Data Sharing Tool? HDD per Therm

BillCinMHD

I am new to the chat. Can some one tell me if there is a tool where we can share/compare our own data on HDD/Therm with others?

Jamie Hall

I don't think we have a formal tool for that, and in any event it would be difficult, as there are so many variables in what is being heated and how big it is and where it is and what fuel is being used. If it's any help, I can tell you that Cedric (powering a 7,000 square foot building with poor insulation) uses around half a gallon of oil per degree day,

fentonc

I embarked on an effort to monitor my home heating system this year, and built a little system to closely track outdoor temperature and fuel usage. The house has a 140K BTU/hr natural gas WM boiler, 3 zone hydronic heat in a home with two ~800 ft^2 floors + a heated basement. I was surprised to see that my BTU/HDD-hr (which I expected to be roughly constant, based on my readings thus far) increases pretty linearly the colder it gets (the different colors are me experimenting with different supply water temperatures).

Jamie Hall

Mine does that too, though not as dramatically -- based on about 20 years of data. I think -- but have no good way of proving -- that the effect you (and I) are seeing is due to infiltration, which is not linear with temperature, unlike thermal conduction, which is.

Unfortunately, I have no handy record of mean and peak windspeeds at the tracked location; that data, I expect, would be a major parameter.

Hot_water_fan

I think flipping it to therms/HDD makes more sense. Here's about 4 years worth of data: about 38,000 btu input per HDD_65. Naturally, the boiler is wildly oversized at 164kBtu input, so could heat the house through the next Ice Age. This drafty old house doesn't seem much impacted by wind.

Hot_water_fan

Unfortunately, I have no handy record of mean and peak windspeeds at the tracked location; that data, I expect, would be a major parameter.

@Jamie Hall NOAA will have this info for the closest airport

fentonc

Here it is as therms vs HDD65. I do actually have mean/peak windspeed data as well as solar radiation data, but I hadn't tried to incorporate that into my modeling yet. I also track how much estimated heat actually gets dumped into each zone - I almost never break 50% estimated efficiency.

Hot_water_fan

I do actually have mean/peak windspeed data as well as solar radiation data, but I hadn't tried to incorporate that into my modeling yet.

@fentonc I'd used those before too - the solar didn't do anything for me and the wind made a difference, but extremely slightly - about .03 therms/MPH per day.Interested to see your results.