For Denver-based ProLogis, a provider of distribution facilities and services that added 17 million-sq.-ft. of industrial space through the first nine months of last year, the average size of a new building six or seven years ago was around 150,000 sq. ft. Today the average building size is 375,000 sq. ft. The average clear height used to be around 28 ft. Now the average height ranges from 32 to 36 ft.
"We've seen a fairly significant increase in the building size. Along with that has come an increase in the clear height for the obvious reasons. Companies can rack higher and store more product at one location," says Jack Rizzo, managing director of global development for Prologis, which owns 343 million sq.-ft. of industrial space. The average facility size is even higher in core logistics hubs such as Atlanta, New Jersey, Dallas, Chicago, Los Angeles and San Francisco. "A million sq.-ft. building in those markets is not unusual at all," he adds.
Other new facility design trends include more parking for trailers, more dock doors, improved sprinkler systems, and better lighting and floors. All of which support larger sized buildings. Rizzo attributes the growing footprint to shifting production and distribution strategy. As more manufacturing has moved overseas, companies are importing more products into ports on the east and west coasts. They need larger facilities to handle high volumes of product coming in by the container load. Another growth factor is the consolidation of distribution facilities.
A company may shrink its network from 32 to 16 facilities to take advantage of economies of scale, but it won't reduce its overall square footage of storage space. For example, a 100,000-sq.-ft. building may cost around $35 per sq. ft. to build. This compares to the low $20 per sq.-ft. range for a million-sq.-ft. building, Rizzo estimates.
Changing logistics strategies have also changed how managers look at and use trailers. They now serve as staging areas for product before it's crossdocked, and as buffer storage during seasonal highs and lows. Another factor, rather than have containers sit at the docks, racking up demurrage fees, it's cheaper to have them sit in the lot.
"Five years ago hardly anyone would require trailer storage. Now they're looking for excess trailer storage to use as buffer storage for their warehouses," confirms Mike Russell, who heads up the preconstruction group at ProLogis. A 750,000 to 1 million sq.-ft. facility, for example, may require enough parking spaces for 80 to 125 trailers.
Today's trailers are also longer (53 ft.), and therefore heavier. Parking spots and driveways have to be constructed so that their landing gear doesn't sink into the blacktop on a hot day.
"With the larger facilities and the higher volume of truck traffic at these facilities, we've also increased our requirements for pavement design. So our pavements have tended to get a little thicker over the past 10 years," says Russell.
More Trailers Means More Doors
"Dock doors have become just slightly more valuable than gold," says Geoffrey Sisko, a senior vice president for material handling logistics consultants Gross & Associates (Woodbridge, N.J.). "Up to a few years ago I would have said, as a rule of thumb, that you needed a dock door for every 10,000 sq. ft. of distribution center, assuming a normal operation. Now I'm saying 7,500 sq. ft.," he adds.
Hours-of-service rules and revisions have forced carriers to be more focused on driver productivity. More companies want to drop trailers, full or empty, and pick them up later rather than have drivers wait from them to be unloaded and loaded.
Other regulatory issues continue to influence the shape and configuration of new facilities. One reason buildings tend to be long and narrow, especially the larger ones, is the need for workers to be able to exit the building in case of an emergency. As Sisko notes, laws specify that occupants must be within 250 ft. of an exit, or 400 ft. depending on the sprinkler system.
On the topic of saving lives and protecting property, early suppression fast response (ESFR) sprinkler systems, introduced in the early 1990s, continue to grow in use. Mounted to the ceiling, these systems can replace in-rack sprinkler systems for certain classes of product, ceiling heights and with the right water pressure. By detecting a fire sooner, and spraying more water with larger droplet sizes than conventional sprinkler heads, which increase the likelihood of water reaching the fire, ESFR systems can compensate for the sprinkler heads being further from the fire.
The primary advantage of ESFR sprinkler systems is that they make it easier to reconfigure racks as distribution needs change. They can also reduce product damage.
"You don't have lift truck drivers hitting sprinkler heads," says Sisko. "There are more claims due to water damage due to that than there are for fire damage."
"Five years ago hardly anyone would require trailer storage.
Now they're looking for excess trailer storage to use as
buffer storage for their warehouses," says Mike Russell of ProLogis.
More Energy Efficient Lighting, Flatter Floors
On the technology front newer T5 and T8 fluorescent lights with electronic ballasts offer significant energy savings compared to round metal halide and mercury vapor lamps. Because they are linear, these fluorescent lights are naturally better suited for illuminating the space between racks. They can be installed with sensors that adjust the lighting levels depending upon whether someone is working in an aisle or not, or the amount of ambient light coming from other sources.
As the working height of facilities increases (up to 40 ft.), flat floors become more important for rack stability and the accurate and safe operation of very narrow-aisle configurations as well as for automated storage and retrieval systems. Pouring these super-flat floors— measured by an "F-number" system, the higher the F-number (FF100) the flatter the floor—has been made possible by laser-guided concrete leveling equipment.
Surface hardeners are also improving the smoothness and durability of concrete floors. Such additives can make it unnecessary to seal floors.
Sealing works, notes Sisko, but sealing wears out, and it's expensive to redo.
Beyond the trend toward larger facilities, one of the most exciting changes to warehouses and distribution facilities over the past 15 years hasn't been the buildings themselves, says Sisko, but the information systems used to run them. Warehouse management software has become much more affordable and more powerful. Randomized product storage and the ability to work in zones have increased storage utilization dramatically. This software, he says, is what has made it possible to efficiently run the million sq.-ft.-plus facilities.
The Prologis distribution center in Palmetto, Ga. (near Atlanta) covers more than 1 million sq. ft. It is leased to Unilever.
European Design Trends
In Europe there's also a trend toward bigger facilities. Partly because of import growth trends similar to North America, but also because the formation of the European Union has reduced trade barriers, making it easier for companies to serve more countries from a single location.
"Companies are really looking into ways to cut their costs, so instead of using two warehouses, one for the north in Europe and one for the south, they can put one big facility in Northern Europe," says Reginald Neirynck, the U.S. country manager for Eurinpro, a real estate project development company based in Belgium. The firm custom builds distribution facilities for a variety of customers, including logistics service providers, a growing market segment that generally requires larger facilities to serve the distribution needs of multiple customers.
Larger distribution facilities require larger and more expensive heating and cooling systems to bring fresh air from outside and fans to move air around. In a facility with a 40-foot clear height, the temperature difference between the floor and the upper pick levels can be significant. These large facilities also require more break rooms. "As the warehouses became larger, the walking distance to the social rooms became large," says Koen Symus, concept and calculation department manager for Eurinpro. It's more expensive to build separate break rooms throughout a facility, rather than a single, central room, but it saves time and improves labor efficiency.
Another tactic to improve working conditions is by allowing more natural light by adding more windows, skylights and translucent materials. Some countries, France for example, require a certain percentage of direct light. Companies like Eurinpro must know how to navigate a sea of European regulations that impact the design distribution facilities.
"It's becoming stricter and stricter on everything we're doing, especially with fire safety regulations," says Neirynck. In Europe, this means that materials like rock wool (also known as mineral wool), a less combustible material than petroleumbased products, must be used for insulating walls and roofs.
"The unit sizes of our warehouses in some countries have to be smaller than in others," Neirynck adds. "The country we have the most difficulty with right now is France which has a requirement of having a maximum unit size of 6,000 sq. meters [64,583 sq. ft]." Any space larger than that has to be divided by firewalls, which changes the design parameters compared to what's possible in other countries. In Germany, for example, the space limit is 10,000 sq. meters [107,639 sq. ft.].