What Does Office Tenant Improvement MEP Design Include?

Office TI MEP design engineers the heating, cooling, ventilation, lighting, power, and plumbing for a leased interior space. The work includes load calculations for the new layout, HVAC ductwork and controls modifications, lighting design meeting current energy code, power distribution for workstations and equipment, and plumbing for restrooms and break areas. Every TI starts with a survey of the base building systems — available capacity, existing distribution, landlord standards — because the TI design lives inside constraints the engineer didn't create. The TI is a renovation inside someone else's building, and that changes the engineering posture. On new construction I optimize systems freely; on a TI I investigate first, design second. The field survey — above the ceiling, in the electrical rooms, at the mechanical penthouse — is where I earn the fee, because the drawings I produce are only as good as my understanding of what's actually up there.

On the mechanical side, the first question is capacity: can the base building system serve the new layout? I calculate the actual loads for the TI's occupancy, equipment, and glazing exposure, then compare against what's available. The design then reroutes or extends ductwork for the new partitions, adds or relocates diffusers and thermostats for proper zoning, and updates controls sequences. Conference rooms and dense open offices often need dedicated attention — the people and equipment loads in a packed conference room will overwhelm a system zoned for general office. Electrical follows the same investigate-then-design pattern. I verify panel capacity and spare breaker space, design the lighting to current energy code with proper controls, lay out power for workstations, and coordinate any specialty loads like server rooms or EV-adjacent parking circuits. Lighting is frequently the biggest design effort in a TI because the energy code treats altered lighting as new work, and the compliance documentation has to be right for permit.

TIs fail in predictable ways, and coordination prevents all of them. The classic failure is designing from outdated as-builts — the ceiling gets opened and nothing matches, so the ductwork and conduit routes get redesigned in the field at the worst possible time. The second is ignoring the landlord's standards until the landlord's engineer rejects the submittal. The third is the demising wall problem: the TI shares walls, slabs, and shafts with neighboring tenants, so noise, smoke, and fire separation details at the boundaries need explicit design. My TI process front-loads all of this: field survey first, landlord standards and as-builts second, design third. The permit set then includes demolition plans showing exactly what comes out, new work plans, and details at every base building interface. That thoroughness is what gets a TI through plan check without the correction cycles that blow up tenant schedules.

• Field survey of base building systems before any design begins
• HVAC load calculations and redistribution for the new floor plan
• Lighting design meeting current energy code, including controls
• Landlord standards compliance and base building tie-in coordination
• Permit drawings covering demolition, new work, and interface details