Not suggesting you use this long abandoned deeco framework but it dealt with the same question using “thermal sub‑networks” or TSN. As described here in §8.6 (p146–150) (starting 161 on the PDF):
- Morrison, Robbie (31 July 2000). Optimizing exergy-services supply networks for sustainability — MSc thesis. Dunedin, New Zealand: Physics Department, Otago University.