Assessing materials for recycling-
suitability & benefits

Paola Sassi of the Welsh School of Architecture looks at a way of assessing specified materials for their recycling potential.

Introduction

Environmentally conscious architects and designers are faced with difficult choices when it comes to material specification. Difficult choices because of the lack of environmental information about materials. Recycling is regarded as an effective approach to environmentally benign specification, but very little information is available to guide the specifier. The study summarised in this article considers the potential for recycling in the building industry and the indexing system developed by this study has the aim of providing guidance for architects and designers wanting to design for recycling, recycle elements of buildings or use recycled materials.

Survey results

	no	SUMMARY OF MATERIALS STUDIED description of materials to be reused/ reclaimed/ reprocessed	current recycling practice	index for suitability for recycling	ranking	index of benefits from recycling	ranking
External	1	clay brick wall with lime mortar, to be reclaimed and reused	minimal	0.86	6	0.60	14
walls	2	clay brick wall with cement mortar, reprocessed for hard-core	minor	0.76	13	0.51	18
	3	calcium silicate bricks cement mortar, reprocessed to hard-core	major	0.76	12	0.51	18
	4	dense blocks with plaster internally, reprocessed in aggregate	minimal	0.71	16	0.50	19
	5	aerated blocks with external render, reprocessed in aggregate	minimal	0.79	11	0.50	19
	6	aerated blocks with plasterboard, reprocessed in aggregate	minimal	0.84	7	0.50	19
	7	stone ashlar walling, stones to be reclaimed and reused	minimal	0.71	16	0.56	16
	8	stone cladding to external wall, to be reclaimed and reused	minimal	0.88	4	0.56	16
	9	stone ashlar walling, stones to be reprocessed as hard-core	minor	0.77	12	0.51	18
Structure	10	steel welded structure, sections to be reprocessed	major	0.67	19	0.63	11
	11	steel bolted structure, sections to be reused	major	0.66	20	0.76	4
	12	timber structure, timber sections reused	minor	0.76	13	0.66	9
	13	timber structure, reprocessed to manufacture timber boards	minimal	0.69	18	0.49	20
	14	pre-cast concrete elements, to be reused	minimal	0.80	10	0.60	14
	15	concrete structure, to be reprocessed to form aggregate	major	0.72	15	0.47	22
	16	timber windows reused as a whole element	minor	0.77	12	0.68	8
	17	timber windows disassembled and reprocessed	minimal	0.65	21	0.58	15
	18	aluminium windows disassembled and reprocessed	minimal	0.71	17	0.70	7
	19	profiled metal cladding coated with plastisol reprocessed	major	0.86	6	0.70	7
	20	untreated timber boarding reprocessed to form board material	minor	0.88	4	0.43	25
	21	profiled PVC cladding to be reprocessed	minimal	0.69	18	0.74	5
Roof	22	clay roof tiles reused	major	0.90	3	0.53	17
	23	fibre cement slating to be reprocessed to hard-core	minor	0.88	4	0.45	24
	24	natural slating to be reused	major	0.90	3	0.53	17
	25	lead sheet roofing removed and reprocessed	major	0.82	9	0.61	13
	26	aluminium sheet roofing removed and reprocessed	major	0.92	1	0.65	10
	27	copper sheet roofing removed and reprocessed	major	0.91	2	0.58	15
	28	zinc sheet roofing removed and reprocessed	major	0.82	9	0.53	17
	29	stainless steel sheet flashings removed and reprocessed	major	0.91	2	0.66	9
	30	tern coated steel sheet roofing removed and reprocessed	major	0.82	9	0.65	10
	31	epdm membrane roofing reused	minimal	0.82	9	0.83	3
	32	pvc membrane roofing reused	minimal	0.69	18	0.73	6
	33	asphalt roofing removed and reprocessed	minimal	0.60	23	0.70	7
Internal	34	blockwork partitions, blocks reprocessed to form hard-core	minor	0.76	13	0.47	22
elements	35	plasterboard partitions dismantled and reused	minimal	0.83	8	0.62	12
	36	plasterboard partitions dismantled and reprocessed	minimal	0.74	14	0.48	21
	37	timber doors removed and reused	minor	0.83	8	0.62	12
	38	timber doors removed and reprocessed	minimal	0.76	13	0.48	21
	39	steel doors disassembled and reprocessed	minor	0.87	5	0.70	7
	40	ceramic floor finish reprocessed	minimal	0.80	10	0.46	23
	41	timber floor finish reused	major	0.87	5	0.62	12
	42	vinyl floor finishes reused	minimal	0.88	4	0.93	1
Insulation	43	foam glass reused	minimal	0.91	2	0.53	17
	44	expanded polystyrene reused	minor	0.87	5	0.86	2
	45	cellulose fibre reprocessed	minimal	0.63	22	0.33	26

Conclusion

Is recycling technically feasible and environmentally desirable?
For most materials the answer is yes. Current recycling has proved in its limited extent technically successful and economically interesting. The environmental benefits are in some cases minimal and in some cases substantial, but generally undeniable. If all materials could fulfil the technical and economic requirements for recycling, they too would be recycled.

To extend the recycling practice it is paramount that in addition to the structuring of a recycled materials market, recycling itself is facilitated through new design approaches and building methods.

The new design approaches may include the use of natural, durable, non-composite, non-toxic materials and components, possibly prefabricated, in any case mechanically fixed. This would allow for reusing elements over again, until they are eventually reprocessed to produce new materials.

While the practice of recycling and designing for recycling is not widely spread, there are examples to build upon. In ten years time recycling in the building industry may become a standard procedure and designing for recycling the common approach to design.

References

(1) Salvo - Reclamation Theory - April/May 1995
(2) Deutsche Bauzeitschrift - Recyclinggerecht planen and bauen - Vol. 43 - Feb. 1995
(3) Deutsche Bauzeitung - Recycling am Bau - Nov. 1994
(4) The Green Building Digest - Issues 1 to 15 - ACTAC The Technical Aid Network - 1995-1997
(5) CIRIA - Environmental impact of Building and Construction Materials Vol. A-E - June 1995

Designing for recycling, re-use, dismantling and durability. Contents:

Assessing materials for recycling- suitability & benefits

Introduction

Survey results

Conclusion

References

Assessing materials for recycling-
suitability & benefits