The site, www.fightingbackwithfacts.com, was created by PVCu window producer Crystal Direct.
"Our aim is to challenge misleading claims from manufacturers using alternative materials," said Martin Randall.
In particular, he cited "aggressive campaigning from the pro-timber lobby" as a trigger for the initiative.
In a ‘factsheet’ on the site, it states that on eight of the 13 points used by the BRE Green Guide to assess environmental impact, "PVCu is at least as good as timber and on five is better".
It adds that "overall" PVCu commercial windows are given an A+ rating by the BRE, whereas "only the best wood windows" achieve this.
The factsheet also quotes Friends of the Earth saying that UK timber imports were responsible for "illegal logging of 130,000ha of tropical forest".
WWA spokesperson Barnaby Dickens said that the website couldn’t "change the facts, that wood windows made from legal and sustainable timber are more environmentally-friendly than PVCu".
"It is not surprising to see the PVCu industry taking such a negative stance given that the Palmer Report 2012 shows wood window sales up 4% and PVCu down 6.5%," he said.
He pointed out that products made under the British Woodworking Federation Timber Window Accreditation scheme achieved the top Green Guide A+ rating and that a new study showed choosing a wood window over plastic saved 89kg of CO2 during its lifetime.
Mr Dickens also said that the WWA membership used only legal and sustainable timber.
