Northgate Clinic HVAC Replacement
Replacement of fourteen aging rooftop units serving a two-story outpatient clinic that remained fully operational, including curb adapters, duct transitions, hydronic heating coil reconnections, new DDC controls and a weekend crane sequence. The mechanical subcontractor needed a Division 23 estimate priced unit by unit with temporary cooling and infection control included.
Location
Minneapolis, MN
Size
14 rooftop units, 92,000 SF
Estimated value
$3.1M
Estimate turnaround
4 business days
Scope estimated
What we measured and priced
- 14 packaged rooftop units from 12.5 to 40 tons totaling 318 tons of cooling with energy recovery wheels on 6 units
- 14 custom curb adapters and 2,400 SF of roof patching and flashing at the new footprints
- 6,800 lbs of galvanized sheet metal in supply and return transitions with 14 new smoke dampers
- Hot water heating coil reconnections at 14 units with 1,100 LF of hydronic piping modifications and 28 new isolation valves
- 14 DDC unit controllers, 196 control points and integration to the existing building automation front end
- 4 weekend crane picks with a 165-ton hydraulic crane and street closure permits
- Temporary cooling with 2 trailer-mounted 60-ton units and 1,200 LF of flexible duct over 6 weeks
- Test and balance of 14 systems and 212 terminal units with infection control barriers at 38 ceiling access points
The estimating challenge
Replacing rooftop units over an occupied clinic is a sequencing problem before it is a quantity problem. The structural engineer had confirmed the roof could take the new units only if weights stayed under the existing curb loads, forcing adapters rather than new curbs. Each pick had to happen on a weekend with the affected zones on temporary cooling, and the controls integrator's point list did not match the mechanical schedule on four units. The subcontractor also had to carry infection control barriers at every ceiling opening under the clinic's ICRA requirements.
The result
LEEDS priced each of the fourteen units as its own line with crane, adapter, transition, controls and reconnection costs attached, then grouped them into four weekend picks with temporary cooling costed per pick. We reconciled the controls point list to the mechanical schedule and issued a 22-point discrepancy list for the engineer before bid. SMACNA labor was adjusted for occupied healthcare conditions and ICRA barriers were quantified at each access point. The subcontractor bid $3.1M and was awarded the work. All four picks were completed on schedule with no unplanned clinic closures.
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