setting base temperature
I'm currently trying to set the base temperature for our building. Since we began using smeasure about 2 months ago our building has not used any heating. Would i be correct in thinking that the our degree days for each week should be 0? and if it is significantly higher than this then we have our building base temperature set too high?
Do you have any tips on how we could possibly calculate our building base temperature more accurately?
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2 Posted by russ on 01 Dec, 2010 01:28 PM
If your heating system was able to go on but didn't then it means the degree days for that time period were zero. If the degree days used for your weather station was greater than zero then your base temperature is too high. You can sometimes tell if a wrong base temperature is used if the performance line is a curve rather than straight - though you need low scattered data for this.
3 Posted by patrick.byrd on 22 Feb, 2011 06:18 PM
I also have the same question... what is an appropriate base temperature.
As the temperature has steadily increased since the start of the year (when I started to use SMeasure), the Control Chart has shown a very steady downward trend, from +30KWh to -30KWh now.
Is this likely to be due to the base temperature being set incorrectly?
Also, I notice that if I do change the base temperature, the graph remains the same... how interactive is it? Or does the system take the base temperature as it was at the time of entering the meter reading?
Support Staff 4 Posted by sMeasure Administrator on 22 Feb, 2011 07:39 PM
Hi,
The base temperature for a building is a building wide setting that will affect all calculations on your building. Accordingly changing this will change the degree day values (these are created for different base temperatures) and thus affect the performance line and control charts and thus your rating.
As the outside temperature has been warming the degree day values should have been dropping as well as heating energy consumption.
Basically you can think of the base temperature as the setting you have on the thermostat in your building that when passed will cause the heating to turn on and thus consume energy.
If you don't have a thermostat (or centrally controlled heating source) to reference when the heating will come on then you can use the ambient temperature of a building. When the ambient temperature passes a threshold value (say 15.5 deg C) one will turn the heating on (and thus start consuming energy).
In summary if you have a thermostat to control heating then use the threshold value on this, if not then detect the ambient building temperature when you turn your heating on and use this as the base temperature.
I hope this helps.
Cam
5 Posted by don_johnston100 on 21 Mar, 2011 03:22 PM
Hi all, is there not also a problem using degree days in relation to the hours which a building is used. If a building is occupied at night (eg hospital) then all the degree days hours for any given month will have to be used as the hospital has to be heated 24/7.
However, if an office is only used and heated if necessary between 7:00am - 7:00pm (for example) then it could well be that in a given month the day time temperatures do not fall below 15.5 deg C and therefore there is no need to heat the building.
It is almost always colder at night so in the above example all the other night time hours could well be below 15.5 deg C thus giving you degree day hours for the month but there was no need to heat the building because the outside temperature was at or above 15.5 deg C for all the day time hours.
If this were the case would the performance graph simply show a point 'c' intercept lower down on the energy axis, or even on the degree day axis?
regards
Don Johnston
Chair Solent Energy & Environment Management Group
sMeasure Administrator closed this discussion on 18 Apr, 2011 09:18 AM.