Arbejdsrapport fra Miljøstyrelsen 42/2006 – Affaldsforebyggelse ved renovering

Affaldsforebyggelse ved renovering

Summary

Background and Aim
The Study
Principal Findings
Results of the Project

Prevention of Construction Waste during Building Rehabilitation is Difficult, but Feasible

The quantities of construction waste are increasing. Is there a potential of increased prevention of construction waste from building rehabilitation? The current status for several building materials is that methods of preservation or reuse elsewhere are exploited to a very limited extent only. A potential for further prevention of construction waste exits, a.o. floors, doors, windows, bricks and tiles, whereas the potential of reusing materials such as plasterboards, precast concrete units and, in part, mineral wool is small. Moreover, the general conditions of the building sector complicate potentials of further prevention of construction waste. Intensified municipal efforts can be useful, even though they may turn out to be difficult to put to practical use.

Background and Aim

Construction waste comprises a large part of the total flow of waste and is produced in connection with demolitions, building rehabilitations and new construction projects. Since the 1980’es, increasing amounts of construction waste have been recycled in stead of disposed in landfills due to heightened focus on the subject.

Several development projects have aimed at demonstrating feasible efforts of preventing construction waste within the building and construction sector, but the concept of prevention of construction waste has gained no particular foothold in the building and construction sector.

This project concerns prevention of construction waste deriving from building rehabilitations. The project holds two central points: Is rehabilitation an alternative to total demolition of buildings? Can rehabilitation of buildings be performed in such a way that building materials become preserved in the actual building or reused in other buildings to maximum possible extent?

The Study

A series of interviews was conducted, primarily as telephone interviews.

Urban planners and residential building inspectors of 14 municipalities were interviewed. Employees within the waste range in a few selected municipalities were interviewed too.

As to the building trade, 17 interviews were conducted with architects, consulting engineers, contractors, workmen and demolishers. Some few construction material manufacturers were interviewed. Interviews were supplemented with a questionnaire.

During the project phase, case study and registration of construction waste formation in connection with overall rehabilitation of residential Aalborg building from the 1920’es were accomplished.

Finally, overall information retrieval was performed together with collection and processing of statistical data.

Principal Findings

In general, existing statistical data on formation and prevention of waste in connection with building rehabilitations and demolitions are deficient.
In practice the potential of accomplishing rehabilitations as an alternative to demolitions is limited. Demolitions are often well-founded due to the current overall conditions.
In general, prevention of waste is not widely used during rehabilitation, neither as maintenance in existing building nor as reuse in other buildings except up to a point for materials such as floors, doors and windows. The study also indicates that underlying fundamentals such as sorting of waste may be inadequate at times.
Substantive barriers are assignable to the overall conditions of the building sector such as expensive labour, affordable building materials, guarantees and stringent standards regarding project management and time schedules.
A certain potential exists as to increased prevention of construction waste, a.o. floors, doors, windows, bricks and tiles. In contrast, the potential of prevention of waste for materials such as plasterboards, precast concrete units and, in part, mineral wool is small. This is unfortunate as the matter is about substantial waste fractions on the rise.
With few exceptions, regulatory authorities’ focus on waste prevention is only low because of general shortage of resources as to supervision of building waste.

Recommendations:

Focus should be maintained on basic sorting of waste in connection with demolition and rehabilitation of buildings.
Future assignment of priorities regarding prevention of building waste should be based on a detailed analysis of the potential of each individual building material compared against current practical as well as economic problems.
Focussing on high quality (value) materials and/or low-cost materials as to waste prevention might be appropriate. Focus can be put on floors, doors, windows, bricks and tiles.
Further efforts could be targeted at information on specific constructional experience on waste prevention.
Regulations on commercial waste with particular reference to directly reusable waste issued by the Municipality of Copenhagen open up interesting perspectives. Moreover, the possibility of making environmental demands in connection with urban renewal etc. should be kept in mind.

Results of the Project

Formation of Construction Waste in connection with Demolition and Building Rehabilitation

Construction waste totalled approx. 25% of the overall 2001 waste amount, i.e. 3.4 million tons. From 1994-2001 the increase amounted to about 40%.

In general, statistical data on formation and prevention of waste in connection with building rehabilitations and demolitions are deficient. However, previous assessments indicate that construction waste from demolitions accounts for 40-47% of the total proportion of construction waste. The proportion of construction waste from rehabilitation projects is estimated to 9-10%.

In general, key figures indicate that rehabilitation results in much less construction waste than demolition. However, the gain is considerably reduced when the matter is about extensive general rehabilitation projects. A case study of the project demonstrates that waste formation of a general rehabilitation amounts to approx. 420 kg waste/m² corresponding to 25-35% of the amounts deriving from total demolition.

Furthermore, the case study demonstrates that procedures of basic sorting of waste in connection with rehabilitation projects do not operate as intended and that waste prevention is very limited in reality.

The composition of construction waste changes between years, a.o. due to changes in building material preferences. Concrete and mineral wool will become increasingly dominating waste fractions. New materials such as joint filler may also complicate waste prevention and waste handling.

Status and Potentials for Rehabilitation and Demolition

On a long-term basis the need for rehabilitations and demolitions of residential as well as non-residential buildings is increasing. A.o. because of a 15% increase in the number of square meters from 1987-2002.

The first basic point of the project is to examine the extent of rehabilitation being an alternative to demolition. Altogether, demolition of residential buildings is limited for the time being – and in most cases well-founded. The overall assessment is therefore that the potential of prevention of construction waste by rehabilitating instead of demolishing is low when the matter is about residential buildings.

An open question is whether rather new concrete-built residential buildings will be demolished in future if outdated and socially worn-out etc.

As to non-residential buildings, demolitions are made currently, e.g. worn-out agricultural buildings and worn-out industrial and storage buildings in connection with urban development and harbour rehabilitation. Demolitions of this kinds will be performed currently also in future.

The assessment regarding non-residential buildings is that the potential of prevention of construction waste by rehabilitation in preference to demolition will be limited.

Prevention of Waste during Building Rehabilitation – Practice and Potential

Prevention of construction waste during building rehabilitation is furthered by preserving building materials in the existing building or reusing the materials in other buildings. However, expensive labour and affordable building materials squeeze the prevention of construction waste.

Builder’s design of the building programme is a decisive factor, because priority can be given to prevention of construction waste. However, the possibility is not often used.

During the planning stage, technical advisers usually consider new materials less risk-bearing and easier to handle, and of course that viewpoint limits the possibility of prevention of construction waste. To strengthen the possibility in general, demolition projects should be operated according to the principles of selective demolition. Builder and technical adviser should involve the demolition enterprise in the initial planning.

Purchase and sale of reused building materials are primarily handled by demolition enterprises, and the materials are often sold on to junk dealers. Junk dealers sell primarily to private persons, but some few specialised recycling storages and do-it-yourself centres exist.

Experience shows that reuse of building materials in other buildings is very limited. Building materials are reused in existing buildings, but only on a limited scale.

The players involved assess that the technical and functional potential for further prevention of construction waste regarding the majority of the buildings materials amounts to 20-30%. If asked to give an overall assessment of technique, economy and organisation, however, the players indicate a lower potential.

The answers indicate that a certain potential exists as to increased prevention of construction waste, a.o. floors, doors, windows, bricks and tiles. In contrast, the potential of materials such as plasterboards, precast concrete units and, in part, mineral wool is small. This is unfortunate as the matter is about substantial waste fractions on the rise.

Prevention of construction waste seems to be almost impracticable as regards a long range of building materials. The selection of waste strategy should therefore be based on current assessments of each individual waste fraction.

Authorities’ Role as to Prevention of Construction Waste

In general, local authorities do not particularly focus on prevention of construction waste. An initial start could be that municipal waste handling authorities urge increased dialogue among technical advisers, contractors and resource profiles on the issue. The Municipality of Copenhagen is the pioneer, supporting its prevention efforts by means of regulations on commercial waste, thus rendering it possible to enforce the rules.

Aside from issuing regulations, municipalities can also intensify the prevention of construction waste by issuing guidelines in connection with urban renewal, publicly subsidized housing construction and municipal building projects. The municipalities of Copenhagen, Aarhus and Aalborg have already issued such guidelines.