Thanks for the feedback.
I've updated electricity cost to $0.04/kW h and RIO to 730 days. It made value $20K less, but still above the price.
Daily fluctuation happens because for the difficulty change, formula uses last 6 months, which is not fixed amount of periods to take into account (It may be 12,13,14).
I may need to adjust formula to take fixed amount of periods to prevent those fluctuations.
Value&Premium in your terms is something different from Graham/Warren's Value Investing.
Also my idea not to calculate some figure to tell miners it's attractive or not to invest in mining, but to tell what's the current difference in production costs to current market price (as for commodity), which may be used a signal to buy/sell.
you are also not using the most efficient asic for your hardware cost measure if the value you now measure is still higher then current price
if you are wanting a average of the world cost. then take the bottom efficient as value.. and then use 48 cents for the most expensive measure.. then do the middle of them
however if you are looking for VALUE then thats the bottom
there is nothing wrong with having more then one metric. as long as you explain the methodology that matches the terminology