Sandywoods Farm Net Zero Spec House #1

Project Subtitle: 

Lot 8 Sandywoods Farm Net Zero

Project Description: 

This is the first of two Net Zero houses built on spec by Church Community Housing in the market rate portion of a mixed-income, mixed-use, arts and agricultural community called Sandywoods Farm.  The development includes 50 Affordable apartments in single family and duplex buildings and 17 unsibsidized market rate lots for sale.  The two Net Zero spec houses have been built in the hope that it will stimulate the sale and development of the other lots and that it will set a precedent for energy efficient home construction that will be followed by the purchasers of those lots.  Furthermore, the Town of Tiverton where Sandywoods Farm is located has a relatively high property tax rate relative to the surrounding communities.  It is hoped that the Net Zero houses would compete favorably with spec houses for sale in those communities by offsetting the higher taxes with low/no utility costs.  Lastly, Church Community Housing has long been dedicated to increased energy efficiency, renewable energy development and sustainable and healthy building materials and practices.  The construction of these Net Zero houses was simply the next step in a long road of ever increasing residential construction performance. The houses stats are:  R-60 SIP Roof, R-50 .8 lb open cell spray foam 12" double stud walls, R-15 closed cell spray foam under the basement slab, R-20 closed cell spray foam on interior of basement walls, R-50 open cell spray foam in rim joist.  Triple glazed, low-E, Krypton gas filled windows and sliding glass door achieving .20 or better U-value.  Super high efficiency "hyper heat" Fujitsu mini-split HVAC system: one floor mounted 15,000 btu unit on first floor, one compact ducted 12,000 btu unit on 2nd floor.  Less than 1 ACH @ 50 Pascals.  Panasonic programable bath fans in both bathrooms set to run continuously based on results of blower door test to ensure healthy indoor air quality.  Tier II vapor retarder interior primer and gasketed electrical boxes to prevent vapor drive through wall assembly.  Electric heat pump hot water tank for domestic hot water.  9kw PV array atop south facing roof. 

Building Type Summary: 

single-family residence

Address: 

34 Vitruvian Lane
Tiverton, RI 02878
United States

Elevation: 

270

Lat. / Long.: 

POINT (-71.2133801 41.6259357)

Location Type: 

Rural

Köppen Climate Type: 

Dfa

Climate Region: 

Zone 5

Solar Insolation: 

3.81 kWh/m2/day

Annual HDD : 

6119

Annual CDD: 

762

HDD Base Temp: 

65 deg F

CDD Base Temp: 

65 deg F

Occupancy Type and Details: 

Owner-occupied. Construction is not yet complete. This is a 4 bedroom house.

Number of stories: 

2

Conditioned Floor Area: 

1 372

Conditioned Building Volume: 

11 222

Semiconditioned Floor Area: 

870

Unconditioned Floor Area: 

272

Multiple buildings?: 

Total number of units in project (all buildings): 

1

Total floor area of project (all buildings): 

2 160

Historic?: 

Completion date: 

Wednesday, June 15, 2016

Site description: 

The unsubsidized or "market-rate" portion of a mixed-income, mixed use arts and agricultural development that has 50 subsidized apartments as well as the 18 undeveloped lots, one of which this house is built on. The overall parcel was 190 acres before the sale and preservation of 90 acres to the local land trust. Of the remaining 100 acres all development of the 50 apartments, arts and agricultural buildings and outbuildings were placed on the 25 acres with soils with the lowest agricultural or forest/wildlife value and the remaining 75 acres are preserved as farm or forest lands. All roads constructed for this development were designed to allow perfect south facing home orientation

Materials: 

FSC certified lumber was used for all framing materials and sheathing. Construction is not yet complete so finish materials have not yet been selected but we will encourage the buyers to choose renewable materials such as bamboo hardwood flooring and low voc paint and/or stains.

HERS Index: 

4

Annual renewable energy generated: 

10 890

Power Rating: 

9 075Watts

Electric Utility Company: 

National Grid

Gas Utility Company: 

N/A

Datasets and Utility Bills sources and reliability: 

Mark Rosenbaum's Net Zero Homes Modeling Software

Electricity amount (imported from grid): 

10 890

Electricity amount (credited or exported to grid): 

10 890

Net electricity usage (purchased electricity): 

0

Natural gas amount (purchased energy): 

0

Energy Storage Capacity: 

0

Energy Storage type: 

Grid tied system w/revenue grade meter

Subslab assembly: 

R20 closed cell spray foam sprayed on top of 3/4 stone under concrete basement floor slab.

Slab edge assembly: 

before the slab is poured the closed cell spray foam is sprayed on the stone and up the interior of the foundation walls. Therefore the slab is completely insulated from the outside.

Foundation wall assembly: 

closed cell foam sprayed to R20 on inside of foundation walls

Above grade wall assembly: 

12" double stud walls filled with open cell spray foam insulation.

Flat attic assembly: 

No flat attic. Cathedral SIP roof

Cathedral ceiling assembly: 

16" thick EPS SIP Panel Roof

Door Area: 

80

Space heating - Manufacturer & Model: 

Fujitsu XLTH

Space heating - capacity: 

32

Space cooling - Manufacturer & Model: 

Fujitsu XLTH

Space cooling - capacity: 

24

Domestic hot water - Manufacturer & Model: 

GE Geospring Heat Pump Hot water Heater

Domestic hot water - capacity: 

60

Domestic hot water - efficiency: 

225

Ventilation - Manufacturer & Model: 

Panasonic FV 05 11VKSL1

Process: 

House aesthetic and floor plan designed by Northeast Collaborative Architects with input from CCHC regarding function. CCHC staff member completes NESEA Net Zero Homes course and applies lessons learned to ensure the house will function as Net Zero.

Design for Adaptability: 

There are 16 remaining house lots to build on. If this design proves popular it can be used over and over again. Also, the most cost effective features of these houses have been incorporated into the design and construction of all other single family homes CCHC develops. So far the result of this is 6 affordable land trust homes being built to zero energy ready and being sold for $150,000. All of these homes will be finished by June of 2016 with Purchase and Sales Agreement in place with buyers for all of these homes.

Other Software tools: 

N/A

Energy Modeling Software: 

Mark Rosenbaum's software that is provided in the Zero Energy Homes class.

Outcome of project goals: 

Keeping cost of construction to as close to the standard for a conventionally built home built "on spec" wasn't achieved because of the SIP roof which was expensive both in material and labor costs as compared to a truss built roof. This SIP roof was used because the house is not a full 2 stories it is a 1 3/4 story home with dormers and cathedral ceilings. If a full 2 story design had been started with savings would have resulted from the simple roof design, lack of dormers, and ability to use blown in cellulose insulation in the attic.

Discrepancies: 

Not yet able to do actual measurements.

Finances Description: 

Built using a line of credit for CCHC.

Total Cost of Project: 

368 059

Construction hard cost: 

327 671

Gross Cost of Renewable Energy System: 

34 596

Value of Tax Credits for renewable energy systems: 

0

Net Cost of renewable energy systems: 

25 947

Cost breakdown info.: 

State incentives: 

CommerceRI Renewable Energy Fund $8,649 grant.

Utility incentives: 

Energy Star Tier III and HVAC and Hot Water Rebates: $5,650

Annual Electric Savings: 

1 495

Ratings: 

The house will receive a HERS rating upon completion as a result of it's enrollment in the Energy Star Certification program. Initial modeling showed a HERS of 4 - before installation of the larger PV array and higher density spray foam in the walls. The house is expected to achieve a negative HERS rating (net energy exporter) upon completion.

Special architectural measures: 

Southern window glazing was maximized with roof overhangs built to provide maximum winter solar gains and summer solar shading.

Energy Strategies: 

Conservation 1st, energy generation 2nd. Super insulate, ensure envelope tightness below 1 ACH/50, super high efficiency HVAC and hot water heating, then generate adequate electricity with south facing solar array to heat, cool, heat water, and provide all typical plug loads.

Energy Use and Production Documentation: 

Subslab R-value: 

20.00

Slab edge R-value: 

20.00

Foundation wall R-value: 

20.00

Above grade wall R-value: 

40.00

Cathedral ceiling R-value: 

60.00

Average window U-factor: 

0.20

Solar Heat Gain Coefficient: 

0.22

Visible Light Transmittance: 

0.32

Door U-Factor: 

0.20

Cost per square foot of Conditioned Space: 

268.00

Air Changes per hour, ACH50: 

1.00

Number of Bathrooms: 

2.00

Scope Description: 

New construction single-family home built "on spec". No buyer in place yet.

Site conditions: 

previously undeveloped land

Other Purchased Fuels Description: 

N/A

Storage Strategies & System Details: 

N/A

Summary of enclosure strategy/description: 

R-60 SIP Roof, R-40 double stud open cell spray foam walls, R-20 closed cell spray foam under slab and covering entire surface of interior of concrete basement walls. R-40 open cell spray foam in rim joist. Triple glazed R-5 windows and doors.

Roof Assembly: 

16" thick EPS SIP Panel Roof

Roof R-value: 

60.00

Window Description: 

vinyl new construction triple glazed, low-e, krypton gas filled double hung windows from Harvey Tribute Line

Door Description: 

Sliding glass door is from same Harvey Tribute line with same spec's as windows. Entry doors are Therma-Tru Classic Craft models

Mechanical Equipment Installation Details and Comments: 

blower door testing will be done at end of construction. All ducting is within the conditioned space.

Number of Bedrooms: 

4

Project Team: 

Other Team Member

Team Member: 

Christian Belden

Team Members: 

Church Community Housing Corporation, Northeast Collaborative Architects, NPTRE (Newport Renewables), UG Nasons HVAC, FOARD Panels, Bodington Plumbing, Ecologic Insulation, Foster Electric

Status: 

Live

Zero Net Energy Definition Used: 

Site Energy Use

Basis of Performance Claim: 

Modeled

Type of Construction: 

New

Renewable Energy System Type(s): 

Photovoltaics

Renewable Energy System Description & Details: 

33 Solpower 275kW photovoltaic panels connected to 33 Enphase microinverters.

Annual Renewable Energy Generated Data Type: 

Modeled

Source of Annual Production Data: 

Estimated gross annual production

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

12.3 EER

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

12.8

Days per year Building is fully occupied: 

365

Submitter Contact Email: 

Submitter Contact Phone Number: 

(401) 846-5114 x15

Project Type: 

Zero Energy

Lighting Manufacturer and Model: 

LED screw in

Lighting Efficiency: 

LED

Indoor Environment Description: 

programmable bath fans are set based on results of the blower door test performed upon house completion and XLTX model Fujitsu mini-splits are used for heating and cooling. These models are rated to -15 degrees Fahrenheit for heating and are therefore sufficient for this region. Additionally we selected a compact ducted indoor unit for the 2nd floor to provide heating and cooling in each of the bedrooms and main bathroom and a floor mounted indoor unit for the 1st floor given it's open floorplan.

Weight: 

0