CS55 Energy Code Feasibility Study in Revere, Massachusetts
Energy code feasibility study for a 12-unit Multifamily Mid-rise in Massachusetts. Compares multiple design paths. Recommended: ALL-ELECTRIC. View full study.
- Study Type
- Energy Code Feasibility Study
- State
- Massachusetts
- Units
- 12
- Building Type
- Multifamily Mid-rise
- Fuel Type
- All-Electric OR Mixed
- Recommended Path
- ALL-ELECTRIC
Goal
To find the most cost-effective compliance path, this report isolates energy code related costs from total construction. We use real bid data from vendors & clients to create a reliable framework for aligning incentives and design, with all recommendations confirmed by detailed energy modeling.
Project
- Revere, MA 02151
- 12 Units | 10,453 sqft
- New Construction | 3 stories of multifamily over 1 story of podium parking
- All-Electric or Mixed | Stretch | HERS ≤ 45 OR HERS ≤ 42 (mixed) | ESTAR MFNC v1.2
Overview
Read This: This report compares different ways you can build the project and meet energy code, looking at both cost and incentives, with the ultimate goal as finding the most affordable path.
- The overview outlines the key differences between each of the paths we show in this report and why we recommend the one we picked over the others.
- The recommended design section is where we share the requirements and incentives for the path we think is best based on affordability.
- The path comparison section shows the detailed requirements and incentives for each path we compared, basically showing our work if you want to dig in.
Path Summaries
ALL-ELECTRIC (Recommended): HERS/ERI compliance path with ENERGY STAR MFNC v1.2 certification. The recommended all-electric design carries no gas service, so it is held to the HERS 45 ceiling rather than the stricter HERS 42 required of a mixed-fuel building. That margin lets the building meet code with double-pane windows and a lighter envelope while every unit clears the target, and it removes the gas service, meter, and in-unit gas piping entirely. In-unit heat pump water heaters carry the domestic hot water load. It is recommended because it is the lowest net cost of the three paths, the simplest to permit and build, and the only path that also earns the in-unit heat pump water heater incentive.
GAS + CI: HERS/ERI compliance path with ENERGY STAR MFNC v1.2 certification. A gas condensing tankless water heater is the only gas appliance, which places the building under the stricter HERS 42 mixed-fuel ceiling. It meets that ceiling with double-pane low-E windows and a wall of fiberglass batt plus continuous exterior insulation; every unit clears the target with margin. The gas service, meter, and in-unit gas piping put net cost above the all-electric path. Included for a developer who prefers a gas tankless water heater over a heat pump water heater.
GAS + SPRAY FOAM: HERS/ERI compliance path with ENERGY STAR MFNC v1.2 certification. Identical to GAS + CI on fuel, windows, and mechanical systems, but replaces the batt-plus-continuous-insulation wall with a closed-cell spray-foam cavity wall and no continuous insulation. This removes the continuous-insulation detailing (furring, longer fasteners, window bucks) at the cost of a spray-foam subcontractor. Net cost is essentially the same as GAS + CI. Included for a GC who would rather coordinate a spray-foam sub than continuous-insulation trim work.
Code Path
The project is governed by the Massachusetts Stretch Energy Code, 2025 cycle. Because the building is four stories above grade plane (a grade-level parking podium with three residential stories above), it exceeds the three-story threshold of 225 CMR 22 (low-rise residential) and falls under 225 CMR 23 (mid-rise multifamily and commercial), as amended from the 2021 IECC.
Each dwelling unit demonstrates compliance through a RESNET-certified HERS Index rating - the methodology used by ENERGY STAR MFNC v1.2 and accepted under 225 CMR 23 for mid-rise multifamily dwelling units. Common areas (lobby, corridors, trash and mechanical rooms) comply with 225 CMR 23's commercial provisions and are covered by a COMcheck report.
Revere has adopted the Stretch Code but not the Municipal Opt-in Specialized Code, so neither PHIUS certification nor a zero-energy target applies.
ENERGY STAR Multifamily New Construction v1.2 certification is required by 225 CMR 23 §C407.4 for the HERS compliance pathway this project uses; meeting that requirement also unlocks the MassSave incentive on all three paths. The two gas paths qualify because gas serves only the water heater, which the program permits.
The MA Stretch Code holds new multifamily dwelling units to a maximum HERS Index of 42 for a mixed-fuel building and 45 for an all-electric building, each evaluated before any on-site renewable generation. The all-electric path is therefore held to 45 and the two gas paths to 42. All twelve units must individually meet the applicable ceiling; the worst-case unit governs.
Mandatory provisions apply regardless of path: continuously operating balanced mechanical ventilation with heat or energy recovery for every unit, EV-ready parking provisions, and a solar-ready roof zone or installed solar. Air leakage is verified by a unit-level compartmentalization (blower-door) test. There are no ducts in any path, so duct-leakage testing does not apply.
Permit / Certificate of Occupancy Requirements
High Rise Buildings
Recommended Design
This section outlines the design requirements, product recommendations, and incentives for the design that we believe will be the most affordable path to meeting energy code.
Recommended Design - Incentives
Incentives Available: $33,000
MassSave Multifamily Low Rise Program Energy Star Tier ($30,000) (Program Breakdown): You get this rebate for having your building(s) certified for the Energy Star MFNC v1.2 program. This requires pre-approval via an application to be submitted before construction starts. This rebate comes in the form of a check within 4 months of certification documentation being provided to MassSave, typically this is 4 months after construction is complete.
MassSave Multifamily Heat Pump Water Heater Adder ($3,000): You get this rebate for having each townhome install a heat pump water heater. This rebate only applies to the units undergoing the multifamily path. Rebates are typically processed at the end of construction when certificate of occupancy is received. This rebate comes in the form of a check within 4 months of the paperwork being provided to MassSave.
Recommended Design - Units
| Item | Detailed Specifications |
|---|---|
| Exterior Walls | R-21 fiberglass batt in 2x6 wood studs @ 16in OC + R-5 continuous insulation |
| Slab | N/A- Level 2 floor sits on the concrete parking podium. |
| Floor Over Parking | R-30 insulation below the Level 2 framed floor over parking; drop-ceiling batt or continuous spray foam over steel I-beam framing |
| Rim Joists | R-21 batt at Level 3 floor band |
| Roof | R-49 cavity insulation, framed flat roof |
| Windows | Double pane low-E argon; U-0.28; SHGC 0.30 |
| Doors | Opaque insulated; R-4.75 |
| Air Sealing | ≤0.30 CFM50 per sqft of shell area, blower-door tested (Air sealing protocol) (Backup Air Sealing) |
| HVAC | Ductless mini-split cold-climate heat pump; SEER2 19.0 / HSPF2 10; EER2 12.0; ENERGY STAR CCHP; R-454B (1 Bedrooms) (2 Bedrooms) |
| Ductwork | N/A |
| Duct Sealing | N/A |
| HVAC Grading | N/A |
| Mechanical Ventilation | ERV; sized per ASHRAE 62.2-2022 (1Bed: 30 CFM; 2Bed: 50 CFM); 85% SRE; 75% TRE (Product Rec). |
| Local Mechanical Exhaust | Bath ≥50 CFM intermittent (≤3.0 sones); kitchen ≥100 CFM intermittent; ENERGY STAR; vented through the ERV. |
| Thermostats | Programmable thermostat. |
| DHW | Heat pump water heater; UEF 3.5; 50 gal; 240V/30A; in-unit (Product Rec) |
| DHW Piping | Supply piping insulated to R-3; Max DHW pipe run length: 1BR: 26.3 ft 2BR: 32.4 ft |
| Water Fixtures | WaterSense: lavatory ≤1.2 GPM; shower ≤2.0 GPM; kitchen ≤2.2 GPM; toilet ≤1.28 GPF. |
| Refrigerator | ENERGY STAR; 450 kWh/yr (Product Rec) |
| Dishwasher | ENERGY STAR; 240 kWh/yr (Product Rec) |
| Clothes Washer | ENERGY STAR front-load; (Product Rec) |
| Clothes Dryer | Electric vented dryer; CEF 3.93; ENERGY STAR (Product Rec) |
| Stove / Oven | Electric range; non-induction; standard oven (Product Rec). |
| Lighting | 100% high-efficacy LED, interior and exterior. |
| Solar Ready | Designated Solar Zone: Reserve a contiguous area equal to at least 40% of the total horizontal roof area. Contiguity: Zone free of obstructions, minimum 5 ft wide. Structural Capacity: 5 PSF collateral dead load. Electrical Infrastructure: Conduit pathways and reserved breaker space. |
| EV Ready | EV-Ready parking per R404.4; dedicated 240V branch circuit terminating within reach of the space. |
| HPWH Ready | N/A- HPWH installed. |
| Paperwork & Modeling | HERS/ERI energy model; ENERGY STAR MFNC v1.2 certification; IECC compliance checklists; MassSave incentive documentation. |
| Testing & Verification | Unit blower-door (compartmentalization) test; mechanical ventilation balancing; pre-drywall + final inspection; RESNET sampling plan. |
Recommended Design - Common Space
| Item | Detailed Specifications |
|---|---|
| Exterior Walls | Common-area exterior walls are part of the building's thermal envelope and use the recommended residential assembly: R-21 batt in 2x6 wood studs plus continuous exterior insulation. Assembly U-factor meets 225 CMR 23 / IECC C402.1.4, Climate Zone 5, wood-framed. |
| Below-Grade Walls | N/A - no conditioned below-grade space. Any wall enclosing conditioned area below grade meets the C402.1.4 below-grade wall C-factor for Climate Zone 5. |
| Slab | Grade-level common-area slab-on-grade (lobby, entry): R-10 perimeter insulation to 24 in depth per 225 CMR 23 / IECC C402.2, Climate Zone 5 (unheated slab). |
| Rim Joists | Floor-band areas at common-area floor transitions air-sealed and insulated continuous with the wall assembly; R-21 minimum. |
| Roof | Common-area roof is part of the building thermal envelope: R-49 framed flat roof, matching the recommended design. Meets 225 CMR 23 / IECC C402.1.4 Climate Zone 5 roof maximum U-factor. |
| Windows | Common-area glazing (lobby, stair): double-pane low-E, U-factor and SHGC within 225 CMR 23 Table C402.4 (as amended) for Climate Zone 5. The recommended low-E double-pane glazing (U-0.28 or better) satisfies the commercial maximum. |
| Doors | Common-area exterior doors: opaque insulated, U-factor per 225 CMR 23 Table C402.4 for Climate Zone 5; glazed entrance doors per the same table. |
| Air Sealing | Continuous air barrier across the building thermal envelope per 225 CMR 23 C402.5. Whole-building air leakage not greater than 0.35 CFM per sqft of envelope area at 75 Pa (C402.5.2), verified by an accredited independent testing laboratory. |
| HVAC | All-electric per the 225 CMR 23 C401.4 all-electric provision - no fossil fuel for space heating, ventilation-air heating, or service water heating. Conditioned common areas served by cold-climate heat pump equipment at minimum efficiency per 225 CMR 23 / IECC C403. |
| Duct Sealing | Where common-area ductwork exists, sealed and leakage-tested per 225 CMR 23 / IECC C403; corridor and lobby systems are typically ductless. |
| Mechanical Ventilation | Common-area outdoor-air ventilation per ASHRAE 62.1-2019 rates by space type (corridor, lobby, stairway). Energy recovery ventilation per 225 CMR 23 C403.7.4 where airflow and climate thresholds require it. |
| Local Mechanical Exhaust | Exhaust for common-area restrooms, trash and refuse rooms, and mechanical rooms per ASHRAE 62.1-2019 exhaust rates; refuse room exhaust continuous. |
| Thermostats | Programmable thermostats with setback and setup capability for all conditioned common areas, per 225 CMR 23 / IECC C403.4. |
| DHW | Common-area service water heating (restroom lavatories): point-of-use electric, no fossil fuel per C401.4; minimum efficiency per 225 CMR 23 / IECC C404. |
| DHW Piping | Common-area service hot water piping insulated per 225 CMR 23 / IECC C404, R-value by pipe diameter. |
| Water Fixtures | WaterSense-labeled fixtures in common-area restrooms: metering lavatory faucet ≤0.5 GPM, water closet ≤1.28 GPF, urinal ≤0.125 GPF. |
| Lighting | 100% LED. Interior lighting power within 225 CMR 23 / IECC C405.3 limits by space type (corridor, lobby, stairway, mechanical/electrical, storage, restroom); exterior lighting power per C405.4. |
| Lighting Controls | Occupancy/vacancy sensors in corridors, stairwells, storage, restrooms, and mechanical rooms; automatic time-switch and daylight-responsive controls where applicable, per 225 CMR 23 / IECC C405.2. |
| Solar Ready | Solar-ready roof zone with conduit pathway from roof to electrical room and reserved electrical capacity, per the applicable solar-ready appendix. |
| EV Ready | EV-ready parking provisions at the podium parking level: dedicated 240V branch circuits to EV-ready spaces, consistent with the dwelling-unit EV-ready requirement. |
| Paperwork & Modeling | COMcheck report covering all common-area spaces; ASHRAE 62.1-2019 ventilation calculations; interior and exterior lighting power calculations; 225 CMR 23 compliance documentation. |
| Testing & Verification | Whole-building air leakage test (C402.5.2); mechanical ventilation balancing; lighting controls functional testing; commissioning per 225 CMR 23 C408 where applicable. |
Exterior Wall Assembly (Recommended Design)
Rim Joist (Recommended Design)
Roof (Recommended Design)
Podium (Recommended Design - Option 1)
Podium (Recommended Design - Option 2)
Path Comparison
This section shows the detailed requirements and incentives for each path we compared, basically showing our work of how we determined the recommended path is the most affordable way of meeting energy code compliance.
Path Comparison - Incentives
Electric: $33,000
MassSave Multifamily Low Rise Program Energy Star Tier ($30,000) (Program Breakdown): You get this rebate for having your building(s) certified for the Energy Star MFNC v1.2 program. This requires pre-approval via an application to be submitted before construction starts. This rebate comes in the form of a check within 4 months of certification documentation being provided to MassSave, typically this is 4 months after construction is complete.
MassSave Multifamily Heat Pump Water Heater Adder ($3,000): You get this rebate for having each townhome install a heat pump water heater. This rebate only applies to the units undergoing the multifamily path. Rebates are typically processed at the end of construction when certificate of occupancy is received. This rebate comes in the form of a check within 4 months of the paperwork being provided to MassSave.
Gas Paths: $30,000
MassSave Multifamily Low Rise Program Energy Star Tier ($30,000) (Program Breakdown): You get this rebate for having your building(s) certified for the Energy Star MFNC v1.2 program. This requires pre-approval via an application to be submitted before construction starts. This rebate comes in the form of a check within 4 months of certification documentation being provided to MassSave, typically this is 4 months after construction is complete.
Path Comparison - Net Cost Summary
| Path | Total Cost $/sf | Total Incentive $/sf | Net $/sf | OpEx Factor | Worst HERS | $/HERS Point |
|---|---|---|---|---|---|---|
| ELECTRIC | $39.14 | $3.16 | $35.98 | 0.96 | 42.06 | $0.86 |
| GAS + CI | $43.29 | $2.87 | $40.42 | 0.96 | 40.71 | $0.99 |
| GAS + SF | $43.09 | $2.87 | $40.22 | 0.96 | 40.75 | $0.99 |
Path Comparison - Envelope
| Item | Path | Detailed Specifications | Cost $/sf | Incentive $/sf | Net $/sf | OpEx Factor |
|---|---|---|---|---|---|---|
| Exterior Walls | ELECTRIC | R-21 fiberglass batt in 2x6 wood studs @ 16in OC + R-5 continuous insulation | $4.60 | $0.00 | $4.60 | 0.85 |
| GAS + CI | R-21 fiberglass batt in 2x6 wood studs @ 16in OC + R-7.5 continuous insulation | $5.20 | $0.00 | $5.20 | 0.85 | |
| GAS + SF | R-38 closed-cell spray foam, full 2x6 wood-stud cavity @ 16in OC (no continuous insulation) | $5.00 | $0.00 | $5.00 | 0.85 | |
| Slab | ELECTRIC | N/A no slab-on-grade; Level 2 sits on the parking podium. | $0.00 | $0.00 | $0.00 | 1.00 |
| GAS + CI | Same as ELECTRIC. | $0.00 | $0.00 | $0.00 | 1.00 | |
| GAS + SF | Same as ELECTRIC. | $0.00 | $0.00 | $0.00 | 1.00 | |
| Floor Over Parking | ELECTRIC | R-30 insulation below the Level 2 framed floor over parking; drop-ceiling batt or continuous spray foam over steel I-beam framing | $3.70 | $0.00 | $3.70 | 0.85 |
| GAS + CI | R-38 continuous insulation below the Level 2 framed floor over parking | $4.50 | $0.00 | $4.50 | 0.85 | |
| GAS + SF | Same as GAS + CI. | $4.50 | $0.00 | $4.50 | 0.85 | |
| Rim Joists | ELECTRIC | R-21 batt at Level 3 floor band | $0.40 | $0.00 | $0.40 | 0.90 |
| GAS + CI | R-21 batt at Level 3 floor band | $0.40 | $0.00 | $0.40 | 0.90 | |
| GAS + SF | R-21 batt at Level 3 floor band | $0.40 | $0.00 | $0.40 | 0.90 | |
| Roof | ELECTRIC | R-49 cavity insulation, framed flat roof | $1.25 | $0.00 | $1.25 | 0.85 |
| GAS + CI | R-49 cavity insulation, framed flat roof | $1.25 | $0.00 | $1.25 | 0.85 | |
| GAS + SF | Same as GAS + CI. | $1.25 | $0.00 | $1.25 | 0.85 | |
| Windows | ELECTRIC | Double pane low-E argon; U-0.28; SHGC 0.30 | $5.20 | $0.00 | $5.20 | 0.95 |
| GAS + CI | Double pane low-E argon; U-0.22; SHGC 0.30 | $6.00 | $0.00 | $6.00 | 0.95 | |
| GAS + SF | Same as GAS + CI. | $6.00 | $0.00 | $6.00 | 0.95 | |
| Doors | ELECTRIC | Opaque insulated; R-4.75 | $1.00 | $0.00 | $1.00 | 0.90 |
| GAS + CI | Opaque insulated; R-6 | $1.20 | $0.00 | $1.20 | 0.90 | |
| GAS + SF | Same as GAS + CI. | $1.20 | $0.00 | $1.20 | 0.90 | |
| Air Sealing | ELECTRIC | 0.30 CFM50 per sqft of enclosure; compartmentalization test | $0.40 | $0.00 | $0.40 | 0.85 |
| GAS + CI | 0.25 CFM50 per sqft of enclosure; compartmentalization test | $0.55 | $0.00 | $0.55 | 0.85 | |
| GAS + SF | Same as GAS + CI. | $0.55 | $0.00 | $0.55 | 0.85 |
Path Comparison - Mechanical
| Item | Path | Detailed Specifications | Cost $/sf | Incentive $/sf | Net $/sf | OpEx Factor |
|---|---|---|---|---|---|---|
| HVAC | ELECTRIC | Ductless mini-split cold-climate heat pump; SEER2 19.0 / HSPF2 10; EER2 12.0; ENERGY STAR CCHP; R-454B (1 Bedrooms) (2 Bedrooms) | $9.50 | $0.00 | $9.50 | 1.10 |
| GAS + CI | Ductless mini-split cold-climate heat pump; SEER2 19.0 / HSPF2 10; EER2 12.0; ENERGY STAR CCHP; R-454B (1 Bedrooms) (2 Bedrooms) | $10.20 | $0.00 | $10.20 | 1.10 | |
| GAS + SF | Same as GAS + CI. | $10.20 | $0.00 | $10.20 | 1.10 | |
| Ductwork | ELECTRIC | N/A - ductless mini-split system. | $0.00 | $0.00 | $0.00 | 1.00 |
| GAS + CI | Same as ELECTRIC. | $0.00 | $0.00 | $0.00 | 1.00 | |
| GAS + SF | Same as ELECTRIC. | $0.00 | $0.00 | $0.00 | 1.00 | |
| Duct Sealing | ELECTRIC | N/A - ductless mini-split system. | $0.00 | $0.00 | $0.00 | 1.00 |
| GAS + CI | Same as ELECTRIC. | $0.00 | $0.00 | $0.00 | 1.00 | |
| GAS + SF | Same as ELECTRIC. | $0.00 | $0.00 | $0.00 | 1.00 | |
| HVAC Grading | ELECTRIC | N/A - ductless; HERS-only path. | $0.00 | $0.00 | $0.00 | 1.00 |
| GAS + CI | Same as ELECTRIC. | $0.00 | $0.00 | $0.00 | 1.00 | |
| GAS + SF | Same as ELECTRIC. | $0.00 | $0.00 | $0.00 | 1.00 | |
| Mechanical Ventilation | ELECTRIC | ERV; sized per ASHRAE 62.2-2022 (30-45 CFM by unit size); 85% SRE; 75% TRE | $1.50 | $0.00 | $1.50 | 1.10 |
| GAS + CI | ERV; sized per ASHRAE 62.2-2022 (30-45 CFM by unit size); 85% SRE; 75% TRE | $1.50 | $0.00 | $1.50 | 1.10 | |
| GAS + SF | Same as GAS + CI. | $1.50 | $0.00 | $1.50 | 1.10 | |
| Local Mechanical Exhaust | ELECTRIC | Bath ≥50 CFM intermittent; kitchen ≥100 CFM intermittent; ENERGY STAR; vented through the ERV. | $0.50 | $0.00 | $0.50 | 1.05 |
| GAS + CI | Same as ELECTRIC. | $0.50 | $0.00 | $0.50 | 1.05 | |
| GAS + SF | Same as ELECTRIC. | $0.50 | $0.00 | $0.50 | 1.05 | |
| Thermostats | ELECTRIC | Programmable thermostat. | $0.14 | $0.00 | $0.14 | 0.95 |
| GAS + CI | Same as ELECTRIC. | $0.14 | $0.00 | $0.14 | 0.95 | |
| GAS + SF | Same as ELECTRIC. | $0.14 | $0.00 | $0.14 | 0.95 |
Path Comparison - Plumbing & Appliances
| Item | Path | Detailed Specifications | Cost $/sf | Incentive $/sf | Net $/sf | OpEx Factor |
|---|---|---|---|---|---|---|
| DHW | ELECTRIC | Heat pump water heater; UEF 3.5; 50 gal; 240V/30A; in-unit | $3.45 | $0.29 | $3.16 | 1.20 |
| GAS + CI | Gas condensing tankless water heater; UEF 0.95; in-unit | $2.30 | $0.00 | $2.30 | 0.95 | |
| GAS + SF | Same as GAS + CI. | $2.30 | $0.00 | $2.30 | 0.95 | |
| DHW Piping | ELECTRIC | Supply piping insulated to R-3; Max DHW pipe run length: 1BR: 26.3 ft 2BR: 32.4 ft | $0.70 | $0.00 | $0.70 | 0.90 |
| GAS + CI | Supply piping insulated to R-3; Max DHW pipe run length: 1BR: 17.5 ft 2BR: 21.6 ft | $0.70 | $0.00 | $0.70 | 0.90 | |
| GAS + SF | Same as GAS + CI. | $0.70 | $0.00 | $0.70 | 0.90 | |
| Water Fixtures | ELECTRIC | WaterSense: lavatory ≤1.2 GPM; shower ≤2.0 GPM; kitchen ≤2.2 GPM. | $0.55 | $0.00 | $0.55 | 0.90 |
| GAS + CI | Same as ELECTRIC. | $0.55 | $0.00 | $0.55 | 0.90 | |
| GAS + SF | Same as ELECTRIC. | $0.55 | $0.00 | $0.55 | 0.90 | |
| Refrigerator | ELECTRIC | ENERGY STAR; 450 kWh/yr | $0.60 | $0.00 | $0.60 | 1.00 |
| GAS + CI | ENERGY STAR; 450 kWh/yr | $0.60 | $0.00 | $0.60 | 1.00 | |
| GAS + SF | Same as GAS + CI. | $0.60 | $0.00 | $0.60 | 1.00 | |
| Dishwasher | ELECTRIC | ENERGY STAR; 240 kWh/yr | $0.39 | $0.00 | $0.39 | 1.00 |
| GAS + CI | ENERGY STAR; 240 kWh/yr | $0.39 | $0.00 | $0.39 | 1.00 | |
| GAS + SF | Same as GAS + CI. | $0.39 | $0.00 | $0.39 | 1.00 | |
| Clothes Washer | ELECTRIC | ENERGY STAR front-load; IMEF 2.92; 85 kWh/yr | $0.59 | $0.00 | $0.59 | 1.00 |
| GAS + CI | ENERGY STAR front-load; IMEF 2.92; 85 kWh/yr | $0.59 | $0.00 | $0.59 | 1.00 | |
| GAS + SF | Same as GAS + CI. | $0.59 | $0.00 | $0.59 | 1.00 | |
| Clothes Dryer | ELECTRIC | Electric vented dryer; CEF 3.93; ENERGY STAR | $0.52 | $0.00 | $0.52 | 1.05 |
| GAS + CI | Electric vented dryer; CEF 3.93; ENERGY STAR | $0.52 | $0.00 | $0.52 | 1.05 | |
| GAS + SF | Same as GAS + CI. | $0.52 | $0.00 | $0.52 | 1.05 | |
| Stove / Oven | ELECTRIC | Electric range; non-induction; standard oven | $0.45 | $0.00 | $0.45 | 1.00 |
| GAS + CI | Electric range; non-induction; standard oven | $0.45 | $0.00 | $0.45 | 1.00 | |
| GAS + SF | Same as GAS + CI. | $0.45 | $0.00 | $0.45 | 1.00 |
Path Comparison - Electrical
| Item | Path | Detailed Specifications | Cost $/sf | Incentive $/sf | Net $/sf | OpEx Factor |
|---|---|---|---|---|---|---|
| Lighting | ELECTRIC | 100% high-efficacy LED, interior and exterior. | $2.00 | $0.00 | $2.00 | 0.85 |
| GAS + CI | Same as ELECTRIC. | $2.00 | $0.00 | $2.00 | 0.85 | |
| GAS + SF | Same as ELECTRIC. | $2.00 | $0.00 | $2.00 | 0.85 | |
| Solar Ready | ELECTRIC | Designated Solar Zone: Reserve a contiguous area equal to at least 40% of the total horizontal roof area. Contiguity: Zone free of obstructions, minimum 5 ft wide. Structural Capacity: 5 PSF collateral dead load. Electrical Infrastructure: Conduit pathways and reserved breaker space. | $0.25 | $0.00 | $0.25 | 0.90 |
| GAS + CI | Same as ELECTRIC. | $0.25 | $0.00 | $0.25 | 0.90 | |
| GAS + SF | Same as ELECTRIC. | $0.25 | $0.00 | $0.25 | 0.90 | |
| EV Ready | ELECTRIC | EV Ready infrastructure for at least 20% of total parking. Branch circuit and termination for required spaces, rated for at least 6.2 kVA per space. | $0.40 | $0.00 | $0.40 | 0.95 |
| GAS + CI | Same as ELECTRIC. | $0.40 | $0.00 | $0.40 | 0.95 | |
| GAS + SF | Same as ELECTRIC. | $0.40 | $0.00 | $0.40 | 0.95 | |
| Gas Service Infrastructure | ELECTRIC | N/A - ELECTRIC; no gas service. | $0.00 | $0.00 | $0.00 | 1.00 |
| GAS + CI | Gas service, meter, and in-unit gas piping serving the tankless water heater. | $2.05 | $0.00 | $2.05 | 1.05 | |
| GAS + SF | Same as GAS + CI. | $2.05 | $0.00 | $2.05 | 1.05 |
Path Comparison - Soft Costs
| Item | Path | Detailed Specifications | Cost $/sf | Incentive $/sf | Net $/sf | OpEx Factor |
|---|---|---|---|---|---|---|
| Paperwork & Modeling | ELECTRIC | HERS/ERI energy model; ENERGY STAR MFNC v1.2 certification; IECC compliance checklists; MassSave incentive documentation. | $0.50 | $2.87 | -$2.37 | 1.00 |
| GAS + CI | Same as ELECTRIC. | $0.50 | $2.87 | -$2.37 | 1.00 | |
| GAS + SF | Same as ELECTRIC. | $0.50 | $2.87 | -$2.37 | 1.00 | |
| Testing & Verification | ELECTRIC | Unit blower-door (compartmentalization) test; mechanical ventilation balancing; pre-drywall + final inspection. | $0.55 | $0.00 | $0.55 | 1.00 |
| GAS + CI | Same as ELECTRIC. | $0.55 | $0.00 | $0.55 | 1.00 | |
| GAS + SF | Same as ELECTRIC. | $0.55 | $0.00 | $0.55 | 1.00 |
Additional Design Considerations Not Represented In This Study
Window Glazing (Triple Pane Tested, Not Needed): Triple-pane windows were initially carried on the gas paths under the assumption that the stricter HERS 42 ceiling required them. On re-analysis, double-pane low-E windows (U-0.22) bring every unit comfortably under HERS 42, with the worst-case one-bedroom unit passing with margin. Triple pane was dropped from all paths - it added cost without being needed for compliance. All three paths now carry double-pane glazing.
Electric-Resistance Water Heating (Ruled Out): An all-electric design using an electric-resistance storage tank was modeled at the client's request. Even with triple-pane windows and a heavily insulated envelope, the worst-case one-bedroom unit landed near HERS 48, failing the 45 ceiling by roughly three points. An electric-resistance tank cannot be offset by envelope or appliance measures. The all-electric path was therefore modeled with a heat pump water heater, which passes comfortably and also earns the MassSave in-unit heat pump water heater incentive.
All-Electric Value Engineering: With a heat pump water heater the all-electric path initially scored in the high 30s, well below the 45 ceiling, so specifications were value-engineered down: triple-pane glazing to double-pane, reduced wall continuous insulation, and a standard cold-climate heat-pump rating. The appliance package was then set to a standard electric range and an ENERGY STAR vented dryer, which costs roughly one HERS point against induction and a heat-pump dryer. Air sealing is held to a 0.30 CFM50 per square foot maximum and the roof to an R-49 minimum, with the higher-recovery 85 percent ERV carried on every path. The worst-case unit lands at HERS 42, a comfortable buffer under the ceiling.
One-Bedroom Unit Glazing: The worst-case unit in every path is the same one-bedroom interior unit type. It is small (452 sqft), so fixed plug and lighting loads weigh heavily on its score, and it carries a high window-to-wall ratio on its single exterior face. Reducing the one-bedroom window area would create additional compliance buffer on all three paths and is worth a conversation with the architect, though it is not required for the recommended path to pass.