When my late father-in-law, a professional mechanic, was shopping for a car for his daughter, he asked to see under the hood. The salesman obliged, and what he saw left him aghast. This was the mid-1990s and the previous generation of cars mostly had generous space within the engine bay. They had room to access spark plugs, change belts, and perform standard repair and diagnostics with little to no gymnastics. This car, a 1994 Chevy Camaro on the other hand, barely had room to fit a wrench into some of the gaps, let alone the hand required to turn it. He inquired “How am I supposed to work on this thing?” The salesman’s response: “That’s for your mechanic to worry about.” When my father-in-law retorted, “I am the mechanic.”, I could almost envision the blank stare back from the salesman. I wish I could have been there to see it.
With ever-increasing costs for buildings, it can be a challenge to provide the appropriate square footage and access for MEP system maintenance. It’s hard to justify to an owner to take away from usable square footage that they may be paying $500-1000 per square foot or more so that a coil can be removed or a pump serviced.
Most major projects start out with a metric that looks at gross square footage versus assignable square footage of new construction. This ratio in a classroom facility is commonly around 60-65%. The converse 35-40% is made up of walls, chases, structure, and support spaces. As you can guess, there is a premium on competition for this space. However, a good Architect/Engineer (A/E) design team will not only provide a functional space, but provide a functional maintenance system.
Air handling units should be designed with both internal and external access in mind. Internal access means access to change filters, clean coils, clean drain pans, remove motors and fans. External access means designing piping to be isolated in a manner that allows coil removal without shutting down the balance of the hydronic system, and means that a coil can be removed without demolishing a wall. It’s not always practical to design around a full replacement, and frankly, a moderately maintained casing can last 50 years or more. It’s about drawing a balance between frequently maintained, occasionally maintained, versus the unlikely failures.
One area that generally gets “the squeeze” is pumping systems. Why install an end suction pump with appropriate clearances all around versus stacking vertical pumps along a wall? That question is easily answered when you discover that a 50 HP motor weighs in at a hefty 600 lbs. Providing an area for a gantry to remove large motors or pump assemblies is the key to safely maintaining these systems.
Another device that may not have appropriate access is a variable volume air terminal unit, or VAV box. These devices should be located where ladder access is easy, outside the occupied space to avoid maintenance disruptions, and with proper clearances above the ceiling to allow for electric code-required clearances and space to maintain controls. Too often we find boxes above walls, 3 feet above a ceiling where ladders can’t reach without removing large portions of ceiling grid, or worse yet, through a 24-inch access door.
Rooftop items are often placed without proper access as well. In northern climates, where snow levels require elevated roof curbs, access platforms are a must for most large equipment. Taking a ladder up to a snowy roof to change a filter isn’t a safe practice, and it’s something the design team and owner should plan around.
Keeping equipment in areas away from roof edges and trying to avoid the requirement for fall protection should be at the forefront of rooftop equipment design.
All the points listed above are presented as a way to allow for proper maintenance of equipment while providing an efficient use of space. What they really accomplish is to provide a safe working environment for your maintenance staff. Protecting the people who will run these facilities for decades is the real focus of this type of design. Making sure that the proper equipment, support, and access are integral to each design by default allows your maintenance personnel to use the proper practices for maintenance, greatly reducing the chance of injury.
Barton Associates incorporates access clearances, maintenance requirements, and user safety as integral parts of design in every facility. It’s our standard practice to show manufacturer-recommended service clearances in every design. We review operation and maintenance manuals for the equipment we specify, and talk with vendors and contractors to make sure our designs are maintainable. A majority of our business is repeat clients, which gives us a vested interest in their safety. While it may cost more up-front to create a maintainable design, it’s certainly worth it to protect our most valuable asset, our people.
If you have any questions about maintainable design, please contact Stephen Oskin, PE at seo@ba-inc.com.