Case Study: Thanksgiving Point Professional Office Commercial HVAC Replacement

Address area: Thanksgiving Point business corridor along Ashton Boulevard, Lehi, UT 84043 (specific building confidential per client request). Project completion: April 2025 pre-cooling season. Scope: Planned replacement of three aging commercial rooftop units serving 12,000 sq ft professional office suite with modern efficient Carrier Weathermaker commercial equipment, integrated economizer operation for free cooling advantage during Lehi shoulder seasons, and building automation system (BAS) integration for scheduling and monitoring. This case study documents the phased replacement approach avoiding business disruption, load calculation methodology for professional office application, equipment selection with modern efficiency and connectivity features, BAS integration through Distech Controls platform, commissioning verification, and client outcome. This case study differs from the earlier Riverton City Park commercial rooftop case (7.5-ton single unit restaurant emergency scenario with R-22 to R-410A refrigerant transition) by presenting multi-unit planned replacement for professional office application with BAS integration scope.

Project Background

Thanksgiving Point Business Corridor

Thanksgiving Point business corridor context: Ashton Boulevard commercial development along I-15 Exit 287 corridor between Lehi and American Fork, mixed-use office park with professional services, medical office, technology, and retail tenants, buildings typically 1990s through 2010s construction with commercial rooftop HVAC serving individual office suites, and proximity to Thanksgiving Point attractions (Museum of Ancient Life, Ashton Gardens) generating adjacent traffic considerations for tenant business operations.

Client Business Context

Client business context: mid-size professional services firm occupying 12,000 sq ft office suite on ground floor of multi-story office building, staff approximately 42 employees with mixed private office and open workspace configuration, conference room spaces used regularly with executive board room, business hours typical 7:30 AM through 6:00 PM Monday through Friday, and business continuity priority requiring minimal disruption during HVAC replacement scope.

Existing HVAC Assessment

Existing commercial rooftop HVAC assessment identifying replacement scope: (1) three Carrier Weathermaker 48TC series rooftop units installed 2007 during original tenant build-out, 18 years old at replacement evaluation with all three units approaching typical 15–20 year commercial rooftop service life; (2) UNIT 1 — 10-ton package unit serving open workspace and reception (primary tenant-facing spaces), showing efficiency degradation with elevated compressor amperage and reduced cooling capacity; (3) UNIT 2 — 7.5-ton package unit serving executive offices and conference rooms, functional but similar age indicators; (4) UNIT 3 — 7.5-ton package unit serving break room, IT closet, and secondary office areas, functional; (5) ECONOMIZER STATUS — all three original units equipped with economizer capability but economizer dampers seized/inoperable due to age and lack of maintenance, resulting in mechanical cooling operation during shoulder seasons when free cooling potential existed.

Load Calculation and Equipment Sizing

ASHRAE 62.1 Ventilation Requirement

ASHRAE Standard 62.1 (Ventilation for Acceptable Indoor Air Quality) requirements for professional office application: 5 CFM per person + 0.06 CFM per sq ft = required outdoor air ventilation calculated as (42 employees × 5 CFM) + (12,000 sq ft × 0.06 CFM) = 210 + 720 = 930 CFM total outdoor air requirement across all zones. This outdoor air ventilation load impacts commercial rooftop unit sizing beyond space cooling load calculation, adding meaningful ventilation cooling load particularly during summer conditions.

Manual N (Commercial) Load Calculation

Manual N commercial load calculation by zone:

• Zone 1 (Open workspace + reception, 5,400 sq ft): Cooling load 38,200 BTU/hr sensible + 8,400 BTU/hr latent, elevated latent from occupancy density and outdoor air ventilation; heating load 42,600 BTU/hr
• Zone 2 (Executive offices + conference rooms, 3,200 sq ft): Cooling load 24,800 BTU/hr sensible + 4,200 BTU/hr latent, elevated variable load from conference room occupancy variation; heating load 28,400 BTU/hr
• Zone 3 (Break room + IT closet + secondary offices, 3,400 sq ft): Cooling load 22,400 BTU/hr sensible + 5,600 BTU/hr latent (elevated from break room equipment loads and IT closet 24/7 cooling requirement); heating load 26,200 BTU/hr
• Whole-suite total: Cooling 85,400 BTU/hr sensible + 18,200 BTU/hr latent (~9 tons cooling), heating 97,200 BTU/hr (~8 tons heating)

Equipment Sizing Rationale

Commercial rooftop unit sizing per zone with modern equipment selection:

• Zone 1 replacement: 10-ton commercial rooftop unit (same nominal capacity as existing, modern equipment provides better efficiency at same capacity)
• Zone 2 replacement: 7.5-ton commercial rooftop unit (matching existing configuration)
• Zone 3 replacement: 7.5-ton commercial rooftop unit including dedicated IT closet cooling coordination
• Altitude adjustment: Lehi elevation approximately 4,600 ft (Traverse Mountain foothills higher, valley floor lower), altitude derating approximately 17% cooling capacity reduction incorporated into sizing verification

Equipment Selection

Carrier Weathermaker 48TCED Commercial Rooftop Units

Carrier Weathermaker 48TCED commercial packaged rooftop units selected:

• Zone 1 Model: 48TCED12 (10-ton nominal cooling, 220,000 BTU/hr gas heat)
• Zone 2 Model: 48TCED09 (7.5-ton nominal cooling, 180,000 BTU/hr gas heat)
• Zone 3 Model: 48TCED09 (7.5-ton nominal cooling, 180,000 BTU/hr gas heat)
• Efficiency: IEER 14.5 (Integrated Energy Efficiency Ratio, commercial equipment efficiency metric), meaningful improvement over existing 2007 equipment efficiency
• Compressor: Two-stage scroll compressor providing part-load efficiency benefit
• Heat exchanger: Aluminized steel with 25-year warranty
• Blower: Variable-speed EC (electronically commutated) blower motor providing efficiency benefit and quieter operation
• Refrigerant: R-410A (no refrigerant transition scope, differentiating from Riverton City Park case study R-22 to R-410A transition)

Modern Economizer Integration

Modern economizer integration on all three replacement units:

• Economizer dampers: Motorized outdoor air dampers with modulating operation
• Economizer controls: Enthalpy-based economizer operation using outdoor air enthalpy sensor and comparison to indoor return air enthalpy, providing accurate free cooling determination during Lehi shoulder seasons (economizer activates when outdoor air enthalpy lower than return air enthalpy, providing cooling without mechanical operation)
• Economizer benefits: Estimated 25–35% cooling season operating cost reduction vs mechanical-only cooling based on Lehi climate profile providing many hours per year where economizer operation reduces or eliminates mechanical cooling
• ASHRAE 62.1 minimum outdoor air: Economizer damper positioned to provide minimum ASHRAE 62.1 outdoor air (930 CFM total split proportionally across three units) during all occupied hours

Building Automation System Integration

Building automation system integration through Distech Controls platform (client’s building landlord platform):

• BAS communication: BACnet MS/TP communication from Carrier Weathermaker units to Distech Controls building controller
• Occupied/unoccupied scheduling: Automatic scheduling based on building occupancy schedule with weekday 7:00 AM startup and 6:30 PM shutdown, unoccupied setback to 82°F cooling / 60°F heating during nights and weekends
• Zone temperature monitoring: All three zone temperatures reported to BAS for monitoring and trending, exception reporting for temperature deviation outside acceptable range
• Alarm notification: Equipment fault codes reported to BAS with automatic notification to building maintenance and Bluffdale Heating & Air Conditioning Comfort Club service contact
• Remote adjustment capability: BAS enables remote schedule and setpoint adjustment for special events (evening meetings, weekend work sessions) without on-site thermostat access
• Energy monitoring: BAS captures runtime hours and equipment operation providing baseline for post-installation efficiency verification

Phased Replacement Execution

Weekend-Only Work Schedule

Weekend-only work schedule protecting business continuity: replacement work executed across three consecutive weekends (one unit per weekend), no weekday disruption to tenant business operations, temporary space cooling deployed during weekend work periods when needed for equipment testing, and after-hours coordination with building landlord for roof access and mechanical space access.

Timeline

Total project timeline across three weekends:

• Weekend 1 (Zone 2 unit replacement): Existing 7.5-ton unit disconnection and crane removal Saturday morning, new Carrier 48TCED09 crane lift and mounting Saturday afternoon, refrigerant line and gas connection Sunday morning, electrical connection and BAS integration Sunday afternoon, commissioning and startup Sunday evening
• Weekend 2 (Zone 3 unit replacement): Same schedule pattern as Weekend 1
• Weekend 3 (Zone 1 unit replacement): Same schedule pattern with additional attention to Zone 1 higher occupancy return-to-service verification
• Post-completion week: BAS integration verification during weekday occupied operation, commissioning verification with tenant operations

Crane Operation and Roof Access

Crane operation for equipment replacement: 40-ton hydraulic crane positioned in adjacent parking lot with building landlord coordination for adjacent parking closure during crane operation windows, existing unit removal with proper refrigerant recovery per EPA Section 608 requirements before crane lift, new unit mounting with proper roof curb sealing (existing roof curbs preserved where dimensional matching allowed, adapter curbs used where existing curb dimensions incompatible with modern equipment footprint), and structural verification of roof loading acceptable for replacement equipment weight.

Commissioning Verification

Refrigerant System Verification

Refrigerant system commissioning for each unit (three units total):

• Vacuum: 380–420 microns achieved and held on each unit
• Refrigerant charge: R-410A charge per manufacturer specification with proper altitude adjustment
• Subcooling and superheat: Within manufacturer specification on each unit at commissioning outdoor conditions
• Two-stage operation: Both cooling stages verified operational with proper capacity output

Gas Heat Verification

Gas heat combustion analyzer verification on each unit:

• CO air-free: 42–58 ppm across three units (all below 100 ppm limit)
• Stack temperature: 380–420°F range (proper for atmospheric commercial rooftop gas heat)
• O2: 7.6–8.2% across three units
• Combustion efficiency: 79.4–80.2% (matching manufacturer specification for altitude)

Economizer Operation Verification

Economizer operation verification on each unit:

• Damper operation: Full range motion verified with modulating operation across 0–100% outdoor air positioning
• Enthalpy sensor calibration: Outdoor and return air enthalpy sensors verified reading accurately
• Free cooling mode: Simulated outdoor conditions verifying economizer engagement when outdoor enthalpy below return air enthalpy
• Minimum outdoor air position: ASHRAE 62.1 minimum position (approximately 25% damper opening) verified providing required 930 CFM total across all units
• Mechanical cooling coordination: Economizer + mechanical cooling operation verified during high-load simulation

BAS Integration Verification

BAS integration verification with Distech Controls building system: BACnet MS/TP communication established with all three units, occupancy schedule programmed and verified, zone temperature monitoring functional, alarm notifications tested with simulated fault conditions, remote adjustment capability verified through BAS interface, and runtime hour tracking functional providing baseline for future efficiency verification.

Client Outcome

Cooling Season 2025 Performance

Post-installation cooling season performance (May–September 2025): tenant reported improved zone temperature stability with modern variable-speed blower operation, quieter operation than existing 18 year-old equipment, economizer operation contributing meaningfully to shoulder season comfort (April, May, September, October) with reduced mechanical cooling demand, and no equipment failures or emergency service calls during first cooling season.

Energy Consumption Reduction

Anticipated energy consumption reduction verified through BAS runtime tracking and Rocky Mountain Power billing analysis: approximately 22% reduction in cooling season electric consumption vs prior year comparable period, driven by (1) modern equipment IEER 14.5 vs existing degraded ~11 IEER equivalent, (2) two-stage operation providing part-load efficiency, (3) economizer free cooling during shoulder seasons, and (4) BAS occupancy scheduling eliminating overnight/weekend cooling operation that occurred with legacy programmable thermostats.

Commercial Maintenance Coordination

Commercial Maintenance Agreement enrolled at $2,850/year for three-unit coverage (differentiated pricing from residential Comfort Club reflecting commercial equipment complexity and multi-unit scope): quarterly filter replacement across all three units, spring and fall comprehensive tune-ups with combustion analyzer verification and refrigerant system verification, economizer operation verification each spring/fall, BAS communication verification, priority emergency response with same-day dispatch commitment, and 15% parts discount for any component service scenarios.

Frequently Asked Questions

What’s the difference between commercial rooftop equipment and residential HVAC?

Commercial rooftop units (RTUs) differ from residential HVAC in multiple significant ways: (1) PACKAGED CONFIGURATION — commercial RTUs are single-cabinet units combining compressor, evaporator, condenser, and heating in one outdoor rooftop location vs residential split-system with indoor air handler + outdoor condenser; (2) ROOFTOP INSTALLATION on building roof with roof curb, ductwork routing through roof to interior spaces; (3) LARGER CAPACITY typically 3–25 ton range vs residential 1.5–5 ton; (4) IEER EFFICIENCY METRIC vs residential SEER2 metric, commercial equipment optimized for extended part-load operation typical of business schedules; (5) ECONOMIZER INTEGRATION standard on commercial units enabling free cooling operation during shoulder seasons; (6) VENTILATION AIR REQUIREMENTS per ASHRAE 62.1 requiring dedicated outdoor air ventilation not typical of residential; (7) BAS INTEGRATION with BACnet or similar protocol for building automation; (8) SERVICE COMPLEXITY typically requiring crane operation for major service, dedicated commercial HVAC technicians; (9) LONGER SERVICE LIFE typically 15–25 years vs residential 12–20 years; (10) COMMERCIAL MAINTENANCE COORDINATION with multiple annual visits and specific commercial-grade preventive scope. Thanksgiving Point office application represents typical commercial installation scope with multiple RTUs, BAS integration, and commercial maintenance coordination.

How does economizer operation save energy in commercial buildings?

Economizer operation provides significant cooling energy savings during shoulder seasons and moderate outdoor conditions: (1) FREE COOLING MECHANISM — when outdoor air temperature or enthalpy lower than return air, outdoor air used directly to cool building without mechanical refrigeration operation, eliminating compressor and condenser energy consumption; (2) TEMPERATURE-BASED ECONOMIZER — simpler control activating economizer when outdoor temperature below setpoint (typically 55–60°F), works well in dry climates like Utah where outdoor humidity typically low; (3) ENTHALPY-BASED ECONOMIZER — more sophisticated control using outdoor and return air enthalpy comparison, better performance in humid climates but also beneficial in Utah’s occasionally variable humidity conditions; (4) LEHI CLIMATE PROFILE — Lehi provides many economizer hours (approximately 1,800–2,400 hours annually where economizer can provide cooling), representing substantial energy savings potential; (5) ENERGY SAVINGS — typical economizer contribution 25–35% of cooling season operating cost reduction on commercial rooftop applications when properly commissioned and maintained; (6) MINIMUM OUTDOOR AIR REQUIREMENT — economizer damper also serves ASHRAE 62.1 ventilation requirement even during non-economizer hours; (7) MAINTENANCE IMPORTANCE — economizer damper motors, linkages, and sensors require regular verification — existing Thanksgiving Point equipment had seized economizer dampers due to lack of maintenance losing potential savings for years. Modern economizer commissioning during replacement restores design potential.

What’s a BAS (Building Automation System) and why integrate HVAC with it?

Building Automation System provides centralized monitoring and control for commercial building HVAC and other systems: (1) BAS FUNCTIONS — centralized monitoring of HVAC operation, occupied/unoccupied scheduling, temperature setpoint management, energy monitoring, alarm notification, and remote adjustment capability; (2) COMMON BAS PLATFORMS — Distech Controls (Thanksgiving Point building), Automated Logic, Alerton, Johnson Controls Metasys, Siemens Desigo, Honeywell EBI; (3) BACNET COMMUNICATION STANDARD — industry-standard communication protocol enabling BAS to communicate with equipment from multiple manufacturers; (4) BENEFITS OF HVAC INTEGRATION — automatic occupancy scheduling eliminating overnight/weekend HVAC operation, coordinated setpoint management across zones, exception-based alarm notification catching equipment issues before major failure, energy consumption visibility supporting operational optimization, remote adjustment for special events without on-site thermostat access; (5) LEED AND ENERGY CERTIFICATION — BAS integration supports building energy performance certification (LEED, ENERGY STAR); (6) COMMISSIONING BENEFIT — new equipment BAS integration during replacement typically 3–8 hours additional labor cost, providing multi-year operational benefit; (7) TENANT VS LANDLORD RESPONSIBILITY — BAS often owned and operated by building landlord with tenant equipment integration coordinated during installation. Thanksgiving Point integration coordinated with building landlord Distech Controls system during replacement.

Why phase the replacement across three weekends instead of doing it all at once?

Phased weekend-only replacement approach optimized for business continuity: (1) BUSINESS DISRUPTION AVOIDANCE — all replacement work performed during weekend hours when tenant business closed, no disruption to weekday operations; (2) PARTIAL COOLING AVAILABILITY — during Weekend 1 with Zone 2 unit replacement, Zones 1 and 3 remained operational; during Weekend 2, Zones 1 and 2 (post-replacement) operational; providing continuous partial cooling capability throughout project rather than complete shutdown; (3) CREW SIZING — single unit per weekend allows appropriately-sized crew and equipment rather than requiring larger crew for simultaneous replacement; (4) CRANE COORDINATION — single crane mobilization per weekend rather than complex simultaneous crane operation, reduces crane rental cost and operational complexity; (5) COMMISSIONING VERIFICATION QUALITY — each unit fully commissioned before proceeding to next weekend allows careful verification vs rushed simultaneous startup; (6) SCHEDULE FLEXIBILITY — weather-dependent scheduling allows optimal weekend selection for outdoor work; (7) TENANT CONVENIENCE — predictable weekend schedule enables tenant staff planning for post-weekend building return; (8) COST TRADE-OFF — phased replacement modestly more expensive than simultaneous replacement (extra mobilization) but justified by business continuity benefit for many commercial applications. Simultaneous replacement more appropriate when building unoccupied (renovation scenarios) or when temporary cooling deployment acceptable.

What does the Commercial Maintenance Agreement include for multi-unit installations?

Commercial Maintenance Agreement scope for three-unit Thanksgiving Point installation at $2,850/year: (1) QUARTERLY FILTER REPLACEMENT — commercial rooftop units require quarterly filter service vs annual/semi-annual residential filter changes given higher airflow and commercial operation; (2) SPRING TUNE-UP (April–May) — complete cooling operation verification, refrigerant system pressure and temperature verification, economizer operation verification with damper motor and sensor testing, condenser coil cleaning, evaporator coil inspection, blower motor verification, drain pan and drain line inspection; (3) FALL TUNE-UP (September–October) — complete heating operation verification with combustion analyzer readings (CO, stack, O2, efficiency), heat exchanger visual inspection through burner access, gas piping pressure verification, ignition system verification, safety limit switch testing; (4) BAS COMMUNICATION VERIFICATION each tune-up ensuring proper BAS integration continues functional; (5) PRIORITY EMERGENCY RESPONSE — same-day dispatch commitment for emergency scenarios during business hours; (6) 15% PARTS DISCOUNT for any component service scenarios during coverage period; (7) DOCUMENTATION — service reports provided after each visit documenting findings and recommendations; (8) ANNUAL EQUIPMENT CONDITION REPORT — year-end summary identifying components approaching service life end enabling proactive replacement planning; (9) EQUIPMENT WARRANTY COORDINATION — assistance with manufacturer warranty claims when qualifying failures occur during coverage period; (10) BUILDING LANDLORD COORDINATION — coordination with building landlord maintenance staff for roof access and BAS coordination. Commercial Maintenance Agreement scope substantially more comprehensive than residential Comfort Club reflecting commercial equipment complexity and multi-unit management scope.

Contact Bluffdale Heating & Air Conditioning

Commercial HVAC installation and replacement for professional office applications with multi-unit rooftop system coordination, Carrier Weathermaker 48TCED commercial packaged rooftop units (7.5-ton through 25-ton capacity range) with IEER 14.5 efficiency and two-stage scroll compressor operation, modern economizer integration with enthalpy-based free cooling control providing 25-35% cooling season operating cost reduction, ASHRAE 62.1 outdoor air ventilation requirement coordination for professional office occupancy, Manual N commercial load calculation by zone, phased weekend-only replacement approach protecting business continuity, 40-ton hydraulic crane operation for equipment lifting with building landlord coordination, BAS integration through BACnet MS/TP communication with Distech Controls, Automated Logic, Alerton, Johnson Controls Metasys, and other major building automation platforms, Commercial Maintenance Agreement quarterly filter service and semi-annual comprehensive tune-ups with priority emergency response, and 24/7 emergency response all route through our office at 14659 S 855 W in Bluffdale serving the greater Salt Lake Valley including Lehi Thanksgiving Point business corridor along Ashton Boulevard.

• Emergency Line (24/7): (801) 610-6528
• Address: 14659 S 855 W bldg b 142, Bluffdale, UT 84065
• Email: info@bluffdaleairconditioningheating.site
• Utah DOPL HVAC Contractor License: #10943221-5501
• EPA Section 608 Universal: #608U-2013-338124

Contact Us →

Office Hours

• Emergency Service: 24 hours a day, 7 days a week
• Office Staff: Monday – Saturday, 9:00 AM – 5:00 PM
• Closed: Sundays and State/Federal Holidays (emergency line always active)