Images posted on the movement's Twitter account showed a group of people with banners sitting in the road on Parliament Square near the Peers' entrance to the Houses of Parliament.
Another group was blocking Bridge Street as Insulate Britain began the 19th day of road-blocking actions in and around London despite legal injunctions banning them from England's major roadways.
On Wednesday, the ecological movement confirmed that at least 32 activists could be sentenced to up to two years in prison for openly defying the court orders.
They claimed, however, that their campaign has been a success as the group's name recognition went from zero to 77% among the general public since protests started three weeks ago.
"We have attracted enormous media interest and we have started thousands of conversations, in the press, on social media and in homes up and down the country. Importantly, we have exposed the government's refusal to act on home insulation as cowardly and vindictive and their refusal to protect our country", Insulate Britain said in a statement.
They claim that 8,500 deaths in an average British winter are the result of cold homes.