Solar Energy House

Our home is a newly constructed single-family residence located in downtown Maynard, Massachusetts. Maynard is a micro urban community west of Boston full of sidewalks, stores, and eateries.  We reside in the house with our two children.

As potential first-time homebuyers we had initially searched Maynard for an existing starter home that would provide 1) comfort 2) healthy indoor air quality 3) walkability enabling us to function as a one-car family and 4) outdoor space for our children to play.  But what we found left us uninspired. We envisioned living in a passive solar home that was efficient, sunny, and contemporary and wondered: is it possible for a family on a small budget to build such a home onsite using conventional methods and materials?

Initially we had doubts, and almost abandoned the idea. But visiting the three winning entries of the Massachusetts 2009 Zero Energy Challenge encouraged us. We committed to the project when we found a rare 1/4 acre lot in Maynard perfect for our needs.  To stay within budget we kept the footprint small at 1248 sq ft and the house was designed with multi-functional spaces on a single floor. The result of the integrated design team approach is a solar energy home that is beautiful and comfortable and which reflects our values and our aesthetics, while more traditional choices for exterior materials and details allow the house to fit into our New England neighborhood. And with ample attic storage and no need for a furnace we gratefully omitted the New England basement. The design also reflects the idea that 'home' is the outdoors, too.  We included three exterior doors for easy access to the patio, yard and garden. The great room with its vaulted ceiling is filled with natural sunlight such that we rarely need electric lighting before sundown.

The passive solar space heating, solar hot water system, and the superinsulated envelope result in very low energy use, while the solar PV array produces more energy than what is used on site. What makes our house unique is that we are net-zero energy not just on a year-to-year basis, but every month since the PV and solar hot water systems went online we have produced as much or more than we consumed—even in the coldest and cloudiest months and without sacrifice to comfort or convenience.  Our 4,000 kWh yearly surplus would cover the energy needed for daily driving with the electric car we hope to someday acquire. Other sustainable features include Energy Star appliances, WaterSense fixtures, and a rain water collection system for gardening.

One unexpected result from building in a downtown location is the community response.  From passers-by and groups of students to NESEA open house participants, our community wants to learn from what we have done.  Our message is simple: sustainable, comfortable, and attractive net-zero homes are now within reach of moderate income families. We will continue to send this message as we enjoy our home for years to come.

Quick Facts

General

Location
16 Euclid Ave
Maynard, MA01754
United States
Building Type Single-family residence
Project Type
Basis of Performance Claim
Bedrooms
Conditioned Floor Area 1 248

Energy Summary

Energy Data Type
Renewable Energy System Type(s)
Ratings
Annual renewable energy generated 8 292

Envelope and Mechanicals

Subslab assembly

6” total thickness rigid XPS (3 layers of 2” thick boards), entire area, R-30

Foundation wall assembly

2” thick rigid XPS exterior insulation (R-10) below and above grade, entire depth of foundation wall to the top of foundation footing (4 ft). No basement.

Above grade wall assembly

Double stud wall, 12” wall cavity, dense pack cellulose (GreenFiber Cocoon2), R-43
Cedar board siding (1”) with vented rain-screen (3/8”).

Door Assembly
Air Changes per hour, ACH50

Project Team:

Other Team Members:

Ratings:

Awards:

Completion

Completion Date:

Scope

Type of Construction
Number of buildings
Floor area of each building
Bedrooms
Stories 1
Conditioned Building Volume
Conditioned Floor Area 1 248

Location and Climate Details

Single-family residence

Address
16 Euclid Ave
Maynard, MA01754
United States
Location Type Urban
Climate Region Zone 5
Köppen Climate Type Dfb
Lat. / Long. POINT (-71.4556653 42.4328107)
Elevation 160
Solar Insolation 4.47 kWh/m2/day
Annual CDD and Base Temp |
Annual HDD and Base Temp |

Site

Site Conditions:

Site Description:

Monthly Energy Data and Utilities

Energy Data Type:

Electric Utility:

Gas Utility:

Renewables and Energy Balance

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

Renewable Energy System Description & Details:

Annual renewable energy generated 8 292
Annual Renewable Energy Generated Data Type
Power Rating 6Watts
Renewable Energy System Type(s)
Source of Annual Production Data

Walls and Roof

Subslab assembly

6” total thickness rigid XPS (3 layers of 2” thick boards), entire area, R-30

Subslab R-value 30.00
Slab edge assembly

overall R30, but complex detail:
4” total thickness rigid XPS (3 layers of 2” thick boards), R-20.
6” thick section of concrete foundation wall above grade
2” thick rigid XPS exterior insulation with protective coating (Tuff II Coating, Styro Industries), R-10

Slab edge R-value 30.00
Foundation wall assembly

2” thick rigid XPS exterior insulation (R-10) below and above grade, entire depth of foundation wall to the top of foundation footing (4 ft). No basement.

Foundation wall R-value 10.00
Above grade wall assembly

Double stud wall, 12” wall cavity, dense pack cellulose (GreenFiber Cocoon2), R-43
Cedar board siding (1”) with vented rain-screen (3/8”).

Above grade wall R-value 43.00
Cathedral ceiling assembly

24” depth loose fill cellulose (GreenFiber Cocoon2), R-80. Cold attic (vented)

Cathedral ceiling R-value 80.00

Windows and Doors

Window Assembly:

Because window configuration is optimized for passive solar space heating, they have different solar heat gain coefficient (SHGC) and U-values, based on their orientation: high SHGC on the South side, low SHGC on all other sides. Of the total 155.6 sf glazing area, 66% is on the South side, 9% on the North side, and 25% on the East and West sides.
All windows are Inline Fiberglass, Series 325, triple-pane argon filled. Listed SHGC and U-values are full frame.

Door Assembly:

Average window U-factor 0.19
Door U-Factor
Door Area

Mechanical Systems

Space cooling - Manufacturer & Model Mitsubishi,
Space heating - Manufacturer & Model Mitsubishi,
Domestic hot water - Manufacturer & Model Solar domestic hot water as described in the “Renewable Energy” section.
Domestic hot water - capacity
Ventilation - Manufacturer & Model Fresh air ventilation system ,
Lighting Manufacturer and Model
Lighting Efficiency
Mechanical Equipment Installation Details and Comments

Envelope

Air Changes per hour, ACH50
Air Changes per hour, CFM50

General Process

Design for Adaptability:

Software Tools

Software Tools:

General modeling information:

Lessons Learned

Outcome of Project Goals:

Discrepancies:

Rebates and Financial Incentives

Federal incentives
Local incentives
State incentives
Utility incentives
Other incentives
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