Pioneer Valley Habitat for Humanity Net Zero Cottage

Project Subtitle: 

adding energy affordability to the paradigm

Project Description: 

Pioneer Valley Habitat for Humanity: "Not only is this build our first Easthampton home, but it is also our first ever Women Build home and our first zero net energy potential house!  That's a lot of firsts!"  This is a fitting project to be the MJ Adams Legacy Build, in honor of the chapter's first director.

This project aimed to raise the bar in a lot of areas where PV Habitat has been gaining ground in the past decade.  Energy efficiency and waste reduction were getting more and more successful, and we thought a bold goal would be a great way to stretch capabilities.

The cottage-style two-story home is the west side of a zero-lot-line project, where each family independently owns their land and home even though they share a wall, which helps reduce envelope exposure.  A 4-bedroom, 2-bath home, it will be occupied by a single mother with three children.  Due to a generous donation from PV Squared of a huge array--over 7kW--the home has the potential to reach net zero depending on the family's use patterns.

* Orientation and design of the building to have large windows on the south side to capture sun in the winter and large roof overhang to minimize sun in the summer when the sun is higher
* Double 2x4 walls (an outside wall and a separate inside wall) with dense pack cellulose insulation in between
* High efficiency double pane windows
* Sealing all window, door and sheathing joints to minimize outside air infiltration, with multiple air sealing tests made possible by expert volunteers with blower doors
* High efficiency heating, cooling and hot water systems

Building Type Summary: 

single-family residence, attached at lot line

Address: 

East Street
Easthampton, MA 01027
United States

Elevation: 

182

Lat. / Long.: 

POINT (-72.6441199 42.2714174)

Location Type: 

Suburaban

Köppen Climate Type: 

Dfb

Climate Region: 

Zone 5

Solar Insolation: 

3.68 kWh/m2/day

Annual HDD : 

7643 degree days

Annual CDD: 

263 degree days

HDD Base Temp: 

70 deg F

CDD Base Temp: 

75 deg F

Occupancy Type and Details: 

Owner-occupied. One adult, three children ages ~4-15

Number of stories: 

2

Conditioned Floor Area: 

1 575

Conditioned Building Volume: 

16 176

Semiconditioned Floor Area: 

250

Multiple buildings?: 

Total floor area of project (all buildings): 

1 825

Historic?: 

Completion date: 

Sunday, January 31, 2016

Site description: 

Previously undeveloped lot along a through street. Neighbors range from small suburban lots to working farms.

Materials: 

Minimal foam, only for penetration sealing and under slab insulation. Majority of insulation is cellulose.

Energy Highlights: 

Basic net-zero-capable approach, investing in the envelope and minimizing the mechanicals and energy use.

LCA Description: 

No.

HERS Index: 

-7

Annual renewable energy generated: 

7 417

Power Rating: 

245Watts

Electric Utility Company: 

Eversource

Gas Utility Company: 

None.

Datasets and Utility Bills sources and reliability: 

Utility meter (extremely reliable) and Omnisense circuit monitoring (highly reliable)

Energy Storage type: 

None.

Subslab assembly: 

4" XPS (donated by Dow)

Slab edge assembly: 

2" XPS between slab and stem wall

Foundation wall assembly: 

slab on grade

Above grade wall assembly: 

double-stud dense packed cellulose, 11.5" frame to frame

Flat attic assembly: 

small portion of flat ceiling (1.5 story construction) with 24" loose fill cellulose

Cathedral ceiling assembly: 

2/3 of ceiling sloped with dense-packed cellulose in truss depth, average 27" (model assumed R value 79 with thermal bridging of trusses, and at thinnest location for worst-case scenario, though could be up to 102.6 nominal)

Door Area: 

20

Space heating - Manufacturer & Model: 

Fujitsu AOU24RXFZH, ASU12RLF1 and 2 ASU7RLF1

Space cooling - Manufacturer & Model: 

same as above

Domestic hot water - Manufacturer & Model: 

Geospring GEH80DFEJSR

Domestic hot water - capacity: 

80

Domestic hot water - efficiency: 

3

Ventilation - Manufacturer & Model: 

Lunos e2 (3 pairs)

Process: 

All-volunteer design team, including 3 architects (one retired), construction managers, and input from Pioneer Valley Habitat for Humanity Building Committee

Design for Adaptability: 

Floor level is minimally raised from grade, allowing easy construction of ramps for visitability or low-mobility access for the first floor. Also grab bars in showers.

Other Software tools: 

HERS draft rating provided during design phase as backup

Energy Modeling Software: 

Marc Rosenbaum's Excel-based Net Zero Energy model

Outcome of project goals: 

Most of this high-performance building proved possible to build by a volunteer workforce. It should be noted that some volunteers were extremely skilled, including a local high-performance contractor who donated a day of her crew to install all the windows in both homes.
Air sealing sequence turned out to be difficult for the many supervisors involved in the volunteer model. Building has tightened since the ACH reported here, but it is not likely quite to our air sealing goals.
Building was designed for simpler mechanicals, but it proved impossible to convince installers of likely comfort. It is still early in the super-insulation movement and a lot of expectations will shift slowly.

Discrepancies: 

We look forward to the data we will be gathering from these homes, indoor and in-wall temperatures and RH, and energy usage.

Finances Description: 

Due in large part to donated labor and materials, these homes are extremely affordable, per the mission of Habitat for Humanity.
Cost below is estimated, and includes one home.

Total Cost of Project: 

163 183

Construction hard cost: 

126 380

Gross Cost of Renewable Energy System: 

20 100

Federal incentives: 

None.

State incentives: 

MA DOER Pathways to Zero Net Energy Grant $12,000 per unit

Utility incentives: 

MassSave New Construction Program $4,000 per unit

Other incentives: 

Pioneer Valley Habitat for Humanity raises funds from a variety of sources for construction including the Federal Home Loan Bank of Boston, the Bike & Build Foundation, Easthampton Savings Bank, the Amelia Peabody Foundation, Pioneer Valley Photovoltaics, Lowes and many individual donors.

Pioneer Valley Photovoltaics donated the full cost of the materials and installation of the solar panels and will receive any SRECS.

Advice: 

Get all constituents on board prior to construction to finalize decisions, as changes are very costly.

Ratings: 

Energy Star Tier III
Pathways to Zero Grant Program, Mass DOE

Special architectural measures: 

Passive solar orientation of openings and tuned windows. Overhangs sized for seasonal change. Roofs sloped for optimal PV performance.

Energy Strategies: 

Basic net-zero-capable approach, investing in the envelope and minimizing the mechanicals and energy use.

Energy Use and Production Documentation: 

Subslab R-value: 

22.00

Slab edge R-value: 

11.00

Above grade wall R-value: 

37.50

Flat attic R-value: 

81.60

Cathedral ceiling R-value: 

80.00

Average window U-factor: 

0.32

Solar Heat Gain Coefficient: 

0.28

Visible Light Transmittance: 

0.53

Door U-Factor: 

0.19

Cost per square foot of Conditioned Space: 

89.00

Air Changes per hour, ACH50: 

1.40

Number of Bathrooms: 

2.00

Scope Description: 

All new construction, all single-family residential.

Site conditions: 

previously undeveloped land
pristine land (greenfield)

Renewable Energy Sources: 

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

Other Purchased Fuels Description: 

No.

Summary of enclosure strategy/description: 

Double-stud, dense-packed cellulose, with some loose-fill in roof, and some rigid foam under slab. Air sealing primarily at sheathing, with backup at drywall.

Roof Assembly: 

all insulation in depth of trusses

Window Description: 

Paradigm casements low-e with argon, tuned with high-solar-gain glass on south windows

Door Description: 

Therma-Tru Smooth Star S601LE

Number of Bedrooms: 

4

Project Team: 

Architect

Team Member: 

Rachel Stevens
Architect

Team Member: 

Edy Ambroz
Builder

Team Member: 

Edy Ambroz
Other Team Member

Team Members: 

Chuck Witham, Lynne Badgett, Libby McLarty on Build Team

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: 

TrinaSolar TSM-PC05 / TSM-PA05 panels

Annual Renewable Energy Generated Data Type: 

Estimated

Source of Annual Production Data: 

Estimated/modeled by installer

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

20 SEER COP: 3.79

Days per year Building is fully occupied: 

365

Submitter Contact Email: 

Submitter Contact Phone Number: 

(413) 570-3213

Project Type: 

Zero Energy

Indoor Environment Description: 

Lunos e2 distributed HRV pairs provide fresh air with heat recovery without requiring ducts; easier for volunteer installs.

Weight: 

0