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Life cycle analysis: wood and PVC window frames

This life cycle analysis was carried out for the UK Government. It looked at a single window frame, measuring 1200mm x 1200mm. It did not take into account any benefits from recycling the window frames.

Roll over each to see an explanation of the data.

Cost to consumer

This looks at the purchase price of the window frame and also the on-going maintenance costs of paint for the wooden frames.

It is an indication of the total costs of production but does not include items such as disposal and treatment of environmental impacts.

Wastes

Recycling would reduce the amount of wastes for both types of window frames. PVC could be recycled to produce new window frames. Wooden frames can be incinerated to generate heat.

This analysis looked at a life cycle that did not include recycling.

Depletion of non-renewable resources

Even though wood was assumed to come from a renewable source, it still requires energy from fossil fuels and also paints to maintain the window frame during its life time.

This analysis looked at a life cycle that did not include recycling.

Eutrophication

This is the process by which oxygen is depleted from rivers and lakes due to the increased growth of algae.

Wood performs worse than PVC.

Photochemical oxidants

Nitrogen oxides and hydrocarbons can react in sunlight to produce secondary pollutants called photochemical smog.

Wood performs worse than PVC (2.3 times more). This is due to emissions from the paints used to preserve the wood.

Air acidification

Nitrogen oxides and sulfur dioxide emissions are quantified as an equivalent amount of hydrogen ions (H⁺).

Greenhouse effect

This describes the overall contribution to the greenhouse effect and global warming. It includes emissions such as carbon dioxide and methane released during production, use and disposal.

Wood will biodegrade in landfill and this produces some methane.

The analysis does not include the recycling of the PVC frame or incineration of the wood.

Coal and oil

PVC production uses hydrocarbon raw materials.

Wooden frames need to be regularly painted and paints use hydrocarbons in their production.

Natural gas

The amount of natural gas used over the lifetime of the window frame. Most is used in heating the room that the frame is in, to replace heat lost through the frame.

Total energy

Describes the total amount of energy needed in the production, installation, use and disposal of the window frame. A large amount of this is due to the energy needed to replace heat lost through the frame.

Units are MegaJoules and the wood uses 5.7% less than the PVC.

		Wood	PVC
Thermal conductivity This is a measure of heat transfer through the window frame. The lower the conductivity the better. This means that less heat escapes from the room through the frame. The PVC is slightly better than the wood but only by a little amount.	Thermal conductivity (W.m^-2K^-1)	2.6	2.57
	Total energy (production–use–disposal)	9150 MJ	9713 MJ
	Natural gas consumption	178 kg	183 kg
	Coal and oil	5.37 kg	18.23 kg
	Greenhouse effect (kg equivalent CO₂)	457 kg CO₂	487 kg CO₂
	Air acidification (g equiv H +)	29.6	37.7
	Photochemical oxidants / smog (grammes equivalent of ethylene)	893	383
	Water Eutrophication (grammes equivalent of phosphate)	67	1.6
	Depletion of non-renewable resources	81 kg	88.5 kg
	Wastes	16.5 kg	28.8 kg
	Lifetime costs to consumer	£147	£102

Continue to decide which option is the most sustainable.

Click here for a print version of the table.