Moduler construction goes uptown
The phrase “modular construction” brings to mind prefabricated houses or oilsands equipment modules. But there is another side, and when incorporating sustainability and reducing both the number of workers needed and the time it takes to construct are all increasingly important, it just might be the wave of the future.
Today’s modular construction involves constructing entire buildings, or at least large parts of buildings, in a factory and shipping them to a site. And it’s a far cry from the trailers and modular classrooms many of us remember.
“That was the face of the industry a number of years ago, and there were quality issues. But they were due to the fact that somebody asked for a temporary structure—‘Give me a classroom that will last two years.’ With permanent modular construction, we’re building to the exact same standards as required when you build on site,” says Mark Taylor, vice-president, permanent modular construction, Canadian buildings, with PCL Constructors Inc.
In Europe and, to a lesser extent, the United States, skyscrapers are being built this way, with fully finished pieces—such as apartment units—simply hoisted and attached to the concrete core. Cal Harvey, director of operations at Modus Structures, explains that European adoption of off-site construction was driven by practicalities.
“In Canada, we’re blessed with wide-open spaces and abundant raw materials,” says Harvey. “In Europe, everything is more condensed; the population density is vastly increased and materials are scarce. They have to minimize the impact and maximize construction speed, so they have embraced modular.”
What the Europeans know and North Americans are just realizing is that building in a factory environment typically reduces the amount of waste produced by 15–25 per cent. One reason is that material cuts are carefully planned ahead of time. Where you might quickly cut a sheet of plywood in a way that gives you two usable pieces when you’re working on site, you can use virtual construction technology and computer numerical control equipment in the factory to get five or six pieces out of the same sheet.
Modular construction also minimizes waste because materials are stored in a warehouse so they aren’t exposed to the elements. And, as Taylor points out, two extra pieces of drywall left on site might simply get thrown in a dumpster; in the factory, they go back on the storage racks for use in another project.
For owners who want to achieve sustainability certification such as Leadership in Energy and Environmental Design (LEED) certification, going modular can help.
“The Modular Buildings Institute issued a white paper showing how modular [construction] better supports achieving the various LEED points,” says Taylor. “One of the big things is indoor air quality. You’re in a factory so it’s easy to control things, like moisture, that affect indoor air quality. You also remove the risk of off-gassing in the final location because you remove that process from the project site.”
Modus manufactures buildings that are LEED Silver compliant, in part thanks to structural insulated panels that consist of two layers of recycled 26-gauge steel sandwiching a layer of expanded polystyrene (EPS). Unlike other types of insulation, the EPS is fixed in place so there is no risk of sagging over time, which creates gaps where there can be thermal transfer.
“Typically, we are looking at R26 in our walls versus R16 to R20 for a typical insulated wall. The building uses less energy, your power consumption drops and it has a substantial impact on sustainability,” says Harvey. “It’s not just the materials you use—it’s also how the materials are used to reduce consumption.”
Modular buildings can also score high on daylighting as a result of using oversized windows and advanced control systems that bring the lights up when the room is occupied and shut them down when it isn’t. Lumen sensors can also be used to adjust lighting according to the amount of sunlight coming into the room.
Modular is still an ideal solution for classrooms because they can quickly add space to a school when the population increases. However,
modular classrooms no longer need to be temporary. Modus designs and builds high-performance modular classrooms for the Alberta government that will last as long as a conventionally constructed building.
“The Alberta government has a policy that all new schools are built as a core with a gym, offices and common areas. Then classroom modules are clicked together and added on,” says Harvey. “You can’t tell where the core school stops and the classrooms start.”
If enrolment drops at a school, one or more classrooms can be picked up and taken to another school that requires more space.
PCL builds full buildings—including a new Bank of Montreal for High Level, Alta.—but it also uses virtual construction technology to identify components of a project that can be prefabricated. Taylor explains that this is an extension of the growing trend to prefabricate as much as possible.
“Individual trades—plumbing, electrical—are trying to do as much as they can in a workshop environment before getting to the site so they are delivering a more finished product. But there is only so much they can do before they start running into another trade’s work. We’re getting the trades in the same space at the same time so we can prefabricate larger portions,” says Taylor.
An interesting example of prefabricating parts of a building is Humber River Hospital in Toronto. The billion-dollar project is being built under the private-public partnership model and led by PCL. Seeing that the patient bathrooms would all be the same, PCL chose to build them in its facility. In less than three months, 360 bathrooms were finished to the drywall stage and ready to be hoisted and slipped into place.
The challenges of constructing anything in northern parts of Canada are well-known—a limited labour pool, costly materials and unpredictable or hard-to-manage weather. Using modular construction to overcome these challenges often results in cost savings. PCL recently saw significant savings using an off-site solution when building a hospital for a remote island site on British Columbia’s northern coast. Doing the work off site, in a location with a more readily available labour pool, saved costs compared to the stick-built alternative.
“If you’re building anywhere north of Edmonton, it quickly becomes very cost effective. We’ve launched a venture with a company in [British Columbia] that is building highly recognized restaurants across northern Alberta and Saskatchewan, and because of our construction cycle and the efficiencies of building modular, it makes more sense to send them to the site than to build them in those locations,” says Harvey.
Perhaps one of the most interesting things about modular construction is that rooms can arrive on site fully finished and equipped for accommodation. A camp accommodation for the energy industry might arrive in northern Alberta in 200 or 300 modules, with each room already furnished with a bed, desk and even a TV mounted to the wall. Everything in the room is secured and sealed before transport and then the modules are clicked together on site.
Unfortunately, contrary to what many might believe, modular construction isn’t always cheaper; the cost of the bathrooms for Humber Hospital worked out to be about the same as it would have been building on site. Because it is done in a controlled environment where productivity can be maximized, labour costs are typically lower. But even though companies like Modus use lean manufacturing practices, such as making sure material is at hand and people don’t have to spend time looking for it, and achieve a 15–20 per cent increase in labour efficiency, those savings are generally offset by transportation costs.
But as those in the prefab industry see it, the sustainability and timeline benefits, combined with a higher degree of quality control and fewer people and materials on site, will result in more work being done in the factory.
“I think what’s happening in Europe is the future of construction in North America as well,” says Harvey. “We’ve had problems with construction in downtown cores, with materials blowing off buildings and trying to keep sites contained in the middle of congested areas. Modular could really shine there. It minimizes disruption and improves site safety, and I think slowly but surely it will win that market over.”