H + H UK jumped 20 places in this year's Sunday Times Best Green Companies list, making the top 10 for the first time.
The aircrete company says it has worked hard to lower its carbon footprint over the last 12 months, achieving a 6% reduction, which is double their set target.
H + H chief scientist Colin Cook said: "In last year's list we appeared at number 29, so to enter the top 10, we are of course delighted. We focused primarily on the three Rs: reduce, reuse, recycle -whilst also making significant reductions in gas electricity and water use, demonstrating our continuing commitment to reducing environmental impact despite tough market conditions."
The company also reduced aircrete block waste significantly, again beating internal targets, and is now investigating ideas such as using block waste on green roofs rather then sending it to landfill.
B&Q also made it onto the list, coming in at 44th place after entering the awards for the first time.
The company has made significant changes to its operations and reduced its absolute carbon emissions by 16% in the last few years. Changes included making all in-store lighting displays energy efficient, creating skip-less stores to reduce waste to landfill, reducing packaging and introducing double-decker lorries to substantially cut road miles.
Kingfisher UK & B&Q ceo Euan Sutherland said: "We are absolutely delighted to be recognised by the Sunday Times Best Green Companies List 2010 and to make the top 50, especially when we're one of only four retailers and it's the first year we've entered... It's the right thing for our employees, suppliers, customers and all our shareholders that our own house is in order whilst we work with customers to make it easier for them to green up their own homes."
B&Q also recently launched eco advice centres in its flagship stores.
The awards, now in their third year, aim to celebrate British businesses making a concerted effort to improve their environmental performance.
Tile manufacturer Johnson Tiles came in 33rd place, up eight places from last year.