 bags kiln dried is approx. 1 metre cubed neatly stacked.

 7 Metre cubed loose load is approx. 5 - 5.5 metres cubed neatly stacked.

Wood that has been freshly cut is full of water. The sapwood (outer layers) is like bundles of microscopic straws through which water and nutrients are drawn up the tree to feed the leaves. Freshly cut wood is around 50% moisture, which means 1 tonne cut contains 500kg of water, which is a massive 500 litres.

This is why you never buy logs by weight! Only volume. ***

To burn wood properly you should dry it to at least 25% moisture, preferably 20% but better still 10-15% to increase the efficiency and reduce pollution. 

Wood at 15% moisture has 50% more energy than fresh cut logs.

To achieve this, logs need to be kiln dried or cut to length split and stored under cover. The drying time will vary according to you storage. From 1 year, just out side, to 4 weeks in a greenhouse or solar kiln. (Please ask for details).

To calculate the volume of the load of your trailer: width x depth x length.

All wood has roughly the same calorific value (energy/Kg)

Soft woods are approximately half the density of hard wood, so you burn/need twice as many logs, (same weight) as hard woods

Just bringing in a weeks supply to your sitting room or conservatory can increase the energy value of the wood by over 5%.

If your wood is a bit wet, try buying some kiln dried or 'briquettes' and burning a mixture.

With a proper wood burner you can also burn some pellets, which have just 5% moisture.

Costs/Value/Energy calculations. The Government started a programme to make all fuel suppliers use the same Units K.Watts, so that people could make price comparisons of the different fuels. As with most governments they started well, but gave up at the first hurdle. So you buy electricity in Kw, gas is priced in kW, but oil & LPG is in litres, bottle gas by kg, coal by weight and wood by the ubiquitous 'load'.

The completion of the governments work is below, but you will have to get out  your bills and a calculator, (there's one in the start/programs/accessories file). I've put in rough prices for Jan 2010 in Kent, but you must look at what you are paying.

Electricity

approx. 12p/kW and 7p at night. Bought in kW's, electricity to heat is virtually 100% efficient whether using a heater or light bubs. So the cost is 12p/Kw usable heat.

Natural gas

4.7p per Kw. Bought buy volume at a fixed pressure and converted by the gas supply company to kW's. approximately 4p/kW at any time. Appliances range from 65% to100% (Flue less) efficient. So the cost of 1 Kw of heat if you have a wet heating system that is 85% efficient overall, (remember its not just the boiler efficiency, but pipe losses, electricity to run the pump etc etc) is  4p/85 * 100 = 4.7p per Kw , but a good gas coal effect fire is only about 40% efficient so its 4p/40/100=10p per Kw. If you have a converted open coal fire, this will be 20% efficient if you lucky that works out at 20p/Kw heat to the room, but remember when you are not using an open fire heat is flowing up the chimney out of the house so over a year it is a massive waste. No wonder they're going out of fashion.

LPG

5.8p/ kW. sold by the litre or kg, very useful for the supplier, as this tells you nothing, so you can't compare. So here goes:

1 litre of LPG has 8.2kW energy.            1kg of LPG has 12.9 kW/kg.

So take you cost per litre at say 40p then use the calculations in the Natural gas section , i.e.  40p/8.2kW= 4.9p/kW, Central heating in good boiler is now5.8p/usable kW, but a good decorative fuel effect fire is a massive 12.25p, more than electricity?.

But if you buy your gas in bottles at £ 48.00 for a 47kg bottle, that's £48/47*12.9= 8p/kW, so Central heating is 9.5p/kW but a good fire is 20p/kW!. That will come as no surprise to many people who have found this out the hard way.

Oil: 

4.6pkW. Sold by the litre, but there are 10.3kW/litre, so @ 40p/litre that's 3.9p/kW, very similar to Nat Gas, Central heating is  4.6pkW. Whist there is no Oil fired open fire there is the near equivalent in an AGA wick type of atmospheric burner. These are a low as 55% efficient so the cost is 7p/kW. When left on 24/7 this can add up to a massive £1,000/annum for an oil AGA.

Coal/smokeless:

 7.4p/kW. The dirty one. Should this fuel be banned for domestic use, where it is burnt uncontrollably compared to high tech power stations with fluidized beds and chimney scrubbers?  The main advantage over wood is the higher calorific value/density means it stay in longer, 8 hours instead of 2-3.

Anthracite @ £22 for 50kg is 44p/kg and with 9.2kW/kg that works out at 4.8p/kW. More than oil? yes and you must take into account the efficiency of the appliances. Typical coal room heaters are around 75% efficient so with system losses use a more realistic 65% and that's optimistic when you think how much heat is produced when you do not need it at night and during the day. So at 65% it costs 7.4p/kW and an open fire at 20% is 24p/kW.

Wood/renewable Biofuel. 3.5p to 50p/kW

: This is the fuel that is the nearest to 100% renewable as only a small amount of petrol is used cutting and chopping if bought locally and even pellets the most processed form are over 90% renewable. The calorific value varies tremendously depending on the water content ( not the species) of the fuel. See above.

1kg fresh cut wood has <2kW/kg,     1 kg wood at 18% moisture has  4.5 kW/kg     1kg wood/pellets/briskets at <10% moisture has 5kw/kg.

For central heating using a pellet burner @85% at £ 195/tonne = 19.5p/kg. then that's 19.5p/5/85*100 = 4.6p/kW i.e. oil at 40p/litre is equal to pellets at £195/tonne. If you buy bulk cheaper and oil goes up, you'll win and be green!

That was easy but now for the really difficult bit, how much do your logs really cost? that dreaded ubiquitous 'load'. You must measure the delivery vehicle, Length X breadth X height, but watch for wheel arches in the smaller pickup trucks. You must buy a moisture meter, split a coupe of logs and check the inside, that's what counts and no log should be more that 3",(75mm) at its thickest. You will rarely find a bulk supplier with logs much below 30%, that's 1litre of water in a 3kg log! Ours are stored in a barn and have come down to about 28%, so still need further drying. Then you have the efficiency of your stove, and these quoted efficiency crash, when wood at 25% or above is used, so you only kid your self further. Then you have different density of the different species and then you have to convert volume back to weight to get to the calorific values. The only way I think I can show you, is to do some worked examples below using the following researched facts averaged out.

The facts I have used are that: an open fire @ 20% efficient, a stove at 50% efficient when using wood over 25% moisture and 85% efficient when burning wood under 20%. and that one cubic meter of fresh cut hard wood is approx. 560kg, and contains 230 kg of actual wood and 230 litres of water.

Typical service station/DIY store net approx  12.5kg @ 25% moisture cost about £5.00, say 3kw/kg, stove runs' @ 50% efficiency in a closed stove: £5/12.5/3/50*100= 26p/kW  or a good 20% efficient open fire, 55p/kW

Typical bulk local supplier used that year, @ say £45.00/ cubic meter at 30% moisture with a calorific value of say 2.8kw/kg. that works out at 8.5pkW in your stove, but your stove would have difficulty getting to 50% efficiency so in reality that's just over 9.5p/kW and a tarred up chimney and polluted neighbours.

Kiln dried logs 1 pallet 80 bags @ £365 = 2.8 cubic meter and is at 20% moisture, 800kg @ 4.5kW/kg thus;  £365/2.8/287/4.5/75*100=13.5p/kW or 50p/kWopen fire

Briquettes, sourced locally at £ 5.45/15kg bag, 5kW/kg, 80% efficient as dryer :  £5.45/15/5//80*100  = 10p/kW in a stove but  36p/kW open fire.

Bulk stored and home dried, so £45/cubic meter @20% moisture. 1 cubic meter loose now weighs 290kg.   £ 45/290/4.75/75*100= 4.5p/kW

Best buy, using a Burley T3 small @ 89.1% efficient, bulk stored home dried @ £45/cu/mt. works out at just 3.5p/kW

The lesson for today, build a proper log store, buy your logs in bulk 1 year early and treble your money.

If the above has been of any help or you would like to comment please contact Graham at info@cosi.co.uk

If you know any other way of legally trebling you money in one year, could you also please contact me. Thanks