# convert hdd/yr to btu



## 101x81 (Jan 31, 2010)

is someone can convert 5000*C hdd/yr in btu's, i know there is good geeks in this forum


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## ewdudley (Jan 31, 2010)

wood eater said:
			
		

> is someone can convert 5000*C hdd/yr in btu's, i know there is good geeks in this forum



Could you spell out what 'hdd' stands for please?

--ewd


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## DaveBP (Jan 31, 2010)

Heating Degree Days. 5000C would end up being about 9000F, I believe. Bigger annual heating bill than most of us south of the border.


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## ewdudley (Jan 31, 2010)

wood eater said:
			
		

> is someone can convert 5000*C hdd/yr in btu's, i know there is good geeks in this forum



[edited to correct for arithmetic errors]

To convert from heating degree days to btu you would first have to know what the heat loss of the system would be at some particular condition.

If the house loses heat at a rate of 15 kW when the outside temperature averages -12C, and if your degree day reference temperature was 18C, then your heat loss would be 360 kW-hr per 30 kelvin-day, or 12.0 kW-hr per Centigrade-heating-degree-day.

Converting the above example to parochial units, you'd have  22747.61 btu / Fahrenheit-heat-degree-day.  For 5000 Centigrade-heating-degree-days that would work out to about 204 million btus for the year, or 42651 btu / hour average for a 200 day heating season, IF your heat loss was 15 kW on a -12C day.

Also keep in mind that air infiltration make a lot of difference, so it's not as simple as considering just heating-degree-days.

--ewd


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## 101x81 (Jan 31, 2010)

tanks  eliot

i just want to have a rought estimate,
i known the household affect, i want to see how is the differencial between my wood consonption and the hdd/years.
thank you very much for those numbers, i will worked out further from your very usefull input.


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## 101x81 (Jan 31, 2010)

probably dave, i think the quebec is a bit colder then the south border, depending is you live near the coast or not.
for example, if you live in vancouver, you have a good warm temp because a the sea stream, the sea water containt lots of btu's.
think about alaska, are they north enought but the hdd/year is not that far of the south central canada.
very complex.


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## ewdudley (Jan 31, 2010)

wood eater said:
			
		

> tanks  eliot
> 
> i just want to have a rought estimate,
> i known the household affect, i want to see how is the differencial between my wood consonption and the hdd/years.
> ...



For comparing wood usage from one year (or any other period of time) to another in terms of heating degree days, in theory you should be able to compare directly by proportion.  The idea of heating degree days was formulated specifically to make this type of comparison possible.

If for one period of time you recorded some number of heating degree days, and for some other period of time you recorded twice as may heating degree days, you would expect to use twice as much fuel, assuming all other factors remained constant.  (I mentioned wind specifically earlier because it is one factor that can really throw off comparisons.)

For the purposes of comparing wood usage for two different periods of time it doesn't matter if you use Centigrade-heating-degree-days or Farenheit-heating-degree-days because if you have twice as many of either you would expect to use twice as much wood either way.  (Assuming of course that the Centigrade-heating-degree-days and the Farenheith-degree-days both measure from the same zero-heating temperature, usually they use 65F or 18C, which are about the same.)

So if you used 8 cords in a year that recorded 5000 Centigrade-heating-degree-days, that would be 8 cords per 9000 Farenheit-heating-degree-days.  As Dave says, one Centigrade-heating-degree-day is 1.8 Farenheit-heating-degree-day, same as one kelvin is equal to 1.8 rankine.  If some other year recorded 4000 chdd you would expect to burn four fifths as much wood, or 6.4 cord.  Converting 4000 chdd to 7200 fhdd we still end up with four fifths, namely 7200 fhdd divided by 9000 fhdd.

It sounds nice and cold up there, 5000 chdd is beau-coup for sure, but I've always found that _encore plus du froid, meme moins des canaille_.

--ewd


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## 101x81 (Feb 1, 2010)

thaks eliot

yes it is beaucoup and nothing to protect the house from the northen nasty wind.
i will keep note and play with these numbers.

woodeater


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