Editor's note: This is Part 1 of a two-part series.
Mechanical and electrical engineers have a significant impact on the success of Leadership in Energy and Environmental Design (LEED) projects and should recognize their role as technical resources for project teams. Engineers typically are responsible for the computerized energy model, which directly sets the number of attainable LEED energy credits. As a result, engineers have an opportunity to make recommendations regarding the energy performance of architectural systems, such as the impacts of glazing, building orientation and aspect ratio, passive-solar features, and insulation.
Engineers have similar opportunities to promote efficient lighting and daylighting, water-efficient fixtures, and indoor-air-quality (IAQ) friendly materials and finishes. And, of course, they should put forward high-performance HVAC systems with above-standard filtration and environmentally friendly refrigerants. Ongoing research suggests ventilation and daylighting are the most significant contributors to green-building health and productivity benefits. Engineering systems also have a significant impact on project costs. On every LEED project, engineers should encourage a smart “green-building” approach (i.e., a green building that is cost-effective and within budget).
There are two aspects of potential additional costs of green projects: soft costs, which include the costs of design, commissioning, and LEED certification, and hard costs, which include the costs of constructing the building and systems.
Green design requires a more rigorous approach and additional documentation for LEED certification. The additional costs can be 10 to 20 percent of typical architectural-team design fees.
Soft costs include commissioning, a LEED requirement the value of which many owners do not perceive until they have gone through it. Until then, they see it merely as a significant line-item cost. The cost of commissioning can range from 0.5 to 1.5 percent of construction costs, depending on the level of commissioning and the size of the building. Engineers should help owners realize that commissioning, particularly of mechanical systems, typically provides a return in terms of utility-cost savings and reduced startup and maintenance costs.
Among the goals of a project should be the development of a well-integrated design that achieves a LEED certification with an aggressive approach toward maintaining the project budget. There are shades of green (i.e., you can pursue a LEED Certified rating up to a LEED Platinum rating). In other words, incorporate as much “green” as possible for the project budget. Cost estimates should be developed at the outset of a project and continually reviewed to ensure the project is within budget.
When planned from the outset, LEED Certified and, sometimes, LEED Silver should be accomplished easily, with no additional construction cost. However, the smaller the project, the greater the potential cost impact of additional green features/systems. Larger projects benefit from economies of scale.
In addition to initial construction costs, green projects are evaluated in terms of life-cycle costs for architectural and engineering systems and materials, including operation-and-maintenance, replacement, financial, and demolition and disposal costs. For example, least-first-cost materials may be the most expensive on a life-cycle-cost basis because of high associated-maintenance costs. High-tech systems also may incur greater maintenance costs.
The key to providing a building that provides environmental performance while potentially maintaining the same budgets for construction costs is integrated design. Integrated design views a building as a “system of architectural and engineering systems” that complement one another to achieve the best performance. To be as successful as possible, integrated design needs to be incorporated into the design process at the beginning of a project.
Starting with the envelope, engineers should recommend high-performance glazing in combination with high-performance wall/roof insulation and passive-solar design. This will reduce HVAC heating/cooling loads, which, in turn, will lead to smaller HVAC-equipment requirements, including those for ductwork, piping, and wiring, thereby reducing system costs. Mechanical/electrical-system savings can offset the costs of an improved architectural envelope, which may limit overall project-cost increases.
High-performance glazing systems have lower U-values for the overall assembly, which should be selected with a visible-light-transmittance value for daylighting that is approximately twice that of the solar-heat-gain coefficient. Double-glazing systems with interstitial coated mylar films (or triple glazing) with thermally broken framing provide the best performance.
Another example of architectural/engineering integration is the selection of low/no-volatile-organic-compound, low-maintenance finishes, carpeting, and furniture systems. The avoidance of pollutant sources is a key element of IAQ design outside the scope of the mechanical engineer. Moisture control is another critical IAQ issue requiring close interdisciplinary collaboration; however, it usually has little or no cost impact when integrated early in the design process.
Although integration works best on new, freestanding projects, it can be applied on any project.
In July, this series will conclude with discussion of taking advantage of low-cost LEED credits, matching green systems to the needs of buildings, and the return on investment offered by LEED.
A principal of CJL Engineering Inc., Alan Traugott, LEED AP, is a founding member of the U.S. Green Building Council (USGBC), past chair of the USGBC chapter committee, the USGBC liaison to ASHRAE, a member of the Green Guidelines for Healthcare steering committee, a member of the Green Building Alliance (GBA) board, and chair of the GBA committee responsible for developing green-building performance data.