# Ambient heat: How energy resides

How moving heat beats making it

Source page: https://www.materialinsights.org/energy/e_ambient/resides/

What this tab covers The physical form in which the energy is held or carried, where it comes from, the chain of transformations that put it there, and how concentrated it is.

Low-temperature heat held in outdoor air, the shallow ground and bodies of water, almost all of it absorbed sunlight. It is too cool to use directly, so heat pumps spend electricity to lift it to useful temperatures, typically delivering three to four units of heat per unit of electricity.
 Form Sensible heat at near-ambient temperature in outdoor air, shallow ground and water Origin Indirect solar

#### How it got there
 Fusion in the Sun Sunlight Absorption by land, sea and air Warm air, ground and water Heat pump lifts it to temperatures useful for heating

#### How concentrated it is

| Measure | Value | Note |
|---|---|---|
| **Share of incoming sunlight absorbed at Earth's surface** | 48% of 340% of W/m2 (about 163 W/m2, calculated)^[1](https://science.nasa.gov/earth/earth-observatory/climate-and-earths-energy-budget/) | Global average; the ground and oceans re-radiate and release it as air heat. |
| **Temperature of shallow ground (upper 3 m)** | 10-16 °C (50-60 °F)^[2](https://www2.nrel.gov/research/re-geo-heat-pumps) | Roughly constant through the year in the upper 10 feet (about 3 m) of ground (NREL, United States). |
| **Heat delivered per unit of electricity (ground-source)** | 3-6 (300-600% efficiency) kWh heat per kWh electricity^[3](https://www.energy.gov/sites/prod/files/guide_to_geothermal_heat_pumps.pdf) | Even on the coldest winter nights, according to the US DOE. |

Ambient heat is the most diffuse form of energy on this list: it is everywhere, but at roughly the temperature of its surroundings, and heat only flows on its own from hot to cold. A heat pump reverses that flow. A refrigerant evaporates at low temperature, picking up heat from air, ground or water, is compressed by an electric motor until it is hotter than the building's heating water, and gives the heat up in a condenser.

Because the pump moves heat rather than making it, the energy delivered exceeds the electricity used, typically three to four times in buildings (REN21). The extra two or three units are ambient heat, which energy statistics count as renewable. The smaller the temperature lift, the better the ratio, so mild outdoor air, stable ground and low-temperature radiators all help.

#### Sources

1. [Climate and Earth's Energy Budget](https://science.nasa.gov/earth/earth-observatory/climate-and-earths-energy-budget/) NASA Earth Observatory, 2009
2. [Geothermal Heat Pump Basics](https://www2.nrel.gov/research/re-geo-heat-pumps) NREL
3. [Guide to Geothermal Heat Pumps](https://www.energy.gov/sites/prod/files/guide_to_geothermal_heat_pumps.pdf) US Department of Energy

## Other sections

- [Summary](https://www.materialinsights.org/energy/e_ambient/index.md)
- [Overview](https://www.materialinsights.org/energy/e_ambient/overview/index.md)
- [Correlation](https://www.materialinsights.org/energy/e_ambient/correlation/index.md)
- [Abundance](https://www.materialinsights.org/energy/e_ambient/abundance/index.md)
- [Fluctuation in time](https://www.materialinsights.org/energy/e_ambient/time/index.md)
- [Across the Earth](https://www.materialinsights.org/energy/e_ambient/geography/index.md)
- [Impact on nature](https://www.materialinsights.org/energy/e_ambient/nature/index.md)
- [Relationships](https://www.materialinsights.org/energy/e_ambient/links/index.md)