[Anchor]

With temperatures climbing above 30°C (86°F), many people are likely worried about their air conditioning electricity bills. Recently, an increasing number of buildings are saving electricity and reducing carbon emissions by utilizing discarded groundwater.

Reporter Seo Donggyun explains more in this installment of Signal, our year-long series on climate change.

[Reporter]

This is a mixed-use complex in Gangdong-gu, Seoul.

Although the air conditioning is always running as the summer heat sets in, there is little concern about electricity costs.

The secret lies in groundwater.

Let us head down to the building's basement.

When a building is constructed, groundwater often springs up from the ground.

This is because water from nearby rivers and streams constantly seeps underground.

Most buildings pump this water out and discard it, even paying sewage fees to do so. However, this building pumps the water up and directs it to a heat pump located nearby.

Groundwater maintains a temperature of around 16°C (61°F) throughout all four seasons.

During summer, the groundwater absorbs heat from the heat pump's refrigerant, which is warmed by indoor cooling, keeping the refrigerant cool. Conversely, in winter, it supplies heat that is warmer than the outside air to the heat pump, enabling efficient heating.

This building was the first to apply technology that returns the groundwater used for heating and cooling back into the ground, which also helps prevent sinkholes caused by indiscriminate underground development.

Compared to conventional heating and cooling systems, the energy efficiency is also superior.

[Lee Young-il / Technical Committee Member, Korea Groundwater and Geothermal Energy Association: It is currently estimated that energy consumption is reduced to half that of city gas, and about 30% compared to standard electric air conditioners.]

Cases of utilizing discarded groundwater for heat pumps are also increasing in private homes.

[Groundwater Heat Pump User: Since heating and cooling a large house costs a lot of money, I could not ignore the expenses. I am saving more than 40% on electricity bills.]

Nationwide, there are 13 billion tons of groundwater available for use as an energy source annually.

Experts predict that if just 10% of this is utilized for heating and cooling heat pumps, it could achieve 20% of the government's greenhouse gas reduction target for 2035.

The government is currently pushing to classify groundwater as a renewable energy source.

Reported by Seo Donggyun | Video by Jo Chang-hyun, Park Jin-ho, and Bae Moon-san | Video Editing by Choi Hye-young | Produced by Kim Do-gyun and Han Seung-ho | XR by Lee Jun-ho and Jeon Yu-geun