Talk to any mechanical engineer who’s worked on a net-zero project in the past two years, and they’ll tell you the same thing: the architects who start thinking about electrical capacity in schematic design have projects that actually get built on budget. Everyone else ends up value-engineering their way back to gas boilers through construction documents.
The shift toward net-zero carbon buildings and full electrification changes fundamental assumptions about HVAC, domestic hot water, power distribution, and how buildings interact with the grid. But here’s what most guides won’t tell you: the MEP decisions that make or break these projects happen long before anyone opens Revit. They occur in the first conversation about glazing ratios, in the proactive early coordination call with the utility company, and in the contract language that defines who owns the performance risk.
Efficiency First, or You’ll Regret It Later
Let’s be direct: you cannot solar-panel your way out of a poorly performing building envelope. Yet project after project tries exactly that—beautiful rooftop PV arrays sitting atop buildings, hemorrhaging heat through thermal bridges and oversized glazing.
The math is unforgiving. Every unnecessary BTU requires more heat pump capacity, more electrical infrastructure, more PV panels, and more battery storage. On an 85-unit multifamily project in Denver, the design team ran two scenarios: a code-minimum envelope versus an enhanced continuous-insulation system with better windows. The enhanced envelope cost an additional $180K but reduced the electrical service upgrade from 4000A to 3200A, shaved $220K off the heat pump system, and cut the required PV array by 30%. The efficiency-first approach not only saved $190K net but also demonstrated the design team’s prudence and resourcefulness—before accounting for reduced operating costs.
Passive strategies need to be locked in during schematic design. Not “considered.” Not “value-engineered later.” Locked in. Use energy modeling to compare real tradeoffs among glazing ratios, orientations, and shading strategies. Make efficiency targets contractual—specify target EUI ranges in the architect-owner agreement so the MEP team designs to a clear performance baseline. Specify continuous insulation, airtightness targets (typically 0.25 CFM50/sf of enclosure for commercial buildings), and daylighting strategies tied to realistic internal gains.
Teams that skip this step inevitably end up in the same place: six months into construction documents, realizing the electrical service won’t support the loads, and scrambling to find cuts that don’t compromise energy goals.
Heat Pumps: Size Them Right and They Work Perfectly
There’s a conversation that happens on almost every electrification project around 30% design development. Someone asks: “But what about backup heat?” The question reveals a fundamental misunderstanding. Modern air-source heat pumps aren’t supplemental heating—they’re the primary system, and they’re incredibly good at it.
Units like Mitsubishi’s H2i series or Carrier’s Greenspeed systems perform reliably down to -15°F, covering roughly 90% of U.S. climate zones. The “emerging technology” language needs to stop; these are proven systems that have been heating buildings in Scandinavia and northern Japan for over a decade. The catch: they need proper sizing using actual modeled loads, not rules of thumb.
On a 12-story Minneapolis office conversion, detailed thermal modeling with proper zoning reduced peak heating load by 35%. That reduction meant converting to air-source heat pumps without the need for expensive distribution-piping rework. Installed cost: $285/ton compared to $340/ton for the original gas boiler replacement.
The design approach should shift from “one-size-fits-all” central plants to hybrid strategies: centralized heat pump plants for larger buildings, distributed air-to-air or packaged units for mid-rise residential or smaller commercial projects. Water-loop heat pump systems work well for multi-tenant office or residential buildings where simultaneous heating and cooling allows internal load balancing—one tenant’s cooling becomes another’s heating source.
But thermal zoning matters more in electrified buildings than traditional systems. With gas heating and electric cooling, poor zoning wastes energy, but systems muscle through it. With heat pumps handling both, bad zoning creates competing loads that kill efficiency and create comfort complaints.
Electrical Infrastructure: The Work That Determines Everything
The most common mid-project crisis in electrification: the electrical engineer runs demand calculations in design development, discovers the building needs a service upgrade requiring utility transformer work, contacts the utility and learns there’s a 14-month lead time, and the project schedule implodes.
This isn’t hypothetical. It happened on three separate projects in the past 18 months. Every case traced back to the exact cause: the lack of a preliminary electrical demand analysis during schematic design.
Electrifying space heating, hot water, cooking, and vehicle charging doubles or triples electrical demand compared to mixed-fuel designs. We’re seeing transformer upgrades run $80K-$150 for 50-unit residential buildings, with utility coordination adding 6-12 months in major metros.
The fix is straightforward: run preliminary electrical demand analysis during schematic design. Include provisions for future expansion—spare capacity and reserved conduit paths cost little during construction but are prohibitively expensive later. Coordinate with the utility on service capacity, interconnection requirements for distributed energy resources, and demand response arrangements.
For projects where full electrification isn’t in the initial budget, incorporate electric-readiness: dedicated receptacles, 240V branch circuits for future conversion, and appropriately sized conduit runs. Recent model code updates are making electric-readiness mandatory in many jurisdictions.
A practical schematic deliverable should include: estimated peak electrical demand; suggested transformer size and location; EV charging strategy with Level 2 or DC fast charging specifications; space planning for charging equipment; rooftop PV layout with structural coordination; and an identified interconnection point with a one-line diagram.
On-Site Renewables and Storage: Plan the Real Estate First
Rooftop PV requires structural capacity designed in from the beginning, fire-code-compliant setbacks that affect array layout, weatherproofing details requiring architectural coordination, and dedicated electrical rooms for inverters. Battery systems require dedicated rooms with specific ventilation, varying fire-suppression systems by chemistry, and thermal management that affects HVAC design.
At a net-zero California elementary school, the team allocated roof space for PV in schematic design but didn’t coordinate structural capacity or inverter locations. In design development, the roof structure couldn’t support the array weight without expensive reinforcement, and there was no space for inverters. The solution required relocating mechanical equipment, adding structural reinforcement, and creating a new electrical room—changes that added $120K and six weeks to the schedule.
Set realistic PV yield assumptions in the energy model and iterate array placement with structural and architectural teams during schematic design. Plan inverter locations, DC combiner rooms, and battery rooms early—these spaces need rated enclosures, dedicated ventilation, and specific clearances per NFPA 855.
Consider how batteries will be used: peak shaving, emergency backup, or both. This choice affects sizing, control logic, and permitting. A battery for peak shaving provides 2-4 hours of capacity and cycles daily. An emergency backup battery provides 8-24 hours of power and sits idle until needed. The cost difference can exceed $200K on mid-size commercial buildings.
Federal and state incentives matter significantly. The Investment Tax Credit for solar sits at 30% for commercial projects, and the Inflation Reduction Act added credits for battery storage, EV charging, and efficiency improvements. These programs change frequently—verify current guidance during budgeting.
Ventilation Strategy: Don’t Create IAQ Disasters
Increased airtightness without proper mechanical ventilation creates indoor air quality disasters. Buildings meet energy targets and pass blower door tests, yet occupants complain about stuffiness and odors within the first year.
Modern commercial buildings target 0.25 CFM50/sf of enclosure or better—tight enough that natural infiltration provides essentially zero ventilation. Everything must be mechanical and intentional.
Energy recovery ventilators (ERVs) and heat recovery ventilators (HRVs) are non-negotiable for net-zero buildings in most climates. These systems recover 70-85% of exhaust air energy. Key specifications: highly sensitive recovery efficiency (75% minimum), low pressure drop (under 0.8″ w.g.), and reliability since these systems run continuously.
But installing ERVs and operating them at constant speed wastes energy. Demand-controlled ventilation based on CO₂ sensors or occupancy detection solves this. In a recent Seattle office building, switching from constant ventilation to CO₂-based demand control reduced ventilation energy by 40%.
Higher filtration (MERV 13 or higher) conflicts with minimizing pressure drop and fan energy. The tradeoff needs to be explicit—higher filtration means higher fan energy, more frequent filter changes, and potentially larger equipment.
Electrical Distribution and EV Charging: Design for Growth
Most buildings undergo significant changes within their first decade. Electrical distribution systems with no flexibility become expensive bottlenecks for minor renovations.
The single-line diagram needs development in the schematic design, not in the construction documents. This shows how power flows from utility service through transformers, switchgear, and distribution, visualizing capacity and identifying bottlenecks.
Include automatic transfer switches and standby power for critical loads. Battery backup is increasingly cost-competitive with generators for moderate durations (4-12 hours), especially when batteries also provide peak shaving. Submetering pays for itself within 2-3 years—install meters on major systems to enable performance tracking and support utility demand response programs.
For EV charging, the question isn’t whether to include it but how much to install now versus making “charge-ready” for future activation. Commercial office buildings typically target 10-15% of charging stalls as active, with another 30-40% charge-ready. Multifamily buildings trend higher—20-30% active with 50-100% charge-ready.
Networked charging systems with load management prevent oversized electrical services. A parking structure requiring 1600A service with unmanaged chargers can often operate on 1000A with intelligent load management—saving $60K–$100K in infrastructure costs.
Differentiate between Level 2 charging (6-19 kW, for extended parking) and DC fast charging (50-350 kW, for high turnover). Six Level 2 chargers might share a single 100A circuit, while one DC fast charger might require a dedicated 600A service.
Controls: The System That Makes Everything Work
The control strategy determines whether an electrified building meets performance goals or descends into operational chaos. Yet controls are often treated as procurement items rather than design decisions.
The “island of automation” problem remains common: heat pumps controlled by one system, lighting by another, PV and batteries by a third, with no communication between them. The result: batteries charging from the grid during peak periods because they don’t know PV is producing, heat pumps running at full capacity during demand response events, and ventilation operating at maximum while the building sits empty.
Specify open protocols—such as BACnet, Modbus, or other interoperable standards—to prevent vendor lock-in and enable future integrations. Proprietary controls might cost less initially, but they can trap owners in expensive service agreements.
Define supervisory control logic in construction documents, not during installation. Spell out how PV and battery systems dispatch during peaks, how heat pump setpoints shift during demand response, and how ventilation ramps with occupancy. In a mixed-use Austin building, the control sequence specifies that during 2-7 PM on weekdays, batteries discharge if PV is insufficient, setpoints shift by 2°F if outdoor temperatures permit, and EV charging throttles unless vehicles are below 40% charge, resulting in a $3,200/month reduction in peak demand charges.
Performance verification at turnover is critical. Commissioning must cover distributed energy resources, energy management systems, and building automation integration. Test that systems communicate properly and supervisory sequences execute as intended.
Making Performance Goals Stick
Owners increasingly want performance guarantees tied to energy use or carbon outcomes. This requires defining what “performance” means, how it gets measured, and who’s responsible when targets aren’t met.
Use objective metrics with agreed-upon measurement periods. “Net-zero energy” means nothing without specifying the measurement boundary, the period (monthly, annually, rolling 12-month), whether it’s source or site energy, and how on-site generation is credited. Energy Use Intensity (EUI) in kBtu/sf/year provides clarity but requires weather normalization and occupancy adjustments.
Peak demand targets matter as much as total energy use in buildings with time-of-use rates. A building might hit annual EUI targets while still experiencing peak demand, resulting in enormous utility bills. Specify both total energy and peak demand targets.
The measurement and verification (M&V) plan should tie directly to the project’s energy model assumptions. Identify key performance metrics—total EUI, peak demand, percent of loads met by renewables, IAQ parameters—and specify measurement frequency and acceptable performance. Cover at least the first full year to capture seasonal variations.
Deliver an as-built energy model and baseline EUI for comparison against actual performance. The as-built model should reflect construction changes and be calibrated using utility data from the first three months.
Facilities teams need training on seasonal setpoint strategies, battery cycling schedules, PV maintenance requirements, and heat pump defrost cycles. Create a simple operations playbook—not a 300-page manual—focusing on decisions operators need to make.
Include provisions for stepwise upgrades when full electrification exceeds budget. The first phase might include envelope improvements and electric-ready infrastructure while retaining gas equipment. The second phase, triggered by equipment end-of-life or by available capital, completes the conversion. This preserves the pathway to net-zero while managing near-term constraints.
What Success Looks Like
Projects that work—hitting energy targets, staying on budget, commissioning smoothly—share common characteristics. They make key decisions early, particularly around envelope performance and electrical capacity. They treat controls as a design priority. They build measurement and verification into the project from the beginning. They have clear contract language that defines performance expectations and allocates responsibility.
They maintain tight coordination between architectural and MEP teams throughout the process, with structured decision gates at 30%, 60%, and 90% design to catch problems before they become expensive. They invest in commissioning to verify that integrated systems operate as designed and meet performance targets.
The path to net-zero and full electrification is well-established. The technologies work. The design approaches are proven. Economics increasingly favor electric systems, particularly when lifecycle costs and carbon pricing are considered. What separates successful projects from troubled ones is design rigor, early coordination, and a clear understanding of how electrified systems differ from conventional approaches.
For architectural teams navigating these projects, specialist MEP support makes the difference between smooth processes and struggles. National MEP Engineers provides tailored planning, load modeling, and design integration for electrified systems, PV, storage, and EV infrastructure—translating design intent into measurable operational performance while keeping projects on schedule and within budget.
