Cary Smith, speaking as part of MIT's IAP 2025 course Geothermal Energy Networks, Transforming Our Thermal Energy System, walks through how ambient temperature loops and district thermal systems work. He covers the basic architecture of shared-loop networks that move water at near-ground temperature between buildings, letting heat pumps extract or reject heat as needed rather than each building generating its own. The talk situates these systems within the broader push to decarbonize heating and cooling, explaining how a single loop can serve mixed building types with different seasonal demands. Drawing on HEET's involvement in real district system projects, Smith lays out the practical pieces, piping, pumping, balancing loads across buildings, that distinguish ATLs from conventional district heating. It is a focused technical briefing rather than a general survey, aimed at viewers who already know the course's earlier sessions.