Buildings have an economic, social and environmental impact on our world. The U.S. Department of Energy reports that there are nearly five million commercial buildings in the United States and 76 million residential buildings. These buildings use one-third of the energy consumed in the U.S. and nearly two-thirds of all electricity. It is also projected that by 2010 the U.S will have another 38 million buildings. There is a growing awareness of the need to change the ways buildings are built such that we create buildings that improve the economic, social and environmental performance compared to buildings of the past.
Changing the way buildings are sited, oriented, designed and constructed can reduce the lifetime costs of buildings. In a 30-year life of a building, the initial cost is just 2%, while the salaries are 92% of the cost of ownership (Figure 1). A green building or a high-performance commercial building is one that is designed to improve the environmental performance while increasing the productivity of the people that use them.
Creating a successful high-performance building starts with an integrated design approach early in the project. An integrated team consists of the owner, building occupants, operations and maintenance (O&M) staff, as well as design professionals. The challenge to the team is to design (construct and operate) the building from a whole building perspective that understands that buildings are complex and building systems are interdependent.
The goals of a high-performance building include lower lifetime costs, a healthy indoor environment that enhances employee productivity and well being, as well as minimizing the impact to the surrounding community.
One of the first steps in achieving a green building is setting goals for the project to achieve certain levels of environmental and energy performance. The LEED(TM) 2.1 (Leadership in Energy and Environmental Design) Green Building Rating System is a tool that can be used as a framework to set goals for the project. LEED 2.1 has national recognition and is a product from the U.S. Green Building Council (USGBC). The USGBC is a coalition of leaders from across the building industry working to promote buildings that are environmentally responsible, profitable and healthy places to live and work. The USGBC is actively working to transform the building environment to produce a new generation of buildings that deliver high performance inside and out. (For more information on the USGBC, visit the Web site at www.usgbc.org.)
The LEED Green Building Rating System is a voluntary, consensus-based national standard for developing high-performance, sustainable buildings. Members of the USGBC representing all segments of the building industry developed LEED and continue to contribute to its evolution.
LEED was created to: define "green building" by establishing a common standard of measurement; promote integrated, whole-building design practices; recognize environmental leadership in the building industry; stimulate green competition; raise consumer awareness of green building benefits; and work to transform the building market. LEED provides a complete framework for assessing building performance and meeting sustainability goals. Based on well-founded scientific standards, LEED emphasizes state-of-the-art strategies for sustainable site development, water savings, energy efficiency, materials selection and indoor environmental quality.
Integrated Sustainable Design ApproachOnce an owner has decided to pursue a high performance building design, a design team needs to be selected. The request for design services should clearly state the owner's intent to select an architectural and engineering (A&E) team with the capability and experience to deliver green buildings as evidenced by successful completed--and monitored--projects. The scope of work should include periodic meetings for team integration and the time to research and evaluate design options.
Once the sustainable A&E team is on board, the collaborative process often begins with a design charrette. The team is comprised of everyone involved in the use, operation, construction and design of the facility to achieve the best results. The charrette is a brainstorming session to look at how the building and its systems are integrated, not just within the building but on the site and in the larger community. The topics that are often discussed during the charrette are: the building's location and microclimate; orientation and envelope; interior spaces; fenestration, daylighting and lighting; energy and water needs; heating, ventilating and air-conditioning (HVAC) systems; landscaping and exterior spaces. The goal is not to prepare a final design but to explore and understand all the design issues. The design issues and possible solutions are identified and well documented. Follow-up assignments are made to analyze in detail specific integrated solutions chosen by the team as potential strategies for the project that will meet the sustainable goals set forth by the owner.
Sustainable SitesHow you site a building can enhance its aesthetic value, decrease its environmental impact and improve energy performance for the entire life of the structure. Other site factors to evaluate include cost, future flexibility, ease of maintenance, and impact to occupants and the surrounding community.
Since the siting of a building is a major impact in every aspect, from direct environmental impact, to energy consumption, to indoor environmental quality (IEQ), considerations include location and building orientation. Initial site investigations include determining what the impacts from the surroundings such as exhaust fumes and noise are, as well as what the existing transportation corridors and infrastructure are. Are there water or soil containment problems, and can they be mitigated? Site issues include transportation, greenfield impacts, existing pollution on the site, stormwater management and orientation of the building to improve energy efficiency and IEQ.
High-performance building principles discourage the development of greenfields. Greenfields include previously undeveloped land, restored land, agricultural properties and parks. These areas have high ecological, social and community values. In addition, often the development of greenfields increases sprawl, which can often burden the local infrastructure if it is not considered early in the process.
A climate-responsive design is impacted by the building's orientation with relation to the sun. Elongating a building along the east-east axis can improve the building's ability to optimize passive heating and cooling, natural ventilation and daylighting. Maximizing the south-facing building façade not only optimizes the exposure to the sun but also allows for more diffused daylighting. The sun is low in the sky in the morning (east) and afternoon (west), and the light coming in would be more likely to cause glare.
Heat islands are areas that have higher ambient temperatures than the surrounding area. This is due to the use of dark, impermeable surface areas, and lack of vegetation and tree cover. Heat islands can be 2-10 degrees hotter, which creates higher HVAC loads and reduces both outdoor and indoor comfort. Heat islands can be mitigated by using cool roofs or green roofs, by strategically landscaping the perimeter of the building with trees to increase shade cover, and by decreasing impervious surface areas.
Site developments involve covering permeable ground with impervious surfaces (parking lots, buildings, etc.) that significantly increase the stormwater runoff of the site. The runoff will often contain pollutants, such as oil and gasoline, from the parking lot. Infiltration techniques can be utilized to treat the water before it leaves the site. The benefits of infiltration include less water needed to irrigate the landscape, as well as reducing the impact on local creeks. Using an integrated landscape management plan with techniques such as vegetated runoff areas to filter the water before it leaves the site and increasing the landscape-to-paved-area ratio reduces the impact of the water leaving the site.
Transportation to and from the site is a major consideration for high-performing buildings. Issues including access to mass transit, the feasibility of bicycle use and pedestrian access need to be evaluated. Transportation by automobiles increases traffic congestion and air pollution, which have negative impacts on the local community.
Proper siting of a building can improve the triple bottom line by maintaining an efficient infrastructure, creating a sense of community and preserving natural systems.
Building in Water EfficiencyOn a daily basis in the U.S. we use approximately 25% of the renewable fresh water supply to support residential, commercial, industrial, agricultural and recreational activities. This accounts for about 340 billion gallons a day taken from rivers, streams and reservoirs. Additionally, we withdraw from underground aquifers to support our water use habits. Currently in the U.S., we are using an estimated 3,700 billion gallons more of water than we are returning to the natural water system to recharge our supply.
The most cost-effective design strategy for a new building is one that uses less potable water. Costs for potable water are expected to escalate over the next few years, and a design today that reduces that need will save money and resources in the years to come. Design strategies include low-flow fixtures, innovative wastewater technologies and landscaping design.
Water efficiency measures in commercial buildings can easily reduce water usage by 30% or more. In a typical 100,000-square-foot office building, low-flow fixtures coupled with sensors and automatic controls can save a minimum of one million gallons of water per year, based on 650 building occupants each using an average of 20 gallons per day. Currently, the standard toilet fixture is 1.6 gallons per flush (gpf) and the standard urinal is 1.0 gpf. Two other low flow options in toilets are a dual flush model (1.6 gpf for solids and 0.8 gpf for liquids) and a 1.1 gpf model. Urinals have a 0.5 gpf model available, as well as a waterless urinal. Waterless urinal technology has improved over time, and the current models on the market are achieving great success. These strategies have little or no costs associated and produce a rapid payback to the owner.
Water-efficient landscaping starts during site selection and continues through occupancy. As shown in Figure 2, irrigation is 25% of the water use for commercial buildings. This is true for schools as well. The most cost-effective strategy is to reduce the need for water in the landscape. By combining water conservation practices with creative landscape design, you can create an outdoor space that is welcoming and attractive. Involving a landscape architect that understands the local climate early is important to long-term water efficiency. Simple strategies, such as using native plants, grouping plants according to their watering needs, using shade, taking advantage of natural runoff, and using mulch, can produce a landscape that is water efficient yet beautiful. If an irrigation system is needed, check the availability of tying into a non-potable system rather than using the potable water. Gray water, the reuse of water from baths and showers, and rainwater harvesting are two strategies often used elsewhere in the U.S. to reduce the need for potable water for irrigation.
As with any resource, the most cost-effective strategy is to turn the water off. Starting with a commercial building design that minimizes water use in the restroom and on the ground will impact 70% of water use in the building and start the savings immediately.
When the integrated sustainable design process is used to develop a building, the interplay between disciplines is readily apparent to seasoned integrated practitioners and is an eye-opener to newcomers. The impact of the site selection on water and energy use is obvious to the team as the design evolves. The design continues to evolve and the designer needs to evaluate the energy use, selecting appropriate materials and creating a healthy indoor environment. A successful high-performance building optimizes the use of all resources, people, places and profit to create a building that improves the triple bottom for all.