Charlotte VT House

Project Subtitle: 

Net Zero House

Project Description: 

This is a 2800 SF single family residence for a family of four located in East Charlotte, VT. The house was completed August 1st 2007   The goal was to create a house with as little environmental impact as possible while maintaining a high level of design and detail in a cold northern climate. The house has been designed to, and has been functioning for the last 9 years( since completed) at net zero energy use with zero carbon emissions, using only electricity generated on site with its 10KW net-metered wind turbine and 5kW PV tracker (added in 2010). Since built the house has been net positive putting 4000 kWh back into the grid.   Being in a rural Vermont landscape we designed the house by taking cues from the local agricultural context. The exterior form expresses the simplicity found in barns and farm houses, allowing us to create a simple building envelope which was more efficient to build and to heat.  The interior was designed with a clean minimal aesthetic allowing focus to the carefully framed views out into the landscape. The design of the house is large enough for a family of four with future flexibility, and small enough to limit energy use and resources. 

 

Project Description

The house maximizes energy efficiency by being long and narrow on the true east west axis with simple massing.   It is a super insulated passive solar design which uses a ground source heat pump for all heating and domestic hot water; the finished floor on the first level is a 4” ground and polished concrete slab for thermal mass and the open plan allows for flexibility as well as southern daylight into all living spaces. The 10KW net-metered wind turbine produces all of the electricity required for heating, hot water, cooking, lighting and appliances. No fossil fuels are used.   Using an integrated design approach, involving the architect/client, energy consultant, structural engineer and the builder allowed us to coordinate all of these strategies into a moderately priced net zero house which maintains a high level of design and detail.  

Building Type Summary: 

Single Family Residence

Other Awards: 

2008 AIA VT Honor award
2009 SBIC High Performance Building award
2008 Effficiency Vermont Best of the Best Honor Award
2012 Vermont Green Building Network Net Zero award and Vermont's Greenest Building Award

Address: 

Charlotte, VT 05445
United States

Elevation: 

500

Lat. / Long.: 

POINT (-73.2609928 44.3098476)

Location Type: 

Rural

Climate Region: 

Zone 6

Solar Insolation: 

3.7

Annual HDD : 

8000

Occupancy Type and Details: 

Family of 4

Number of stories: 

2

Conditioned Floor Area: 

2 800

Semiconditioned Floor Area: 

1 400

Unconditioned Floor Area: 

0

Multiple buildings?: 

Total number of units in project (all buildings): 

1

Total floor area of project (all buildings): 

2 800

Historic?: 

Completion date: 

Wednesday, August 1, 2007

Site description: 

Rural site with an existing 14,000 SF riding arena, horse stalls and residence. Building was disassembled and re-built a 1/4 mile away. New home constructed on the already disturbed land.

Materials: 

Triple glazed windows U = .17
FSC certified wood
Cedar clapboard
Metal siding - durability
Metal roofing - durability
Materials from local sources
Concrete counters locally crafted
Local sustainably harvested maple flooring and hardwoods for cabinetry
Butcher block counter locally harvested and crafted
Reclaimed fir columns
Cellulose insulation
Denim insulation
Closed cell spray foam insulation
Low/no V.O.C. paints and finishes

Energy Highlights: 

High performance envelope with passive solar strategies combined with renewable energy generation and an EV charging station added in 2014. This allows occupants to use renewable energy generated on site to drive approx. 8000 miles per year and still be a net producer of energy

HERS Index: 

0

Annual renewable energy generated: 

16 000

Power Rating: 

14 000Watts

Electric Utility Company: 

Green Mountain Power

Datasets and Utility Bills sources and reliability: 

100% reliable from utility bills, although varies from year to year. Information given is the average of the last few years with an electric car driven approx 8000 miles per year for commuting

Electricity amount (imported from grid): 

8 000

Electricity amount (credited or exported to grid): 

8 000

Net electricity usage (purchased electricity): 

0

Subslab assembly: 

4" of EPS wrapped up to isolate 4" conc slab

Slab edge assembly: 

2" EPS

Foundation wall assembly: 

From exterior to interior - 8" of concrete, 2" of EPS 2x4 dense pack cellulose

Above grade wall assembly: 

2 x 6 studs with closed cell foam with 1.5" of continuous rigid insulation on the exterior.

Cathedral ceiling assembly: 

Attic 2x12 rafters filled with closed cell foam

Door Area: 

60

Space heating - Manufacturer & Model: 

Econar ground source heat pump

Space heating - capacity: 

10 000

Domestic hot water - Manufacturer & Model: 

Econar ground source heat pump

Domestic hot water - capacity: 

80

Ventilation - Manufacturer & Model: 

Venmar

Total Cost of Project: 

600 000

Gross Cost of Renewable Energy System: 

40 000

Value of Tax Credits for renewable energy systems: 

12 000

Net Cost of renewable energy systems: 

28 000

State incentives: 

Vermont Renewable Energy Resource Center - $12,500 incentive for small wind

Utility incentives: 

Net metering

Annual Electric Savings: 

1 200

Annual Revenue from SRECs or other renewable energy credits: 

1 200

Ratings: 

LEED Platinum - first one in Vermont

NESEA Awards: 

2009 Won the first Net Zero NESEA prize

Published References: 

Northeast Sun
Design New England Magazine
Journal of Light construction Magazine
Fine Home Building Magazine
Toward a Zero Energy Home - Book
Home Sweet Zero Energy Home - Book

Special architectural measures: 

This project uses daylighitng, passive solar combined with thermal mass, super insulation, ground source heat pump and a 10kW wind turbine/4kW PV to be a net producer including the use of an all electric car for commuting

Energy Strategies: 

The house maximizes energy efficiency by being long and narrow on the true east west axis with simple massing. It is a super insulated passive solar design which uses a ground source heat pump for all heating and domestic hot water; the finished floor on the first level is a 4” ground and polished concrete slab for thermal mass and the open plan allows for flexibility as well as southern daylight into all living spaces. The 10KW net-metered wind turbine produces all of the electricity required for heating, hot water, cooking, lighting and appliances. No fossil fuels are used

Subslab R-value: 

20.00

Slab edge R-value: 

10.00

Foundation wall R-value: 

22.00

Above grade wall R-value: 

42.00

Cathedral ceiling R-value: 

67.00

Average window U-factor: 

0.17

Solar Heat Gain Coefficient: 

0.65

Visible Light Transmittance: 

0.45

Cost per square foot of Conditioned Space: 

196.00

Air Changes per hour, ACH50: 

1.00

Number of Bathrooms: 

2.50

Site conditions: 

previously developed land
agricultural land
preexisting structure(s)

Renewable Energy Sources: 

Renewable energy is generated on-site but not on the building (e.g. wind turbine in the parking lot)

Summary of enclosure strategy/description: 

The house was conventionally framed with 2 x 6 studs with closed cell spray foam, with rigid insulation on the exterior, creating a thermal bridge free wall system. Air barrier on the exterior. All plates and double studs caulked. Roof -2x12 rafters filled with closed cell spray foam

Roof R-value: 

60.00

Window Description: 

Thermotech fiberglass windows

Door Description: 

Thermatru doors fiberglass.

Mechanical Equipment Installation Details and Comments: 

System was designed by an engineer, third party tested. HRV was tested with Flow hood, blower door was performed.

Number of Bedrooms: 

4

Project Team: 

Architect

Team Member: 

David Pill
Energy Consultant

Team Member: 

Andrew Shapiro
Builder

Team Members: 

Jim Huntington - Builder
John Higgins - Structural Engineer

Status: 

Live

Zero Net Energy Definition Used: 

Site Energy Use

Basis of Performance Claim: 

Verified

Type of Construction: 

New

Renewable Energy System Type(s): 

Photovoltaics
Wind

Renewable Energy System Description & Details: 

10 kW Bergey Wind turbine, 4kW Allsun tracker added in 2010

Annual Renewable Energy Generated Data Type: 

Modeled
Measured

Source of Annual Production Data: 

Monitoring with meters

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

COP 2.7 measured

Air Changes per hour, CFM50: 

600.00

Days per year Building is fully occupied: 

365

Submitter Contact Email: 

Submitter Contact Phone Number: 

(802) 735-1286

Project Type: 

Net Exporter

Lighting Manufacturer and Model: 

All CFL as they burn out switching to LED

Indoor Environment Description: 

All materials vetted for V.O.C's. House uses an HRV for fresh air, windows placed strategically for daylighting