<?xml version="1.0" encoding="utf-8"?><!DOCTYPE Zthes SYSTEM "http://zthes.z3950.org/xml/zthes-05.dtd">  <Zthes><term><termId>31377084</termId><termName>passive solar heating</termName><termType>PT</termType><termNote><![CDATA[ Solar heating systems that collect and transfer heat by the natural laws of convection, conduction, and radiation with little or no mechanical assistance; for solar heating systems utilizing mechanical devices to transfer heat, use "active solar heating." ]]></termNote><termCreatedDate>2026-03-30 20:41:42</termCreatedDate><relation><relationType>UF</relationType><termId>31377085</termId><termName>heating, passive solar</termName><termType>ND</termType></relation><relation><relationType>UF</relationType><termId>31377086</termId><termName>passive solar heating systems</termName><termType>ND</termType></relation><relation><relationType>UF</relationType><termId>31377087</termId><termName>solar heating, passive</termName><termType>ND</termType></relation><relation><relationType>UF</relationType><termId>31377088</termId><termName>systems, passive solar heating</termName><termType>ND</termType></relation><relation><relationType>BT</relationType><termId>31346564</termId><termName>solar heating</termName><termType>PT</termType></relation><relation><relationType>RT</relationType><termId>31478861</termId><termName>Trombe walls</termName><termType>PT</termType></relation></term>  </Zthes>