Extrapolating Yearly Energy Usage from Manual J Calculations
I have an HVAC design that was created by a firm specializing in that work; the design includes Manual J and S (plus D and T) reports plus the data used to perform the calculations (e.g., wall construction and R value). I now know the correct size of equipment (BTU-wise) to ensure I’ll have heat at the lowest temperatures expected to occur in my area. I also know the AVERAGE low temperature my area will likely see based on historical data.
How do I take the information from the load calculation and come up with how many BTUs I would use in an average heating season? It seems like there’s a calculation using Heating Degree Days lurking about. Simplistically it seems I’d take the maximum BTU requirement and multiply that by a fraction expressed by (design base – average temperature) / (design base – lowest temperature expected) * 24hours * HDD, but that results in really LARGE values which don’t seem to make sense.
Thanks for any pointers you can provide!
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