Original windows with weatherstripping, when well-maintained, can often be as energy-efficient as new double-glazed windows.  Photo 7 of 9 in The Eco-Friendly Guide to Upgrading an Existing Home from A Cramped Attic Became a Sunny Dining Room in this Renovation of a Copenhagen Tudor

The Eco-Friendly Guide to Upgrading an Existing Home

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Original windows with weatherstripping, when well-maintained, can often be as energy-efficient as new double-glazed windows.