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Choosing ΔTmin: The Capital-Energy Trade-off

Why the minimum approach temperature is an economic choice, not a fixed constant — balancing utility cost against heat-exchanger capital cost.

10 min read · Jacob Willis, Net Zero Lead · Last reviewed July 2026


The streams lesson told you ΔTmin is a design choice, not a fixed constant, and asked you to take it on faith for a while. This lesson shows exactly why it's a choice, by running the same process through the problem table algorithm at three different ΔTmin values and pricing the result.

In this lesson

  • 01The same process, three approach temperatures
  • 02Why tighter isn't automatically better
  • 03Pricing the trade-off
  • 04The practical takeaway
  • 05Sources and further reading