1) In some cities CHP + district heating is used for heating in the winter, and the same (or parallel) piping is used for cooling in the summer. Eg https://www.euroheat.org/knowledge-centre/case-studies/helsi... & http://www.districtenergy.com/technologies/district-cooling/
2) In single building systems, ground source heat pumps are sometimes used for both heating and cooling. (https://en.wikipedia.org/wiki/Ground_source_heat_pump)
1) In some cities CHP + district heating is used for heating in the winter, and the same (or parallel) piping is used for cooling in the summer. Eg https://www.euroheat.org/knowledge-centre/case-studies/helsi... & http://www.districtenergy.com/technologies/district-cooling/
2) In single building systems, ground source heat pumps are sometimes used for both heating and cooling. (https://en.wikipedia.org/wiki/Ground_source_heat_pump)