Net Zero Engineering for Rhode Island Homes

By Kenneth A. Hayes, P.E. · RI #7252  ·  Published May 9, 2026

A Net Zero home produces as much energy as it consumes over the course of a year. Done well, the building is fully electrified — no oil, no propane, no gas connection — and pairs with on-site solar PV, battery storage, and EV charging into a single self-sustaining energy system. Done poorly, it is a stack of expensive components that fail to perform at the worst hour of the worst month.

This reference explains how we approach Net Zero engineering at South County Design Group: the cascade of cause and effect that ties envelope, mechanical, solar, and storage into a single integrated model; the three principles that govern every Net Zero analysis we run; the third-party certification path we use to verify the finished home performs to spec; and what this approach delivers for homeowners.

Net Zero is a system, not a checklist

The temptation in Net Zero design is to treat each component as an independent specification — pick the best windows, pick the right heat pump, pick a solar array size, add a battery. That approach reliably over-builds in some places and under-builds in others, because none of the components are truly independent.

The real picture is a cascade of cause and effect:

A change at any stage cascades downstream. Tighten the envelope and the heating load drops, which means the heat pump downsizes, which means the electrical service can be smaller, which means the PV array needs fewer panels, which means the battery needs less capacity, which means the 30-year operating cost shifts. The same is true in reverse — undersize the envelope and every downstream component is forced to pick up the slack, with capital cost and operating cost both penalized.

This is why we model Net Zero as a single connected system rather than a stack of independent design steps.

The optimization point

When the full chain is integrated, the design can be iterated until it reaches the optimization point — the point where a dollar invested in any one component still produces about a dollar of savings somewhere else in the chain. Push past that point and returns diminish: each additional dollar buys less than a dollar back across the rest of the system. The optimization point is where an engineered Net Zero design lives, not the maximum spec on any one line item.

The best way to produce that result is to have a single engineer own the full chain end to end — the same person specifying the envelope, sizing the mechanical equipment, sizing the electrical service, sizing the PV array, sizing the battery, integrating the EV charging, and running the 30-year proforma. The alternative — splitting the design across multiple specialists who hand off to each other — tends to break down in practice. Each specialist optimizes their piece in isolation against assumptions handed to them, rather than against the live state of the rest of the model. The cascade does not propagate because the downstream specialist cannot re-run the upstream analysis when inputs change. The pieces that require cross-system integration — the 30-year proforma, the thermodynamic coupling between battery storage and the heat pump water heater — fall between the seams because no single party owns them. We run the entire pipeline through one engineer to keep the integration intact.

Three principles that govern our analysis

Three principles govern every Net Zero analysis we do. They are not preferences. They are the basis on which the engineering can be defended to a lender, an underwriter, an appraiser, or a peer engineer.

Net Zero Ready is not Net Zero

Rhode Island’s residential energy code changed in 2024. The 2024 IECC, adopted as RISBC-8 (510-RICR-00-00-8), became effective November 14, 2024; the consolidated version that includes Appendix RK was fully in force December 1, 2025. Every new home built in Rhode Island now arrives Net Zero Ready in the practical sense — Appendix RK mandates dedicated 240-volt circuits and sized panel capacity for future heat-pump space heating, heat-pump water heating, induction cooking, and heat-pump clothes drying; the code separately requires a solar-ready roof zone reserved for future photovoltaic installation (R404.6) and electric vehicle charging infrastructure (R404.7); and the envelope is tightened to 3.0 ACH50 prescriptive air leakage, R-49 ceilings, and R-20+5ci (or equivalent) walls in Climate Zone 5 (Table R402.1.3).

The code stops there. Rhode Island’s adoption of the 2024 IECC explicitly deleted the zero-energy and stretch-code appendices that the base code contains — Appendix RC (Zero Net Energy Residential Buildings), Appendix RG (2024 IECC Stretch Code), Appendix RE (All-Electric Residential Buildings), and Appendix RI (On-Site Renewable Energy), among others. A code-minimum new home in Rhode Island today is therefore ready to become Net Zero but is not, by code, Net Zero. The infrastructure is in place; the appliances, the on-site generation, the storage, the load matching, and the verification are not.

That is the gap this engineering practice fills. Net Zero requires the cascade described above — envelope sized for the actual climate and lot rather than to the code minimum, heat pump sized to the small heating load that follows, PV array sized to the home’s full annual electric load including the EV, battery storage sized to the worst-case demand, all of it integrated and verified through DOE Efficient New Homes certification. The code now delivers a building that is wired and roof-prepared to host that engineering. It does not, on its own, deliver a building that performs to Net Zero.

What a Net Zero home actually does

A Net Zero home produces as much energy as it consumes over the course of a year. A fully electrified home carries no fossil-fuel combustion — no oil, no propane, no gas connection for heating, cooking, or domestic hot water. Add electric-vehicle charging that draws from the home's own PV array, and the building is self-sustaining and all-electric, with no fossil fuels on site. The EV is not an accessory to the design. It is part of the home's energy ecosystem.

The vehicle charges from on-site solar during daylight where possible, draws from the battery or grid as needed, and — where the vehicle and inverter support it — can contribute back to the home during outages or peak demand. The building, the storage, and the vehicle operate as one connected energy system rather than three disconnected pieces.

How we verify the design performs

Engineering a Net Zero design and finishing a Net Zero home are two different things. We close that gap through three steps that are not optional:

1. Direct trade coordination. When the design is complete, we walk through every system with the trades who will install it — the electrician, the mechanical contractor, the plumber, the PV installer, the insulation and air-sealing contractor, the general contractor — and confirm how each piece will be built. Net Zero performance only happens when every trade installs to the engineered design, not to a generic specification or a personal preference.
2. Contractual completion criterion. The owner and the general contractor are contractually obligated to install the design as specified and to achieve Net Zero status as a completion criterion of the project. The Net Zero target is not aspirational; it is in the contract documents.
3. Third-party verification under a federal program. Performance is verified through the U.S. Department of Energy Efficient New Homes program (formerly DOE Zero Energy Ready Home), with a qualified RESNET HERS Rater calculating an Energy Rating Index independent of the design team. Because DOE Efficient New Homes is built on top of several federal prerequisite programs, a home earning the DOE certification also earns ENERGY STAR Single-Family New Homes, EPA Indoor airPLUS, and EPA WaterSense Labeled Homes certification through the same verification process.

The combination — single-engineer design ownership, direct trade coordination, contractual enforcement at the build level, and third-party verification under a federal program — is what separates a building that was designed to be Net Zero from a building that actually performs as Net Zero.

What this approach delivers

A defensible Net Zero design that:

• Reaches Net Zero performance in the actual climate of the project's site, not a generic average
• Is not over-built in any one component — the optimization point is where the design lives, not the maximum spec on any one line item
• Provides a path to all-electric operation with no fossil fuels on site, with EV charging integrated into the home's PV and battery system as part of the design
• Has a 30-year operating-cost projection that holds up to lender or appraiser review
• Is engineered for the worst case, so the design margin is real rather than nominal
• Is carried into the build through direct trade coordination and contractual obligations on the owner and general contractor — Net Zero status is part of the project's completion criteria, not an aspiration
• Can be reoptimized at any time — if the homeowner wants to consider a different envelope spec, mechanical configuration, or solar/storage strategy, the cascade re-runs and the new optimization point is visible

This is engineering for buildings that have to perform on their own, in the actual environment they were designed for. Not a sales packet. Not a marketing claim. The numbers are the design.

Common Questions About Net Zero Homes in Rhode Island

What is a Net Zero home?

A Net Zero home produces as much energy on-site over the course of a year as it consumes. The math is annual, not instantaneous: the home draws from the grid in winter, exports to the grid in summer, and the two balance over twelve months. Net Zero status depends on the building envelope being efficient enough that an on-site solar PV array sized for the lot can cover the home's annual energy use.

Do Net Zero homes work in Rhode Island winters?

Yes. Rhode Island falls in DOE climate zone 5A — cold, but well within the operating envelope of modern cold-climate air-source heat pumps, which produce useful heat well below 0°F. A correctly engineered Net Zero home in Rhode Island uses a tight, well-insulated envelope to keep heating loads small, then sizes the heat pump and solar PV array against that small load. The home draws from the grid during winter cold snaps and exports to the grid during summer; the annual balance is what matters.

How much does a Net Zero home cost in Rhode Island?

The cost premium over a code-minimum Rhode Island home depends on envelope choices, mechanical specification, solar PV array size, and battery storage — and is project-specific rather than a generic percentage. The premium is offset over the home's life by near-zero net energy bills, federal and state incentive programs (Rhode Island Renewable Energy Fund, federal residential clean-energy credit), and — when the analysis is integrated — by avoiding over-spec in any one component. A 30-year financial proforma is part of the design deliverable on every Net Zero project SCDG engineers.

Does my home need to be all-electric to be Net Zero?

In practice, yes. Net Zero is defined as an on-site energy balance, and on-site generation is electric. A home with any fossil-fuel appliance — natural gas furnace, propane stove, oil-fired hot water — will have a fossil-fuel energy demand that on-site solar cannot offset. Every Net Zero project SCDG engineers is all-electric: heat pump for heating and cooling, heat-pump water heater, induction cooking, electric vehicle charging, with the building's electrical service sized for the full load at the design stage.

What is DOE Efficient New Homes certification?

The U.S. Department of Energy's Efficient New Homes program (formerly Zero Energy Ready Home) is a federal third-party verification program for high-performance new construction. Certification requires an envelope, mechanical, and renewables specification that brings the home within striking distance of Net Zero, plus a third-party HERS rating, indoor-air-quality measures, and ENERGY STAR appliances. SCDG's Net Zero projects are engineered to meet DOE Efficient New Homes criteria; verification is performed by an accredited rater outside SCDG.

Built work

Net Zero new construction · 60 Rockland Drive · South Kingstown, Rhode Island · completed spring 2026.

SCDG provided the full Net Zero engineering described on this page. Construction was performed by NJ&J Builders, LLC.

SCDG and NJ&J Builders, LLC are separately insured and licensed Rhode Island entities operating independently in their respective fields.

About the Engineer