is the fuel cells used in hybrid cars. Also under the renewable energy sector are Biofuels. This group includes companies that use or supply biological resources (like algae, corn or waster wood) to create energy or fuel. Other companies that are included in the renewable energy group are geothermal power companies who use or convert heat to electric energy and hydroelectric companies who harness water energy to make electricity. Investment into green sectors often involves the development of new technologies that are more environmentally friendly. This comes with high up-front costs that are more difficult to justify to investors. The Buildings and Efficiency sector refers to companies that manufacture green building materials or energy-efficient services in the world of engineering and architecture. Green building materials include energy-efficient glass, insulation, and lighting among others. Recycling companies and energy conservation companies also fall under this sector. The Eco Living sector refers to companies that offer sustainable goods and services for healthy living. This includes "green" pesticides, health care, and pharmaceuticals. Green investment has significantly grown in the UK and there are now 136 funds listed on the Worldwise Investor fund library under the themes: Agriculture, Carbon, Clean Energy, Forestry, Environmental, Multi-thematic and Water. All of these funds account for around £21.8bn in the UK. Environmental ratings Companies have emerged to evaluate and rate companies' overall performance in their impacts to the environment. Sustainalytics and RepRisk are two examples of firms now collecting, compiling and publishing lists and scorecards of environmental and other risks. See also Climate finance Climate-related asset stranding Ethical banking Greenwashing Market-based environmental policy instruments Sustainable products Terror-free investing References External links Eco-investor Guide – A resource for investing in the Eco Sector provided by the Global Energy Network Institute. Social Investment Forum – A US membership association for professionals, firms, institutions and organizations engaged in socially responsible and sustainable investing. - UK database of sustainable, responsible and ethical investment funds Investment Industrial ecology Natural resources Resource economics