NGS - The problem with pvc

The problem with PVC

One of the most controversial construction materials today is PVC. It is used in windows, electrical cables, floor coverings and waste pipes.

Its environmental impact stems, firstly from its high chlorine content, with pure PVC being 57% chlorine by weight and secondly from its additives. These include lead, cadmium, organotin compounds and phthalates.

In the case of construction materials the main hazard comes on disposal. The additives can leach out in landfill or contaminate ash and flue gas on incineration. However, it is the PVC itself that presents the main concern. On incineration, which is where at least 80% of Camden's waste is destined, PVC produces significant amounts of hydrochloric acid. Some highly toxic dioxin is also formed despite careful control of the flue gas temperatures.

Hydrochloric acid is absorbed by lime along with sulphuric acid from other parts of the waste stream. The resultant material (mainly calcium sulphate or gypsum – for 'O' Level chemistry aficionados) is contaminated by dioxins and other chemicals and is a hazardous waste.

Incineration of domestic waste reduces the quantity of solid waste by 80%, but this is not true of PVC. Its high chlorine content means that 1 tonne of PVC becomes 1 tonne of hazardous waste after incineration!

The 20% balance is landfilled. What happens to PVC in the complex bio-chemistry of a landfill site over decades and centuries is unknown. However, some of the additives like phthalates and organotins could leached out and contaminate water courses. Should there be a landfill fire, which have been known to last years, the production of dioxin will be unchecked as the temperature will be uncontrolled.

uPVC Windows

The UK uses about 300 thousand tonnes of uPVC window sections in 2000.

Their disposal will be an increasing issue as the 2.5 million tonnes of uPVC window section has been used in the UK since 1980 reach the end of their life. Research shows that the average age of uPVC windows on disposal is 18 years, shorter than for timber and aluminium windows. (Report for the PVC window industry by Michael Rigby Associates ‘02)

Costs of uPVC windows in relation to other materials
Research is consistently showing that windows made from these materials have whole life costs over the 30 and 60 year period, which are lower if not comparable to uPVC windows.

One such was by Carlisle City Council between uPVC and high performance, softwood double glazed units. It found that uPVC windows were initially 25% more expensive and with negligible difference in costs over a 30-year period. The cofor st timber was based on a five-year cycle at water-based staining and a maintenance allowance for uPVC.

Pt L double glazed window units	Capital Cost/m2	60 year NPV 6% discount
Average high performance softwood*	£214	£366
Average PVC *	£262	£393
Pultruded Fibreglass **	£282	£359

* from Building Performance Group article in Building 28 Apr 2002.
** from BRE report to Lindman Ltd 30 yr NPV extrapolated to 60 years

Properties of the materials
The alternative window materials are timber, aluminium, aluminium & wood composite, steel and fibreglass.

	Embodied energy	Life years	Maintenance	Repairable	Recyclable	Hazards on disposal
Wood	very low	long	medium	very good	moderate	very low
Aluminium	high	long	low	poor	easy	low
PVC	high	short	medium	poor	moderate	high
Aluminium & wood composite	medium	long	low	poor	difficult	low
Steel	medium	medium	medium	poor	easy	low
Fibreglass	medium	long	low	good	difficult	low

Note: For accurate information of costs, comparable quotations for windows in different materials are required. For information about maintenance and disposal, a full whole life costing will need to be conducted.

Electric Cables

Virtually all houses today are wired using PVC sheathed cables. This probably represents the second highest construction use of PVC. A serious concern of PVC cabling is the toxic fumes which are released during fires. In high risk buildings like airports, “low smoke” halogen free, LSHF cables are used. These use sheathing materials like polythene and polyolefin. For BS6004 cable commonly used in house wiring, the average cost of LSHF over PVC is 17% more. For the most common 2.5mm2 “twin & earth” this rises to 37%. (price comparison for FS cables and RS Components 1km batches)

Plumbing and Drainage

PVC is used for waste fittings and pipework. Alternatives to this material include HDPE for both above below ground drainage. Below ground, ceramic pipes should be used as these have the advantage of low cost and long life.

Floor Covering

Whole life costs for flooring materials

	Environmental issues	Projected life in years	Purchase and installation £/m2	Floor care per year £/m2	Strip out and dispose £/m2	Whole life cost 30yr @6% £/m2
Linoleum	Renewable low embodied energy	25	3.75	2.54	1.58	70
Vinyl	Non-renewable fossil fuels, chlorine content	15	3.15	2.83	1.56	78
Carpet	Low durability, solvent content of adhesives	7	1.80	3.57	1.48	96
Rubber	Renewable if based on natural rubber	25	4.65	2.54	1.61	80
Safety Floor	Non renewable fossil fuels, high chlorine content	15	3.65	3.61	1.60	95

from: Forbo Flooring life cycle analysis (linoleum manufacturers and may not be independent).

Linoleum is made from linseed oil and is a natural product. During its life, it does not exude synthetic chemicals found in other flooring products. On disposal, it is biodegradable in landfill sites and on incineration it does not produce hazardous chemicals. The CO₂ produced is carbon neutral as the flax from which it was made absorbed CO₂ during its life.