CS53 Energy Code Feasibility Study in Worcester, Massachusetts
Energy code feasibility study for a 170-unit Townhome Units in Massachusetts. Compares multiple design paths. Recommended: DUCTLESS. View full study.
- Study Type
- Energy Code Feasibility Study
- State
- Massachusetts
- Units
- 170
- Building Type
- Townhome Units
- Fuel Type
- All-Electric
- Recommended Path
- DUCTLESS
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
- Worcester, MA 01603
- 170 Units | 244,680 sqft
- New Construction | Townhome Units
- All-Electric | Specialized Opt-In | HERS ≤ 45 | ESTAR SFNH v3.2 | Energy Star NextGen v1.0
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
DUCTLESS (Recommended): HERS/ERI path with ENERGY STAR NextGen certification. Uses a 4-zone ductless cold-climate heat pump with ceiling cassette indoor heads (recessed flush with the ceiling, similar in appearance to standard supply registers) and a value-engineered envelope. The ductless system eliminates ductwork entirely and simplifies trade coordination. Recommended because it delivers the lowest net cost ($31.42/sf) and the lowest execution risk. Every incentive is a MassSave check with a predictable timeline and no transfer discount risk.
DUCTED: HERS/ERI path with ENERGY STAR NextGen certification. Uses a ducted cold-climate heat pump with full forced-air distribution, paired with heavier wall and roof insulation to compensate for the lower ducted efficiency. Adding ductwork, duct sealing, and the heavier envelope pushes net cost about $7.30/sf above DUCTLESS. Not recommended due to higher cost, but included for clients who require concealed HVAC distribution.
GEOTHERMAL: HERS/ERI path with ENERGY STAR NextGen certification. Uses ground-source heat pumps with vertical closed-loop bores, sharing the same value-engineered envelope as DUCTLESS. On a net-cost basis it is the lowest-cost option among ducted paths at $34.50/sf, but only if every incentive lands as projected, most importantly the Federal ITC (Section 48) credit being sold to a third-party buyer at the assumed discount range. The operational risk should not be understated: roughly 2,040 feet of vertical bore must be drilled on a constrained urban site, and schedule delays during drilling can cascade through the entire construction program.
Code Path
This project is governed by the 2021 International Energy Conservation Code as adopted by Massachusetts, with the Worcester Specialized Opt-In overlay. The Specialized Opt-In imposes stricter requirements than both the base 2021 IECC and the Massachusetts Stretch Code, including a mandatory HERS ≤ 45 target for residential units, required heat pump water heaters for townhomes, and mandatory ENERGY STAR NextGen certification.
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: $1,097,500 - $1,157,000
MassSave Single-Family/Multifamily ENERGY STAR Certification ($1,080,000): You get this rebate for having each townhome ENERGY STAR NextGen certified. Certification typically occurs at the end of construction around when certificate of occupancy is received. This rebate comes in the form of a check within 4 months of the certification paperwork being provided to MassSave.
MassSave Single-Family/Multifamily Wifi Enabled Thermostat Adder ($5,000): You get this rebate for having each townhome install a WIFI enabled thermostat. 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.
MassSave Multifamily Heat Pump Water Heater Adder ($12,500): 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.
DOER Alternative Energy Credits ($0 - $59,500): This rebate is received for installing APS eligible air source heat pumps. There is an extensive process to get this incentive. It comes in the form of a check approximately 6-12 months after the heat pumps are installed and fully operational.
IMPORTANT: Although an estimate is provided, this incentive can vary widely typically between $300-1,500 per heat pump. It is based on expected kWh usage of the system as well as the market value of the alternative energy credits when sold.
| Item | Detailed Specifications |
|---|---|
| Exterior Walls | R-30 spray foam insulation in 2x6 @ 16" OC. No CI. |
| Slab | R-10 XPS perimeter insulation 4 ft deep ext only. No underslab. |
| Floor Over Garage | R-19 fiberglass batt insulation in floor joists over attached garage. |
| Rim Joists | Interior rim cavity sealed with 3.5" ccSPF (R-23). |
| Roof | R-49 blown cellulose in vented attic (13.5" depth). |
| Windows & Glass Doors | Double pane; U-0.25; SHGC 0.25 (Product Rec). |
| Doors | Opaque: R-4.75 insulated steel. |
| Air Sealing | ≤ ACH50 1.5; full air sealing protocol; additional sealing (MUST DO BOTH AIR SEALING METHODS TO HIT ACH50 TARGET). |
| HVAC | 4-zone ductless mini-split cold-climate heat pump; SEER2 20.0; HSPF2 9.5; EER2 12.5; ENERGY STAR CCHP; R-454B. Outdoor unit Product Rec. Ceiling cassette indoor heads Product Rec. |
| Ductwork | N/A (ductless system). |
| Duct Sealing | N/A (ductless system). |
| HVAC Grading | Fan Flow Test: N/A; Watt Draw Test: N/A; Refrigerant Charge: N/A (Track B credential path). |
| Mechanical Ventilation | ERV; 85 CFM; 90% SRE; 80% TRE. Product Rec. |
| Local Mechanical Exhaust | Bathroom(s): ≥ 50 CFM intermittent & ≤ 3.0 sones OR ≥ 20 CFM continuous & ≤ 2.0 sones. Kitchen(s): ≥ 100 CFM intermittent & ≤ 3.0 sones OR continuous, ≥ 5 ACH. Both: Exhaust directly outdoors, ENERGY STAR certified, utilize ERV. |
| Thermostats | Programmable thermostat. |
| DHW | 2BR (THB1): HPWH; UEF 3.5; 50 gal; 240V/30A; located in garage. Product Rec. 3BR (THC1): HPWH; UEF 3.5; 65 gal; 240V/30A; located in garage. Product Rec. |
| DHW Piping | Supply piping insulated to R-3 minimum; Max length: THB1 35.5 ft / THC1 39.2 ft. |
| Water Fixtures | WaterSense Certified Fixtures (Lavatory ≤ 1.2 GPM; Shower ≤ 2.0 GPM; Toilet ≤ 1.28 GPF; Kitchen ≤ 2.2 GPM). |
| Refrigerator | All: ≤ 550 kWh annual usage; ENERGY STAR; Electric. Product Rec. |
| Dishwasher | All: ≤ 240 kWh annual usage; ENERGY STAR; Electric. Product Rec. |
| Clothes Washer | All: ≤ 300 kWh annual usage; ≥ 1.5 IMEF; Standard top-load; Electric. Product Rec. |
| Clothes Dryer | All: Standard electric dryer; CEF 3.01; Vented; Non-ENERGY-STAR. Product Rec. |
| Stove / Oven | Standard electric range; No induction; No convection. Product Rec. |
| Lighting | 100% high-efficacy (LED). |
| Solar Ready | Solar-ready zone of not less than 150 sf per unit on the roof (for townhomes ≤ 2,000 sf per unit, ≤ 3 stories). Zone must be minimum 5 ft wide, minimum 80 sf per contiguous area. Plus conduit pathway from roof to panel and reserved breaker space. |
| EV Ready | One EV Ready space per townhome unit. Dedicated 240V branch circuit labeled EV READY in the panel, terminating in a NEMA receptacle (or SAE J1772/J3400 connector) located within 6 ft of the parking space. |
| HPWH Ready | N/A (HPWH already installed). |
| Paperwork & Modeling | HERS/ERI energy model, 2021 IECC checklists, ENERGY STAR NextGen checklists, incentive documentation. |
| Testing & Verification | Unit Blower Door Test, Mechanical Ventilation Testing, Room Balancing Tests, Pre-drywall & Final Inspection. |
Exterior Wall Assembly (Recommended Path)
Rim Joist (Recommended Path)
Roof (Recommended Path)
Garage Wall (Recommended Path)
Slab Edge (Recommended Path)
Floor Over Garage (Recommended Path)
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
DUCTLESS: $1,097,500 - $1,157,000
MassSave Single-Family/Multifamily ENERGY STAR Certification ($1,080,000): You get this rebate for having each townhome ENERGY STAR NextGen certified. Certification typically occurs at the end of construction around when certificate of occupancy is received. This rebate comes in the form of a check within 4 months of the certification paperwork being provided to MassSave.
MassSave Single-Family/Multifamily Wifi Enabled Thermostat Adder ($5,000): You get this rebate for having each townhome install a WIFI enabled thermostat. 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.
MassSave Multifamily Heat Pump Water Heater Adder ($12,500): 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.
DOER Alternative Energy Credits ($0 - $59,500): This rebate is received for installing APS eligible air source heat pumps. There is an extensive process to get this incentive. It comes in the form of a check approximately 6-12 months after the heat pumps are installed and fully operational.
IMPORTANT: Although an estimate is provided, this incentive can vary widely typically between $300-1,500 per heat pump. It is based on expected kWh usage of the system as well as the market value of the alternative energy credits when sold.
DUCTED: $1,097,500
MassSave Single-Family/Multifamily ENERGY STAR Certification ($1,080,000): You get this rebate for having each townhome ENERGY STAR NextGen certified. Certification typically occurs at the end of construction around when certificate of occupancy is received. This rebate comes in the form of a check within 4 months of the certification paperwork being provided to MassSave.
MassSave Single-Family/Multifamily Wifi Enabled Thermostat Adder ($5,000): You get this rebate for having each townhome install a WIFI enabled thermostat. 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.
MassSave Multifamily Heat Pump Water Heater Adder ($12,500): 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.
GEO: $3,758,630 - $3,962,630
MassSave Single-Family/Multifamily ENERGY STAR Certification ($1,080,000): You get this rebate for having each townhome ENERGY STAR NextGen certified. Certification typically occurs at the end of construction around when certificate of occupancy is received. This rebate comes in the form of a check within 4 months of the certification paperwork being provided to MassSave.
MassSave Single-Family/Multifamily Geothermal HVAC Adder ($1,130,000): You get this rebate for having each townhome install an energy star certified Geothermal HVAC system. This rebate varies depending on the path the unit is processed under. 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.
MassSave Single-Family/Multifamily Wifi Enabled Thermostat Adder ($5,000): You get this rebate for having each townhome install a WIFI enabled thermostat. 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.
MassSave Multifamily Heat Pump Water Heater Adder ($12,500): 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.
Federal ITC (Section 48) for Geothermal Heat Pumps ($1,530,000 - $1,734,000): You get this credit for installing GSHPs on the GEOTHERMAL path. The base credit is 30% of the full installed cost (drilling, ground loops, equipment, ductwork, labor, soft costs). This project only qualifies for the +10% domestic-content bonus, bringing the headline rate to 40%; the Energy Community bonus does not apply at this site. Most developers sell the credit to a third-party buyer for cash under Section 6418 transferability, with proceeds received 6-12 months after the system is placed in service.
IMPORTANT: The range varies with the cents-on-the-dollar transfer discount, realistically what we have seen based on our buyer partners and other clients who we have helped claim and sell these for is $0.75-$0.85. Net proceeds are further reduced by filing fees, domestic-content burden-of-proof paperwork, and a cost segregation study to appropriately assess the value of the tax credit.
Risks: 5-year recapture (declines 20%/yr) if the property ceases to qualify, plus the current administration's pattern of rapidly rolling back incentives of this nature mid-project.
Path Comparison - Net Cost Summary
| Path | Total Cost $/sf | Total Incentives $/sf | Net $/sf | OpEx Factor | Worst HERS | $ / HERS Point |
|---|---|---|---|---|---|---|
| DUCTLESS | $37.45 | $4.73 | $31.42 | 0.96 | 41.29 | $0.76 |
| DUCTED | $45.02 | $4.49 | $38.72 | 0.96 | 41.82 | $0.93 |
| GEO | $51.73 | $15.36 | $34.50 | 0.95 | 41.17 | $0.84 |
Path Comparison - Envelope
| Item | Path | Detailed Specifications | Cost $/sf | Incentive $/sf | Net $/sf | OpEx Factor |
|---|---|---|---|---|---|---|
| Exterior Walls | DUCTLESS | R-30 ccSPF (4.5" cavity fill) in 2x6 @ 16" OC. No CI. | $4.86 | $0.00 | $4.86 | 0.80 |
| DUCTED | R-38 ccSPF (5.5" full cavity) in 2x6 @ 16" OC. No CI. | $6.08 | $0.00 | $6.08 | 0.80 | |
| GEO | R-30 ccSPF (4.5" cavity fill) in 2x6 @ 16" OC. No CI. | $4.86 | $0.00 | $4.86 | 0.80 | |
| Slab | DUCTLESS | R-10 XPS perimeter insulation 4 ft deep ext only. No underslab. | $0.72 | $0.00 | $0.72 | 0.80 |
| DUCTED | Same as DUCTLESS. | $0.72 | $0.00 | $0.72 | 0.80 | |
| GEO | Same as DUCTLESS. | $0.72 | $0.00 | $0.72 | 0.80 | |
| Floor Over Garage | DUCTLESS | R-19 fiberglass batt insulation in floor joists over attached garage. | $0.30 | $0.00 | $0.30 | 0.85 |
| DUCTED | Same as DUCTLESS. | $0.30 | $0.00 | $0.30 | 0.85 | |
| GEO | Same as DUCTLESS. | $0.30 | $0.00 | $0.30 | 0.85 | |
| Rim Joists | DUCTLESS | Interior rim cavity sealed with 3.5" ccSPF (R-23). | $0.34 | $0.00 | $0.34 | 0.80 |
| DUCTED | Same as DUCTLESS. | $0.34 | $0.00 | $0.34 | 0.80 | |
| GEO | Same as DUCTLESS. | $0.34 | $0.00 | $0.34 | 0.80 | |
| Roof | DUCTLESS | R-49 blown cellulose in vented attic. | $0.97 | $0.00 | $0.97 | 0.90 |
| DUCTED | R-60 blown cellulose in vented attic. | $1.12 | $0.00 | $1.12 | 0.90 | |
| GEO | R-49 blown cellulose in vented attic. | $0.97 | $0.00 | $0.97 | 0.90 | |
| Windows & Glass Doors | DUCTLESS | Glass: U-0.25 / SHGC 0.25. | $5.56 | $0.00 | $5.56 | 0.90 |
| DUCTED | Same as DUCTLESS. | $5.56 | $0.00 | $5.56 | 0.90 | |
| GEO | Same as DUCTLESS. | $5.56 | $0.00 | $5.56 | 0.90 | |
| Doors | DUCTLESS | Opaque: R-4.75 insulated steel. | $1.04 | $0.00 | $1.04 | 0.85 |
| DUCTED | Same as DUCTLESS. | $1.04 | $0.00 | $1.04 | 0.85 | |
| GEO | Same as DUCTLESS. | $1.04 | $0.00 | $1.04 | 0.85 | |
| Air Sealing | DUCTLESS | Units: ≤ ACH50 1.5; full air sealing protocol; additional sealing (MUST DO BOTH AIR SEALING METHODS TO HIT ACH50 TARGET). | $1.75 | $0.00 | $1.75 | 0.85 |
| DUCTED | Same as DUCTLESS. | $1.75 | $0.00 | $1.75 | 0.85 | |
| GEO | Same as DUCTLESS. | $1.75 | $0.00 | $1.75 | 0.85 |
Path Comparison - Mechanical
| Item | Path | Detailed Specifications | Cost $/sf | Incentive $/sf | Net $/sf | OpEx Factor |
|---|---|---|---|---|---|---|
| HVAC | DUCTLESS | 4-zone ductless mini-split cold-climate heat pump; SEER2 20.0; HSPF2 9.5; EER2 12.5; ENERGY STAR CCHP; R-454B. Product Rec. | $10.98 | $0.24 | $10.73 | 1.10 |
| DUCTED | Ducted split cold-climate heat pump; SEER2 17.20; HSPF2 10.80; EER2 12.10; ENERGY STAR CCHP; R-454B. 2.5-ton (30k BTU cooling / 33k BTU heating at 47°F). Variable-speed compressor. AHRI Certified Reference Number 215318762. | $12.48 | $0.00 | $12.48 | 1.05 | |
| GEO | Ground-source water-to-air heat pump; AHRI / ISO 13256-1 GLHP rating. 2BR (THB1): single-stage, 0.75 ton, COP 3.6 / EER 17.4 (Product Rec). 3BR (THC1): two-stage, 2 ton, COP 4.0 / EER 18.6 (Product Rec). Vertical bore closed-loop ground heat exchanger included. | $20.84 | $10.87 | $9.97 | 0.85 | |
| Ductwork | DUCTLESS | N/A (ductless system). | $0.00 | $0.00 | $0.00 | 1.00 |
| DUCTED | Supply and return ductwork in conditioned space. | $4.50 | $0.00 | $4.50 | 0.90 | |
| GEO | Same as DUCTED. | $4.50 | $0.00 | $4.50 | 0.90 | |
| Duct Sealing | DUCTLESS | N/A (ductless system). | $0.00 | $0.00 | $0.00 | 1.00 |
| DUCTED | Greater of 8 CFM25 per 100 sqft CFA or 80 CFM25 to outside (duct sealing protocol). | $0.20 | $0.00 | $0.20 | 1.00 | |
| GEO | Same as DUCTED. | $0.20 | $0.00 | $0.20 | 1.00 | |
| HVAC Grading | DUCTLESS | Fan Flow Test: N/A; Watt Draw Test: N/A; Refrigerant Charge: N/A (Track B credential path). | $0.00 | $0.00 | $0.00 | 1.00 |
| DUCTED | Same as DUCTLESS. | $0.00 | $0.00 | $0.00 | 1.00 | |
| GEO | Same as DUCTLESS. | $0.00 | $0.00 | $0.00 | 1.00 | |
| Mechanical Ventilation | DUCTLESS | ERV; 85 CFM; 90% SRE; 80% TRE. Product Rec. | $1.53 | $0.00 | $1.53 | 1.05 |
| DUCTED | Same as DUCTLESS. | $1.53 | $0.00 | $1.53 | 1.05 | |
| GEO | ERV; 85 CFM; 70% SRE; 60% TRE (Product Rec). | $1.25 | $0.00 | $1.25 | 1.05 | |
| Local Mechanical Exhaust | DUCTLESS | Bathroom(s): ≥ 50 CFM intermittent & ≤ 3.0 sones OR ≥ 20 CFM continuous & ≤ 2.0 sones. Kitchen(s): ≥ 100 CFM intermittent & ≤ 3.0 sones OR continuous, ≥ 5 ACH. Both: Exhaust directly outdoors, ENERGY STAR certified, utilize ERV. | $0.50 | $0.00 | $0.50 | 1.00 |
| DUCTED | Same as DUCTLESS. | $0.50 | $0.00 | $0.50 | 1.00 | |
| GEO | Same as DUCTLESS. | $0.50 | $0.00 | $0.50 | 1.00 | |
| Thermostats | DUCTLESS | Programmable thermostat. | $0.14 | $0.02 | $0.12 | 1.00 |
| DUCTED | Same as DUCTLESS. | $0.14 | $0.02 | $0.12 | 1.00 | |
| GEO | Same as DUCTLESS. | $0.14 | $0.02 | $0.12 | 1.00 |
Path Comparison - Plumbing & Appliances
| Item | Path | Detailed Specifications | Cost $/sf | Incentive $/sf | Net $/sf | OpEx Factor |
|---|---|---|---|---|---|---|
| DHW | DUCTLESS | 2BR (THB1): HPWH; UEF 3.5; 50 gal; 240V/30A; located in garage. Product Rec. 3BR (THC1): HPWH; UEF 3.5; 65 gal; 240V/30A; located in garage. Product Rec. | $1.69 | $0.05 | $1.64 | 1.20 |
| DUCTED | Same as DUCTLESS. | $1.69 | $0.05 | $1.64 | 1.20 | |
| GEO | Same as DUCTLESS. | $1.69 | $0.05 | $1.64 | 1.20 | |
| DHW Piping | DUCTLESS | Supply piping insulated to R-3 minimum. Max length: THB1 35.5 ft / THC1 39.2 ft. | $0.80 | $0.00 | $0.80 | 1.00 |
| DUCTED | Same as DUCTLESS. | $0.80 | $0.00 | $0.80 | 1.00 | |
| GEO | Same as DUCTLESS. | $0.80 | $0.00 | $0.80 | 1.00 | |
| Water Fixtures | DUCTLESS | WaterSense Certified Fixtures (Lavatory ≤ 1.2 GPM; Shower ≤ 2.0 GPM; Kitchen ≤ 2.2 GPM). | $0.60 | $0.00 | $0.60 | 1.00 |
| DUCTED | Same as DUCTLESS. | $0.60 | $0.00 | $0.60 | 1.00 | |
| GEO | Same as DUCTLESS. | $0.60 | $0.00 | $0.60 | 1.00 | |
| Refrigerator | DUCTLESS | All: ≤ 550 kWh annual usage; ENERGY STAR; Electric. Product Rec. | $0.59 | $0.00 | $0.59 | 1.00 |
| DUCTED | Same as DUCTLESS. | $0.59 | $0.00 | $0.59 | 1.00 | |
| GEO | Same as DUCTLESS. | $0.59 | $0.00 | $0.59 | 1.00 | |
| Dishwasher | DUCTLESS | All: ≤ 240 kWh annual usage; ENERGY STAR; Electric. Product Rec. | $0.39 | $0.00 | $0.39 | 1.00 |
| DUCTED | Same as DUCTLESS. | $0.39 | $0.00 | $0.39 | 1.00 | |
| GEO | Same as DUCTLESS. | $0.39 | $0.00 | $0.39 | 1.00 | |
| Clothes Washer | DUCTLESS | All: ≤ 300 kWh annual usage; ≥ 1.5 IMEF; Standard top-load; Electric. Product Rec. | $0.59 | $0.00 | $0.59 | 1.00 |
| DUCTED | Same as DUCTLESS. | $0.59 | $0.00 | $0.59 | 1.00 | |
| GEO | Same as DUCTLESS. | $0.59 | $0.00 | $0.59 | 1.00 | |
| Clothes Dryer | DUCTLESS | All: Standard electric dryer; CEF 3.01; Vented; Non-ENERGY-STAR. Product Rec. | $0.55 | $0.00 | $0.55 | 0.90 |
| DUCTED | Same as DUCTLESS. | $0.55 | $0.00 | $0.55 | 0.90 | |
| GEO | Same as DUCTLESS. | $0.55 | $0.00 | $0.55 | 0.90 | |
| Stove / Oven | DUCTLESS | Standard electric range; No induction; No convection. Product Rec. | $0.45 | $0.00 | $0.45 | 1.00 |
| DUCTED | Same as DUCTLESS. | $0.45 | $0.00 | $0.45 | 1.00 | |
| GEO | Same as DUCTLESS. | $0.45 | $0.00 | $0.45 | 1.00 |
Path Comparison - Electrical
| Item | Path | Detailed Specifications | Cost $/sf | Incentive $/sf | Net $/sf | OpEx Factor |
|---|---|---|---|---|---|---|
| Lighting | DUCTLESS | 100% high-efficacy (LED). | $2.00 | $0.00 | $2.00 | 0.85 |
| DUCTED | Same as DUCTLESS. | $2.00 | $0.00 | $2.00 | 0.85 | |
| GEO | Same as DUCTLESS. | $2.00 | $0.00 | $2.00 | 0.85 | |
| Solar Ready | DUCTLESS | Solar-ready zone of not less than 150 sf per unit on the roof (for townhomes ≤ 2,000 sf per unit, ≤ 3 stories). Zone must be minimum 5 ft wide, minimum 80 sf per contiguous area. Plus conduit pathway from roof to panel and reserved breaker space. | $0.25 | $0.00 | $0.25 | 1.00 |
| DUCTED | Same as DUCTLESS. | $0.25 | $0.00 | $0.25 | 1.00 | |
| GEO | Same as DUCTLESS. | $0.25 | $0.00 | $0.25 | 1.00 | |
| EV Ready | DUCTLESS | One EV Ready space per townhome unit. Dedicated 240V branch circuit labeled EV READY in the panel, terminating in a NEMA receptacle (or SAE J1772/J3400 connector) located within 6 ft of the parking space. | $0.35 | $0.00 | $0.35 | 1.00 |
| DUCTED | Same as DUCTLESS. | $0.35 | $0.00 | $0.35 | 1.00 | |
| GEO | Same as DUCTLESS. | $0.35 | $0.00 | $0.35 | 1.00 | |
| HPWH Ready | DUCTLESS | N/A (HPWH already installed). | $0.00 | $0.00 | $0.00 | 1.00 |
| DUCTED | Same as DUCTLESS. | $0.00 | $0.00 | $0.00 | 1.00 | |
| GEO | Same as DUCTLESS. | $0.00 | $0.00 | $0.00 | 1.00 |
Path Comparison - Soft Costs
| Item | Path | Detailed Specifications | Cost $/sf | Incentive $/sf | Net $/sf | OpEx Factor |
|---|---|---|---|---|---|---|
| Paperwork & Modeling | DUCTLESS | HERS/ERI energy model, 2021 IECC checklists, ENERGY STAR NextGen checklists, incentive documentation. | $0.50 | $4.41 | -$3.91 | 1.00 |
| DUCTED | Same as DUCTLESS. | $0.50 | $4.41 | -$3.91 | 1.00 | |
| GEO | HERS/ERI energy model, 2021 IECC checklists, ENERGY STAR NextGen checklists, incentive documentation, tax credit filing, arranging tax credit buyer. | $0.50 | $4.41 | -$3.91 | 1.00 | |
| Testing & Verification | DUCTLESS | Unit Blower Door Test, Mechanical Ventilation Testing, Pre-drywall & Final Inspection. | $0.00 | $0.00 | $0.00 | 1.00 |
| DUCTED | Unit Blower Door Test, Duct Leakage Total Test, Mechanical Ventilation Testing, Room Balancing, Pre-drywall & Final Inspection. | $0.00 | $0.00 | $0.00 | 1.00 | |
| GEO | Same as DUCTED. | $0.00 | $0.00 | $0.00 | 1.00 |
Additional Design Considerations Not Represented In This Study
R-70 Roof Insulation: R-70 blown cellulose was tested as an upgrade over the standard R-60. The additional 4 inches of cellulose depth provided only a 0.35 HERS point improvement. Given the diminishing returns and minimal energy benefit, R-60 was retained across all three paths.
R-80 Roof Insulation: R-80 blown cellulose was tested as a further upgrade beyond R-70. It provided only 0.30 additional HERS points over R-70, which itself was only marginally better than R-60. Deep diminishing returns made this a non-starter.
R-6 Entry Door: Upgrading from the standard R-4.75 insulated steel door to R-6 was tested and provided only a 0.21 HERS point improvement. The per-unit cost premium across 170 units was not justified by the negligible energy benefit.
R-10 Entry Door: A high-performance R-10 door was also tested, providing 0.55 HERS points over R-4.75. While more impactful than R-6, the margin provided by the Mitsubishi SM36 heat pump made this upgrade unnecessary.
Induction Range: Induction cooktops with convection ovens were tested multiple times across various path configurations. The HERS improvement was consistently around 0.15 points, negligible for the approximately $1,150 per-unit premium over a standard electric range. Standard electric was retained across all three paths.
Heat Pump Dryer (Beko HPD24414W, CEF 11): A standalone compact heat pump dryer was tested and provided approximately 1-2 HERS points. However, the $900+ per-unit premium over a standard electric dryer, combined with it being a 24-inch compact unit that may not suit a luxury BTR market, made it difficult to justify as a standalone upgrade. The heat pump dryer concept survives only within the LG WashTower combo unit on the COMBO path, where it comes bundled with the high-efficiency washer.
High-Efficiency Standalone Washer (Electrolux ELFW7637AT, 85 kWh, IMEF 2.92): This premium front-load washer was tested as a standalone upgrade over standard ENERGY STAR washers. The HERS improvement was approximately 0.2 points, not enough to justify the cost premium. Like the HP dryer, this spec only survives bundled within the LG WashTower on the COMBO path.
450 kWh Refrigerator: A tighter 450 kWh refrigerator specification was tested against the standard 500 kWh ENERGY STAR threshold. The difference was only 0.19 HERS points. The 500 kWh threshold offers a wider product selection, lower cost, and more flexibility for the developer, so it was adopted for the DOUBLE path while 450 kWh was retained on the ducted paths where margin is tighter.
80 Gallon HPWH on All Units: The Rheem ProTerra 80 gallon (UEF 4.07) was initially specified across all unit types. Testing revealed that right-sizing to 50 gallon for 2BR units and 65 gallon for 3BR units actually scored the same or slightly better in the energy model due to reduced standby heat losses from a smaller tank. The smaller units are also less expensive, making oversizing a pure cost penalty with no energy benefit.
Electric Tank Water Heater (UEF 0.93-0.95): Standard electric resistance tank water heaters were considered as the lowest-cost DHW option. However, Worcester's specialized opt-in code requires heat pump water heaters for townhomes, making this option non-compliant regardless of its energy performance. Additionally, the HPWH provides a 3-5 HERS point advantage that is critical for compliance on every path.
Bosch IDS 2.0 Ducted Heat Pump (Advertised SEER2 20 / HSPF2 11): The Bosch IDS 2.0 Premium was initially selected as the ducted HVAC system based on published specifications suggesting SEER2 20 and HSPF2 11. Upon AHRI verification, the HSPF2 of 11 was determined to be the old HSPF metric, not HSPF2. The actual HSPF2 is approximately 9.5. Additionally, the Bosch IDS Premium is not ENERGY STAR Cold Climate certified. It was replaced by the Mitsubishi H2i ducted system (SEER2 18.6 / HSPF2 8.6), which carries full CCHP certification.
Mitsubishi FX Single-Zone Ductless (SEER2 23.5 / HSPF2 10.5): The FX single-zone wall-mount was tested early and produced excellent HERS scores. However, it provides only one zone of conditioning per outdoor unit, which cannot adequately serve a 3-4 room townhome layout. It was replaced by the MXZ-SM36NLHZ Smart Multi 4-zone system, which achieves comparable efficiency (SEER2 23 / HSPF2 12) while providing proper room-by-room zoning with ceiling cassettes.
Mitsubishi MXZ-3D24NLHZ 3-Zone (SEER2 20 / HSPF2 10): This 3-zone 24k BTU outdoor unit was evaluated with an AHRI certificate confirming SEER2 20 and HSPF2 10. It failed at HERS 45.6 with U-0.25 double pane windows, 0.6 points over the code target. Additionally, 3 zones are insufficient for the 3BR end units, which have 4 rooms requiring conditioning. The SM36 4-zone system resolved both issues with higher efficiency and an additional zone.
Double Pane Windows on Ducted Paths: Double pane windows ranging from U-0.22 to U-0.30 were tested extensively with the ducted Mitsubishi H2i system (HSPF2 8.6). Every combination failed the HERS 45 target. The lower heating efficiency of ducted systems simply cannot compensate for the thermal losses through double pane glazing in Climate Zone 5A. Triple pane is required on all ducted paths.
Continuous Insulation on Spray Foam Paths: R-3 through R-12 continuous insulation was tested on walls that already had R-38 closed-cell spray foam in the cavity. In every case, the CI was unnecessary. The R-38 ccSPF cavity fill provides sufficient thermal performance and air sealing to pass without any exterior continuous insulation. Adding CI on top of a fully spray-foamed cavity is a redundant cost with minimal energy benefit.
Loosened Air Sealing (2.0 and 3.0 ACH50): Relaxing the blower door target from 1.5 to 2.0 ACH50 cost approximately 1.0 HERS point, and relaxing to 3.0 ACH50 cost approximately 3.0 HERS points and failed the code target outright. Beyond the energy impact, the 1.5 ACH50 target qualifies for the MassSave Energy Star tier incentive, making it financially counterproductive to loosen the air sealing target.
