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Commercial HVAC Design-Build & New Construction Across the NYC Metro
On a ground-up build or a major renovation, the mechanical system is on the critical path — and split design-then-bid contracts are where schedules slip and budgets blow up. Com+ Mechanical delivers HVAC design-build as a single accountable source: load modeling, system selection, engineered drawings, DOB filing, fabrication, installation, and commissioning under one contract. We work alongside owners, developers, GCs, and architects across the five boroughs and surrounding metro to engineer a system that hits the program, the energy code, and the turnover date.
Design Pitfalls a Design-Build Approach Eliminates
Oversized equipment from rule-of-thumb sizing
Systems sized on square-footage rules of thumb instead of a real load calculation short-cycle, control humidity poorly, and waste capital and energy. Engineering the loads to ACCA Manual N or an hourly model right-sizes the plant so the building holds setpoint and runs efficiently — which also matters for Local Law 97 emissions math.
Design-bid-build change orders and trade conflicts
When a separate engineer draws the system and the lowest bidder installs it, gaps in the documents become change orders, and ducts, pipe, conduit, and structure collide in the ceiling. A single design-build team coordinates the model before fabrication, so clashes are resolved on screen, not in the field at premium cost.
Late DOB / energy-code filing stalling the schedule
Mechanical and NYCECC energy-code filings that start after design is 'done' delay permits and push the turnover date. Carrying filing inside the design-build scope means the energy-code path, ventilation, and mechanical permits move in parallel with construction documents rather than after them.
Ventilation and outdoor-air shortfalls discovered at TCO
Under-designed outdoor air, missing make-up air, or undersized exhaust surface during sign-off and stall the certificate of occupancy. Designing ventilation to ASHRAE 62.1 and the mechanical code from the start — DOAS, ERV, and balanced exhaust — keeps the building compliant and the schedule intact.
Equipment long-lead times blowing the turnover date
Chillers, custom AHUs, switchgear-dependent units, and large RTUs can carry long manufacturing lead times. Locking equipment selection and releasing submittals early in design-build protects the construction schedule instead of discovering a 20-week lead the month before turnover.
Systems that were never commissioned to design intent
A system that is installed but never balanced or commissioned rarely delivers the comfort, airflow, or efficiency it was drawn for, and the owner inherits the callbacks. Carrying TAB and commissioning inside the contract verifies airflow, water flow, controls sequences, and capacity against the basis of design before turnover.
Single-Source HVAC Design-Build, Engineered for NYC Construction
Design-build collapses engineering and construction into one team and one contract, so the firm that draws the system is the firm that installs and commissions it — eliminating the design-bid-build finger-pointing that drives change orders. Com+ Mechanical provides turnkey commercial HVAC design-build for new construction, core-and-shell, tenant fit-outs, gut renovations, and additions throughout the NYC metro. We start at programming with block heating and cooling loads, run ACCA Manual N (or full hourly energy modeling) against the actual envelope and occupancy, then engineer the distribution — central plant, packaged rooftops, VRF, hydronics, or a hybrid — and produce coordinated, sealed mechanical drawings and equipment schedules. From there we carry the project through DOB/DOB NOW mechanical and energy-code filings, sheet-metal and pipe fabrication, equipment procurement, rough-in coordinated against structure and other trades, testing and balancing (TAB), controls and BAS integration, and full commissioning. Because we own the design intent and the installed result, the system that gets turned over to the owner performs to the loads it was drawn for — and is documented for Local Law 97, energy-code, and warranty purposes from day one.
What a Com+ HVAC Design-Build Engagement Includes
Why Owners and GCs Choose Design-Build With Com+
Our Simple Process
From call to comfort in 4 easy steps
Programming & Basis of Design
We work with the owner, architect, and GC to define the program, comfort and ventilation criteria, and budget, then run block loads and develop a basis-of-design with a system comparison (central plant vs. packaged vs. VRF vs. hybrid) and a budget-level cost and operating-cost picture.
Engineering & Construction Documents
We complete room-by-room loads, select and schedule equipment, lay out ductwork, piping, and controls, and produce coordinated, sealed mechanical drawings. The NYCECC energy-code path is locked and DOB / DOB NOW mechanical and ventilation filings are prepared in parallel.
Procurement, Fabrication & Installation
We release submittals and long-lead equipment, fabricate sheet metal and pipe, and install rough-in coordinated through MEP/structural clash detection and trade sequencing. Work is phased to the construction schedule and inspected at each required milestone.
TAB, Commissioning & Turnover
We balance airflow and water flow, integrate and check out the BAS, run functional commissioning of equipment and control sequences against the basis of design, and hand over as-builts, the TAB and Cx reports, O&M manuals, and owner/operator training.
Types of Systems We Install
Central Plant & Hydronic Systems
Engineered chilled-water and hot-water plants — chillers, boilers, cooling towers, pumps, and air handlers — for larger office, institutional, healthcare, and mixed-use new construction where central distribution is the efficient choice.
- •Chiller, boiler, cooling-tower, and pump selection sized to modeled loads
- •Primary/secondary or variable-primary pumping and hydronic piping design
- •Air handlers and DOAS with hydronic coils and energy recovery
- •BAS-integrated plant sequencing for efficiency and Local Law 97 performance
Packaged Rooftop & DOAS Systems
Packaged rooftop and dedicated-outdoor-air designs for retail, commercial, and low- to mid-rise new construction — engineered curbs, structural and rigging coordination, and balanced ventilation built into the documents.
- •Packaged RTU and DOAS selection with engineered curbs and structural loading
- •Economizer and demand-controlled ventilation for energy-code compliance
- •Make-up air, exhaust, and ASHRAE 62.1 outdoor-air design
- •Rigging-path and roof-access coordination engineered before fabrication
VRF & Heat-Pump Electrified Systems
Variable refrigerant flow and air-/water-source heat-pump systems for fit-outs and electrification-driven new construction — zoned comfort with simultaneous heating and cooling and no on-site combustion.
- •Zoned VRF/heat-pump design with branch controllers and refrigerant routing
- •DOAS-paired ventilation since VRF handles space load, not fresh air
- •All-electric design supporting decarbonization and Local Law 97 targets
- •Controls integration and refrigerant-leak/code provisions engineered in
Why NYC Developers and Building Owners Choose Com+ Mechanical
Engineering and Field Under One Roof
We don't hand a drawing set to a separate installer and walk away. The same firm that engineers the loads, selects the equipment, and seals the documents fabricates, installs, and commissions the system — so design intent and installed reality stay aligned.
Built for NYC Construction & Code
We design and file for the realities of NYC buildings — DOB / DOB NOW mechanical and ventilation filings, NYCECC energy code, structural and rigging constraints, and occupied-building phasing on renovations and fit-outs..
Energy & Compliance Driven
We engineer to the energy code and Local Law 97 emissions thresholds from the basis of design — right-sized, high-efficiency, and electrification-ready systems — rather than building first and discovering a compliance gap later.
Multi-Building & Portfolio Capable
From a single fit-out to repeatable mechanical packages across a developer's portfolio, we standardize equipment, controls, and documentation so each project turns over consistently..
Transparent Pricing
No fees. No surprises. Just honest service.
Feasibility & Concept Design
A programming review, block load study, and basis-of-design with a system comparison and budget-level pricing to validate scope, approach, and code path before full engineering.
- Programming and design-criteria workshop with owner/GC/architect
- Block heating and cooling load study
- System options comparison with life-cycle and operating-cost view
- Budget-level (ROM) pricing and preliminary schedule
- Energy-code and Local Law 97 strategy outline
Full Design-Build Delivery
Turnkey engineering through commissioning: sealed construction documents, DOB filing, procurement, fabrication, installation, TAB, and commissioning under one contract.
- Room-by-room loads, equipment selection, and sealed mechanical drawings
- DOB / DOB NOW mechanical, ventilation, and NYCECC energy-code filing
- Equipment procurement, fabrication, and coordinated installation
- Clash detection, trade sequencing, and inspection coordination
- TAB, BAS integration, commissioning, as-builts, and owner training
Post-Occupancy Service & Maintenance Agreement
A scheduled maintenance and service agreement on the newly built system to protect the warranty, hold commissioned performance, and keep the building running after turnover.
- Seasonal preventive maintenance on installed equipment
- Controls/BAS monitoring and sequence verification
- Filter, coil, belt, and water-treatment service as applicable
- Priority response for agreement clients across the portfolio
- Documented performance and warranty-compliance reporting
All design-build pricing is scoped after a programming and feasibility review, because system type, building loads, structural and rigging conditions, code path, and schedule drive the real engineering and construction cost. Pricing is presented as a written, fixed-scope proposal (or a guaranteed-price design-build agreement) before construction begins..
Own a Commercial Property?
Business+ plans start at $499/year — includes 2 rtu tune-ups, 10% off all services, and priority scheduling.
Equipment & Brands We Service
Factory-trained technicians for all major HVAC manufacturers
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Frequently Asked Questions
Get answers to common questions about our services
What's the difference between design-build and design-bid-build for an HVAC project?
In design-bid-build, an owner hires an engineer to produce drawings, then bids those drawings to a separate installing contractor — and any gaps between the two become change orders. In design-build, one firm owns both the engineering and the construction under a single contract. Com+ Mechanical engineers the loads, selects and schedules the equipment, files with the DOB, fabricates, installs, and commissions the system, so there's one accountable party for both the design intent and the installed result. That typically means fewer change orders, tighter coordination, and a faster schedule because design and construction phases overlap.
At what point in our project should we bring in a design-build mechanical contractor?
As early as programming or schematic design. The biggest cost and schedule savings in design-build come from engaging during concept — when block loads, system selection, shaft and roof space, electrical service, and long-lead equipment can still be influenced. Bringing us in early as a design-assist partner lets us budget realistically, value-engineer while changes are still cheap, and lock long-lead equipment before it lands on the critical path. We can also join a project already in design development and take it through documents, filing, and construction.
Do you handle the DOB filings and energy-code compliance, or do we need a separate engineer?
We carry the mechanical design and the filing inside the design-build scope. That includes DOB / DOB NOW mechanical and ventilation filings and the NYCECC energy-code compliance path, prepared in parallel with construction documents so permits don't stall the schedule. The drawings are produced and sealed by the licensed professional of record..
How do you design the system to meet Local Law 97 and the energy code?
We engineer compliance in from the basis of design rather than retrofitting it later. That means right-sizing equipment to a real load calculation instead of rules of thumb, selecting high-efficiency and electrification-ready systems (heat-pump, VRF, high-IEER plant) where they fit the program, designing economizers and DOAS/ERV for ventilation efficiency, and modeling the result against the NYCECC and the building's Local Law 97 emissions intensity limits. Designing it correctly up front avoids an expensive compliance retrofit after the building is occupied.
Can you deliver design-build across multiple buildings or a development portfolio, and do you respond 24/7?
Yes. We deliver design-build for single projects and for developers and owners building or renovating across a portfolio in the NYC metro, standardizing equipment, controls, and documentation so each building turns over consistently. After turnover, we provide 24/7 response and maintenance agreements across the five boroughs, Nassau, Westchester, northern NJ, and Stamford to protect the commissioned system..
What do we receive at turnover, and is the system commissioned?
Yes — commissioning is part of the scope, not an add-on. At turnover you receive a system that has been tested, balanced, and functionally commissioned against the basis of design: verified airflow and water flow, checked-out BAS sequences, and confirmed equipment capacity. The handover package includes sealed as-built drawings, the test-and-balance (TAB) report, the commissioning (Cx) report, O&M manuals, equipment warranties, and operator training so your facilities team can run the building from day one.
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Planning New Construction or a Major Renovation? Let's Engineer It Right.
Whether you're at programming on a ground-up build or scoping the mechanical package for a gut renovation or fit-out, Com+ Mechanical delivers the loads, the engineered drawings, the DOB filing, the installation, and the commissioning under one accountable design-build contract. Get a system engineered to your program, your energy-code and Local Law 97 obligations, and your turnover date — with one team responsible from concept to commissioning.
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