Hobart Net Zero in Massachusetts

Project Subtitle: 

Rebuild/DER on Martha's Vineyard

Project Description: 

This is a rebuild and Deep Energy Retrofit of a 1970's ranch with a full poured cement cellar, with a 1990's addition on concrete piers. The location, within the coastal zone, precluded any expansion of the footprint, but expansion upward was allowed. The original ranch was torn down to the first floor deck, preserving the cellar, and the addition was completely gutted, but left standing. The ranch was rebuilt into a two story house with SIPs, the addition was insulated, top, sides and bottom, with exterior nail base SIPs and interior fiberglass and the cellar was sealed with spray foam, foam panels and fiberglass. High efficiency windows, ventillation, minisplits, HP water heater, energy star appliances, LEDs and a monitored 5.36 KW PV system complete the package. The house is totally electric, and has a Net electric meter, tied to the grid. The HERS rating is 22.

Building Type Summary: 

Single family residence

Address: 

39 Sengekontacket Road
Edgartown, MA 02539
United States

Elevation: 

12

Lat. / Long.: 

POINT (-70.5728337 41.4192946)

Location Type: 

Suburaban

Köppen Climate Type: 

Cfb

Climate Region: 

Zone 5

Solar Insolation: 

3.74 KWh/m2/day Annual Average

Annual HDD : 

5600

Annual CDD: 

41 Ave over las 5 years

HDD Base Temp: 

65 deg F

CDD Base Temp: 

78 deg F

Occupancy Type and Details: 

Owner occupied; 2 occupants full time. Occasional house guests: 4 for 2-3 weeks per year

Number of stories: 

2

Conditioned Floor Area: 

2 700

Conditioned Building Volume: 

23 000

Unconditioned Floor Area: 

1 000

Multiple buildings?: 

Total number of units in project (all buildings): 

1

Total floor area of project (all buildings): 

3 100

Historic?: 

Completion date: 

Saturday, November 1, 2014

Site description: 

The house is on a ~.85 acre lot on a peninsula including a tidal salt marsh and on the edge of a salt pond, totally within the coastal zone.

Materials: 

As it is in the coastal zone, no increase in footprint was allowed; a variance was obtained for a slight increase in height, to allow a second floor. Local regulations limit the amount of fertilizer which can be applied per year; we actually apply none, using native plants. The existing cellar and pilings were preserved and minimal excavation was done to install a nitrogen reduction septic system.

Energy Highlights: 

4 minisplit air source heat pumps provide heat. Steibel Eltron heat DHW.

LCA Description: 

No

HERS Index: 

22

Annual renewable energy generated: 

7 741

Power Rating: 

5 360Watts

Electric Utility Company: 

NStar / Eversource

Gas Utility Company: 

None

Datasets and Utility Bills sources and reliability: 

Locus Energy LGate-101E monitoring system.

Electricity amount (imported from grid): 

10 642

Electricity amount (credited or exported to grid): 

7 741

Net electricity usage (purchased electricity): 

2 910

Natural gas amount (purchased energy): 

0

Energy Storage type: 

None yet. Ordered Tesla 10 kW storage battery, but has not yet been delivered.

CHP System Description: 

NA

Subslab assembly: 

slab was pre-existing poured concrete. Was insulaed with 2 inches of foam panels covered with 1.5 inches plywood.

Slab edge assembly: 

2 inches of foam paneling on floor to cellar wall .

Foundation wall assembly: 

preexisting poured concrete. Covered with 3 inches of foam panels, 3.5 inches of fiberglass and .75 inches of plywood. Rim joists were spray foamed to 4 inches.

Above grade wall assembly: 

Same as foundation wall

Cathedral ceiling assembly: 

10.5 inch foam SIPs for Ranch;

Door Area: 

21

Space heating - Manufacturer & Model: 

Daikin FFQ12LVJU
Daikin FFQ12LVJU
Daikin FFQ15LVJU
Daikin CDXS18LVJU

Space cooling - Manufacturer & Model: 

Daikin same as heating

Domestic hot water - Manufacturer & Model: 

Steibel Eltron 80 gallon

Domestic hot water - capacity: 

80

Domestic hot water - efficiency: 

3

Ventilation - Manufacturer & Model: 

Zender ComfoAir 550 Luxe

Process: 

Attended NZE course from NESEA; designed house as capstone project

Other Software tools: 

Marc Rosenbaum custom software

Finances Description: 

self financed

Total Cost of Project: 

1 000 000

Construction hard cost: 

500 000

Gross Cost of Renewable Energy System: 

40 000

Value of Tax Credits for renewable energy systems: 

10 000

Net Cost of renewable energy systems: 

30 000

Federal incentives: 

3000

State incentives: 

7000

Annual Electric Savings: 

2 000

Annual Revenue from SRECs or other renewable energy credits: 

1 000

Advice: 

Get financing before starting the project

Special architectural measures: 

South facing window area, along long axis of house, was maximized; other exposures were minimized. All windows have overhangs which minimize heat gain in summer but allow maximum heat gain in winter. Window SHGC is 0.440, U factor is 0.150. Windows were installed with foam and taped around the edges. Windows are hurricane glassed. House walls are about R-45, roof is R-65. The ranch is build with SIPs and the (gutted) addition is sheathed with nail-base SIPs. Cellar was foam paneled and the rim joists were spray foamed. Blower door testing revealed it met the Passiv Haus standard for air infiltration.

Energy Strategies: 

The house is super insulated, with the building envelope extremely well sealed. The long axis of the house faces south and window area is maximized, with overhangs to take advantage of solar insolation. All appliances are Energy Star or use minimal energy for their type.

Energy Use and Production Documentation: 

Subslab R-value: 

7.00

Slab edge R-value: 

7.00

Foundation wall R-value: 

19.60

Above grade wall R-value: 

19.50

Cathedral ceiling R-value: 

63.80

Average window U-factor: 

0.15

Solar Heat Gain Coefficient: 

0.44

Visible Light Transmittance: 

0.50

Door U-Factor: 

0.15

Cost per square foot of Conditioned Space: 

370.00

Air Changes per hour, ACH50: 

0.46

Number of Bathrooms: 

3.50

Scope Description: 

Original 1970's single story ranch (with full cellar) with 1990's one room addition with porch, on pilings. Ranch was demolished to first floor deck, cellar was preserved. One room addition was gutted to studs, floor and roof, and porch removed.

Site conditions: 

previously developed land
wetlands
lake/pond,
sensitive habitat
preexisting structure(s)

Renewable Energy Sources: 

Renewable energy is generated within the building footprint (e.g. solar PV on the roof)

Other Purchased Fuels Description: 

No

Storage Strategies & System Details: 

Will be wired to provide power for limited heat, ventilation, lighting and refrigeration until PV system can recharge the battery.

Summary of enclosure strategy/description: 

super insulated with SIPs and fiberglass, with high efficiency windows, taped and foam sealed.

Roof Assembly: 

6 inch nail base SIPs over 12 inches fiberglass for addition

Roof R-value: 

65.00

Window Description: 

triple pane, triple gasketed tilt and turn inert gas filled windows. PVC frame. hurricane glass on outer pane. Manufacturer is Shuco. custom built.

Door Description: 

Same as windows; 7 full glass doors

Number of Bedrooms: 

4

Team Members: 

Local builder

Status: 

Live

Zero Net Energy Definition Used: 

Site Energy Use

Basis of Performance Claim: 

Modeled
Verified

Type of Construction: 

New
Retrofit

Renewable Energy System Type(s): 

Photovoltaics

Renewable Energy System Description & Details: 

5.36 kW Grid Interactive PV system: 16 SunPower SPR-X21-335-BLK modules with Solar Edge SE6000A-US-U with P400 Optimizers Inverter.

Annual Renewable Energy Generated Data Type: 

Measured

Source of Annual Production Data: 

Power production is metered and measured; see attached pdf for generation/house consumption performance since installation.

Space Heating - Efficiency (e.g., 92 AFUE): 

8.6 HSPF
8.6 HSPF
8.6 HSPF
8.6 HSPF

Space Cooling - Efficiency (e.g., 16 SEER): 

15.3 SEER

Days per year Building is fully occupied: 

365

Submitter Contact Email: 

Submitter Contact Phone Number: 

(973) 723-7858

Project Type: 

Zero Energy Ready / Near Zero Energy

Lighting Manufacturer and Model: 

LEDs

Indoor Environment Description: 

There is a Zender 550 ERV system set to 125 cfm for the house.

Weight: 

0