Embarking on a new construction project requires many decisions by project team members and owners—everything from budget and schedule concerns to long-term maintenance and utility costs. Today’s savvy owners have access to more information than ever before when undertaking a project and yet they are faced with more confusion and challenges because of that volume. A focus that used to be on financing, fulfillment, and life-cycle costs, today’s owner now must be aware of indoor air quality (affected by volatile organic compounds or VOCs), raw material depletion, and recycled content among many other new concepts. This new frontier of data acquisition and decision making evidences that owners are pursuing sustainable projects at a dramatically increasing rate. Beyond the societal benefits of designing and constructing sustainable facilities, owners desire a sustainable structure to reduce both short-term costs, by incorporating recycled materials, and long-term operating costs, by selecting better building systems for their facility.
Concrete is a sustainable construction material found throughout the built environment, even before the green and sustainable building movement took hold. Offering the attributes of durability, low maintenance, local availability, high strength, and no impact on indoor air quality, concrete can be used on every type of end-use facility. Site-cast tilt-up offers not only these attributes, but many more that make it an optimal solution for sustainable construction. In addition to the natural beauty of concrete, tilt-up construction offers the versatility to reduce environmental impact by offering smaller footprints and stacked structures, resolving urban infill, and reducing the required site area for construction.
“By offering a reduced footprint while achieving the desired space and program requirements by going vertical, the area around the tilt-up structure can become a larger green space than those required by code minimums or it can even be used for solar panel arrays or other clean energy resources,” says Todd Edge, project manager at Kenneth R. Carlson, Architect—P.A., Deerfield Beach, Fla. “Therefore, tilt-up as a design medium can possibly foster additional eco-friendly and high-performance decisions that create a lasting influence.”
Beyond design and the versatility of tilt-up, local material acquisition and the use of the building site for production can reduce the carbon footprint and carbon dioxide emissions. Wall sections are thinner and material is used more efficiently as structural components result in less materials delivered to the jobsite and less waste generated during construction. The horizontal casting surface for vertical panels also greatly reduces the forming material requirements. Both virgin material demands and consumption of landfill space are reduced through the use of tilt-up concrete. Similarly, transportation costs, fuel consumption, and therefore carbon output are minimized through the reduction of vehicles traveling to the site to deliver materials or remove waste. In addition, the speed of construction afforded by tilt-up leads to less vehicles and machines being used during construction when compared to other construction methods. A specific benefit to contractors, developers, and owners is a savings in fuel costs.
Sustainable construction focuses in part on the concepts of recycle and reuse. Tilt-up construction applies these concepts in several ways.
- During construction, recycled materials, such as steel reinforcement, large and small aggregates, commonly are used.
- Increased use of supplementary cementitious materials, such as fly-ash, slag, foundry sand, limes sludge, and silica fumes, encourages the concept of recycling during construction.
- Tilt-up buildings are more easily expanded during renovations or adapted for reuse. “For reuse, existing tilt-up structures offer an ease of expansion and retrofit that is not readily available with other construction methods,” says Edge. “Panels can be designed to be movable and engineered with the structural efficiency to allow for the modification and/or removal of openings. Knock-out openings can be designed into panels to allow for new doorways and windows based on the future phasing of a project.”
- During renovation, remodeling, or demolition, recycling occurs as tilt-up wall panels are crushed and used as the subbase for sidewalks, parking lots, casting slabs, or roads. Similar recycling occurs with the temporary slab conditions used to cast the panels.
Once the panels are erect, tilt-up continues to offer sustainable benefits through greatly reduced mechanical system requirements.
- The large panel size means joints are minimized, which limits air infiltration.
- As compared to other systems, tilt-up panels provide a lower level of permeability of air as well as loss of conditioned indoor air.
- Proven insulation systems provide uncompromised, continuous insulation layers. Developed specifically for tilt-up construction, they provide the maximum energy efficiency possible. Structures created with insulated wall panels are not affected by the daily temperature fluctuations; thus, lowering both cooling and heating costs, providing comfort for the owners as well as the occupants.
- Thermal mass inherent in the structural concrete layer establishes a dampening effect to the diurnal temperature cycle the building experiences. Combined with the continuous insulation systems in a sandwich wall design, the thermal mass produces a building envelope performance that is unparalleled.
- Through exposed concrete interior surfaces, indoor air quality can be improved by reducing VOCs and lowering maintenance requirements. Concrete itself is a nonoffgassing material, so it qualifies as low VOC.
- Natural concrete surfaces can be designed to actively absorb carbon dioxide from the air through carbonation and can self-clean oxidized organic matter with certain additives. Because natural concrete surfaces, or additive enriched concrete, can help clean the air and reduce the risk of sick building syndrome and building related illness, the need for high-maintenance carbon filters may not be required.
Another key component of sustainable design is maximizing natural day lighting. “Natural day lighting can be provided for and controlled by compatible glazing or window systems with the structural efficiency of tilt-up panels,” says Edge. “Large openings allow for increased amount of natural light, reducing the demand load on the mechanical systems while maximizing views. In addition, tilt-up can be designed, engineered, and crafted in several ways—horizontally, vertically, diagonally, or curved—to help bounce natural light into the depths of the space. Conversely, the strategic placement of tilt-up panels provides critical yet economical sun-shading.”
Case study: One Haworth Center
Tilt-up professionals have begun promoting actively the method’s sustainable attributes as evidence by this year’s 2010 Tilt-Up Concrete Association (TCA), Mt. Vernon, Iowa, Achievement Awards. Winner of the Excellence in Achievement distinction, One Haworth Center is a 300,000-square-foot office building and renovation in Holland, Mich.
Intended to make a statement to their worldwide customers, the One Haworth Center renovation and addition was originally designed with a 54-foot-tall cast-in-place concrete wall along one side of the portion of the building termed “the bookend.” This unusual part of the building resembles a bookend because of its sloped and planted green roof, and tapered shape in plan. Up to 8 feet of this concrete wall is located belowgrade, supported on a cast-in-place retaining wall that forms one edge of an HVAC tunnel below the slab on grade. The design and construction team brought in Steinbicker and Associates, Dayton, Ohio, an engineer with a specialty in tilt-up, to facilitate the conversion of the cast-in-place wall to tilt-up; a value engineering conversion that ultimately saved the owner more than $200,000 and more than one month in the construction schedule.
The original architecture incorporated reveals and form tie “cones” into the exposed finish for the cast-in-place walls. These elements also were cast into the tilt-up panels during construction. Other unique architectural features include full-height diagonal windows and a sloped top on the panels. Although the window layout provides much architectural interest, it made the conversion to tilt-up somewhat difficult. The window layout dictated that some panels would be less than 3 feet wide at their base and more than 16 feet wide at the top, a panel geometry that would be unstable for erection purposes. For this reason, in several instances, multiple panels were temporarily tied together across the windows to create panels that could be erected safely. To accomplish this, temporary recessed horizontal concrete beams were added across the openings. These tie beams also acted to transfer the lifting forces from one side of the diagonal opening to the other, thus minimizing the differential deflections between the two sides of the panel during erection. Overcoming the effects of a full-height vertical depression in some of the panels, which reduced the structural thickness down to 5 1/2 inches, was the final challenge. This LEED registered building is classified as NC Gold by the U.S. Green Building Council.
“The relatively thick concrete walls provided superior thermal mass, which helped combat air infiltration and heat loss,” says Mark Remmetter, managing principal at Steinbicker and Associates. “The selection of tilt-up walls enabled the design and construction team to incorporate locally available materials in the concrete mix as well as recycled steel. These benefits helped the owner in their quest to achieve a LEED certified project.”
Case study: Premier Beverage
When one of Florida’s largest wholesale beverage distributors grew too large for its current location, site-cast tilt-up construction was the natural choice for the construction of its new facility in Tampa, Fla. As one of the top wine and spirits providers in the United States, Premier Beverage challenged the R.R. Simmons, Tampa, Fla., design-build team to not only construct a large industrial facility, but also have the building qualify for LEED certification.
“Given the scale of this project, tilt-up was always the direction we suggested to Premier Beverage,” says Randy Simmons, chairman. “Another reason why tilt-up was the natural choice for this facility was the shear mass of the panels. Florida has a stringent wind code and tilt-up is far and away the best solution for dealing with high wind issues.”
Designed to accommodate the company’s expected future growth, the 570,000-square-foot facility is expandable to the south by 500,000 square feet and to the north by 420,000 square feet. The facility also features a 50,000-square-foot corporate office to handle Premier Beverage’s West Florida operations. As a distributor of fine wines, Premier Beverage also incorporated a 60,000-square-foot, air-conditioned area within the warehouse specifically for wine storage. This large-scale project required 24,000-cubic-yards of concrete and nearly 49,000 tons of steel.
One of the main challenges for this project was the fast-track nature of the delivery program. “By choosing tilt-up, we had far greater control of our panel construction, floor placement, and panel erection,” says Simmons. “Long known for fast-track delivery, tilt-up provides a tremendous advantage when compared to other building systems.”
With a building size the equivalent of 12 acres under a single roof, the R.R. Simmons design-build team had more than enough casting area to start panels while still grading the building pad in other locations. By phasing the project, R.R. Simmons was able to keep the project on track and complete the facility in just over 10 months.
Adding complexity to this already challenging project was Premier Beverage’s desire to have an environmentally friendly facility. A family-owned business, Premier Beverage is the second largest wine and spirit firm in the United States. They wanted a facility that could withstand the rigors of their operation, yet still lower their energy footprint.
“Originally, we planned to just pursue LEED certification, but as we moved through the project, we raised our goal to achieve LEED Silver certification,” says Simmons. “The design-build team worked smartly to mine every possible LEED point.”
Concrete and tilt-up played a pivotal role in the project obtained LEED Silver certification. Recycling goals were improved because the design-build team was able to recycle casting beds for the subbase and other uses. The team studied transportation issues and determined the onsite casting of the tilt-up panels further lowered their energy consumption and transportation costs when compared to other systems. By using exterior panels for loading, the team lessened the structural steel consumption, which saved energy in the production of steel and the transportation from outside of the Tampa market.
Another important factor in the decision to pursue LEED was the proximity of the site to a conservation area that housed a family of eagles. This adjacent site forced all the parties involved on the project to focus on the environmental impact of the project.
The benefits of Premier Beverage’s decision to build an environmentally sensitive facility have been numerous. Not only did the building receive the U.S. Green Building Council’s Silver LEED Certification, but it was recognized as one of the south’s largest LEED facilities. One important green feature of this project is the incorporation of a bright white thermoplastic olefin roof, which incorporates a highly reflective material that will minimize the heat absorption from Florida’s tough solar conditions. Working in concert with the users, the design-build team also implemented a smart lighting program. Motion sensors minimize the energy consumption of the facility. Additionally, the elevated lighting program places the most effective lighting solutions at specific points to provide the picking workforce with optimal clarity and reduce errors.
This project had a substantial benefit to the community. New jobs were created both during the construction process and when the company opened the doors. “The design-build team took a marginal site and vastly improved the stormwater issues for the area, as well as the water quality of the runoff,” says Simmons.
The Premier Beverage facility’s energy footprint has been drastically reduced from what would have been done if LEED would not have been investigated. “All parties involved with this project worked together to develop creative ideas to meet LEED goals, schedule constraints, and ensure the state-of-the-art nature of the facility,” says Simmons.