METAL BUILDING NAMED FIRST PLATINUM-CERTIFIED HANGAR

Project: Hangar 25, Bob Hope Airport
Location: Burbank, California

The Project: The world’s first LEED Platinum-certified aircraft hangar resides at the Bob Hope Airport in Burbank, California. At the heart of Hangar 25 is a maintenance facility that can service planes as large as a Boeing 757-200. The $17-million building is situated on a 2.81-acre site at the airport and has 50,630 square feet of hangar space, plus approximately 12,000 square feet of office and meeting area.

The versatility of the building is manifested in the combination of the office and hangar space, allowing the nose of an aircraft to pierce the typical office-hangar line. This design allows for the first- and second-floor offices to be situated on both front corners of a building while utilizing a fully glazed translucent front entryway, showcasing views of an aircraft. There is also a steel bridge across the foyer that allows occupants to cross to either side of the offices and provides excellent views of the hangar operations.

Sustainable Construction: The hangar uses a metal building system including a metal roof and metal wall panels that incorporate a multitude of sustainable features. Metal building systems are popular choices for airport hangars because they are cost-effective and can offer clear spans to suit any size aircraft. Hangar 25 demonstrates that they are also sustainable. The hangar gained valuable LEED points for its recycled content with recycled steel used for the primary structural members being a large part of that. Steel is generally regarded as the most recycled and recyclable building material in the world. In the quest for efficiency, the structural members in this metal building system are custom engineered to handle the specific load needs for Hangar 25. This optimizes the steel used in the building and keeps costs down. In this case, that also meant designing a structure that could handle a 225 kW photovoltaic (PV) system on the roof. The PV panels are mounted to a standard R-panel roof on a rack system that attaches to the purlins. An added benefit of the PV system is the shading it provides to the roof. This helps to keep the cooling costs down and, along with the highly reflective white metal roof panels, reduces the heat island effect of the building. The roof itself is considered a cool roof, with a solar reflectance of 0.70, an infrared emittance of 0.85, and a solar reflective index (SRI) of 85.

Renewable Energy: The solar array has more than 1,500 PV panels, producing 110 percent of the power needed to operate the facility. It is expected to produce more than 400,000 kWh of energy per year. The electricity savings from the solar array are significant. The building has operating expenses that are approximately 2 cents per square foot compared to a traditional hangar that operates at about 20 cents per square foot. All of the equipment for the hangar, including rechargeable tractors, forklifts, and tugs, run off the electricity produced by the solar array. Further, when aircraft receive maintenance, the power to keep all the systems running comes from the solar array. Using the solar power is not only cost-effective, but it also does away with fumes and odors from the diesel and jet fuel that would ordinarily be required.

Ventilation: Six large metal fans hang from the steel frame of the building and provide a low-cost system for circulating air. The large-volume, slow-moving fans help to maintain high air quality and keep the hangar cool in the summer and warm in the winter. Additionally, when a plane comes in fresh from a flight they can blow away condensation quickly.

Natural Lighting: Daylighting is also a popular energy saving feature in new buildings, and the ease with which a metal building system can handle this is evident in Hangar 25. There are more than 100 translucent panels in the metal roof, keeping lighting costs down and creating a better work environment. More than 95 percent of the regularly used areas of the facility, including the office space, receive natural daylight.

Other Sustainable Features: The concrete floor of the hangar incorporates a unique, diamond-polished surface. In many maintenance hangars, the floors often have a coating with epoxy and other potentially harmful contaminants; they also need to be resurfaced every few years. The natural concrete floor of Hangar 25 was polished to a bright finish using a diamond-bladed polisher. The final product is a chemical-free concrete floor that is estimated to last at least 20 years, and those who work here won’t have to worry about toxic compounds. Another benefit of the polished floor is the high reflectivity, which increases the impact of daylighting. Other sustainable features include low-flow plumbing fixtures, natural landscaping, and a special water mist fire-suppression system.

Results: Hangar 25 at the Bob Hope Airport is an excellent example of how metal building systems can incorporate the benefits of sustainable designs.

Based on a case Study by Jay D. Johnson, LEED AP, Director of Architectural Services for the Metal Building Manufacturers Association

WALTER P. MOORE COMPARATIVE CASE STUDIES OF BUILDING TYPES

Comparative Case Study Overview: The Metal Building Manufacturers Association (MBMA) engaged Walter P. Moore and Associates to conduct a whole-building life-cycle assessment (WBLCA) comparing the environmental impacts of a metal building system against other forms of construction based on the results of the Athena Institute Impact Estimator software. The purpose of the study was to compare the environmental impacts for the building envelope of 10 case study buildings that included metal building systems1 and other forms of construction located in three different climate regions in the United States. As a result, 30 total building case studies were evaluated in this study.

This study compared WBLCAs between metal buildings and alternate construction types for the three different building uses and footprints using Athena Impact Estimator software. WBLCA is not intended to give exact calculations of environmental metrics but instead gives a picture of how the buildings compare in various categories. This study focused on the following environmental metrics:

• Global warming potential
• Ozone depletion potential
• Acidification potential
• Smog potential
• Nonrenewable energy
• Eutrophication potential

The Comparisons: This case study comparison looks at three different but common building types, namely a small office building, a medium-sized storage building, and a large-sized industrial building. Each type is compared based on being constructed of one or more of five different structural building system types: 1) a metal building system, 2) a wood-framed building, 3) load-bearing masonry, 4) concrete tilt-up construction, and 5) wide-flange steel construction. Case study A compared a metal building with a wood-framed building for a small office, while case studies B and C compared a metal building with a load-bearing masonry, concrete tilt-up, and wide-flange steel buildings for a medium storage facility and a large industrial building. Each of the case studies are analyzed in three different climate locations, namely Florida, California, and Minnesota.

Case Study A: Small Office Building

For the small office building case study, a metal building was compared to a wood-framed building. Overall, the wood frame building materials showed less embodied impact than the metal building in the categories of global warming, ozone depletion, acidification potential, and nonrenewable energy for all project locations. It showed more impact for eutrophication potential. The results for smog potential varied by project location and were within 10 percent and are considered within the error of the data reporting.