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"The New York Times has a great graphic explanation of the principles of the Passive House, \"airtight buildings that use heat from appliances and even the occupants' bodies for warmth.\" The Times notes that while they are popular in"^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.treehugger.com/sustainable-product-design/passive-houses-get-good-graphic-explanation.html>