Fly ash is a solid byproduct of electric power generation often added to concrete and cement that improves durability, and reduces the need for other materials by making use of a byproduct.

Formaldehyde is a naturally occurring volatile organic compound (VOC, see below), but it is highly carcinogenic and an irritant in high concentrations causing headaches, dizziness, mental impairment, and other symptoms.

Fossil fuels (mainly coal, oil, and natural gas) are decayed fossils. The combustion of fossil fuels releases carbon dioxide into the atmosphere, contributing to the greenhouse effect and climate change.

FSC Certified wood is certified by the Forest Stewardship Council, a third-party certifier of environmentally, socially responsible, economically viable wood. Entire forests can be certified and wood can be chain-of-custody certified, which means the product is tracked from forest to consumer.

Fuel cells convert chemical energy into electricity and hot water without using a combusted fuel source