How Do Heat Pumps Work When It's Freezing Outside?

Freezing winter air still has plenty of heat in it. A heat pump doesn't make heat: it moves it, from the cold outdoors into a warm house. In plain words, no maths: why freezing air still holds heat, why heat only flows from warmer to colder by itself, how a special liquid that's colder than the freezing air soaks up that heat, how squeezing it makes it hot, why your fridge is a heat pump too, whether heat pumps work in really cold places, why the box outside sometimes puffs out a white cloud, and how the same machine cools a home in summer. More everyday science in plain words: What is lightning, really?    • What Is Lightning, Really? (And What Makes...   0:00 How does a heat pump work in the freezing cold? 0:26 You're in good company 0:43 A fair hearing: does it make heat? 1:24 Where the heat hides in freezing air 2:08 Heat flows from warm to cold 2:42 How it pulls heat out of freezing air 4:15 You already own one 4:40 Why move heat? 5:04 Really cold places 5:50 Why the outdoor box puffs steam 6:46 Summer: the other way round 6:59 Feel it yourself 7:44 The one idea to keep 8:08 Recap Sources: US Department of Energy (energy.gov): like a refrigerator, heat pumps use electricity to transfer heat from a cool space to a warm space; "heat pumps transfer — rather than generate — heat"; in summer they move heat from the home to the outdoors: https://www.energy.gov/articles/pump-... Energy Saving Trust (UK), "Heat pumps: how they work": "Even when it feels cold, there's still plenty of heat there that can be used"; the four steps (the refrigerant absorbs heat and evaporates, the compressor raises its pressure and temperature, it gives up its heat and turns back into a liquid, the expansion valve lowers its pressure and cools it below the outside temperature); a fridge in reverse: https://energysavingtrust.org.uk/advi... Energy Saving Trust, "The most efficient way to run a heat pump": heat pumps can perform down to -15 °C or lower; it's quite normal for a heat pump to need a little help from an extra heater element in the coldest periods: https://energysavingtrust.org.uk/how-... ENERGY STAR (US EPA), "Air-Source Heat Pumps": can deliver up to three times more heat energy to a home than the electrical energy it consumes, because it moves heat rather than converting it from fuel; heats in winter and cools in summer: https://www.energystar.gov/products/a... International Energy Agency, "The Future of Heat Pumps" (2022): 60% of buildings in Norway are equipped with heat pumps, with Sweden and Finland at over 40%: https://www.iea.org/reports/the-futur... Natural Resources Canada, "Heating and cooling with a heat pump": the heating cycle, and the defrost cycle (frost forms on the outdoor coil; the reversing valve switches to cooling mode to send hot gas to the outdoor coil, and the outdoor fan is shut off): https://natural-resources.canada.ca/e... Natural Resources Canada, guidance on heat pumps in buildings: cold-climate air source heat pumps developed in recent years can provide comfort-level heat down to -30 °C: https://natural-resources.canada.ca/s... Absolute zero (no heat left at all) is -273.15 °C, or -459.67 °F (rounded in the video to -273 °C and -460 °F): NIST, SI base unit of temperature, the kelvin: https://www.nist.gov/si-redefinition/... Footage: AI-generated clips (Google Flow) and Pixabay. Narration voice is AI-generated. New here? Wonder Simply explains how everyday things work, in plain words. Three times a week we take one everyday mystery and explain it, checked against real sources. If you'd like this explanation handy next winter, save this video so you can find it again. #science #explained #heatpump