Green Design Trends: The New Green Standard
By Martha G. VanGeem, PE, LEED® AP
Published in the April 2010 issue of Today’s Facility Manager
A new standard for the design of high performance green buildings is set to revolutionize the building industry. Published by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), in conjunction with the Illuminating Engineering Society of North America (IES) and the U.S. Green Building Council (USGBC), Standard 189.1, Standard for the Design of High Performance, Green Buildings Except Low-Rise Residential Buildings, is the first code intended commercial green building standard in the country.
The new standard was developed over 3.5 years using the ASHRAE consensus process. Many federal agencies, state agencies, and local jurisdictions prefer to adopt consensus standards—those developed using ANSI procedures. (Leadership in Energy and Environmental Design, also known as LEED, is not an ANSI consensus standard.)
Standard 189.1 was controversial because of its effects on the environment and the effects on a particular organization or industry. The committee was required to reach consensus on how far to reach on any particular environmental issue and on whether the criteria were reasonable and enforceable.
Another difference between LEED and 189.1 is that 189.1 is not a point system. Instead, it provides minimum requirements that must be met.
A frequent approach to meeting point systems is to garner as many of the least expensive points as possible. For standard 189.1, all of the mandatory requirements must be met, and then either the prescriptive or performance requirements must be met.
The prescriptive requirements specify a relatively simple method for showing compliance that generally involves little or no calculations. The performance path specifies an alternate method for showing compliance that is typically more complex than the prescriptive path.
Unlike a point system, where certain points can be avoided, standard 189.1 requires that criteria in all areas be met. The standard allows some choices and flexibility in the form of alternative paths or exceptions.
Examples of major criteria as well as criteria based on new concepts not included in LEED are presented in the following summary.
Site sustainability. This chapter provides criteria to minimize suburban sprawl, protect environmentally sensitive areas, mitigate heat island effects, manage on-site storm water control by using pervious surfaces, retaining native plantings, and minimizing light pollution. A new criterion is a requirement for shade on a portion of east or west walls, or a minimum Solar Reflective Index (SRI) requirement for these walls.
Water efficiency. This chapter provides maximum site and building water use requirements. Some fixtures need to meet the U.S. EPA WaterSense requirements.
Measurement of large sources of water use is required. A new criterion is the requirement that 60% of altered (improved) landscape has to include plantings other than turf.
Energy efficiency. This chapter includes requirements for the building envelope, mechanical equipment, ventilation, lighting, peak load reduction, and renewable energy. New criteria include the use of ENERGY STAR equipment, when available.
Another new criterion is a requirement to turn off plug loads (e.g., televisions and lights) in empty motel/hotel guest rooms. This chapter has the goal of saving 30% energy on average (compared to ASHRAE Standard 90.1-2007 for all buildings in all climates).
Indoor environmental quality. This chapter includes minimum requirements for indoor air quality (IAQ), thermal comfort (portions of ASHRAE Standard 55), acoustical control, and daylighting (skylights) under large roofs and side lighting (windows) for classrooms and offices. Shading is required in office buildings to prevent glare.
The IAQ requirements include source control, air cleaning, and dilution. Source control is met by requiring low emitting materials and entry mats and prohibiting smoking in buildings.
Impact of materials and resources. This chapter covers construction waste, refrigerants, recyclables, and reused goods. In addition, two paths are available for reducing the impact of building materials. The prescriptive path requires a minimum recycled, regional, or certified wood content, while the performance path requires a life cycle assessment is performed and certain criteria are met. New criteria include a maximum amount of total waste per square foot of new building floor area. Also included is a requirement of a storage area for reusable goods and used fluorescent lamps.
Construction and plans for operation. These plans include commissioning, maintenance (ASHRAE/ACCA Standard 180), service life, green cleaning, and transportation management. Commissioning requirements are more stringent for buildings with greater than 5,000 square feet of floor area. Tracking and assessing water and energy use is mandatory for large sources. The service life plan ensures that materials used for site work (and to construct the building envelope) have a design or estimated service life that is reported to the owner.
Integrated design. Integrated design is not required; however, guidance is provided in the form of an informative appendix. Savings in utility costs often offset any higher initial costs, especially if these utility costs are monitored to catch spikes from faulty equipment.
Released earlier this year, this national green building standard was written in mandatory, code intended language. It is not a point or rating system but has actual minimum requirements, thus providing clearer application and guidance for its use and its adoption into local codes. Visit this link for more information on the 189.1 standard.
VanGeem, principal engineer for Skokie, IL-based CTLGroup, has 28 years of consulting experience in energy efficiency, green buildings, and work on related standards (including being a member of ASHRAE SPC 189.1). CTLGroup provides engineering and scientific services to the transportation, construction materials, power, building and facilities, and legal and insurance industries.
Hidden Risks Of Green
By J. David Odom, ASHRAE
Richard Scott, AIA, NCARB, LEED® AP, and
George H. DuBose, CGC
The great irony of green construction is that the very concepts intended to enhance a building’s performance over its entire lifetime are many of the same things that make a building highly susceptible to moisture and mold problems during its first few years of operation.
While green buildings have many positive benefits, there is also evidence to suggest a direct correlation between new products, innovative design, and building failures. Departing from the “tried and true” can increase the risk of building failure.
The chart below summarizes some of the differences between green buildings and the concepts found in lower risk buildings. For example, lower risk buildings do not exceed industry guidelines on mechanically introduced outside air; instead, they emphasize humidity control (especially in more humid climates). On the other hand, green buildings reward the introduction of more outside air (compared to current industry standards), which can ultimately lead to indoor humidity problems and mold growth.
The intent of building green is unquestionably noble and good and should be aggressively pursued. However, because of the change this will present to the design and construction industry, its implementation will open up new risks that are likely to be both legal and technical in nature. Some of the legal risks associated with green buildings are fairly obvious, while the following may be more obscure:
• Accepting the higher standard of care that a green building might present—what is currently considered “best practices” may now become the new expected “standard of care.” Most insurance companies exclude anything that exceeds the normal standard of care.
• Failing to recognize (or prepare for) the unknowns in cost and schedule impacts that a green building might present.
• The failure of new products to meet their promoted performance levels.
Moisture intrusion, whether through the building envelope or a relative humidity increase, results in a large percentage of construction claims associated with sustainable building practices. Consider the following examples that can increase the potential for moisture intrusion:
• Vegetative roofs, which are more risky than conventional roofs must be carefully designed, constructed, and monitored after completion.
• Improved energy performance through increased insulation and the use of new materials, which may change the dew point location in walls, can result in damaging condensation and a reduced drying potential for wall assemblies.
• Reuse of existing building or recycled components, which may not be easily integrated to the adjacent new materials, could cause compatibility problems.
• New green construction materials that have not been field tested over time require special assessment by the designer.
• Increased ventilation to meet indoor air quality (IAQ) goals may unintentionally result in increased interior humidity levels.
• Building startup procedures, such as “building flush out,” could result in increased humidity levels and mold growth. Lower risk buildings rely almost exclusively on source control (which is also a green building goal) rather than relying on “flush out” and increased building exhaust.
New green construction materials are entering the market at a staggering rate. Because many of these products help to achieve multiple LEED credits, designers working on green buildings are eager to specify these materials. The risk to contractors is that many of these new items are not time tested, and designers often do not have the time to research their efficacy. If the new product fails, it may be difficult to determine if it is a design error, an installation error, or a product defect. Additionally, contractors must rely on subcontractors to install new materials that they are inexperienced in installing.
What is the greatest risk to the green building movement? It’s likely not the increased costs associated with green buildings—it’s more likely green buildings that don’t perform up to expectations and, in some cases, may experience significant failures.
The increased costs of litigation and insurance that could result from underperforming green buildings will be absorbed by designers and contractors (in a highly competitive marketplace). However, most likely these costs will be passed onto building owners in the form of change orders.
Only recently has the marketplace begun to recognize the various contractual, legal, and technical risks that are inherent to green buildings. A growing number of experts have suggested that the first two steps to improved green building risk management are to: recognize the risks for green buildings; and develop a set of guidelines that merge the regional challenges with green building guidelines, recognizing the lessons learned in lower risk buildings.
The design and construction community must not assume that if it builds green, then it will automatically build regionally correct or even lower risk structures. Until the gaps between lower risk and green buildings are addressed, the design and construction community would be advised to revisit the already learned lessons of lower risk applications (like those associated with waterproofing, humidity control, and building forensics). Without these priorities, poorly functioning green buildings are the likely result, and this could seriously impair the green building movement, especially in demanding climates.
Odom, Scott, and DuBose work for Liberty Building Forensics Group, LLC (www.libertybuilding.com), a firm that specializes in forensic building investigations and expert witness/litigation support. This is the summary of a more extensive technical article which can be found on the Liberty Building and NCARB.org Web sites.