Update: please read this post:
https://www.sunecochina.com/what-happened-to-energysavers-gov/
Ductless mini splits https://www.energy.gov/energysaver/ductless-mini-split-air-conditioners are a great idea for heating rooms in smaller houses. No ducting is required and so it is very efficient. First developed in Japan for their smaller, urban condos.
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- Silencer box for wall (ductless) A/C Unit? (gearslutz.com)