Green Building Materials
A WATgreen / ERS 285 study
This ERS 285 WATgreen report is a cursory assessment of the need and feasibility for the integration of green building materials into current and future on-campus construction projects, specifically the residence building for which construction is scheduled to begin later this year. The material components of the building envelope, that is, the foundation, wall-construction, insulation and roof, have been analysed within a framework of primarily qualitative criteria that aim to evaluate the sustainability of alternate materials relative to the materials cited in the current residence design. This analytical process has enabled the identification of several green construction materials that can be feasibly integrated into current design and construction standards of the building envelope.
We recommend the serious consideration of the integration of these results into current plans for the new residence as well as future on-campus architectural designs as this will both increase the sustainability of campus operations and provide an opportunity to further the educational goals of the University.
Table of Contents
Sustainability and Green Buildings
Green Building Materials
1.1 The Role of Universities
The University of Waterloo
Realistic Construction Alternatives
4.0 Wall Construction
Analysis of Wall Construction Methods
Discussion of Alternatives
7.0 Conclusions and Overall Recommendations
A building begins as an abstraction, and yet it is built in a world of material realities.
There is a seemingly unbounded range of possibilities for the selection of building materials for the creation of structures of almost any shape or texture. The part of the building structure under consideration in this report is the building envelope of the new university residence - essentially the ëskiní of the building (Monsey-Bakor, online). Its quality will affect the structureís function and longevity, and requirements may differ with climate, soil, site size, and with the experience and knowledge of the architect and designer. The factors that have conjured the most innovative solutions are impermeability, control of heat, air, and water flow, and the durability of the envelope.
There is no evidence in the building project report of any attempt to investigate or integrate cost-efficient green building materials in the design of the new residence. With this in mind, the WATgreen Green Building Materials research project has been undertaken in the hopes of producing recommendations for ecologically sensitive and economically feasible building materials to be integrated in the building of the residence.
WATgreen is an innovative environmental education program where the students involved are able to make a direct contribution to the sustainability of the campus and surrounding community. The program in recent years has become representative of the necessary paradigm shift from a reactive stance to ecological issues to a more proactive stance. Through waste reduction and increased energy efficiency, the integration of green building materials in the new residence would reduce any adverse environmental impacts and is therefore is congruent with the proactive ideals of sustainability (as will be further discussed). In this way, this research project is representative of the goals of WATgreen.
The Green Building Materials project will examine the potentially beneficial effects of using alternative materials in the building of the new residence to decrease environmentally adverse effects in an economically feasible manner. The construction system of the main framework of the house will be examined in terms of the building envelope, including foundations, wall construction, insulation, and roofing. Because of the extensive research necessary to make this comparison, it is only these four framework components that will be examined. Windows, plumbing, energy, heating and air-conditioning, lighting, and landscaping will be examined by concurrent reports.
In recent years, the concept of sustainablility has been the subject of much debate by academics and professionals alike. In 1987, the World Conference on Environment and Development defined sustainable development as development that meets the needs of the present without compromising the ability of future generations to meet their own needs (WCED, 1987). The notion of intergenerational equity is of key significance to sustainability. It implies that development that prejudices the survival of future generations is inherently unsustainable (Holmberg and Sandbrook, 1992).
The Brundtland Commission definintion separates sustainablility into two aspects. Needs can be broadly translated to encompass the socio-economic, political, cultural, material and equity concerns that are often affirmed as rudiments of sustainable development (van Pelt et al., 1995), and is, indeed, a value judgement. Ability , however, is inherently a more specific concept that is especially concerned with the availability of ecological resources (ibid.). As the availability of natural resources is the limiting factor of both economic growth and human survival (Holmberg and Sandbrook, 1992), sustainability must address ecological impacts, regardless of conflicting interpretations of the WCED definition.
Natural capital is a term frequently emplyed to describe ecological resources in the context of economic paradigms. It refers to both the availability of renewable and non-renweable material and energy resources and the ability of sink functions such as the atmosphere, oceans and forests to absorb the detritus of human activities (Holmberg and Sandbrook, 1992). As natural capital is the underpinning of both economic development and biological survival, we must ensure that we use the essential products and processes of nature no more quickly than they can be removed, and that we discharge wastes no more quickly than they can be absorbed (Wackernagel and Rees, 1996). Maintaining the dynamic equilibrium of biosphere processes within ambient conditions therefore requires that we limit the scale of human impacts to the regenerative capacity of ecosystems.
A tangible progression in the direction of sustainability requires that economic and social systems are revised to ensure that each and every act is inherenctly sustainable and restorative (Hawken, 1993). This principle extends far beyond an adherence to the legislative framework of regulatory bodies or the mitigation of certain impacts judged to be of significance. It requires that the tenets of sustainability be internalized by social and economic processes of all types and scales (Colby, 1991). The ideological shift necessary for beginning the transition to living within the regenerative capacity of the ecosystem requires the active participation of all levels of decision-making. Individuals, communities, corporations, governments, and institutions must all commit to sustainable practices.
Sustainability and Green Buildings
The concept of green development relates design practices and material and energy resources to other aspects of sustainability. Green development is a successful fusion of resource efficiency, environmental sensitivity, attention to human well-being, and financial success (Hawken, Lovins and Lovins, 1999). As about 40% of the national annual resource expenditure is consumed by the construction industry (St. John, 1998), and as individuals spend up to 90% of their time inside buildings (Hawken, Lovins and Lovins, 1999), sustainable building construction practices are crucial.
The design and construction of buildings that meet the criteria of sustainability involves crossing traditional professional boundaries and careful planning that takes the right steps in the right order (to) create synergies that both reduce costs and enhance performace (Hawken, Lovins and Lovins, 1999). This strategy of multi-stakeholder planning was successfully operationalized in the construction of MacMillan Hall at Brown Uiversity in New Hampshire (Brown University, 2000). Conscientious consultation with future building occupants or related groups should also occur whenever possible, as this can be beneficial to the identification of areas in need of improvement.
To date there is no standardized methodology for assessing the sustainability of buildings. Instead of a singlular ideal representation of a sustainable building, what currently exists are numerous buildings that have been designed and constructed with the intention of achieving the highest degree of sustainability possible. Their creation has been successfully guided by a piecemeal application of such measures as life-cycle assessments, cost-benefict analyses, and occupant surveys. Fortunately, nationally and internationally standardized green building rating systems, such as the LEED system of the US Green Building Assiciation, are poised to debut imminently (Hawken, Lovins and Lovins, 1999).
Assessments currently used to identify sustainable materials, energy sources, designs, and construction practices for buildings comply with generally accepted axioms of sustainability . Buildings that integrate principles of sustainability into design and construction strive towards maximum energy effieciency, a minimization of the use of virgin renewable and non-renewable resources, the elimination of toxicity from building structures and processes, the reduction of of carbon dioxide equivalent emissions, the conservation of water, and waste minimization (Environmental Building News, 2000).
Sustainability and Green Building Materials
The consistent use of construction materials that meet the criteria of sustainability is an essential element of operating within the regenerative capacity of the ecosystem. Although there is not yet enough empirical evidence to definitively compile a set of design methods and materials standards that are intrinsically sustainable, it is possible to minimize ecological impacts by employing the tenets of sustainability as guidelines for development (Colby, 1991). The application of these guidelines to building materials becomes an exercise in material, object-level decision-making (St. John, 1998), that can be utilized in all undertakings.
In addition to conforming to building codes and environmental policies, owners and contractors should therefore expand their criteria for selecting materials to consider ecological factors. For this study, the six criteria stated in the previous section have served this purpose. It is increasingly condeded that these criteria are the standard aspects of sustainability that must be addressed by the construction industry (Environmental Building News, 2000). Preferably, these would be applied to materials analysis within boundaries of study that extend beyond on-site use to a reasonable degree relative to both financial and ecological considerations. To be sustainable, such an analysis should be quantitative and include: embodied energy; the level of carbon ioxide equivalent and toxic emissions in the production, use and disposal of the materials, durability; water use; and capacity for bio-degradation, recycling or reuse (St. John, 1998).
1.1 The Role of Universities
Human demands upon the planet are now of a volume and kind that unless changed substantially, threaten the future well-being of all living species. Universities are entrusted with the major responsibility to help societies shape their present and future development policies and action into the sustainable and equitable forms necessary for an environmentally secure and civilized world.
(University of British Columbia, 1997)
By reputation and by action, universities are considered to both embody moderate social values and provide a growing edge for innovation. As major community employers, corporate citizens and educators, universities possess a substantial influence that ranges from community to international scales. In light of this pervasive impact, it is clear that transforming campuses into catalysts for environmental sustainability is a very good first step toward changing the world (Blueprint, 2000). Although the pathways towards sustainability are unique to each university, several general precepts apply to the necessary reform of higher education (Cortese, 2000).
In most universities, the academic curriculum serves as the primary vehicle for instituting the concepts and values of sustainability. In a cursory survey of environmental and sustainable dvelopment policies of Canadian universities, the implementation of a curriculum that promoted current environmental theories was commom practice. It is essential, however, that this curriculum stretches across disciplines to reach all students and faculty members rather than being restructed to a specialized department. To achieve sustainability, university pedagogy must model systems and ecosystems thinking in both its structure and its content (Cortese, 2000).
In accordance with system structures, a curriculum that promotes sustainability must extend beyond the classroom. While formal curriculum and research are fundamental to achieving (sustainable development), campus environmental management and university partnerships exercise powerful educational influences (ULSF, 2000). Recently, the concept of shadow curriculum has been linked to the implementation of sustainable practices on campus (ibid.).
Every school, college, and university has a formal curriculum described in its catalog. But it also has a hidden curriculum consisting of its buildings, grounds and operations. Like the infrastructure of the larger society, it structures what students see, how they move, what they eat, their sense of time and space, how they relate to each other, how they experience particular places and it affects their capacity to imagine better alternatives.
According to education al psychologists, humans retain 10-20% of what is heard or read as opposed to about 80 % of what is experienced (Cortese, 2000). The shadow curriculum of the university therefore has considerable impact on the knowledge with which students graduate. Assimilating sustainable practices into the buildings and operations of university campuses and using their design and routine operation as educational resources is imperative (Orr, 1999)
The Campus Earth Summit Initiatives for Higher Education posits that green development on campuses is a necessary component of transforming universities into effective problem-solving institutions for sustainability. Signatories of the resulting declaration recommended that sustainable design principles, including energy-efficiency, proper ventilation, and non-toxic, environmentally- sound construction materials be integrated into university policies and building codes (Blueprint, 2000). If correlated to university partnerships, academic research and curriculum, green development could successfully support both environmental education and sustainability.
Green Buildings and the University of Waterloo
Officially, the University of Waterloo does not have a policy that specifically addresses sustainable development. The environmental policy published through WATgreen does, however, contain a piecemeal agenda for establishing sustainable practices on campus, and also promotes the experiential components of environmental education. There is not, however, an explicit reference to green development, nor the retrofitting of existing infrastructure to heighten the sustainability of the university (WATgreen, 2000).
According to Erik Koopman et al., there is a deficit in the application of the principles of sustainability to the policies, codes and laws of the University (Koopman, March 8/00). Although sustainable alternatives to structural or functional products are occasionally selected by the University, these decisions are not codified and as a result are inconsistently applied (ibid.) The codification of a set of criteria for green development and sustainable infrastructure is therefore needed.
The institution of a true sustainable development policy would be greatly beneficial to both the campus and the community. An unequivocal commitment to reducing wastes and minimizing the material and energy intensity of university operations, including those of buildings, should be included in this policy. Further developments and adjustments to current infrastructure alike should occur with sincere consideration of such a policy.
Section 2.0 Methodology
The intention of this report is to elucidate the potentials for integrating green materials into the design and construction of future buildings on campus, and specifically the new residence slated for development. The research pursued by this WATgreen group was conducted with the mandate of exploring the degree of sustainability of selected construction materials.
This study is exploratory in nature and was conducted with reference to the blueprints for the new residence on campus. It reviewed a range of potential alternate materials for four components of the building envelope: the foundation, wall-construction, insulation and roofing. The general analytical framework utilized is primarily qualitative in nature. Permutations of the aspects of sustainability discussed in the previous section have been operationalized for each of the four components. In addition, cost-effectiveness, the local availability of products and skilled labour and various technical limitations have been considered. The guiding principle for study is the sustainability of these materials at both the specific level of the community and in the general terms of the regenerative capacity of the ecosystem.
The systems diagram in Fig. 1 maps the approach followed for this assessment and demonstrates the links between the four building components examined, the institutional climate of the university and the precepts of sustainability. It identifies the blueprints for the construction of the building envelope and the socio-political atmosphere as boundaries for our research. A cursory examination of the socio-political atmosphere contextualizes the evaluation of alternate construction materials by linking the concept of sustainability and the political attitude of the University of Waterloo to green building.
The process and ideal outcomes diagram identify potential aspects, including the flow of wastes, the socio-political atmosphere of the University, and other ecological elements, that would be impacted by the use of more sustainable construction materials in the building envelope of the new residence. As this study has aimed to identify materials that are likely to increase the sustainability of the new residence specifically and the campus in general, these results should be interpreted as being preliminary in nature. Site-specific studies, life-cycle and other quantitative analyses should therefore be subsequently undertaken when feasible or necessary.
The limitations faced during the research of building envelope materials are discussed individually for each of the components and can be found within the appropriate sections. In general, the scope of this investigation has been restricted to a preliminary qualitative analysis due to time constraints and the lack of expertise. Recognizing this, we recommend more detailed study of the materials identified as sustainable within the report or other materials that conform to the general criteria for sustainability that we have outlined.
Section 3.0 Foundations
In any consideration of which building materials and alternatives can feasibly be integrated into the foundations of a large-scale development, such as a university residence, there are several limitations that must be considered.
In terms of the actual materials that may be used, there are three main limitations. First, because of the large scale and heavy loads that the foundations must support, strength is imperative. Any materials must be consistently strong and able to effectively distribute the weight of the structure. The second major limitation is climate. In areas such as Southern Ontario, with sub-zero winter conditions, frost heave is a major consideration. For this reason, foundations must be deep enough to support the structure despite any changes in near-surface volume; shallow foundations will be insufficient unless certain innovative steps are taken. (These potential steps will be detailed further.) The limitation of climate also influences any decision on insulating foundations. Finally, there is the consideration of cost. This consideration is reliant on material availability, cost per unit, and building techniques and associated labour. Therefore, despite intentions for entirely green building products, reality necessitates recognition of the criteria for feasible materials and alternatives (strength, climate, and cost). For these reasons, the only materials that can feasibly be used are concrete and steel. Therefore, the alternatives for minimizing impact lie more in the methods of construction and any realistic structural changes that can be made.
Realistic Construction Alternatives
The three main foundation components of concrete, steel, and insulation will be examined as the only reasonable materials for the construction of a building with limitations such as the residence, as earlier stated. Important considerations that arise from a life cycle viewpoint will be addressed. Then any different techniques, methods, construction, and composition will be analyzed with respect to the aforementioned life cycle considerations. After discussion of such considerations, a general assessment of alternatives for the criteria described in the introduction ( green building material criteria) will be used to come up with general recommendations. In these ways, realistic construction alternatives for the residence foundations will be examined for feasible implementation.
Concrete is defined as, a structural material produced by mixing predetermined amounts of Portland cement, aggregates, and water, and allowing this mixture to cure under controlled conditions (Allen, 1999). Portland Concrete accounts for about 95% of the concrete produced in North America (Wilson, 1993). It is the fundamental component of the foundation construction, receiving the building loads through walls or posts and distributes them down and outwards through the footings (Canadian Wood Council, 1997). Concrete and cement have ecological advantages which include durability, longevity, heat storage capability, and (in general) chemical inertness (Wilson, 1993).
The life cycle concerns of concrete are as follows. First, there is land and habitat loss from mining activities. Furthermore, the quality of both air and water quality suffer from the acquisition, transportation, and manufacture. Carbon dioxide emissions are also a negative environmental impact accrued through the production and use of concrete. Similarly, dust and particulate are emitted at most stages of the concrete life-cycle. Both carbon dioxide and particulate matter have negative impacts on air quality (Solstice.Crest, 2000). Water pollution is also another concern associated with the production of concrete at the production phase. Richard Morris of the National Ready Mix Concrete Association believes that, wash-out water with high pH has serious environmental implications (E. Build, 1993). However, the largest environmental concern with this building material is the disposal of demolition waste. Concrete accounts for 67% of the weight and 53% of the volume of all demolition waste in North America (Solstice.Crest, 2000). Though this is not a consideration in the initial building of the residence, it is a fact of which the university should be aware in future endeavors and in the eventual disposal of the residence concrete. Despite these considerations, concrete is still one of the most green alternatives available.
In examination of alternative concrete usage for more sustainable building, three main options will be addressed. First, the innovative technique of ëfoamed concreteí will be analyzed for environmental benefits and feasibility. Second, the use of fly ash as a component of cement will be assessed. Finally, the option of pre-cast concrete systems will be analyzed for environmental benefits.
Foamed Concrete is also known as Autoclaved Aerated Concrete (AAC). It was invented in Sweden in 1914 and is just starting to be available in North America, distributed by Hebel USA. In concrete, the coarse aggregate is made with lime, water, and finely ground sand (Allen, 1999). If aluminum powder is added then ëfoamed concreteí is created to harden in a mold and then cured in an autoclave (a pressurized steam chamber). The benefits of this method are that it has a lesser density, but a higher insulating capacity. Therefore less concrete material is required, reducing mining impacts. As well, the higher insulating capacity reduces heat and energy loss by creating a more efficient building envelope. Autoclaved Aerated Concrete could potentially be integrated into a portion of the foundations. However, there are limiting factors that rule out the possibility that AAC could be the sole concrete used in the foundation. First of all, it has a compressive strength of only one tenth and that severely restricts its use in a large heavy structure such as the residence. As well, as new product it has limited availability in Southern Ontario, and is not reasonably priced per unit. For these reasons, ëfoamed concreteí may not be feasible as the entire foundation for the residence. However, for a portion of the foundation, a smaller portion of the larger building, or a smaller structure, AAC could potentially be integrated in the future and should therefore be kept in mind as a reasonable alternative. (E. Build, 1996).
Another way to reduce the environmental impacts surrounding concrete use in building foundations is to specify a high ëfly ash contentí (Wilson, 1993). Fly ash is by-product of the energy production from coal-fired plants and increasing its proportion in cement is environmentally beneficial in two ways. First, it helps in reducing the amount of solid waste which requires disposal. As well, fly ash in the cement mixture reduced the overall energy use by changing the consistency of the concrete. Fly ash, increases concrete strength, improves sulfate resistance, decreases permeability, reduced the water ratio required, and improves the pumpability and workability of the concrete (Wilson, 1993). Now in the United States, the Environmental Protection Agency requires that all buildings that receive federal funding contain fly ash and most concrete producers have access to this industrial waste (Wilson, 1993).
Finally, the option of pre-cast concrete systems should be considered as a way to reduce environmental impacts. The integrated footer/ foundation wall/ insulation system , as produced by Superior Walls, Inc., uses a reduced amount of raw materials and thereby reduces demand on natural resources (Wilson, 1993). This system is more clearly examined in the section on Wall
There are alternative methods of both making concrete and building foundations with this concrete that have environmental benefits, no matter the structure scale or climate. These include Autoclaved Aerated Concrete, the increased integration of fly ash into the cement mixture, and the use of pre-cast foundation systems to reduce resource use. Through consideration and possible integration of these alternatives, impacts could potentially be reduced.
As wood resources are becoming limited, steel is increasingly popular with builders. In the case of a large-scale building such as the McKenzie-King Residence, steel reinforcement is basically a necessity for overall strength and weight distribution.
The initial life cycle impacts of steel use are similar to those of concrete. These include land and habitat loss from mining activities, and air and water quality degradation from materials acquisition and manufacture (Solstice.Crest, 2000).
However, the largest proportion of steel used nowadays contains a percentage of recycled materials. In terms of improving environmental conditions by reducing impacts, this is the only real recommendation for the use of steel in building foundations; to purchase recycled steel products. Not only would this reduce industrial and commercial solid waste, such a decision would also reward the manufacturers of such products.
Insulation and Concrete Construction Systems
New and innovative pre-cast building foundations are becoming increasingly available and feasible for implementation, as earlier addressed. These new systems can reduce the overall raw material use, as well as conserve energy through the creation of an efficient building envelope. The two main insulation and concrete alternative construction systems which will be examined include ëFrost Protected Shallow Foundationí (FPSF), and ëslab-on-gradeí systems.
A ëFrost Protected Shallow Foundationí (FPSF) is a reasonably new alternative which may lack the local know-how for immediate implementation but may also be a potential consideration for future undertakings. This foundation technique is often considered a practical alternative to deeper, more costly foundations in cold regions with seasonal ground freezing and the potential for frost heave (Anderson, 1999). FPSF has been used most extensively in Nordic countries and accounts for the foundations of over one million homes built in the last forty years.
In slab-on-grade construction of foundations, the concrete slab is both the foundation and finished floor surface, and is insulated underneath by rigid polystyrene insulation (www.its-canada.com). A further used of this rigid insulation as a skirt around the building foundations helps to eliminate any potential frost problems, improve drainage, and help further reduce heat loss (www.its-canada.com, 2000). A polyethylene air and water vapor barrier is applied above the insulating layer, as is a three to four inch layer of sand.
These shallow foundation systems have excellent insulating properties, decreased use of raw materials for concrete, and comparatively low demands for labour. However, the use of rigid insulation is increased. Also, in soils where frost and drainage is a consideration additional piles in the centre of the foundation may be required to prevent movement (www.its-canada.com, 2000). This increases the relative land disturbance, although it remains still much less than that of deep foundation systems.
Shallow foundations are structurally sound and are becoming increasingly common in colder climates. There are strength considerations associated with these new techniques which must be addressed by someone with the technical ability to do so, before they can be feasibly recommended for the building of the new residence.
As discussed above, there are limitations to the sustainability of any foundation construction materials used. In other words, there are environmental impacts associated with all types of foundations. For these reasons, a primary recommendation is the use of secondary materials (fly ash and recycled steel) in the construction of foundations. This reduces the overall demand for virgin renewable resources and non-renewable resources, which is an important criteria for any material to be considered green .
Section 4.0-Wall Construction
A necessary component of the human habitat is wall construction. A wall construction provides a source of load bearing structural support, similar to a foundation. It must act as an anchor, as well as a source of barrier from outside elements such as rain, snow, wind, and both cold and warm temperature (Robinson, 1998). The goal of the following analysis is to provide an answer/recommendation to the question, what is a sustainable and green wall construction alternative? However, the construction industry and following analysis is limited in the availability and cost of green alternatives on the market. Furthermore, possible alternatives are also limited due to the type of design and proposed size of the future residence at the University. Therefore, the wall construction chosen will reflect these limitations, and fulfill the following definitions. Sustainability is defined as meeting the needs of the present, without compromising the needs of future generations (Draper, 1998). Green is understood as being within the ecological and restorative capacity of the environment. Thus, such an alternative must facilitate lower energy input in transport through local availability and production, requiring less raw material but greater recycled content, reducing its environmental impact from production to its ultimate decay.
Analysis of Wall Construction Methods
Wood Stud Wall
The single wood stud is the most common form of wall construction used in residential construction in North America (Anonymous, 2000b). Although there are several different variations of the wood stud wall, the reasons for its popularity remain the same. It is most used in construction due to the relative ease of building, and the relatively cheap cost and availability of wood in North America, making it the accepted standard in the construction industry today. The wood stud wall is composed of two distinct elements (See diagram below-Anonymous, 2000b). The inner element is composed of the interior finish, vapor barrier, insulation, wood stud, and air barrier. The stud carries the structural load and anchors the entire wall construction to the
foundation of the home. The outer element provides the exterior finish of the wall. This finish material can be brick, aluminum siding, stonework etc., and it is anchored to the load-bearing inner element. By providing two separate wall components, the wall can provide a drainage space for any water that penetrates the outer element. The second function of this wall construction, is that the thickness of the wood stud itself, provides the space necessary for insulation placement, as opposed to adding additional thickness to the wall. (Robinson, 1998).
The question remains, though, as to whether this standard fulfills the definition of a sustainable and green wall construction based on the criteria above? The answer is clear, in that although its serves the functional purposes, the wood stud wall construction is a very material and energy intensive structure. The actual cost and ease of labor do not truly reflect the actual ecological or environmental costs of its production. For example, according to Laurence Doxsey, Coordinator of the City of Austin Green Builder Program, a standard wood-framed home consumes over one acre of forest and the waste created during construction averages from 3 to 7 tons (Anonymous, 2000a).
There are alternatives to wood within this type of standard wall construction, such as substituting concrete block, or the metal stud as the supporting wall members. Using concrete blocks decreases the amount of wood used for construction, but increases the number of joints in the wall construction, possibly decreasing the overall energy efficiency as result. It also requires the outer component of a brick or veneer of some sort to act as the barrier to the outside element of precipitation. This requires further and extensive use of materials and labor, as well as potentially adding additional waste of material on site during construction.
The use of the metal stud also has its limitations. Although an alternative, which seems more environmentally friendly than using the wood, stud, this only produces alternative problems, rather than creating a solution . For example, metal studs are conductors of heat by nature. Therefore, added materials and costs must be used in addition to the typical construction, to prevent thermal bridges, or heat leaks from reducing the energy efficiency of the entire wall construction (Kosny, 1997). The process of mining for the material needed for the metal stud is also costly, in the same manner as clear cutting a forest for wood is a burden on the environment. Both cause the physical destruction at the site of the resources, while also causing biological harm to surrounding ecosystems. In the case of a forest, the loss of tree species speeds erosion of soil and destroys natural nutrient cycles. At a mine site, there is always potential for the leaching of sediments and minerals in toxic amounts, into the ecosystems surrounding the site of the mine (Rowlands, 1999). This will also disrupt the natural processes of plants and animals that rely on the system for survival. The consequences that occur as a result of the discrepancies between man and nature are never added to the cost of the material, or its construction. Thus, as shown, the wood stud wall construction is clearly not an environmentally friendly or responsible alternative.
An alternative to the wood stud construction is the curtain wall. This wall system is widely available and is used in buildings of a larger size, requiring a greater structural load than that of a smaller residential construction. This system typically uses expanded polystyrene panels, glass, masonry, or concrete panels, combined with wood, steel or concrete structural members for structural strength, making the panels themselves, lightweight. These systems derive their structural strength from the integral-framing members embedded inside the insulation panels. To reduce the amount of material wasted on the construction site, these wall components are pre-designed and factory built, ready to be erected on site. An additional factor, increasing the benefit of this wall construction, is the lower cost of maintenance and energy requirements, as the system can be built to any specified RSI value; a measure of resistance to heat loss. (Anonymous, 2000b).
The pre-fabricated panels are only one component of the wall system. They must be fastened to a metal load-bearing frame, such as aluminum or steel. The benefits of this system, are many, but the separate use of a frame and skin construction enables freedom of design, and resistance to heat and energy loss. The higher resistance to heat loss is a result of the design of the pre-fabricated panels, pieced together like a jigsaw puzzle (See diagram on previous page-Anonymous, 2000b). This method also reduces initial raw material use, on site waste, and labor costs necessary for construction (Robinson, 1998). It is obvious that this system is more sustainable, reducing initial raw material requirements and waste produced, and it is composed of materials available locally. It is obviously a green alternative, as the panels can be made using recycled materials (i.e. concrete-composed of water, stone and gravel).
Sandwich Panel Wall
Another alternative is the use of pre-engineered structural sandwich panels. This wall system is typically used in large size commercial buildings and is similar to the structure of the curtain wall. The main difference between this wall system and the curtain wall system is that these pre-fabricated panels are generally composed of a urethane, polystyrene, or foam core interior, enclosed by an exterior membrane (See diagram above-Anonymous, 2000b). The outer skins can be composed of oriented strand board, wafer board or plywood, depending on strength and weight specifications, and therefore can be produced from recycled or typically unused wood material. The panels are also available with interior surfaces pre-finished with drywall. The panels are then attached to the load-bearing frame, also composed of aluminum or steel.
The advantage of this system, similar to that of the curtain wall, is primarily due to its pre-fabricated nature. This allows the panels to be built out of recycled material, and reduces the waste produced during construction, as well as decreasing the amount of labor required to build the wall. It also adds energy efficiency to the building by placing the insulation on the outside of the wall construction, where it is most effective at restricting heat loss (Robinson, 1998). Other benefits of this system result from the panelís internal composition, making them lightweight in comparison to a typical wall construction composed of multiple materials and fasteners. By combining necessary elements such as insulation, structural support and the desired finish, into a single panel, the building requires much less steel for structural support. Based on green and sustainable criteria, this wall construction method is also much more environmentally friendly than is the wood stud wall. (Anonymous, 2000b).
Upon completion of my explorative research and analysis, the answer to the question posed, what is a sustainable and green wall construction alternative is clear. Ultimately, based on my knowledge and limited expertise, both the curtain wall system and the sandwich panel wall are undeniably the most suitable wall construction methods. Both meet all criteria; present limitations of the proposed size and design of the future residence; address climate and energy requirements; as well as fulfilling green and sustainable criteria mentioned above. However, the sandwich panel system requires extensive material and man-made material use and fabrication as compared to that of a curtain wall system panel, for this reason alone it places second to the curtain wall (Robinson, 1998). The strengths of this system are obvious. Concrete is undeniably one of the greenest materials available for wall construction today. It combines water with stone and gravel, all renewable resources that are readily available and undeniably recyclable. Furthermore, combining these green materials with a prefabricated panel system used in a curtain wall, and additional energy efficiency of the overall building is attained. Lower energy is required for heating and cooling against the North American climate. This results, as the amount of breaks in the wall construction are greatly reduced, because the pre-fabricated panels are engineered in such a manner as to fit together like a jig-saw puzzle. The production of unnecessary waste on site during construction is also limited, and labor reduced, due to its prefabricated nature. These benefits ultimately increase the curtain wall systems compatibility with sustainability (Robinson, 1998). Therefore, the recommendation of this analysis, is to use concrete in junction with a curtain wall system, which utilizes a prefabricated system, decreases joints in the wall construction, and utilizes the ëgreenestí material in construction today, concrete.
In a conversation with Dan Parent, University of Waterlooís Architect, he stated that the residence will be constructed using a standard wall construction, similar to the wood stud wall, but substituting concrete block in place of the wood stud. The wall construction will use concrete block in combination with a type of rigid insulation (2000). It is apparent that my findings are not in accord with the decision by the University of Waterloo, and its residence design committee, to the wall construction method for which the residence will be constructed. Although this method will definitely have less impact on the environment than using wood stud as the structural member, there is the potential in using a prefabricated wall system to address and incorporate a truly green and sustainable alternative. If the University of Waterloo wishes to be a true example of sustainability and a front runner in this field, it must do more to set the example.
The questions surrounding the true meaning of sustainability and environmentally friendly, green, alternatives are endless. Even if a curtain wall system was to be used in the future residence, will this change make the proposed residence truly sustainable? It is apparent that the University could design and build a group of smaller residences. Imagine if the cost associated with the latest environmentally green materials and truly sustainable technology was not an issue. The idealistic residence housing would be filled with the latest environmentally friendly gadgetry. The homes would be built with solar and wind power sources, with a garden and water recycling facility in the middle natural, native plant filled green space, which the homes would surround. This self-supporting community would truly fit sustainable, by its most literal definition. Similar, is the idea of using straw bales for wall construction. Straw is readily available, a green and sustainable product of the land which could replace the synthetic insulation component of a wall construction (Anonymous, 2000c). Although this material incorporates true sustainability, it is not a reality.
Thus, does sustainability, in absolute terms, mean an immediate halt to any further growth? No. It is obvious that future growth is imminent. Urban sprawl continues to push into natural areas. The construction industry is booming. However, in the hope of one-day achieving true sustainability, small steps are still necessary to begin the transition. The construction industry is beginning to implement and seek alternatives to its material intensive, standard practices, evident in the wall systems that are discussed in this report. More must be done. Architects, engineers, members of building committees, and contractors alike, still make the ultimate decision to use environmentally friendlier alternatives. Often this does not happen. For example, in a conversation with Yanick Cyr (2000), Professional Engineer for the Region of Waterloo, he says that most wall panels, for the pre-fabricated sandwich panel systems, can be built using recycled cellulose material. However, engineers and architects often specify to build with new. More must be done. The environment must become an integral and necessary consideration in development of design and construction methods. These changes can only happen in response to genuine concern for the environment and the pursuit for a sustainable future.
Section 5.0 Insulation
Wall insulation is another component of our groupís building envelope. Although it is not a visible component of a home, or in this case, a residence, insulation plays an integral role in the life of a building. Insulation reduces energy consumption, and provides continual environmental benefits throughout the buildingís lifetime (Environmental Building News, 2000)
When considering which insulation is the best choice for a project, several factors must be considered. Typically, R-value, cost, suitability to the specific project, and effort required for installation are the deciding factors. R-value refers to the ability of the insulation material to slow the transfer of heat through to the exterior of the material (Owens Corning, 2000). Therefore, the higher the R-value, the stronger the insulation materialís ability to resist the flow of heat through it.
However, the focus of this project is to evaluate green building materials, and additional factors must be considered as well. Upon conducting primary research through literature reviews, it was decided that for the purpose of this project, insulation as a green building material would be evaluated based on the following criteria:
Is it manufactured within Ontario and available within the Kitchener- Waterloo area?
What is its recycled material content?
Is there any pollution from resource extraction, manufacturing and use of the product?
Are there any health impacts associated with the product?
What is its R-value (which is its ability to resist heat loss) and cost
According to Dan Parent (2000), the University of Waterloo architect, the University is considering using either a foam insulation by Owens Corning similar to polystyrene or Roxul, a fiber insulation. Roxul is made from stone wool and slag wool. Slag wool is an industrial by-product. It is marketed as the most energy efficient in terms of life cycle analysis. It has an R-value of approximately 4.0/inch ( Rockwool International, 2000 ). Given that the university has done prior investigation of this product, an in depth report on the product will not be given in this report.
Information for the comparison of various insulation materials was primarily found in an issue of Environmental Building News, available online. Researchers provided information on the three major forms of wall insulation; fiber insulation, foam spray insulation and radiant barriers. Specific types of each form were evaluated. Individual brands were not identified, except in the case of patented products that do not go by a generic name.
Examples of fiber insulation materials that were evaluated are fiberglass, cellulose and cotton. Polystyrene, Polyurethane, and Icynene are some of the foam products that were mentioned. Bubble pack and foil faced paperboard are two radiant barriers which were analyzed.
For the purpose of this project, radiant barriers will not be considered. Based on a telephone conversation with Dan Parent (2000), the new planned residence will have three inch insulated walls. Given that this project aims to make recommendations for products to be used in the planned residence, and more likely, residences to come, products which are not suitable (such as radiant heat barriers) need not be evaluated.
Further research was conducted in the form of literature reviews on the environmental consequences of insulation. Based on the information provided by Environmental Building News, I began to search for specific brands of the various products. Using the evaluation criteria which were initially identified, and the information gathered through literature reviews, the focus of the project was narrowed to two specific forms of insulation. Cellulose, a fiber insulation, and Icynene, a foam insulation will be evaluated. These two products appeared to meet the majority of the criteria upon initial examination
Icynene foam is a two-part system made up of Polyicynene MDI and Polyicynene Resin. The two components are mixed in a 1:1 ratio, and applied with a mixing gun. The material expands to 100 times its size after being applied (Lambton Insulating Ltd., 2000). Icynene fills building cavities and cracks upon application, and acts as an excellent sealant (Icynene Inc, 2000). Icyneneís ability to act as a sealant allows it to control moisture, and air pollution. It can be sprayed without using HCFCs or CFCs. It contains no formaldehyde and is non-corrosive (Environmental Building News, 2000).
It is marketed as the Healthy Choice due to its superior sealant qualities and ability to control moisture and indoor pollution, which can irritate allergies and other respiratory problems (Lambton Insulating Ltd., 2000)).
It has an R-value of 3.6/inch (Icynene Inc., 2000) and is manufactured in Mississauga by Icynene Incorporated.
The product is supplied locally through Great Northern Insulation, located in Woodstock and has a Waterloo Region sales representative.
The product costs $1.30 per square foot (personal communication, Steve Reesor, Icynene Sales Representative, March 24th, 200).
It is certified by the Envirodesic Program for maximum indoor air quality (Icynene Inc, 2000).
Climatizer Plus is a cellulose, fibrous, loose- fill, spray insulation made of 100% recycled paper, mainly newsprint treated with dry fire-retardant chemicals. (Climatizer Plus product information Mice Hate It! ).
It is non-corrosive and non-carcinogenic (Climatizer Plus Material Safety Data Sheet). There is no pollution created in the manufacturing and use of the product, but the problems associated with pulp and paper mills apply, as the product originates as newsprint (Environmental Building News, 2000).
The fibers are treated with a blend of approved borate powders which prevent the formation of mould, mildew and rot ( Climatizer Plus product information pamphlet).
It is manufactured in Etobicoke by Climatizer Insulation, and is available to the Kitchener -Waterloo Region.
It has an R-value of 3.84/inch, the Canadian National Building Code requires that this type of insulation have and R-value of atleast 3.7 for a 150 mm sample (National Research Council-Evaluation Listings for Loose-Fill Cellulose Insulation, 2000).
It costs $10.26/bag when purchased by a contractor, and $15.66/bag for regular purchase. Each bag contains 33 lbs. of insulation (personal communication, Climatizer Insulation receptionist, March 24th, 2000).
It has been designated as an Environmental Choice product by Environment Canada.
Section 6.0 - Roofing
The roof plays a primal role in our lives. The most primitive buildings are nothing but a roof. It the roof is hidden, if its presence cannot be felt around the building, or if it cannot be used, then people will lack a fundamental sense of shelter.
Shelter is one of the most basic and elemental needs of our species, and as such, roofing may have been one of the earliest trades in the world (Baker, 1980). From an engineering perspective, the roof is the buildingís first line of defense against the weather. It is vital to the sheltering function of the building, yet is singularly vulnerable to the destructive forces of nature (Allen, 1999).
Global warming and a thinning ozone layer are issues that the current generation is addressing. As a consequence, modern roofing materials are designed with the Earthís changing atmosphere in mind. It is now not only the criteria for fire, snow, rain, and wind resistance that must be met, but the resistance to UV radiation has also become a major factor in design.
With increasingly rapid, noticeable, and occasionally even tangible changes to the health of the Earth comes an increased awareness that fundamental changes must be made in the design of the materials we use. This demand for alternative, ëgreení materials is beginning to be met in the roofing industry, but implementation has been fairly slow. It is the aim of the following report to introduce the reader to the roofing materials in popular use, and to propose several ëgreení alternatives, with the hope that these will be given due consideration in future building design here at the University of Waterloo.
Background / Baseline Conditions
Roofs can generally be divided into two main categories: low-slope and steep-slope. Since most commercial and industrial buildings have low-slope roofs, these are the kind that will come into consideration. Low slope roofs are defined as having less than a 25% slope (Allen, 1999). They are obviously of simpler geometry than the often stylized towers and turrets of residential steep roofs, for example, and for that reason are simpler to build and often more inexpensive. The components of the roof can roughly be divided into the deck, thermal insulation, vapor retarder, membrane, drainage, and flashings (see Appendix A for definitions). The membrane will be the main component coming under consideration, and can be divided into: built-up roof (BUR) membrane, single-ply membrane and fluid applied membrane. Single ply membranes are a diverse and rapidly growing group of sheet materials (Allen, 1999) and have the benefit of requiring less onsite labour. They are more attractive because of their elasticity, being less likely to rip or tear during temperature/weather-induced expansion and contraction. There are two kinds of single ply membranes, these being thermoplastic and thermosetting, examples of which follow:
[applied by application of heat] [attached by adhesives/fasteners]
1) Polyvinylchloride (PVC) 1) EPDM (ethylene propylene diene
2) Polymer modified bitumen monomer)
-SBS (styrene butadiene styrene) -low in cost
-APP (atactic polypropylene) -most widely used
SBS and APP are added for increased 2) Neoprene
cohesion and resistance to degradation -good UV resistance
3) PVC alloys 3) CSPE (chlorosulfonated
4) Chlorinated polyethylene polyethylene)
The building materials that are ultimately chosen will be influenced by the knowledge and experience of the architect and designer, by building and fire codes, and by other legal restrictions. The system selected should be one that has demonstrated performance in the area in which the project will be constructed (Herbert, 1989).
The new university residence has been designed with a low sloping roof. The roofing system that has been chosen is a modified asphalt product (Appendix B), and an alternative consideration is a rubberized membrane (Appendix C) - both of which are Monsey-Bakor products (Daniel Parent, Personal Interview; Jeff Benn, E-mail Correspondence). The membrane would provide maximum protection against freeze-thaw action and flexibility over a range of temperatures (Monsey-Bakor [On-line], 2000).
There is an unfortunate tendency to choose materials based on what Wilson (1999) calls first cost. Most material costs, once energy savings over time, durability, worker productivity, and green design features have been incorporated, are comparable (Wilson, 1999). In short, one must factor in life cycle costs to determine the true worth of a product. Since this is beyond the scope of this report, all proposed alternatives will be based on the statement above - that in most cases, prices are comparable, especially when the long-term considerations are key factors in the discussion.
Knowing that cost is usually a major motivation, it is important to remember that if one limits product selection strategy to only a first cost approach, that this may not be in the long term interest of the client, since it may actually result in a loss of opportunities to save even more in the future. Integration, therefore, is the key to achieving the energy and environmental goals we desire (Wilson, 1999).
With integration in mind then, the following are the criteria around which the discussion of the proposed alternatives will centre:
GIVEN that the roofing system meets specifications for:
impermeability heat retention cost fire resistance
durability maintainability warranty ease of installation
as outlined in the Sustainable Building Sourcebook (On-line, 1999), then the
Criteria for Discussion of Proposed Alternatives are:
1)ëgreení building material, as defined by one or more of the specifications in the Greenspecs of
Environmental Building News (Appendix D)
2) manufactured in Canada
3) local, qualified contractor for installation and maintenance
As mentioned above, the discussion will be limited to alternatives for low-sloping roofs only. For reference, however, Appendix E outlines several companies that manufacture recycled shingles for steep-sloped roofs, should future buildings have a tower or twoÖ
Discussion of Alternatives
A. Single-Ply Halogen-Free Roofing Membranes
The concern with the popular use of PVC membranes is that they contain plasticizers and that they are halogen based. Halogens will emit toxic gasses during fire, and dioxins will be emitted if material is incinerated when disposed. PVC is usually about 50% chlorine (Cl) by weight, and is fairly fire resistant, but if it does catch on fire, it releases high concentrations of hydrochloric acid (Anonymous (a) [On-line], 1999).
Firestone Building Products, one of the largest manufacturers of commercial roofing products has introduced an alternative, called UltraPly TPO (thermoplastic polyolefin) (Firestone Building Products Company [On-line], 1999). Since its introduction, the TPO single-ply membrane had captured 55% of the commercial thermoplastic roofing market by 1998 (Anonymous (a) [On-line], 1999). These membranes reflect solar radiation and meet fire resistance standards without the use of halogens, through a combination with an inert hydrated mineral salt (Anonymous (a) [On-line], 1999).
While the TPO is cheaper than the PVC membrane, it is derived wholly from petrochemicals. Firestone does claim, however, that the production process is closed, and that there is therefore no release of any harmful toxic by-products. The TPO membrane is of recycled origin, and it also meets the U.S. Energy Star Roof Program standards for reflectivity (Anonymous (a) [On-line], 1999).
Other membranes that are not halogen-based include the EPDM thermosetting membrane, and the APP and SBS modified bitumen roofing systems as were mentioned above. These are all alternatives to the usual halogen-based membranes, and have met the same standards as outlined by the National Research Councilís Canadian Construction Materials Centre.
A Local Contractor is: Firestone Master Contractor (Canada)
Nedlaw Roofing Ltd.
There is an ongoing debate between advocates of the BUR (built-up roof) and the single- ply system. The BUR system is almost a century old (Frank Nanasi, personal interview) and has a good track record if installation directions are followed. Nanasi, an independent roofing consultant, supports its continued use and believes that no viable alternatives exist for low slope roofs. In his experience, the single ply membranes have been known to shrink and lose their elasticity, causing tears and cracks along the roof perimeter and at projections. In contrast, Herbert (1989) writes positively of the single ply membrane, stating that it has the advantage of not involving the hot bitumen mixes and mopping procedures that are used with BUR. Installation is therefore less materials and labour intensive. According to his sources, the single ply membranes are actually more isotropic (having strength in both directions), have higher moisture resistance, and higher elasticity within a larger temperature range.
This instance where there is a discrepancy between site experience and performance, and written, scientific facts is a difficult one to resolve, but if one keeps in mind the environmental considerations and practicality, single ply, halogen-free membranes should be the final choice.
B. Photovoltaic Cells
The assumption has been made that building siting, aspect, and orientation will incorporate the concept of passive solar design. This section will then suggest the possibility of installing or incorporating active solar collectors in building design. The concurrent projects on energy for both the new residence and the architecture building may be found to be complimentary.
Photovoltaic power generation is now commercially available, at increasingly attractive prices, in such forms as opaque or clear glass, asphalt-like shingles, standing-seam metal roofing, and other elements that directly replace normal parts of the building shell. They look and work the same as ordinary building materials but produce electricity Ö even through clouds. An efficient building surfaced with such materials can renewably produce more daytime electricity than it uses.
-Hawken, Lovins and Lovins
An example of this material replacement is the shingles and metal roofing produced by Michigan-based United Solar Systems Corporation that are really durable photovoltaic modules. These modules are produced from thin, flexible, amorphous silicon solar cells (Anonymous (b) [On-line], 2000). They are laminated with advanced polymers to prevent cracking, and the roofing modules are installed alongside normal roofing materials with the same tools and methods (Anonymous (b) [On-line], 2000). The electricity produced, even under shady/cloudy conditions, will generate direct current for lights and small appliances, and an inverter can convert the power to alternating current for use with other standard appliances (Anonymous (b) [On-line], 2000).
One local specialist on solar design is Ian McLellan from Arise Technologies Corporation. In a presentation given on the 25th of March, 2000, he stated that a solar roof would have a longer life span than a regular roof. The payback rate is around 20-25 years, and the cost of the roof is approximately $7 per kilowatt (Brendan Sparling, E-mail Correspondence). A solar roof has numerous benefits, and I will refer the reader to the concurrent project on Energy Systems for the Architecture building for further analysis.
Conclusions and Recommendations
Each research section on potential green materials for the building envelope components came to individual conclusions and resulting recommendations. These can be found at the end of the foundations, wall-construction, insulation and roofing sections. Our paramount conclusion is that construction materials that are more ecologically sustainable are available for use in the Mackenzie-King Residence and other large-scale buildings at a cost that is equivalent to that of the materials currently scheduled to be used.
The possible alternatives that have been identified require further qualitative as well as quantitative research before implementation. However, these preliminary findings indicate that there are reasonable alternatives available for more ecologically sustainable building construction. Therefore, a primary recommendation is that further research projects be undertaken on the subject.
The University of Waterloo is a recognised leader in environmental education. However, to become a model for sustainability, the University should integrate the principles of sustainability discussed in this report into its routine operations, including construction practices. As the University has a unique and significant influence in the community due to both its size and its reputation, it has an intrinsic responsibility to initiate the changes necessary for sustainable development. It is therefore our recommendation that ecologically sustainable development practices be implemented at the University.
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