Sustainable Office Buildings

5. Materials Use

5.0 Introduction

The construction, renovation, maintenance and operation of buildings accounts for very large quantities of materials which are extracted from nature, processed, used and ultimately discarded.

The extraction, transformation, use and disposal of materials all have environmental costs, such as habitat destruction, resource depletion, energy use, air pollution, water pollution and solid waste problems.

In meeting the dictates of sustainability:

·            Resources must be used more efficiently and effectively in meeting human needs. Simply stated, we must use significantly less materials per capita;

·            Buildings must last longer and their constituent materials and components must remain in the material cycle, i.e., there must be increased durability, reuse and recycling;

·            Renewable raw materials must be extracted from nature at rates that can be sustained and non-renewable materials must be extracted with the least disruption to the ecosystem;

·            The concept of waste must be eliminated. The building industry must begin to use its own 'waste' to produce 'resources' for future building through increased reuse and recycling, i.e., buildings must be designed and renovated to minimize the use of new resources, and at the end of their useful life to form the resources for other buildings or applications;

·            Waste material that is ultimately returned to nature must be radically reduced, and waste should, at the very least, be environmentally benign.

5.1 Reduction

Of the three-R's, Reduction is the primary method of conservation. If the scale of demand for material goods and energy is not managed, then Reuse and Recycling is hardly relevant. Moreover, while these latter strategies are still important, can only extend the usefulness of resources and, particularly in the case of recycling, still involve processes with potential environmental impacts.

5.1.1 Planning for the Efficient Use of Space

The potential of an existing building for efficient space use is dictated by its floor plate, floor-to-floor height and structural grid. For new designs or renovations, careful concept development and space planning will pay off in a better match between the building structure and the interior plan.

Interior spaces can be more intensively used by:

·               Reviewing all space allocations programming with the view to achieving more with less;

·               Carefully designing to optimize the size and configuration of interior spaces;

·               Consideration of multi-functional spaces and space-sharing;

·               Using or eliminating non-inhabited spaces;

·               Open planning of interiors, eliminating inefficient circulation areas, using perceptual volume cues, grouping like functions together;

·               Carefully integrating services to reduce building volume, e.g., full service space depth is only required in certain areas not over complete building area.

5.1.2 Eliminating Finishing Materials

A great deal of the interior finishes within buildings are to cover or hide potentially unsightly service spaces or inferior surfaces.

The deliberate exclusion of traditional interior finishing materials or limiting their application to specific areas within an interior where they would be most effective, represents a highly visible way of reducing materials use. Exposed services and self-finishing systems are examples of this approach.

The amount of material can be reduced by:

·                     Either reducing in amount or eliminating completely typical finishing materials such as wall and floor coverings by restricting their application to specific critical applications.

5.1.3 Longevity

Longevity is central to environmentally responsible building design. Longevity can relate to a building as a whole by adaptive reuse rather than building new, or to its components through increased recycling and use of salvaged materials. The common aim of each is to keep materials within the materials cycle as long as possible without the need for further processing.

Consideration of longevity points to the importance of distinguishing between:

·                     Strategies which result in immediate environmental benefits such as reusing existing buildings and materials, materials reduction, using materials with increased recycled content, low embodied energy etc.;

·                     Strategies which result in benefits which are deferred to the future, such as designing for materials recovery, reuse, providing 'reserve' (e.g., additional floor to ceiling height) into buildings for greater adaptability to other uses etc.

A building can be made to last longer by:

·                     Making building longevity an explicit issue in the overall approach to building design;

·                     Designing spaces which are not overly specialized for one use since they will have greater potential for flexibility in the future;

·                     Considering how the building might be adapted for alternative future uses.

 

5.2 Retaining and Reusing Materials

When renovating, a detailed inventory of existing materials can identify which materials and components are viable for reuse or which can be made available for other projects.

 

5.2.1 Retaining Quality Materials

Some materials commonly found in older buildings should be retained because they may be superior to the contemporary materials that have replaced them. While some new materials offer better performance capabilities or life expectancies that may justify the higher energy costs of production, others have been adopted for purely economic reasons. Some synthetic materials do not weather well, are damaged by ultraviolet light, and pose disposal problems because they are not biodegradable.

In some cases the quality of natural materials have declined over the years. Wood, for example, found in older buildings is generally superior to the lumber that is commonly available today.^[1]

5.2.2 Using Salvaged Materials

Building design and operation is currently premised on a single throughput of resources, i.e., materials are used once only and wastes from construction or building operation are typically sent directly to the landfill.

When buildings are renovated or demolished there are often substantial quantities of materials which are salvageable if the time and effort is committed, e.g., millwork, doors, architectural metals, bricks. Lighting and mechanical components may also be salvaged if they are new enough. The salvage of materials and their reuse in other applications reduces demolition waste and avoids the environmental impact of producing new materials.

The reuse of intact, salvaged materials, components or systems in new applications has been limited mostly to the residential market, but is beginning to appear in commercial buildings. Increased reuse of building materials, components and systems will have a profound effect on the way buildings are designed to promote the life of these elements and to facilitate their easy recovery.

Using salvaged materials will require a much more comprehensive view of materials use:

·                     Materials that cannot be used in the renovation will be removed in such a way that they can be incorporated into other buildings;

·                     Components that can be reused in their present form, such as lumber, doors, moldings, and fixtures will have to be carefully removed in order to avoid damage;

·                     It will require engaging contractors who are willing to undertake such work and allocate the time necessary. It also adds time and money to any project;

·                     It will require more extensive sourcing of possible components from salvage operations;

·                     A shift in the perception that 'new' is better;

·                     Development of an economic infrastructure to support reuse.

5.2.3 Designing for Materials Recovery

Salvaging of materials is currently difficult because:

·                     Buildings are not designed to facilitate the easy recovery of materials at the end of their effective life;

·                     Salvaged materials do not enjoy a widespread demand and the mechanisms for sorting, storing, validating, marketing, distributing do not widely exist.

Designing to facilitate the recovery of materials or components for reuse or for more effective recycling relies on the ability to separate material.

Designing with the view to effective resource recovery after the useful life of the building will involve:

·                     Separating the structural and space enclosure elements and generally long life components from those with short life spans to facilitate change in the future;

·                     Detailing so that long life components will not be damaged when shorter life span elements are being replaced;

·                     Keeping components and elements distinct to facilitate removal without damage to themselves or other parts of the building;

·                     Reducing the mixture of material types used and using 'separable' materials, i.e., making a clear distinction between the building shell, systems and interior finishes and their connection and accessibility;

·                     Considering greater modularity in building proportions and assemblies;

·                     Designing and detailing building components and assemblies for ease of disassembly; e.g., where possible, use mechanical fastening rather than adhesives;

·                     Specify single material components or easily disassembled multi-material components;

·                     Carefully removing materials that cannot be used in the renovation in such a way that they can be incorporated into other buildings.

5.3 Selecting Low Environmental Impact Materials

Much of the current emphasis in environmentally responsible design centres on specifying 'environmental' materials.^[2, 3] When renovating, all new materials should ideally have lower environmental impacts over their life-span than those they are replacing. Producing construction and finish materials requires large inputs of raw resources and energy, and incurs emissions of air and water pollutants and solid waste. Although there has been a significant increase in the quality of information to support such comparisons, it is extremely difficult to compare the environmental impacts of different products since there are currently only a few common scales of comparison.

Life cycle assessment of building materials has emerged as the most effective basis by which to compare pare materials and products, and provides information over four stages:

1.            Raw materials acquisition;

2.            Manufacturing - materials manufacturing, product fabrication, packaging and distribution;

3.            Use, reuse and maintenance;

4.            Recycling and waste management.

The manufacturers of some building materials are beginning to define and make explicit the environmental strengths of their respective products. However,

·                     Complete and consistent life-cycle assessment environmental information is not currently available to discern clear choices;

·                     Many of the manufacturers of "environmental" building materials and systems are new in business and do not have extensive performance or market histories to rely on;

·                     The selection of new, relatively untested environmental options, as with all new technologies, requires a delicate balance of caution and risk-taking.

In the short term, it is most appropriate to identify materials with lower "environmental cost" using a screening process which includes some of the more established environmental criteria such as:

Recycled Content

True recycled content is the percentage of post-consumer (i.e., returned and recycled after having been used by consumers) used in manufacturing as distinct from the degree of internal recycling within the industry itself.

The production and use of materials draws on limited reserves of raw feed stocks, some of which are renew able and some which are not. Some of these raw materials may come from recycled sources, thereby reducing; the impact of the industry on reserves, and often on energy use.

Recycled content is one of the most easily identified factors which indicates a material with lower environmental impact.

Recyclable Materials

A recyclable material is one which can be returned to a manufacturer and reconstituted into and new product.

Some materials are currently recyclable and other will be in the future through industry advancements and incentives. Consideration should be given to the ability of materials and components to be recovered and recycled, particularly those that may be replaced relatively frequently over the building's life, e.g., reviewing "Takeback" programs on products such as carpet.

Reusable Materials

A reusable material or product is one which can be directly reapplied for essentially the same purpose in its original form.

Reusable materials are clearly durable ones which can hold their value over time. Mover, equal attention must be given to being able to recover these materials and components intact during renovation or demolition so they can be reused either in the same or another project.

Low Embodied Energy Materials

Embodied energy is the amount of energy used to manufacture and install a material or component and is a useful, but not complete indicator, of environmental impact.

Although comprehensive, current embodied energy information is not available for all building materials and components, relative differences can be judged with reasonable confidence. Judgments and comparisons of embodied energy are only relevant between materials, components and assemblies offering the same performance.

Locally Produced Material

Where possible, the specification of locally available building materials is viewed as an environmentally sound strategy since it both involves reduced transportation and packaging and supports a regionally based economy.

Durable Materials

Buildings are maintained and repaired over their lifetime. Since these recurring environmental costs can often outweigh the initial environmental cost of producing and installing the materials and components, the selection of durable materials and components is a key strategy in reducing life-cycle environmental impacts.

The frequency and extent of maintenance and repair is not solely a function of the materials characteristics, but influenced by the way the material in incorporated into a design. Designing for durability also involves considering how to detail and protect materials and components from premature deterioration and prolong their life span.

Manufacturer's warranties can be use to provide a marginal measure of a product durability.

Selecting environmentally sound materials involves:

·                     Reviewing and evaluating the recycled content of current and emerging materials;

·                     Specifying materials meeting Ecologo standards for recycled content and recyclability;

·                     Specifying materials and components which can be readily recovered, reused as close to their existing form as possible or which can be easily recycled;

·                     Selecting materials and components which offer the lowest embodied energy;

·                     Considering the use of local materials to reduce transportation energy impacts;

·                     Selecting materials which have a longer service life before replacement;

·                     Selecting materials that have low maintenance and cleaning requirements.

5.3.1 Wood Products

Tropical Woods

The preservation of tropical hardwoods is critical for the survival of the most varied ecosystems on earth.

The two main efforts to shift wood purchases towards more appropriate choices are wood labelling programs for more sustainably harvested traditional woods and the marketing of species which have been less utilized or wasted in the past.

Domestic Woods

The demand for oak and maple is very large and the supplies of quality wood are shrinking. Moreover, other species such as walnut and cherry are now scarce, making it increasingly important to both limit the use of these materials and seek alternatives.

The environmental impacts associated with wood finishes and millwork can be minimized by:

·                     Avoiding products listed on the Convention on International Trade in Endangered Species (CITES);

·                     Specifying tropical woods which: are labelled by a recognized authority;

·                     Considering alternative wood products which incur less environmental impact in their production;

·                     Selecting laminates on cores of engineered wood, domestic softwood or wood which is less utilized and evaluating other potential environmental concerns associated with their production.

5.4 References

Article : http://www.tpsgc-pwgsc.gc.ca/biens property/archtct/page-5-eng.html

1.            Kellogg, R.M., and Keith, C.T., "Regional Wood Quality Interests and Coordination - Is There the Interest and Support". Wood Quality Considerations in Tree Improvement Programs. Ottawa: Forintek Canada Corp., 1986, p. 51. (back to 1)

2.            Stein, R., Architecture and Energy. Garden City, New York: Anchor Press/Doubleday, 1977, p. 101. (back to 2)

3.            Leclair, K., and Rousseau, D., Environmental by Design, Vol. 1: A Sourcebook of Environmentally Aware Interior Finishes, Hartley and Marks, Vancouver 1992. (back to 3)

4.            PWGSC, The Environmentally Responsible Construction & Renovation Handbook, Cat No.En 40-481/1994, Ottawa, 1995.

5.            Cole, R.J., Rousseau, D.L., and Theaker, l.G., Building Environmental Performance Assessment Criteria (BEPAC), The BEPAC Foundation, Vancouver, BC., 1993.

6.            Dickey, E., and Wellner, P., The Wood Users Guide, The RainForest Action Network, San Francisco, 1991.

7.            US EPA, 1995, Comprehensive Guideline for Procurement of Products Containing Recovered Materials, US Environmental Protection Agency (full text available on: http://www.epa.gov) .

8.            Penher, R., Building Material Recycling/Re-Use Centre Survey Report, Earthworks Environmental, Winnipeg, 1994.

 

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