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stevehull · 06-04-13, 08:48 PM

AC,

You are correct that the information can be VERY helpful. I use this type of analysis all the time.

However, one correction. For heating, the baseline is at 65 degrees. Just a couple people in a house, normal activity, appliances, etc. all add in an effect so that the neutral point for heating is 65 F.

One flaw is wind - and this factors very strongly in a windy climate like Oklahoma. Therefore, I try to get my DD data on houses on a very cold, but still day (before the sun comes up) typically at 4-5 AM. This gives me the degree of insulation the house has. The same temperature, same time, but WITH wind allows me to know the degree of infiltration. Faster/cheaper than a blower door and I have an automated device that does this.

Basically, I just look at the run time of the heating unit and by knowing the BTU output at 100% run time, I can calculate the BTU input. I will get a graph of some data later and put it up showing how the degree day (DD) data vs. heater run time is a linear relationship.

Points taken with and without wind are very illustrative to homeowners.

Great observations.

Steve

06-04-13, 08:48 PM	#2
stevehull Steve Hull Join Date: Dec 2012 Location: hilly, tree covered Arcadia, OK USA Posts: 826 Thanks: 241 Thanked 165 Times in 123 Posts	AC, You are correct that the information can be VERY helpful. I use this type of analysis all the time. However, one correction. For heating, the baseline is at 65 degrees. Just a couple people in a house, normal activity, appliances, etc. all add in an effect so that the neutral point for heating is 65 F. One flaw is wind - and this factors very strongly in a windy climate like Oklahoma. Therefore, I try to get my DD data on houses on a very cold, but still day (before the sun comes up) typically at 4-5 AM. This gives me the degree of insulation the house has. The same temperature, same time, but WITH wind allows me to know the degree of infiltration. Faster/cheaper than a blower door and I have an automated device that does this. Basically, I just look at the run time of the heating unit and by knowing the BTU output at 100% run time, I can calculate the BTU input. I will get a graph of some data later and put it up showing how the degree day (DD) data vs. heater run time is a linear relationship. Points taken with and without wind are very illustrative to homeowners. Great observations. Steve __________________ consulting on geothermal heating/cooling & rational energy use since 1990