On non-Inverter ACs, I only need to use the power input (e.g. 800W) to calculate my energy cost for a 12-hour usage. (800*12/1000 = 9.6kW-hr)
On Inverter ACs though, I know they don’t operate at 100% all the time, and most of the time the only information I get is their cooling capacity (e.g. 1hp ≈ 746W) and their EER (e.g. 12.2 kJ/hW).
How do I use these to get a rough estimate of the energy cost?
Conventional ACs don’t “operate at 100% all the time” either. The compressor is cycled by the thermostat. You cannot calculate consumption of either without knowing the temperature gradient between the conditioned and outside space.
It gets even more difficult with inverters… they’re unquestionably more efficient as they don’t run balls to the wall all the time, but without taking actual readings and logging them the math is basically impossible.
I’d say it’s pretty damn difficult for both. The VFD speed is dependent on the gradient, just like the duty cycle of a conventional AC is.
Great point. The temperature delta changes all the time. It’s almost impossible to accurately know even with rough math. Might be what you came up with using historical data, might not, if the temps are unseasonably warm or cold.
Depends on your cooling requirements? Full blast it is the same as before. Anything less proportionally less.
Too many variables. Energy usage isn’t constrained to efficiency of the hvac.
What’s the energy consumption of your current unit? compare that equipment to a newer model to get an idea.
https://en.wikipedia.org/wiki/Seasonal_energy_efficiency_ratio
Wikipedia is almost LMGTFY for this type of thing.
A power meter is like 10 bucks. If you really want to know, that’s probably the easiest way.
