Hello,
I am considering using the ccf calculator for professional use. But I was curious to estimate my current company CO2 emissions on private and on-prem DCs. So, I tried to manually calculate our emissions with your methodology. But the results I got are well under what I expected.
You will find below the calculation I applied to my data. I believe I made a mistake somewhere, but I can’t find it.
For simplicity sake, I will not detail the different coefficients, but I applied different coefficients depending on several factors such as DC's size, location and other parameters such as PUE.
Calculation:
Total CPU Calculation in Wh:
= Total number of CPU * Number of Hours in Year * Average CPU Watts
With:
Average CPU Utilization = 0,5
Number of Hours in Year = 8760
Average CPU Watts = 2,27
Total Storage Calculation in Wh:
= Total SSD in GB * (SDD energy estimation (Wh/TB)/1000) + Total HDD in GB * (HDD energy estimation (Wh/TB)/1000)*Number of Hours in Year
With:
SSD energy estimation (Wh/TB) = 1.2
Number of Hours in Year = 8760
Total Memory Calculation in Wh:
= Total RAM in GB * Memory Watts per GB * Number of Hours in Year
With:
Memory Watts per GB = 0.392
Number of Hours in Year = 8760
Total Wh Calculation:
= Total CPU Calculation in Wh + Total Storage Calculation in Wh + Total Memory Calculation in Wh
Total Carbon Emission Calculation:
=(Total Wh/1000) * Grid emission factor (tCO2/kwh)
My calculations miss some elements and other elements (as RAM) will be overvalued, but the result I get from this calculation is very low compared to what I expected.
Do you think this calculation is correct or did I miss something?
Sincerely,
Elie
Hi Elie,
Thanks for reaching out!
We have not completed work to calculate on-prem emissions just yet so we are very excited to get this going and have been looking to work with a contributor to configure a good methodology!
Would you be interested in setting up a call to discuss in more detail? In the meantime, I have provided some notes:
Compute:
Our Methodology:
Kilowatt hours = ((minWatts + (averageCPUUtilization / 100) * (maxWatts - minWatts)) *
virtualCPUHours *
powerUsageEffectiveness) /
1000 // convert to kWh
((minWatts + (averageCPUUtilization / 100) * (maxWatts - minWatts): I am thinking your value of 2.27 is too low. With our methodology, we are working with virtual CPU's so we are dividing the min/max watts by the number of threads. Since I believe you are working with physical CPU's rather than virtual, you should not need to divide by the threads. Instead, you should use the average across the entire SPECPower DB, or if you know what microarchitecture you are using, take the average of that subset. You can even go even more granular if you know exactly which processors are used.
Here you can reference the SPECPower Database: https://github.com/cloud-carbon-footprint/cloud-carbon-coefficients/blob/main/data/SPECpower-full-results.csv
I'm thinking your min/max watts should ideally be at least 100x higher so hopefully this makes sense.
virtualCPUHours: in your case i'm thinking this may be 24 hours (per day) * number of physical server chips which could be determined from your underlying micro-architecture or looked up in the SpecPower DB
PUE: this would need to be determined probably somewhere in the range of 1.2 - 1.6
Storage:
Our Methodology:
Kilowatt hours = (terabyteHours *
this.coefficient *
powerUsageEffectiveness /
1000 // convert to kWh
I'm thinking here you may just need to convert your total SSD/HDD in GB to TB Hours based on hours per day which would be: (usageAmount / 1000) * 24
Then you would use the correct coefficient based on SDD: 1.2 or HDD: .65
as well as the determined PUE
Memory:
Our Methodology:
Kilowatt hours = Memory usage (GB-Hours) x Memory coefficient
I think you have this correct at a high level, I would again just use hours in a day
Hope this helps!
Thanks,
Cam
Hi CCF,
Thank you for your answer!
On compute:
You are right, I recalculated my results with the ratio of min & max watts/chips, and the results look way more coherent.
For service providers, Average CPU Wh = 65
For local DC, Average CPU Wh = 53
Unfortunately, I don’t have access to the type of micro-architecture.
For memory:
I have also adjusted my calculations to avoid overestimating the RAM energy consumption. Using the following Excel formula:
IF(Sum of RAM/Sum of Chips> Average Ratio RAM/Chips; Sum of RAM-(Sum of Chips* Average Ratio RAM/Chips);0)
Average Ratio RAM/Chips = 51 (source: SPEC DB)
Concerning meeting to discuss a methodology, I would be happy to discuss this issue in detail and help develop a method for on-prem clouds. But I first have to get approval from my hierarchy. Hence, I will get back to you soon with an answer.
For the time being, I would prefer to keep our discussion private, of course, you can republish your insights and mines (anonymously).
Sincerely yours,
Elie
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Memory:
Our Methodology:
Kilowatt hours = Memory usage (GB-Hours) x Memory coefficient
Which I think the PUE was forgotten.
Finally today I've arrived at a number for each category, I'll post it above later
Thank you!
Juli
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