Project Description:
The inspiration for this house came from three sources: Marc Rosenbaum (especially the Hanover NH house), Carter Scott (Transformations Inc. and the Coppersmith Way development in Townsend MA) and Sarah Susanka’s book – The Not So Big House. I was introduced to all three by the NESEA Building Energy conferences.
The motivation for this house was the desire to live comfortably in a way that minimized our contribution to global warming. I also wanted to show that not all new homes had to be big, ugly, and inefficient. Lastly, I wanted to employ the Evergreen Solar panels that I had spent the last 14 years helping to manufacture right here in Massachusetts.
I was very fortunate to work with Carter Scott and Jeff Richards of Transformations Inc. and Rick Gilles of Barnraisers Inc. during the design phase of the project. They did a great job of taking my rough sketches of a one and a half story Maine farmhouse and turning them into a set of construction drawings that incorporated many of the features Carter employed in the Coppersmith Way homes.
I decided to manage the construction phase myself and put in a lot of sweat equity to save money. I was fortunate again to hire Robert Austin of RT Construction to handle the framing and siding. He did a first class job.
Nothing about this house is really new or radical. It uses standard materials and construction practices that are becoming common. It cost about the same to build as a typical home. It’s success lies in the attention to the details – both architectural and energy wise.
Unlike most zero energy homes being built today, this house uses a solar thermal system to satisfy most of its heat and hot water needs. Although it cost more than a pure PV design, the benefits of this system are that it enables the use of radiant floor heating (which is very efficient, comfortable, quiet and draft free), it’s capable of collecting an amazing amount of energy on a sunny day and it enables the use of a simple instantaneous electric water heater for inline backup.The drainback design eliminates the need for antifreeze, eliminates stagnation problems in the summer and is basically maintenance free. Judging by the last years real world results, it worked out very well.
What I think is great about this house is as follows:
1. Net positive performance – no electric bills or fuel bills
2. It’s architecturally pleasing
3. It ‘s the right size – not too big, not too small
4. It’s very pleasant to live in – warm floors, bright sunlit spaces,cool in the summer, warm in the winter, quiet, uniform temperature throughout, comfortable humidity levels in winter
5. Everyone likes the cozy bench seating at the dining table
6. The kitchen layout is great and the pantry keeps it uncluttered
7. The interior windows above the sliding door bring amazing natural light to the second floor bathroom and master bedroom and allow for natural air circulation
8.The vestibule entry with the stained glass window is as practical as it is beautiful.
9. The floor grate by the front door is great for preventing dirt from getting tracked inside
10. The wide windowsills are great for plants
Building Type Summary:
Address:
Elevation:
Lat. / Long.:
Location Type:
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Climate Region:
Solar Insolation:
Annual HDD :
Annual CDD:
HDD Base Temp:
CDD Base Temp:
Occupancy Type and Details:
Except for three weekends, the house was occupied by at least one person. Since June of 2011 it has been inhabited by me, my wife and my 16 year old son. My college daughter was also home for several weeks. Deducting time for vacations, the total number of person days was 1005.
Conditioned Floor Area:
Multiple buildings?:
Total number of units in project (all buildings):
Total floor area of project (all buildings):
Historic?:
Energy Highlights:
Net positive – 3,146 kWh (Oct 12, 2011-Oct 12, 2012)
Warm in winter, cool in summer (without air conditioning)
Humidity level pretty constant around 35-40% RH
Quiet
Very little backup heat required, portable electric baseboard unit used very infrequently
328 gallon solar tank water rose 62 degrees in one day (March 5, 2011 – 64 degrees to 126 degrees)
Annual renewable energy generated:
Electric Utility Company:
Datasets and Utility Bills sources and reliability:
utility bill data
Electricity amount (imported from grid):
Electricity amount (credited or exported to grid):
Net electricity usage (purchased electricity):
Subslab assembly:
2” XPS Foamular R10
Foundation wall assembly:
3.5” closed cell polyurethane foam, 2.5” polyisocyanurate R36
Above grade wall assembly:
Double 2x4 wall construction – very little thermal bridging
Wall insulation: 12” sprayed open cell polyurethane foam R42 (done by Greenstamp Insulation)
Space heating - Manufacturer & Model:
Domestic hot water - Manufacturer & Model:
Domestic hot water - capacity:
Ventilation - Manufacturer & Model:
Outcome of project goals:
What I would do differently next time:
optimum value engineered framing
real time electricity use meter in kitchen
Total Cost of Project:
NESEA Awards:
NESEA Zero Net Energy Building Award 2013 runner-up
Special architectural measures:
True south orientation
Garage on NW corner
Vestibule entry
Large unobstructed 14-12 pitch south facing roof
Living space on south side for natural lighting and passive gain – can be closed off with pocket doors
Internal windows for natural light and air circulation to upstairs bath and master bedroom
No fossil fuels burned on site – except propane barbeque grill
Outside wall penetrations minimized – no furnace or boiler vent, no chimney, kitchen fan vent eliminated by using recirculating type, clothes dryer located outside heated envelope, air to air heat exchanger vents are two in one design – only one hole required for each
1800 sq.ft. of living space, not counting basement
Three bedroom, one and a half bath
Energy Use and Production Documentation:
Subslab R-value:
Foundation wall R-value:
Above grade wall R-value:
Average window U-factor:
Solar Heat Gain Coefficient:
Door U-Factor:
Cost per square foot of Conditioned Space:
Air Changes per hour, ACH50:
Project Photos:
Number of Bathrooms:
Renewable Energy Sources:
Roof Assembly:
External roof insulation: 4.5” polyisocyanurate Hunter Panels Cool – Vent R18.5, 1” air gap
Internal roof insulation: 11” dense pack cellulose R63 total roof
Roof R-value:
Window Description:
Thermotech casement style, fiberglass, triple pane, argon filled, U value 0.19
Different glass with higher SHGC of .64 used on south side for more passive solar gain
No sloped glass
Double cell honeycomb shades
Door Description:
Steel, insulated U.16
Number of Bedrooms:
Team Members:
Peter Kane
Carter Scott, Transformations Inc
Jeff Richards, Transformations Inc
Rick Gilles, Barnraisers Inc
Robert Austin, RT Construction
Mechanical Equipment Installation Details and Comments:
Solar hot water system:
Four (4’ x10’) Heliodyne Gobi flat plate collectors – 160 sq.ft.
STSS 328 gallon storage tank with two 120’ copper coils – one for domestic hot water, one for radiant floor heat
STSS 160 gallon storage tank with 6,000 watt element and 120 ft copper coil for backup heat – not yet used
Drainback design – no antifreeze, just plain water ( ¼” per foot pitch)
Caleffi iSolar BX differential temperature controller with display unit in kitchen
Grundfoss sensors measure kWh –temp. leaving tank, temp returning to tank, flow rate
Tank temp. limited to 160 degrees F.
Pumps - Wilo
Backup :SteibelEltronTempra 15 instantaneous electric hot water heater
TTi Flat Jack roof mounts
All hot water pipes insulated and as short as possible
Ventilation:
Two Fantech SHR 1505 142 CFM air to air heat exchangers
One in basement – services first floor, pulls from bathroom and kitchen, supplies living room
One in attic – services second floor, pulls from bathroom, supplies bedrooms
Controls: 20 minute pushbutton timers, flow switch in shower automatically turns system on
Venmar Transition Tandem exterior vent – only one hole required in outside wall
PV system
5.88 kW, 28 Evergreen Solar ESA210 Fa-3 modules
Estimated anual production 6,500 kWh, actual anual production 7,399 kWh
SolectriaPVI5300 grid tied inverter
Revenue grade meter
TTi Flat Jack roof mounts
Unirac SolarMount rails
Installation by Alteris - now Real Goods Solar
Radiant floor heat system (first floor only):
Roth ¾” radiant floor panels
One zone, six loops of 3/8 PEX tubing – in first floor only
8mm laminate flooring
controls: TEKMAR tN2 House Control 400 outdoor reset, networked thermostats
Caleffi manifold
120’ copper heat transfer coil in storage tank
Taco 009 circulator pump
Upstairs heat system:
1500 W electric fireplaces in each bedroom, rarely used
Windows:
Thermotech casement style, fiberglass, triple pane, argon filled, U value 0.19
Different glass with higher SHGC of .64 used on south side for more passive solar gain
No sloped glass
Double cell honeycomb shades
Doors:
Steel, insulated U.16
Appliances:
Induction cooktop
Highest rated Energy Star fridge and LED TV
Convection oven
Lighting:
No lights are needed during the day
2700K LEDS and compact fluorescents used exclusively
Performance:
Net positive – 3,146 kWh (Oct 12, 2011-Oct 12, 2012)
Warm in winter, cool in summer (without air conditioning)
Humidity level pretty constant around 35-40% RH
Quiet
Very little backup heat required, portable electric baseboard unit used very infrequently
328 gallon solar tank water rose 62 degrees in one day (March 5, 2011 – 64 degrees to 126 degrees)
Msc:
Ultra high efficiency Niagra Conservation Stealth toilets - .8 gallons per flush- work great
Delta low flow showerhead – 1.5 gallon per minute
Kitchen faucet flow shut off
Switched outlet reduces 23 Watt cable TV box standby loss
Quartersawn spruce rain screen siding