 Okay, so this is a much shorter video than the last one Based on example 9.3.1 Which focuses on heating degree days, I just wanted to chat a bit about heating degree days Do one simple calculation and sort of talk about some of the meaning behind it So in this example We're given a Base temperature of 18 degrees Celsius and we're in Madison, Wisconsin an example goes into much more detail on calculating Heating degree days for different months But at the real basic level We're gonna calculate just December's here Heating degree days are calculated simply by the number of days in the month and the base temperature and the month's Ambient average temperature so T ambient bar is T average for the month so for December There's 31 days in the month the base temperature is 18 and This is given a negative five. It's pretty cold in Wisconsin So what we end up with is 31 times 23.3 Which is 722 heating degree days And so it's a pretty high number and again, I just want to chat a bit about what this kind of means And why it's important and Essentially this number is It gives you an idea for how often you are far away from the a Reasonable temperature for your indoor space so If it's really cold then you'll get a high number and that means you need to be heating a lot whereas if Your ambient temperature is close in temperature If T ambient say was 18 degrees right here if this was 18 you would get zero and so you'd have zero You wouldn't end up with zero Degree days so you know that means that you don't need any heating that month if your months average temperature was 18 degrees Celsius so That's that's really the essence of what heating degree days are and then in in the Summer months when you need cooling it goes the other way around where then you would end up with some degree days If you're in a location that required cooling and they'd be cooling degree days So if your T ambient was very hot And then you would end up with a different Number there as well. So again that that these numbers are used essentially to calculate overall heating and cooling loads And how much a specific location would need in light of the ambient temperature All right, thanks for listening