Recent research on timber sash windows has also shown that simple measures, including good maintenance, can improve their thermal performance to match that of many double-glazed units.
Mae ymchwil diweddar ar ffenestri codi pren wedi dangos hefyd bod cymryd camau syml, gan gynnwys gwaith cynnal a chadw da, yn gallu gwella eu perfformiad thermol gystal â llawer o unedau gwydr dwbl.