High Concrete Group Maintenance Building
Structural Precast Elements:
• Precast concrete double tees
Sustainability Practices — Leading by Design
If the design and construction decisions precasters make for their own facilities can serve as inspiration for how to approach construction decisions, here is the story of a precaster’s maintenance building located on the East Coast. This precast concrete structure includes many elements of sustainable design, and the precaster served an interesting dual role as both the client and engineer/manufacturer.
At an estimated cost of construction of $4.1 million, the building will be used by the company’s maintenance department to service heavy trucks, pick up trucks and cars, and other plant equipment. The facility was designed and planned so that it is expected to earn Silver Certification in the LEED® rating system for new construction through the U.S. Green Building Council (USGBC). Documentation for 37 LEED v2.2 points has been prepared for submittal to the USGBC.
To determine which green features would be integrated into the building’s design and construction, the project team began the process with a Green Design Charette, which typically lasts anywhere from a half day to a week, depending on the size and complexity of the project. The entire design team was present to discuss project goals, ideas, building systems, local availability of materials, site characteristics, grading, storm water, macro and micro climate including sun and wind considerations and possible code issues. This helped in the evaluation of different systems, cost impacts and the viability of meeting the credit criteria.
Elements Enhance Sustainable Design and Performance
PRECAST CONCRETE. In the LEED materials and resources category, it may seem like a given that a precaster would choose precast concrete for its building. But the durability and environmentally sound characteristics of the material make a strong case for its use by diverse clients. Today’s advanced carbon fiber-reinforced precast products are designed to increase durability and thermal efficiency, reduce or eliminate corrosion, and reduce weight. Additional characteristics of concrete result in a long list of green attributes:
- Precast panels can be re-used when buildings are expanded or repurposed in different applications, such as protecting shorelines from erosion
- Since the precast process is self-contained, formwork and finishing materials are reused
- Virtually all reinforcing steel is made from recycled steel
- Light-colored precast reduces heat island effect in urban areas
- Reflective or light-colored concrete requires less artificial light to illuminate the structure
- Thermal mass and reflective properties reduce the amount of electricity used for A/C during the heat of the day
- Thermal mass is beneficial in absorbing and retaining heat
The all-precast concrete building features thermally efficient sandwich wall panels fabricated by the company’s Springboro, Ohio plant. With insulating foam literally sandwiched inside them, the panels provide an R-value of 25 and are reinforced with innovative CarbonCast® carbon fiber shear trusses that make them structurally composite for load bearing. The roof is composed of CarbonCast double tees manufactured by the Denver plant. Also used for the driving surfaces in parking garages, the double tees are made with non-corrosive carbon fiber flange reinforcement and are 10 percent lighter in weight than traditional double tees.
ENERGY USE REDUCED FURTHER. To further enhance the energy efficiency of the precast building, computer energy models and computer daylight modeling were used to optimize the HVAC systems and building envelope, as well as to determine the correct size, location, and glazing type for windows and skylights. The overall projected energy costs of the building have been reduced by 24.5 percent over a typical code-compliant structure through use of:
- Thermally efficient wall panels reinforced with innovative carbon fiber to provide structurally composite performance for thinner, lighter wall sections.
- A highly insulated building envelope with a rating of R-24.
- Carbon fiber grid reinforced double tees that are lighter in weight and non-corrosive.
- Eight inches of insulation on precast concrete roof double tees for a rating of R-40.
- Highly efficient doors and windows.
- A heating system consisting of a water-based radiant heat floor system (to provide uniform distribution of heat and comfort where technicians will work) and a boiler that will use waste oil from fleet vehicles.
- Highly efficient dimmable fluorescent lighting interconnected to photo sensors that determine foot-candle levels from natural light through skylights and dim or turn off fixtures as necessary.
Exciting Growth of Sustainability Practices
From an integrative design-build approach to the use of precast concrete and other environmentally responsible features and practices, the design team embraced the best in green building in this project. The organization looks forward to the operational cost savings this facility will realize. But just as important is the knowledge that more and more of us are makings significant progress as stewards of the environment.
It’s hard to believe how far the industry has come in such a short period of time with the green building movement – from the USGBC’s work to improve the methods and establish the standards, to getting buy-in from the leaders who make construction decisions. Just a dozen years ago, these issues were hardly on the radar screens of business leaders, and today the growth in demand for the best in sustainable design has reached an exciting and unstoppable pace.