The concept of sustainable development within the industrialized nations and the increased worries caused by global warming, has led to a global interest in the need to come up with better ways in which building construction projects within the urban settings can be done in such a manner as to promote sustainability of our environment as opposed to the rather “business as usual” myopic concept in building projects. This will ensure that this generation meets its own needs without negatively interfering with the ability of the coming generation to meet their own needs. In most scenarios, most building projects can be said to major on economic benefits as opposed to their responsibility for the environment and social levels. From past evidence, the living arrangements of the ever growing urban populations have been seen to be on the forefront of environmental degradation, especially through depletion of natural resources, loss of biodiversity through rapid increase in areas covered by human urban settlements, and through pollution.
To establish the impact of the urban settlements on sustainability in respect to environmental, social and financial damages caused, there is a dire need to come up with ways or tools that will measure the performance of the housing developments and therefore provide a basis for comparative analysis. Various assessment systems or tools have been developed to assess building projects to determine their sustainability. These will assist developers, designers and regulatory agencies to largely decrease the negative impacts of building constructions in industrialized countries. A sustainable building rating system is a tool that ensures sustainable design principles have been applied in building construction. These tools even though in the long run measure sustainability; they considerably vary in what and how they measure and how the results are presented and interpreted.
These assessment tools are designed to offer direction during the project design phase and project operational phase under the three pillars of sustainability, namely environmental, economical and social pillars. At both the design and operational stages, the tools will measure performance of the building to ascertain whether it is a sustainable or “green” building. In so doing, the tools will seek to measure various parameters that are considered relevant to a green building. They include fuel consumption of non-renewable fuels; land consumption, water consumption, material consumption; impacts on site ecology; greenhouse gas emissions and other atmospheric emissions; solid/liquid waste management; indoor air quality, acoustics, lighting, longevity, adaptability, and flexibility of the building; operations and maintenance; social and economic considerations: urban planning issues.
Since there are numerous building evaluation tools that focus on different areas of sustainable development and are designed for different types of building projects, there is a need for methods or criteria used to identify the most suitable sustainable building rating system among the available. These criteria will analyze and offer information on the various applicable ratings systems. These criteria are based on various U.S. General Service Administration (GSA) drivers, Federal regulatory drivers and various program goals geared at developing sustainable buildings. These drivers include:
- Memorandum of Understanding by various Federal agencies on high performance and sustainable building signed in January 2006. It envisioned the federal government commitment to designing, constructing, locating, maintaining, and operating its facilities in such a manner that is energy efficient and sustainable so as to achieve high standards of living, optimal reachable reuse and recycling of depletable resources, increased sharing of life’s amenities in an economically logical manner.
- The Energy Policy Act of July 2005 that states that, “if life cycle cost effective, sustainable design principles are applied to the siting, design, and construction of all new and replacement buildings and each building project will comply with third party certification standards for high performance sustainable buildings”.
- Office of the Management and Budget Circular No. A-11, Section 55, “Energy and Transportation Efficiency Management” (2002). A sustainable building rating system is to be used so as to complete the table for energy efficiency data. Any additional cost incurred due to the incorporation of a sustainable design must be reported. It follows the executive order 13123 that requires any funding required for energy efficiency management to be documented.
- Executive Order 13123 on Sustainable Building Design, directed GSA and DOD to use sustainable design principles in efficient energy management in designing and construction of new facilities. Optimization of life-cycle costs, energy costs, pollution and other environmental costs associated with construction was made a priority for all agencies. These sustainable design principles, processes, recommendations and management practices offer qualitative objective resource for comparison of the various rating systems.
- Executive Order 13101 which advocates for waste prevention, recycling and federal acquisition for sustainable development. The Order eliminates the need for virgin material requirements through material selection, use of recovered materials, recyclability, reuse of products, life cycle cost and environmentally friendly products.
- GSA Mission, Values, Priorities and Sustainable Design Program Goals (2006). GSA is involved in designing, constructing and operating sustainable designed buildings.
Other environmental laws such as the National Environmental Policy Act (1969), the Resource Conservation and Recovery Act (1976), the Clean Air Act (1990), Executive Order 13134 (1999), and Executive Order 13148 (2002) through GSA support environmental ethic which in the long run will ensure sustainability.
Based on the mentioned drivers for sustainable design, various sustainable building rating system tools criteria are identified. They are important when it comes to credibility of rating systems. Namely;
Applicability – A rating system needs to be usable in all its building and project type. This is consistent with the Executive Order 13123, the Energy Policy Act and GSA goals.
Development – A rating system must use performance measurement, consensus-based standards, and life cycle concepts in consistence with the Memorandum of Understanding.
Usability – A rating system ought to be simple, user-friendly and practical to use so as to be applied universally to all GSA building types and projects.
System Maturity – A rating system ought to be dependable, be endorsed by respected organizations, have a proven track record, so that it can earn GSA goal of being reliable on sustainable design projects.
Technical Content – A rating system must be committed to addressing fundamental aspects of sustainable design such as energy consumption, water consumption, sitting, interior environmental quality, and material selection so as to be consistent with the Memorandum of Understanding, the Executive Order 13101, and the Energy Policy Act.
Measurability and Verification – A rating system must have a standardized, verifiable system that involves documentation of sustainable design related performance so as to address the Energy Policy Act and GSA goal on performance metrics.
Communicability – A rating system must be able to communicate their sustainable design to attract world class workplaces in the cooperate fraternity. In addition, the outcome must be easy to understand, versatile across the building and project types, and well-known by outside established organizations.
Sustainable Rating Tool Systems
There are numerous building evaluation tools world-wide. Based on the above mentioned criteria that provide a comparison between systems, five sustainable building rating tools meet the criteria. In addition, it can be generally said that most of the other rating tools are just a modification of these earlier models originally developed. The five sustainable building rating systems include:
BREEAM (Building Research Establishment’s Environmental Assessment Method): it was developed in the UK in 1990 and it holds the longest track record in building environmental assessment. Types of buildings covered by BREEAM, ranges from offices, industrial units, rental units, homes, and schools. In assessing a building point are awarded for each of the above criteria. The points are then added to give an overall score, which is either a pass, good, very good or excellent rating. On design and procurement criteria, BREEAM majors on; Management (commissioning, waste recycling, monitoring, pollution and materials minimization); Health and wellbeing (adequate ventilation, lighting, humidification, thermal comfort); Energy (sub-metering, efficiency of system, CO2 impact of systems); Transport (emissions and alternative transport facilities); Water (metering, consumption reduction, leak detection); Materials (asbestos mitigation, reuse of structures, recycling facilities, facade or materials, sustainable timber and use of crushed aggregate); Land use; Ecology (maintaining ecological systems, reduction of bio-diversity impact); Pollution (light pollution design, local/renewable energy sources, on-site treatment, leak detection systems, avoid use of global warming substances).
CASBEE (Comprehensive Assessment System for Building Environmental Efficiency): It was developed in Japan in 2001. It is based on the life cycle of the building that is pre-design, existing buildings, new constructions, and renovation. It relates environmental load with building performance thus presents a measure of eco-efficiency (Building Environmental Efficiency). According to CASBEE, the best sustainable building is one which is lowest in terms of environmental load and highest in performance quality. The rating of each criterion is based on level 1 to level 5, with level 5 representing the highest level of achievement. Major criteria categories within CASBEE include; quality and performance of building (indoor environment, outdoor environment and quality of services); building environmental loading (efficiency in terms of energy, resources and materials, off-site environment, reuse and reusability, avoidance of greenhouse emissions).
GBTool (Green Building Tool): Developed in 1998, for Green Building Challenge, by International Framework Committee, GBTool criteria categories include site selection, environmental loadings, project planning and development, indoor environmental quality, energy and resource consumption, long term performance, functionality and socioeconomic aspects. Ratings of the criteria are based on local benchmark scales. The complete assessment of the building is achieved from the scores of all criteria. The sponsoring organization establishes typical practices and the criteria weightings to represent local codes. GBTool has developed versions that address pre-design, as built, design and operations. The various major categories in GBTool criteria includes: Energy consumption (use of non-renewable energy, electrical peak demand, use of renewable sources); Resource consumption (material used and water usage); Environmental loadings (greenhouse and other atmospheric gas emissions, solid waste, site impacts, storm water, local and regional impacts); indoor environmental quality (indoor air quality, humidification, daylight and illumination, ventilation, noise and acoustic); appropriate site, project planning, urban design, flexibility and adaptability, socio-economic measures and maintenance of operating performance.
Green Globes US: Adapted from Green Globes Canada in 2004. It’s a combination of the BREEAM Canada and Green Leaf. Initial assessment occurs after conceptual design while the final assessment happens after construction documentation stage. Users can participate in evaluating the system through applicable points available. This can be done through their on-line portal. Major criteria categories includes project management (environmental purchasing, integrated design, emergency response plan, commissioning); site (site development area, ecological impacts, watershed features); Energy (energy consumption, demand, efficiency, and renewable sources of energy); Water (flow and flush fixtures, water conservation, off-site water treatment); Indoor environment (ventilation systems, indoor pollutants control, lighting design system, acoustic and thermal comfort); building material and solid waste management.
LEED (Leadership in Energy and Environmental Design): developed in the US in 1998 as a rating system. It addresses environmental building impacts through the environmental performance of the whole building. There are various versions of LEED that can be used in the assessment of existing buildings, homes, commercial interiors, and neighborhood development. An example of this is the LEED-NC used for new constructions and major renovations. Major criteria categories include Sustainable sites (site development impact, construction pollutions, heat island effect, and transportation alternative); water efficiency: Energy and atmosphere; material and resources; indoor environmental quality; innovation and design process (LEED accredited professional and sustainable design innovation strategy).
Of importance to note is that no single tool has addressed all the criteria but differences between the various rating tools mainly occur in the emphasis of each tool on one or more of the broad categories of sustainability, that is, natural resource depletion, environmental care and socio-economic viability in addition to the various themes being measured. This can be attributed to the various climatic zones unique to each locality investigated. Furthermore, this can be argued to be due to the lack of flexibility of the various tools. This reflects the various levels of concern when it comes to the various categories of sustainability as seen by different stakeholders and the current environmental issues of each locality. By providing various criteria of building sustainable buildings embodied in design guides, these tools have offered the numerous professionals necessary information on designing, constructing and to manage properties in a more sustainable way. In a holistic sense the tool will ensure continuous improvement in building performance and reduced negative environmental impacts by setting credible standards by which buildings can be objectively judged. Global parameters should be developed for building standardized rating tools to reduce barriers within the international market without overlooking factors unique to individual country.