How do I compare energy usage between building in different locations? I am involved in a project where I am trying to compare energy usage between similar buildings in different locations. I am using a measure called a degree day, which is equal to the difference between the average daily outside temperature and a 'baseline' temperature of 70 F. The idea is that the more degree days a building has, the more energy required to maintain the internal temperature at 70 F. So the plan is to add up the daily degree days for a building for a month, then divide energy use by that number, to yield a 'Energy use per degree day' variable. This will allow me to make comparisons between buildings in different environments.
There are two issues that I don't know enough about energy use (or physics!) to answer.
First, is the amount of energy required to cool/heat a building constant as temperatures get more extreme? In other words, is the amount of energy required to maintain a building at 70 F at an external temperature of 80 F equal to half the energy required to maintain a building at 70 F with an external temperature of 90 F? Or does the amount of energy required per degree of cooling/heating increase/decrease as you move farther from the 'base' temperature? Obviously if this value is not constant I will not be able to simply sum the degree days per month for a building.
Second, is there any way to account for differences in energy required to heat versus cool a building? I assume (though I am not certain) that different amounts of energy are required to heat and cool (eg 65 to 70 is not the same as 75 to 70). Is there any way to quantify this difference, if it exists, or is this going to vary based on the efficiency of each building's heating and cooling systems?
Many thanks!
There are two issues that I don't know enough about energy use (or physics!) to answer.
First, is the amount of energy required to cool/heat a building constant as temperatures get more extreme? In other words, is the amount of energy required to maintain a building at 70 F at an external temperature of 80 F equal to half the energy required to maintain a building at 70 F with an external temperature of 90 F? Or does the amount of energy required per degree of cooling/heating increase/decrease as you move farther from the 'base' temperature? Obviously if this value is not constant I will not be able to simply sum the degree days per month for a building.
Second, is there any way to account for differences in energy required to heat versus cool a building? I assume (though I am not certain) that different amounts of energy are required to heat and cool (eg 65 to 70 is not the same as 75 to 70). Is there any way to quantify this difference, if it exists, or is this going to vary based on the efficiency of each building's heating and cooling systems?
Many thanks!