Comparing the power consumption of a 30 year old refrigerator to a new one

Original Article ↗ Hacker News Discussion ↗

Methodology & Fairness of the Comparison

  • Many argue the test is unfair because the old fridge is partially broken: one compressor runs 24/7, there’s ice buildup, and likely a failed thermostat and/or door seal.
  • Several people say a meaningful comparison would be:
    • “old fridge in good repair vs new fridge,” not “malfunctioning vs new,” or
    • “fix the old one vs buy new.”
  • Others counter that real‑world decisions do involve worn seals, clogged drains, and degraded parts; comparing a typical 30‑year‑old unit “as found” to a new one is exactly the economic question owners face.

How Much Efficiency Has Really Improved?

  • Some claim fridge tech hasn’t radically changed in 30 years beyond cost‑cutting, so a fixed old unit might approach new‑fridge consumption.
  • Others point to:
    • modern refrigerants (with some ozone‑layer tradeoffs historically),
    • variable‑speed / inverter compressors and better motors,
    • somewhat improved insulation and thicker walls in newer models.
  • A side discussion debunks misapplied “affinity laws”: these work for fans/pumps with variable head, not positive‑displacement refrigerant compressors working across fixed pressures.

Cost, Poverty & Replacement Decisions

  • One line of argument: if an old fridge costs more in electricity than a replacement over ~3 years, passing it to someone else (e.g., a poorer household) effectively saddles them with higher structural bills.
  • Pushback: people in tight circumstances already make constrained, informed trade‑offs; a free but inefficient fridge can still be rational if capital is scarce.
  • Some note many people live without fridges or with very old ones; assumptions about “needing” a fridge are culturally and economically contingent.

Reliability, Lifespan & Repairability

  • Multiple anecdotes: modern fridges and freezers (including well‑known brands) failing in 3–5 years from coolant leaks, compressors, or electronics; older units from the 1960s–1990s often last far longer.
  • Complexity (inverter drives, foamed‑in tubing, embedded wiring) can make modern repairs expensive or impossible; simple old units often fail only in cheap, replaceable parts (thermostats, fans, caps).
  • Some advocate repairing thermostats or retrofitting digital controllers; others note parts on some models are literally foamed into the insulation.

Measurement, Units & Instrumentation

  • Disagreement over using kWh/day vs watts; consensus: kWh/day or kWh/year map directly to bills and implicitly include duty cycle, which watts alone do not.
  • Discussion of billing schemes (energy vs demand charges) and AC power (W vs VA, power factor).
  • Concerns about using smart plugs with shunt resistors and small relays on inductive loads like fridges; suggestions to use current‑transformer–based meters in a separate box instead.

Noise, Placement & Usage Patterns

  • Many complain new variable‑speed compressors and VFDs introduce irritating high‑frequency or “fluttery” sounds; some prefer older on/off “bang‑bang” units with lower‑frequency, predictable noise.
  • A few explore moving compressors or using “quiet” certifications; EU labels can include noise data, but it’s not always prominent.
  • Debate on whether putting fridges in kitchens is “bonkers” from an efficiency standpoint; counter‑arguments note small temperature differences, winter waste‑heat benefits, and losses from opening doors to unconditioned spaces.

Policy & Standards

  • Mention that Energy Star and EU labels have driven big step‑wise efficiency gains; U.S. “Project 2025” proposals to remove appliance efficiency standards are noted with concern.
  • EU energy labels show highly efficient fridges (e.g., ~100–130 kWh/year), but these tend to be expensive and sometimes physically larger with thicker insulation.

Miscellaneous Practical Tips

  • Ice buildup and constant running can stem from bad seals, mis‑leveling, clogged drains, or fans, not only thermostats.
  • Several people share monitoring setups (smart plugs, LoRaWAN/zigbee sensors, buffered probes) and food‑safety tricks (thermometers, ice‑cube/coin tests, alarms) to detect slow failures before food is lost.