Net-Zero Building MEP Design: Engineering Strategies for Decarbonized Construction

Decarbonized construction is no longer an aspirational concept for a small segment of the building industry. In California, it is rapidly becoming the regulatory baseline. Between Title 24 2022 mandates, local all-electric reach codes in over 50 cities, CARB’s economy-wide decarbonization plan, and the state’s 100 percent clean electricity target by 2045, the engineering pathway for new commercial buildings increasingly requires what net-zero advocates have been designing for years: all-electric, highly efficient buildings powered by on-site and grid renewable electricity.

At Budlong, our engineers have designed net-zero facilities with sustainable engineering solutions for commercial, institutional, and public sector clients throughout California. This guide presents the engineering strategies, policy context, and design framework that define net-zero building MEP design for decarbonized construction in the current California market.

1. Net-Zero Energy vs. Net-Zero Carbon Buildings

The terms net-zero energy and net-zero carbon are often used interchangeably but represent distinct performance objectives that have different engineering implications.

The distinction matters for MEP engineering because it has implications for fuel selection. A building that burns natural gas for heating may achieve a favorable net energy balance if it has adequate solar PV offsetting electricity consumption — but it cannot achieve net-zero carbon because gas combustion produces direct CO2 emissions that on-site solar cannot offset. Truly decarbonized construction requires eliminating natural gas from the building entirely. The impact of electrification on MEP engineering is the defining trend that makes this shift technically and economically achievable in today’s California market.

2. Why Net-Zero Requires All-Electric MEP

The case for all-electric MEP in decarbonized buildings rests on a fundamental thermodynamic and energy accounting argument. Natural gas combustion produces CO2 directly at the building — these are Scope 1 emissions that appear on the building’s carbon balance regardless of any renewable electricity generation on or off site. Solar PV and wind energy produce electricity, not natural gas substitutes. There is no mechanism by which generating more solar electricity offsets the carbon from burning gas in a furnace or water heater in the same building.

The Electric Heat Pump Solution

The technology that makes all-electric buildings viable — that allows heating without gas combustion at reasonable efficiency — is the electric heat pump. Heat pumps do not generate heat by consuming electricity; they move heat from one place to another, extracting low-grade thermal energy from outdoor air, the ground, or exhaust air streams and upgrading it to the temperatures needed for space conditioning or domestic hot water. A heat pump with a COP of 3.5 delivers 3.5 units of thermal energy for every unit of electrical energy consumed — making it 3.5 times more efficient than electric resistance heating and significantly more efficient than gas heating on a primary energy basis in California’s partially renewable grid. Electrification’s impact on MEP engineering is explored in detail in Budlong’s technical resource library.

Eliminating Natural Gas Infrastructure

All-electric buildings eliminate the need for natural gas service infrastructure — the gas meter, gas distribution piping within the building, gas equipment connections, and gas equipment venting systems. This simplification reduces MEP coordination complexity, eliminates potential gas leak hazards, and removes the ongoing cost of natural gas utility service. The capital freed from gas infrastructure partially offsets the cost premium of higher-efficiency all-electric equipment. Sustainable engineering solutions from Budlong address the full transition from gas to all-electric for commercial project types across California.

3. California’s Decarbonization Policy Framework

California has assembled the most comprehensive building decarbonization policy framework of any U.S. state, creating a policy environment where net-zero building MEP design is rapidly transitioning from leading practice to standard practice.

Title 24 2022 Code Cycle

California’s 2022 Title 24 code cycle requires all-electric HVAC and water heating for new low-rise residential construction and establishes a performance compliance pathway for commercial buildings that strongly rewards all-electric systems. The performance pathway assigns a lower carbon emission factor to electricity than to natural gas, meaning that all-electric buildings achieve higher performance compliance scores than equivalent gas-heated buildings. Sustainable design services from Budlong are calibrated to the current Title 24 2022 requirements for all California projects.

Local All-Electric Reach Codes

Over 50 California cities and counties have adopted local reach codes that require all-electric new construction for residential and in many cases commercial buildings. These codes go beyond the Title 24 baseline by prohibiting new natural gas infrastructure connections entirely. Cities including San Jose, Palo Alto, Santa Barbara, and dozens of others across the state have these requirements in effect. MEP engineers must verify the applicable local reach code requirements before establishing the MEP system approach for any California project. MEP services in Los Angeles and other California jurisdictions from Budlong incorporate local reach code review as a standard project initiation step.

CARB Decarbonization Framework and SB 100

The California Air Resources Board’s 2022 Scoping Plan establishes California’s pathway to carbon neutrality by 2045, identifying building electrification as one of the four pillars of the state’s decarbonization strategy. Senate Bill 100 (SB 100) requires 100 percent clean electricity generation in California by 2045, meaning that by mid-century all electricity consumed by all-electric buildings will be carbon-free. The combination of all-electric MEP systems with a clean grid produces true net-zero operational carbon buildings without any offset purchasing or carbon accounting adjustments.

4. The Load Reduction Hierarchy

The most cost-effective approach to net-zero building MEP design begins with aggressive load reduction before sizing and specifying active systems. This hierarchy — reduce loads first, then serve the reduced loads efficiently, then offset remaining energy with renewables — is the foundational design principle that separates net-zero buildings that achieve their targets from those that do not.

Passive Design Priority

High-performance building envelopes — continuous insulation, low air leakage, triple-pane or high-performance double-pane glazing, exterior shading — reduce HVAC loads at the source. A well-insulated, well-shaded, airtight building requires a smaller HVAC system, a smaller solar PV system, and ultimately lower first cost for the entire mechanical and electrical infrastructure. The MEP engineer’s role in advocating for passive design investment during schematic design is one of the most impactful contributions to net-zero project success. The five principles of sustainable design and construction place passive design at the foundation of every net-zero strategy at Budlong.

Plug Load Reduction

In all-electric net-zero buildings, plug loads — the electricity consumed by computers, servers, kitchen equipment, and other non-HVAC, non-lighting end uses — represent an increasingly significant fraction of total building energy consumption as HVAC and lighting efficiency improves. The MEP engineer works with the owner and architect to establish plug load densities for the energy model that reflect actual equipment plans, to specify energy-efficient appliances and office equipment, and to design occupant-accessible power management controls that encourage energy-conscious behavior. Overstated plug load assumptions in the energy model result in an oversized PV system that costs more than necessary.

5. All-Electric MEP System Strategies

The MEP engineering strategies for all-electric net-zero buildings span all three disciplines — mechanical, electrical, and plumbing — and require integrated design thinking that treats the building as a coordinated energy system rather than a collection of independent sub-systems.

All-Electric HVAC

Variable refrigerant flow heat recovery systems, heat pump chillers, ground source heat pumps, and heat pump dedicated outdoor air systems are the primary all-electric HVAC strategies for California commercial buildings. VRF heat recovery is particularly effective in buildings with mixed simultaneous heating and cooling loads — the heat recovered from cooling zones serves heating zones at a COP that can exceed 5 in favorable conditions. Air source heat pump technology has advanced to the point where it provides effective heating in all California climate zones without gas backup. HVAC design services from Budlong include all-electric system design for every California climate zone.

All-Electric Domestic Hot Water

Heat pump water heaters (HPWHs) are the preferred all-electric DHW technology, delivering COP values of 3 to 4 that make them significantly more energy-efficient than electric resistance alternatives. For large commercial buildings with high DHW demand — hotels, healthcare facilities, food service — heat pump DHW systems may use CO2 refrigerant-based units that produce higher water temperatures with higher efficiency than conventional refrigerant HPWHs. Solar thermal DHW is also a viable all-electric strategy for buildings with adequate roof area, though it requires backup heating (electric resistance or HPWH) for periods of insufficient solar resource. MEP plumbing services from Budlong address all-electric DHW design for all commercial building types.

All-Electric Cooking and Food Service

Commercial kitchens have historically been one of the last holdouts for natural gas in commercial buildings — gas cooking offers precise flame control and high-temperature performance that early electric equipment struggled to match. Modern induction cooking equipment now delivers performance comparable or superior to gas in most cooking applications, with higher energy efficiency (80 to 90 percent versus 40 to 55 percent for gas burners) and improved indoor air quality by eliminating gas combustion products from the kitchen environment. All-electric kitchen design requires larger electrical service capacity to the kitchen area but eliminates the gas infrastructure, ventilation, and fire suppression complexity associated with gas cooking.

6. Embodied Carbon in MEP Systems

As operational carbon from building energy use is progressively eliminated through electrification and renewables, embodied carbon — the carbon embedded in the materials used to construct the building — becomes the dominant source of building sector carbon emissions. MEP systems contribute significantly to building embodied carbon and are an area where thoughtful specification choices can reduce the carbon footprint of construction without compromising performance.

Refrigerant Global Warming Potential

Refrigerant leakage from HVAC systems is one of the most significant sources of MEP-related embodied and operational carbon. Common refrigerants like R-410A have a global warming potential (GWP) of over 2,000 times that of CO2. Over a building’s lifecycle, cumulative refrigerant leakage can represent a carbon impact comparable to several years of building energy consumption. Specifying equipment using low-GWP refrigerants — R-32 (GWP 675), R-454B (GWP 466), or CO2 (GWP 1) — dramatically reduces this impact. CARB regulations are already driving this transition in California. Sustainable engineering solutions from Budlong specify low-GWP refrigerants as a standard practice on net-zero and high-performance projects.

Material Selection and Recycled Content

Copper, aluminum, and steel in electrical wiring, conduit, ductwork, and piping represent embodied carbon that can be partially addressed through specifying recycled-content materials. Copper wire with high recycled content, galvanized steel ductwork from manufacturers with verified Environmental Product Declarations (EPDs), and structural steel with high-recycled-content mill certificates are all specification choices that reduce MEP embodied carbon without functional performance trade-offs. LEED Materials and Resources credits reward these choices through an EPD-based framework.

7. Calculating the Net-Zero Energy Balance

The net-zero energy balance calculation is the quantitative core of net-zero building design — it determines whether the proposed all-electric building with a specified solar PV system actually achieves the net-zero target or falls short.

Annual Energy Consumption Modeling

Whole-building energy simulation using EnergyPlus, eQUEST, or equivalent tools produces the annual site energy consumption estimate that drives PV sizing. The model must accurately represent all energy end uses — HVAC (the largest category in most building types), lighting, plug loads, domestic hot water, elevators, and miscellaneous electrical loads. The all-electric building model must use heat pump performance data for all heating end uses — not gas heating assumptions — to accurately project annual electrical consumption. Net-zero facility engineering from Budlong integrates energy modeling throughout the design process rather than as a final compliance check.

Solar PV System Sizing

Once annual electrical consumption is established from the energy model, the solar PV system is sized to generate an equivalent annual energy output under the site’s solar resource conditions. PV system sizing tools (PVWatts, SAM, Helioscope) use site-specific solar irradiance data and the proposed array tilt, orientation, and shading conditions to calculate annual generation. The PV system size required for net-zero balance is the annual consumption divided by the site’s capacity factor for a 1 kW array — typically 1,400 to 1,700 kWh/kW-year for California coastal and inland locations. Budlong coordinates with solar PV design and build projects to verify that PV system sizing aligns with the MEP energy model.

8. Demand Flexibility and Grid Integration

Net-zero buildings on a decarbonizing grid have an opportunity to contribute to grid stability and renewable energy integration through demand flexibility — the ability to shift electrical loads in time to match the availability of renewable generation.

Pre-Cooling and Thermal Storage

All-electric buildings with heat pump HVAC systems can pre-cool the building’s thermal mass during periods of peak solar generation (midday) and then reduce or eliminate HVAC operation during peak grid demand periods (late afternoon), shifting load from the highest-carbon and highest-cost periods to the lowest. This thermal mass storage strategy requires no additional equipment investment — only BAS programming and building simulation to quantify the available pre-cooling capacity and thermal decay rate. Smart MEP technology solutions from Budlong include demand flexibility programming as a component of the BAS control strategy for net-zero projects.

Battery Energy Storage

Building-scale battery storage systems (BESS) store excess solar PV generation during peak production periods for use during evening and cloudy periods, reducing grid import and maximizing self-consumption of on-site renewable generation. In California’s net energy metering (NEM 3.0) framework — which significantly reduced export compensation — battery storage has become increasingly economically justified for commercial net-zero buildings. The MEP engineer coordinates battery storage system sizing with the energy model to optimize self-consumption and demand charge reduction. Solar PV design and build services from Budlong incorporate battery storage sizing in the integrated renewable energy system design.

9. Net-Zero Certification Programs

Several certification programs provide third-party verification of net-zero energy performance, distinguishing buildings that have actually demonstrated net-zero operation from those that only predicted it through energy modeling.

New Buildings Institute Zero Energy Building Certification

The New Buildings Institute (NBI) Zero Energy Certified program requires buildings to demonstrate actual metered net-zero energy performance over a 12-month period — using real utility billing data rather than modeled predictions. Buildings must also meet minimum energy efficiency requirements and provide documentation of the renewable energy system generating the offsetting energy. NBI also offers a Zero Energy Ready designation for buildings that have achieved the efficiency requirements and installed the renewable energy system but have not yet completed a full year of metered performance verification.

LEED Zero Energy

LEED Zero Energy is an add-on certification for LEED-certified buildings that have demonstrated 12 months of verified net-zero energy performance. It is available to buildings that have already achieved LEED certification and provides a performance-based credential that complements the design-based LEED rating. LEED certified building MEP engineering from Budlong supports both the design-phase LEED certification and the post-occupancy monitoring required for LEED Zero pathway buildings.

10. Who Pursues Net-Zero Building MEP Design?

11. Related Reading

For technical reference, consult the New Buildings Institute Zero Energy Building Certification requirements, the California Energy Commission Title 24 2022 standards, CARB Building Decarbonization Program, the USGBC LEED Zero Energy certification resources, and U.S. DOE Zero Energy Buildings research and case studies.

12. Frequently Asked Questions