I’ve semi-ranted about this before but it’s still gnawing at the Sense part of my brain.
This topic lives outside of extensive Always On analysis because I see it as a meta-analysis issue and is essentially an argument in response to this:
So, some arguments
Most fridges/freezers are never switched off manually once installed unless for maintenance or replacement. Iceboxes, btw, are considered “non-cyclic refrigeration”.
Ask somebody without Sense “Is your fridge always on?”, what is their answer?
Looking back though 40+ years of fridge energy data, roughly:
In 1972 the U.S. standard for household fridge energy usage was around 2,000 kWh/year.
By 2010 that dropped to around 500 kWh/year.
By 2019 the most efficient fridges use around 300 kWh/year.
Beyond that, and more important to this argument, is that refrigeration technology has been refined. Efficient refrigeration now employs better insulation; fan control; physical thermodynamic design (bottom freezers!); and most importantly perhaps inverter-based compressors. The demands of modern hygiene and refrigeration usage also dictate that temperature variation from optimum has been limited. Fridges work better.
These improvements have resulted in fridges that tend to actually run for longer (i.e. be “on” for longer periods) but at significantly lower average power. By extrapolation, fridges move (technologically) toward a literal always-on and always-running state. This matches the fundamental physics and technological limitations. Insulation is much more challenging to improve than compressor efficiency and ultimately every fridge gets opened so effective insulation is always much less than perfect. Knowing that there is a constant average energy loss due to less-than-perfect insulation and that sporadic door opening requires rapid re-cooling, compressors are designed to run near-constantly in efficient fridges. This is very noticeable if you upgrade to an inverter-based fridge.
Here’s my fridge (on a Wemo Insight) as an example:
A typical month:
A typical day:
Currently the Fridge lives outside of Always On (AO) and it’s AO component is 2W. This gives me a false sense of what I would consider Always On in my house. If you want to argue that “Well, there’s nothing you can do about it” in terms of “unplugging to save energy” (which is a core concept of what AO is all about) then I would argue “Well, I could unplug it and get a new, more efficient one”. Same goal/result just on a much slower cycle!
My argument(s) boil down to this:
A fridge/freezer is a special device in regard to it’s AO; it’s AO should be calculated as (Actual On consumption)/(Time plugged in)
My fridge, for example, could list something like 304.1kWh/(365*24h) = 34.7W.
Better, Sense would integrate actual usage over its actual detected time.
The initial listing under AO for a fridge is debatable … perhaps in the order of weeks/months after being detected vs. hours/days … but, I would argue, the AO component is not.