# Building heat recovery

Recovering heat in homes, hotels and offices.

Source page: https://www.materialinsights.org/energy/e_building_recovery/

Recovery and reuse · Shared heat and everyday recovery · No. 138

- Recovery and reuse
- Heat grade: Low
 Recovery and reuse · Shared heat and everyday recovery · Foundation · Energy

A Mumbai hotel heated its tap water from 30 C to 65 C using waste heat from its air conditioning chiller.

Chart: Illustration: Building heat recovery

##### Where it comes from

Chart: Map of where it comes from

Buildings throw heat away in stale air, shower water, cooking fumes and air-conditioner condensers. Each stream is lukewarm, so recovery uses simple exchangers or heat pumps.

##### Three things to know

1. A heat-pump water heater uses about 73-78% less electricity than an electric tank heater.
2. Drain-water heat units cost USD 300-500 and are just a copper coil wrapped round a vertical drain, with no moving parts.
3. In a US Army kitchen, demand-controlled exhaust cut airflow 23-32% and almost halved fan electricity.

##### The journey

1. 1 **Wasted streams**Stale air, shower water, condenser heat
2. 2 **Exchanger**Passive cores or copper coils catch heat
3. 3 **Heat pump**Upgrades lukewarm heat where needed
4. 4 **Hot water, air**Preheated supply for taps and rooms
5. 5 **Lower bills**Less electricity, gas or diesel bought

##### Go deeper pick a tab to open it in full

## Other sections

- [Overview](https://www.materialinsights.org/energy/e_building_recovery/overview/index.md)
- [Correlation](https://www.materialinsights.org/energy/e_building_recovery/correlation/index.md)
- [Science and thermodynamics](https://www.materialinsights.org/energy/e_building_recovery/rc-sci/index.md)
- [Engineering and integration](https://www.materialinsights.org/energy/e_building_recovery/rc-eng/index.md)
- [Economics and contracts](https://www.materialinsights.org/energy/e_building_recovery/rc-econ/index.md)
- [Impact and additionality](https://www.materialinsights.org/energy/e_building_recovery/rc-impact/index.md)
- [What to track](https://www.materialinsights.org/energy/e_building_recovery/tracking/index.md)
- [Relationships](https://www.materialinsights.org/energy/e_building_recovery/links/index.md)