CS39 Energy Code Feasibility Study in Westborough, Massachusetts
Energy code feasibility study for a 206-unit 6-Story Multifamily Building | 6 residential stories with ground level parking. in Massachusetts. Compares multiple design paths. Recommended: lowest-cost compliant path. View full study.
- Study Type
- Energy Code Feasibility Study
- State
- Massachusetts
- Units
- 206
- Building Type
- 6-Story Multifamily Building | 6 residential stories with ground level parking.
- Fuel Type
- All-Electric
Goal
To find the most cost-effective compliance path, this report isolates energy code related costs from total construction. We use real MA bid data from vendors & clients to create a reliable framework for aligning incentives and design, with all recommendations confirmed by detailed energy modeling.
Project
- Westborough, MA 01581
- 206 Units | 226,572 sqft
- 6-Story Multifamily Building | 6 residential stories with ground level parking.
- New Construction | Stretch Code | HERS ≤ 45 or HERS Mixed Fuel ≤ 42 | All Electric or Mixed-Fuel
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.
Gas (Recommended) : This path delivers the strongest balance of performance, cost, and incentive eligibility. Individual HVAC and ERV systems provide unit-level control, while a centralized gas domestic hot water system captures the efficiency and cost advantages of shared infrastructure. Because gas usage is limited exclusively to water heating, the project retains full eligibility for MassSave incentives, preserving the rebate structure that materially offsets first costs. Installation costs remain the lowest of the three paths, HERS scores are easily achievable without envelope upgrades beyond the base specification, and operational efficiency is high. This is the recommended path.
Electric : This path replaces the centralized gas water heating system with electric resistance domestic hot water heaters, eliminating all fossil fuel from the building. However, the shift to electric resistance significantly penalizes the HERS rating, which in turn requires compensating envelope upgrades, specifically, a transition from double-pane to triple-pane windows and a tighter air infiltration target. These upgrades add substantial cost to both materials and labor, eroding the financial advantage that the gas path provides. While this path achieves a fully electric building, it should be considered a contingency option if gas service presents permitting, infrastructure, or utility challenges rather than the default recommendation.
Central : This path consolidates all mechanical systems. HVAC, energy recovery ventilation, and domestic hot water, into centralized plant equipment. While central systems can offer operational efficiency at scale, the design complexity, equipment cost, and installation labor associated with a centralized VRF and ERV distribution network are significantly higher than the individualized approach. Even after accounting for available incentives, the net installed cost does not justify the marginal performance gains. This path should only be explored if a detailed operational cost analysis demonstrates savings large enough to offset the premium over the project's hold period.
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
Gas: $381,100
- MassSave Multifamily High Rise Program Energy Star Tier ($360,500): 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 High Rise Program Thermostat Adder ($20,600): You get this rebate for installing WIFI enabled programmable thermostats in each unit. This requires pre-approval via an application to be submitted before construction starts. This rebate comes 4 months after construction is complete.
Recommended Design - Units
Item | Detailed Specifications |
|---|---|
Exterior Walls | R-9 - 2" Zip system & R-21 batt insulation in cavity (Product Ref). OR R-6 - Insultex Insulated Housewrap & R-28 spray foam insulation in cavity (Product Ref). |
Slab | R-15 - 4' deep exterior perimeter insulation. |
Podium | R-30 batt insulation resting on drop ceiling. |
Rim Joists | Seal interior rim cavity with minimum 3" closed-cell spray foam for air sealing and thermal performance. Continuous Insulation shall continue over floor transitions without interruption. |
Roof | R-60 cavity insulation OR R-45 continuous insulation at roof deck. |
Windows | Weighted Avg: U-0.25 / SHGC 0.30 |
Doors | Glazed: U-0.25 / SHGC 0.30; Opaque: U-0.21 (R-4.75); |
Air Sealing | Units: ≤ 0.30 CFM50/ft² gross enclosure area; Units: Use this protocol (click here). Emergencies: If the two protocols above are not met, this can be used in case of emergencies, must be implemented immediately after drywall install (click here). |
HVAC | 1 Bed: Ducted split heat pump; SEER2 17.5; HSPF2 9; (Interior Unit) (Exterior Unit) 2 Bed: Ducted split heat pump; SEER2 17; HSPF2 9; (Interior Unit) (Exterior Unit) |
Duct Sealing | The greater of 8 CFM/100 ft² conditioned floor area or 80 CFM (Duct Sealing Protocol) |
HVAC Grading | Fan Flow Test: N/A Watt Draw Test: N/A Refrigerant Charge: N/A |
Mechanical Ventilation | S & 1 Bed (Any): 50 CFM; 90% rated recovery; Any Climate; (Product Ref) 2 & 3 Bed: 70 CFM; 86% rated recovery; Any Climate; (Product Ref) |
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 Based on kitchen volume & ≤ 1.0 sone. Both: Exhaust directly outdoors, ENERGY STAR certified, utilize ERV to meet these requirements. |
Thermostats | Programmable Thermostat (Product Ref) |
DHW | Teal Systems / Raypak XTHERM 2005A Three boilers at 1,999 MBH each (5,997 MBH total), 96% thermal efficiency. Duplex Taco 1919 recirc pumps at 1.5 HP each (Pricing) (Product Ref). |
DHW Piping | Supply piping insulated to R-3 minimum; Max 1.8 gallons stored volume per run; Modeled pipe runs are optimized to 1/2 program default lengths; (See unit breakdowns for run lengths). |
Water Fixtures | Watersense Certified Fixtures (Lavatory: ≤1.2 GPM, Shower: ≤2.0 GPM) |
Refrigerator | All: ≤ 550 kWh annual usage; ENERGY STAR; Electric; (Product Ref) |
Dishwasher | All: ≤ 240 kWh annual usage; ENERGY STAR; Electric; (Low Cost Product Ref) (Luxury Product Ref) |
Clothes Washer | All: ≤ 136 kWh annual usage; ≥ 2.76 IMEF; ≥ 4.8 cubic ft capacity; ENERGY STAR; Electric; (Product Ref) |
Clothes Dryer | All: ≥ 6 CEF; Ventless; Heat Pump Dryer; ENERGY STAR; Electric; (Product Ref) |
Stove / Oven | Any Electric Stove; (Product Ref) |
Lighting | 100% high-efficacy (LED) |
Solar Ready | Designated Solar Zone: Reserve a contiguous area equal to at least 40% of the total horizontal roof area (after excluding skylights, occupied decks, vegetated areas, and fire setbacks). Contiguity & Obstructions: The zone must be free of all obstructions (pipes, vents, HVAC units) and maintain a minimum width of 5 feet. Structural Capacity: Roof structures within this zone must be engineered to support a future collateral dead load of 5 PSF. Orientation (Sloped Roofs): For roofs with a pitch of 4:12 or greater, the zone must be oriented between 110° and 270° of true north. Electrical Infrastructure: Provide identified conduit pathways from the roof to the electrical service and reserve a labeled space for a dual-pole circuit breaker in the main panel or common space service. |
EV Ready | Requirement: 20% of parking spaces; 40-amp dedicated branch circuit (or larger with ALMS); wiring suitable for ≥6.6 kW Level II EVSE, run to within 6 feet of each qualifying space. |
HPWH Ready | N/A |
Paperwork & Modeling | HERS / ERI Energy model, 2021 IECC checklists, ENERGY STAR MFNC checklists, and incentive documentation. |
Testing & Verification | Unit Blower Door Test, Duct Test, Mechanical Ventilation Testing, Room Balancing, Slab, Predrywall & Final Inspection. |
Recommended Design - Common Areas
Item | Detailed Specifications |
|---|---|
Exterior Walls | R-9 - 2" Zip system & R-21 batt insulation in cavity (Product Ref). OR R-6 - Insultex Insulated Housewrap & R-28 spray foam insulation in cavity (Product Ref). |
Slab | R-15 - 4' deep exterior perimeter insulation. |
Podium | R-30 batt insulation resting on drop ceiling. |
Rim Joists | Seal interior rim cavity with minimum 3" closed-cell spray foam for air sealing and thermal performance. Continuous Insulation shall continue over floor transitions without interruption. |
Roof | R-60 cavity insulation OR R-45 continuous insulation at roof deck. |
Windows | Fixed: U-0.32 / SHGC 0.40 Operable: U-0.40 / SHGC 0.40 |
Doors | Glazed Entrance / Exit Doors: U-0.60 / SHGC 0.40; Opaque: U-0.17; |
Air Sealing | Units: ≤ 0.30 CFM50/ft² gross enclosure area; Units: Use this protocol (click here). Emergencies: If the two procols above are not met, this can be used in case of emergencies, must be implemented immediately after drywall install (click here). |
HVAC | ENERGY STAR min: SEER2 16 / HSPF2 8.2. |
Duct Sealing | The greater of 8 CFM/100 ft² conditioned floor area or 80 CFM (Duct Sealing Protocol) |
HVAC Grading | Fan Flow Test: N/A Watt Draw Test: N/A Refrigerant Charge: N/A |
Mechanical Ventilation | Measured supply and outdoor air rates must meet ASHRAE 62.1-2019 minimums. |
Local Mechanical Exhaust | Measured exhaust rates must meet ASHRAE 62.1-2019 minimums. |
Thermostats | Programmable Thermostat (Product Ref) |
DHW | Teal Systems / Raypak XTHERM 2005A Three boilers at 1,999 MBH each (5,997 MBH total), 96% thermal efficiency. Duplex Taco 1919 recirc pumps at 1.5 HP each (Pricing) (Product Ref). |
DHW Piping | MA code and Energy Star DHW piping standards. |
Water Fixtures | Watersense Certified Fixtures (Lavatory: ≤1.2 GPM, Shower: ≤2.0 GPM) |
Appliances | Energy Star Certified / All-Electric. |
Lighting | 100% high-efficacy (LED) occupancy/vacancy sensors or auto controls in all common spaces (except lobby). |
Solar Ready | Designated Solar Zone: Reserve a contiguous area equal to at least 40% of the total horizontal roof area (after excluding skylights, occupied decks, vegetated areas, and fire setbacks). Contiguity & Obstructions: The zone must be free of all obstructions (pipes, vents, HVAC units) and maintain a minimum width of 5 feet. Structural Capacity: Roof structures within this zone must be engineered to support a future collateral dead load of 5 PSF. Orientation (Sloped Roofs): For roofs with a pitch of 4:12 or greater, the zone must be oriented between 110° and 270° of true north. Electrical Infrastructure: Provide identified conduit pathways from the roof to the electrical service and reserve a labeled space for a dual-pole circuit breaker in the main panel or common space service. |
EV Ready | Requirement: 20% of parking spaces; 40-amp dedicated branch circuit (or larger with ALMS); wiring suitable for ≥6.6 kW Level II EVSE, run to within 6 feet of each qualifying space. |
HPWH Ready | N/A |
Recommended Design - Additional Considerations
- For steel stud framing: The exterior walls require ZIP System R-Sheathing (2.5", R-12.6) with R-38 closed-cell spray foam in the stud cavity, and the roof deck requires R-45 continuous insulation.
Exterior Wall Assembly (Option 1)
Exterior Wall Assembly (Option 2)
Roof Assembly (Option 1)
Roof Assembly (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
Gas: $381,100
- MassSave Multifamily High Rise Program Energy Star Tier ($360,500): 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 High Rise Program Thermostat Adder ($20,600): You get this rebate for installing WIFI enabled programmable thermostats in each unit. This requires pre-approval via an application to be submitted before construction starts. This rebate comes 4 months after construction is complete.
Electric: $381,100
- MassSave Multifamily High Rise Program Energy Star Tier ($360,500): 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 High Rise Program Thermostat Adder ($20,600): You get this rebate for installing WIFI enabled programmable thermostats in each unit. This requires pre-approval via an application to be submitted before construction starts. This rebate comes 4 months after construction is complete.
Central: $453,200 - $690,100
- MassSave Multifamily High Rise Program Energy Star Tier ($360,500): 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 High Rise Program Thermostat Adder ($20,600): You get this rebate for installing WIFI enabled programmable thermostats in each unit. This requires pre-approval via an application to be submitted before construction starts. This rebate comes 4 months after construction is complete.
- DOER Alternative Energy Credits ($72,100 - $309,000): 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’s based on expected kWh usage of the system as well as the market value of the alternative energy credits when sold.
Path Comparison - Net Cost Summary
Path | Total Cost $/sf | Total Incentives $/sf | Net $/sf |
|---|---|---|---|
Gas | $29.54 | $1.90 | $27.64 |
Electric | $32.31 | $1.90 | $30.41 |
Central | $41.84 | $2.28 | $39.56 |
Path Comparison - Envelope
Item | Path | Detailed Specifications | Cost $/sf | Incentive $/sf | Net $/sf |
|---|---|---|---|---|---|
Exterior Walls | Gas | R-9 - 2" Zip system & R-21 batt insulation in cavity (Product Ref). OR R-6 - Insultex Insulated Housewrap & R-28 spray foam insulation in cavity (Product Ref). | $3.75 | $0.00 | $3.75 |
Electric | R-9 - 2" Zip system & R-21 batt insulation in cavity (Product Ref). OR R-6 - Insultex Insulated Housewrap & R-28 spray foam insulation in cavity (Product Ref). | $3.75 | $0.00 | $3.75 | |
Central | R-9 - 2" Zip system & R-21 batt insulation in cavity (Product Ref). OR R-6 - Insultex Insulated Housewrap & R-28 spray foam insulation in cavity (Product Ref). | $3.75 | $0.00 | $3.75 | |
Slab | Gas | R-15 - 4' deep exterior perimeter insulation. | $1.39 | $0.00 | $1.39 |
Electric | R-15 - 4' deep exterior perimeter insulation. | $1.39 | $0.00 | $1.39 | |
Central | R-15 - 4' deep exterior perimeter insulation. | $1.39 | $0.00 | $1.39 | |
Podium | Gas | R-30 batt insulation resting on drop ceiling. | $2.00 | $0.00 | $2.00 |
Electric | R-30 batt insulation resting on drop ceiling. | $2.00 | $0.00 | $2.00 | |
Central | R-30 batt insulation resting on drop ceiling. | $2.00 | $0.00 | $2.00 | |
Rim Joists | Gas | Seal interior rim cavity with minimum 3" closed-cell spray foam for air sealing and thermal performance. Continuous Insulation shall continue over floor transitions without interruption. | $0.25 | $0.00 | $0.25 |
Electric | Seal interior rim cavity with minimum 3" closed-cell spray foam for air sealing and thermal performance. Continuous Insulation shall continue over floor transitions without interruption. | $0.25 | $0.00 | $0.25 | |
Central | Seal interior rim cavity with minimum 3" closed-cell spray foam for air sealing and thermal performance. Continuous Insulation shall continue over floor transitions without interruption. | $0.25 | $0.00 | $0.25 | |
Roof | Gas | R-60 cavity insulation OR R-45 continuous insulation at roof deck. | $2.40 | $0.00 | $2.40 |
Electric | R-60 cavity insulation OR R-45 continuous insulation at roof deck. | $2.40 | $0.00 | $2.40 | |
Central | R-60 cavity insulation OR R-45 continuous insulation at roof deck. | $2.40 | $0.00 | $2.40 | |
Windows | Gas | Weighted Avg: U-0.25 / SHGC 0.30 | $1.50 | $0.00 | $1.50 |
Electric | Weighted Avg: U-0.15 / SHGC 0.20 | $4.00 | $0.00 | $4.00 | |
Central | Weighted Avg: U-0.25 / SHGC 0.30 | $1.50 | $0.00 | $1.50 | |
Doors | Gas | Glazed: U-0.25 / SHGC 0.30; Opaque: U-0.21 (R-4.75); | $0.50 | $0.00 | $0.50 |
Electric | Glazed: U-0.15 / SHGC 0.20; Opaque: U-0.21 (R-4.75); | $0.75 | $0.00 | $0.75 | |
Central | Glazed: U-0.25 / SHGC 0.30; Opaque: U-0.21 (R-4.75); | $0.50 | $0.00 | $0.50 | |
Air Sealing | Gas | Units: ≤ 0.30 CFM50/ft² gross enclosure area; Units: Use this protocol (click here). Emergencies: If the two protocols above are not met, this can be used in case of emergencies, must be implemented immediately after drywall install (click here). | $0.50 | $0.00 | $0.50 |
Electric | Units: ≤ 0.25 CFM50/ft² gross enclosure area; Units: Use this protocol (click here). Emergencies: If the two protocols above are not met, this can be used in case of emergencies, must be implemented immediately after drywall install (click here). | $0.65 | $0.00 | $0.65 | |
Central | Units: ≤ 0.30 CFM50/ft² gross enclosure area; Units: Use this protocol (click here). Emergencies: If the two protocols above are not met, this can be used in case of emergencies, must be implemented immediately after drywall install (click here). | $0.50 | $0.00 | $0.50 |
Path Comparison - Mechanical
Item | Path | Detailed Specifications | Cost $/sf | Incentive $/sf | Net $/sf |
|---|---|---|---|---|---|
HVAC | Gas | 1 Bed: Ducted split heat pump; SEER2 17.5; HSPF2 9; (Interior Unit) (Exterior Unit) 2 Bed: Ducted split heat pump; SEER2 17; HSPF2 9; (Interior Unit) (Exterior Unit) | $6.50 | $0.00 | $6.50 |
Electric | 1 Bed: Ducted split heat pump; SEER2 17.5; HSPF2 9; (Interior Unit) (Exterior Unit) 2 Bed: Ducted split heat pump; SEER2 17; HSPF2 9; (Interior Unit) (Exterior Unit) | $6.00 | $0.00 | $6.00 | |
Central | Daikin VRV IV Heat Pump 350 tons total using 10-12 outdoor systems, each up to 34 tons, with 206 FXMQ ducted indoor units. IEER up to 27.3 cooling, COP 4.20 heating. (SEER2 20, HSPF2 10, EER2 12.5) (VRF SYSTEM) (Indoor Units). | $20.00 | $0.38 | $19.62 | |
Duct Sealing | Gas | The greater of 8 CFM/100 ft² conditioned floor area or 80 CFM (Duct Sealing Protocol) | $0.20 | $0.00 | $0.20 |
Electric | The greater of 8 CFM/100 ft² conditioned floor area or 80 CFM (Duct Sealing Protocol) | $0.20 | $0.00 | $0.20 | |
Central | N/A | $0.00 | $0.00 | $0.00 | |
HVAC Grading | Gas | Fan Flow Test: N/A Watt Draw Test: N/A Refrigerant Charge: N/A | $0.00 | $0.00 | $0.00 |
Electric | Fan Flow Test: N/A Watt Draw Test: N/A Refrigerant Charge: N/A | $0.00 | $0.00 | $0.00 | |
Central | Fan Flow Test: N/A Watt Draw Test: N/A Refrigerant Charge: N/A | $0.00 | $0.00 | $0.00 | |
Mechanical Ventilation | Gas | S & 1 Bed (Any): 50 CFM; 90% rated recovery; Any Climate; (Product Ref) 2 & 3 Bed: 70 CFM; 86% rated recovery; Any Climate; (Product Ref) | $2.50 | $0.00 | $2.50 |
Electric | S & 1 Bed (Any): 50 CFM; 90% rated recovery; Any Climate; (Product Ref) 2 & 3 Bed: 70 CFM; 86% rated recovery; Any Climate; (Product Ref) | $2.50 | $0.00 | $2.50 | |
Central | Daikin VAM-GVJU 15-25 units distributed across all floors, available in 300/470/600/1,200 CFM sizes. Sensible recovery 75-82%, total recovery 64-73%. Connects to the VRV IV via DIII-NET controls. (Product Ref). | $1.50 | $0.00 | $1.50 | |
Local Mechanical Exhaust | Gas | 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 Based on kitchen volume & ≤ 1.0 sone. Both: Exhaust directly outdoors, ENERGY STAR certified, utilize ERV to meet these requirements. | $0.20 | $0.00 | $0.20 |
Electric | 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 Based on kitchen volume & ≤ 1.0 sone. Both: Exhaust directly outdoors, ENERGY STAR certified, utilize ERV to meet these requirements. | $0.20 | $0.00 | $0.20 | |
Central | 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 Based on kitchen volume & ≤ 1.0 sone. Both: Exhaust directly outdoors, ENERGY STAR certified, utilize ERV to meet these requirements. | $0.20 | $0.00 | $0.20 | |
Thermostats | Gas | Programmable Thermostat (Product Ref) | $0.10 | $0.00 | $0.10 |
Electric | Programmable Thermostat (Product Ref) | $0.10 | $0.00 | $0.10 | |
Central | Programmable Thermostat (Product Ref) | $0.10 | $0.00 | $0.10 |
Path Comparison - Plumbing & Appliances
Item | Path | Detailed Specifications | Cost $/sf | Incentive $/sf | Net $/sf |
|---|---|---|---|---|---|
DHW | Gas | Teal Systems / Raypak XTHERM 2005A Three boilers at 1,999 MBH each (5,997 MBH total), 96% thermal efficiency. Duplex Taco 1919 recirc pumps at 1.5 HP each (Pricing) (Product Ref). | $0.68 | $0.00 | $0.68 |
Electric | Electric tank heater in unit (UEF ≥0.93) (Product Ref) | $1.05 | $0.00 | $1.05 | |
Central | Teal Systems / Raypak XTHERM 2005A Three boilers at 1,999 MBH each (5,997 MBH total), 96% thermal efficiency. Duplex Taco 1919 recirc pumps at 1.5 HP each (Pricing) (Product Ref). | $0.68 | $0.00 | $0.68 | |
DHW Piping | Gas | Supply piping insulated to R-3 minimum; Max 1.8 gallons stored volume per run; Modeled pipe runs are optimized to 1/2 program default lengths; (See unit breakdowns for run lengths). | $0.50 | $0.00 | $0.50 |
Electric | Supply piping insulated to R-3 minimum; Max 1.8 gallons stored volume per run; Modeled pipe runs are optimized to 1/2 program default lengths; (See unit breakdowns for run lengths). | $0.50 | $0.00 | $0.50 | |
Central | Supply piping insulated to R-3 minimum; Max 1.8 gallons stored volume per run; Modeled pipe runs are optimized to 1/2 program default lengths; (See unit breakdowns for run lengths). | $0.50 | $0.00 | $0.50 | |
Water Fixtures | Gas | Watersense Certified Fixtures (Lavatory: ≤1.2 GPM, Shower: ≤2.0 GPM) | $0.18 | $0.00 | $0.18 |
Electric | Watersense Certified Fixtures (Lavatory: ≤1.2 GPM, Shower: ≤2.0 GPM) | $0.18 | $0.00 | $0.18 | |
Central | Watersense Certified Fixtures (Lavatory: ≤1.2 GPM, Shower: ≤2.0 GPM) | $0.18 | $0.00 | $0.18 | |
Refrigerator | Gas | All: ≤ 550 kWh annual usage; ENERGY STAR; Electric; (Product Ref) | $1.20 | $0.00 | $1.20 |
Electric | All: ≤ 550 kWh annual usage; ENERGY STAR; Electric; (Product Ref) | $1.20 | $0.00 | $1.20 | |
Central | All: ≤ 550 kWh annual usage; ENERGY STAR; Electric; (Product Ref) | $1.20 | $0.00 | $1.20 | |
Dishwasher | Gas | All: ≤ 240 kWh annual usage; ENERGY STAR; Electric; (Low Cost Product Ref) (Luxury Product Ref) | $0.60 | $0.00 | $0.60 |
Electric | All: ≤ 240 kWh annual usage; ENERGY STAR; Electric; (Low Cost Product Ref) (Luxury Product Ref) | $0.60 | $0.00 | $0.60 | |
Central | All: ≤ 240 kWh annual usage; ENERGY STAR; Electric; (Low Cost Product Ref) (Luxury Product Ref) | $0.60 | $0.00 | $0.60 | |
Clothes Washer | Gas | All: ≤ 136 kWh annual usage; ≥ 2.76 IMEF; ≥ 4.8 cubic ft capacity; ENERGY STAR; Electric; (Product Ref) | $0.80 | $0.00 | $0.80 |
Electric | All: ≤ 136 kWh annual usage; ≥ 2.76 IMEF; ≥ 4.8 cubic ft capacity; ENERGY STAR; Electric; (Product Ref) | $0.80 | $0.00 | $0.80 | |
Central | All: ≤ 136 kWh annual usage; ≥ 2.76 IMEF; ≥ 4.8 cubic ft capacity; ENERGY STAR; Electric; (Product Ref) | $0.80 | $0.00 | $0.80 | |
Clothes Dryer | Gas | All: ≥ 6 CEF; Ventless; Heat Pump Dryer; ENERGY STAR; Electric; (Product Ref) | $0.80 | $0.00 | $0.80 |
Electric | All: ≥ 6 CEF; Ventless; Heat Pump Dryer; ENERGY STAR; Electric; (Product Ref) | $0.80 | $0.00 | $0.80 | |
Central | All: ≥ 6 CEF; Ventless; Heat Pump Dryer; ENERGY STAR; Electric; (Product Ref) | $0.80 | $0.00 | $0.80 | |
Stove / Oven | Gas | Any Electric Stove; (Product Ref) | $0.80 | $0.00 | $0.80 |
Electric | Any Electric Stove; (Product Ref) | $0.80 | $0.00 | $0.80 | |
Central | Any Electric Stove; (Product Ref) | $0.80 | $0.00 | $0.80 |
Path Comparison - Electrical
Item | Path | Detailed Specifications | Cost $/sf | Incentive $/sf | Net $/sf |
|---|---|---|---|---|---|
Lighting | Gas | 100% high-efficacy (LED) | $1.05 | $0.00 | $1.05 |
Electric | 100% high-efficacy (LED) | $1.05 | $0.00 | $1.05 | |
Central | 100% high-efficacy (LED) | $1.05 | $0.00 | $1.05 | |
Solar Ready | Gas | Designated Solar Zone: Reserve a contiguous area equal to at least 40% of the total horizontal roof area (after excluding skylights, occupied decks, vegetated areas, and fire setbacks). Contiguity & Obstructions: The zone must be free of all obstructions (pipes, vents, HVAC units) and maintain a minimum width of 5 feet. Structural Capacity: Roof structures within this zone must be engineered to support a future collateral dead load of 5 PSF. Orientation (Sloped Roofs): For roofs with a pitch of 4:12 or greater, the zone must be oriented between 110° and 270° of true north. Electrical Infrastructure: Provide identified conduit pathways from the roof to the electrical service and reserve a labeled space for a dual-pole circuit breaker in the main panel or common space service. | $0.25 | $0.00 | $0.25 |
Electric | Designated Solar Zone: Reserve a contiguous area equal to at least 40% of the total horizontal roof area (after excluding skylights, occupied decks, vegetated areas, and fire setbacks). Contiguity & Obstructions: The zone must be free of all obstructions (pipes, vents, HVAC units) and maintain a minimum width of 5 feet. Structural Capacity: Roof structures within this zone must be engineered to support a future collateral dead load of 5 PSF. Orientation (Sloped Roofs): For roofs with a pitch of 4:12 or greater, the zone must be oriented between 110° and 270° of true north. Electrical Infrastructure: Provide identified conduit pathways from the roof to the electrical service and reserve a labeled space for a dual-pole circuit breaker in the main panel or common space service. | $0.25 | $0.00 | $0.25 | |
Central | Designated Solar Zone: Reserve a contiguous area equal to at least 40% of the total horizontal roof area (after excluding skylights, occupied decks, vegetated areas, and fire setbacks). Contiguity & Obstructions: The zone must be free of all obstructions (pipes, vents, HVAC units) and maintain a minimum width of 5 feet. Structural Capacity: Roof structures within this zone must be engineered to support a future collateral dead load of 5 PSF. Orientation (Sloped Roofs): For roofs with a pitch of 4:12 or greater, the zone must be oriented between 110° and 270° of true north. Electrical Infrastructure: Provide identified conduit pathways from the roof to the electrical service and reserve a labeled space for a dual-pole circuit breaker in the main panel or common space service. | $0.25 | $0.00 | $0.25 | |
EV Ready | Gas | Requirement: 20% of parking spaces; 40-amp dedicated branch circuit (or larger with ALMS); wiring suitable for ≥6.6 kW Level II EVSE, run to within 6 feet of each qualifying space. | $0.50 | $0.00 | $0.50 |
Electric | Requirement: 20% of parking spaces; 40-amp dedicated branch circuit (or larger with ALMS); wiring suitable for ≥6.6 kW Level II EVSE, run to within 6 feet of each qualifying space. | $0.50 | $0.00 | $0.50 | |
Central | Requirement: 20% of parking spaces; 40-amp dedicated branch circuit (or larger with ALMS); wiring suitable for ≥6.6 kW Level II EVSE, run to within 6 feet of each qualifying space. | $0.50 | $0.00 | $0.50 | |
HPWH Ready | Gas | N/A | $0.00 | $0.00 | $0.00 |
Electric | N/A | $0.00 | $0.00 | $0.00 | |
Central | N/A | $0.00 | $0.00 | $0.00 |
Path Comparison - Soft Costs
Item | Path | Detailed Specifications | Cost $/sf | Incentive $/sf | Net $/sf |
|---|---|---|---|---|---|
Paperwork & Modeling | Gas | HERS / ERI Energy model, 2021 IECC checklists, ENERGY STAR MFNC checklists, and incentive documentation. | $0.00 | $0.00 | $0.00 |
Electric | HERS / ERI Energy model, 2021 IECC checklists, ENERGY STAR MFNC checklists, and incentive documentation. | $0.00 | $0.00 | $0.00 | |
Central | HERS / ERI Energy model, 2021 IECC checklists, ENERGY STAR MFNC checklists, and incentive documentation. | $0.00 | $0.00 | $0.00 | |
Testing & Verification | Gas | Unit Blower Door Test, Duct Test, Mechanical Ventilation Testing, Room Balancing, Slab, Predrywall & Final Inspection. | $0.39 | $1.90 | -$1.51 |
Electric | Unit Blower Door Test, Duct Test, Mechanical Ventilation Testing, Room Balancing, Slab, Predrywall & Final Inspection. | $0.39 | $1.90 | -$1.51 | |
Central | Unit Blower Door Test, Mechanical Ventilation Testing, Room Balancing, Slab, Predrywall & Final Inspection. | $0.39 | $1.90 | -$1.51 |
Additional Design Considerations Not Represented In This Study
- Exterior Wall Cavity Spray Foam: Standard 5.5-inch batt insulation provides R-21 more cost-effectively. Upgrading to closed-cell spray foam for maximum R-value of R-38 was assessed but offered a negligible improvement of less than 0.1 HERS points. Given the significant cost increase and lack of energy modeling benefit, standard batts remained the basis of design, although cavity insulation in the exterior walls was ruled unnecessary altogether.
- Tankless Electric Hot Water: Despite an improved 0.98 UEF, these units negatively impacted HERS scores. They are more expensive and perform worse in energy models than standard electric resistance tanks
- Standard Electric Dryer: Upgrading from standard electric to heat pump dryers improves the HERS score by up to 2 points. The higher equipment cost is offset by simpler installation (no venting), critical energy savings, and lower insurance costs (standard electric dryers are a fire hazard).
- High-Efficiency Dishwashers: Reducing annual dishwasher usage below 200 kWh provided less than a 0.2-point HERS improvement. The high cost of these units and the potential move to compact sizes do not align with the luxury apartment feel.