Net Zero Homes in Vermont Better Buildings by Design Conference 2009
Project Team Owner - David Pill and Hillary Maharam Contractor -Jim Huntington, NE Housewrights Architect - Pill - Maharam Architects Energy Consultant - Andy Shapiro, Energy Balance Structural Engineer John Higgins, Artisan Engineering
From this
To this
Just need to build an inhabitable version of this!
Goals Create a house with as little environmental impact as possible Not emit any carbon emissions from the house all electric house Create a house which uses as little energy as possible and offset that energy with a renewable resource Maintain a high level of design and detail Affordability- use the most conventional means and methods possible The challenge was to do all of this in a cold northern climate. Define our strategies for achieving these goals from the easiest to the more diffic lt la of diminishing ret rns
Integrated design approach Using this process was just as important as the design and construction itself. Worked with Andy Shapiro and Jim Huntington to find the right balance of constructability and affordability for different strategies throughout the design process
Site What resources does the site offer? Sun, wind, water, views The sun is free - This is the single most cost effective choice to make Orientation House sited to true south
Looking South
Looking North
Design: Massing
Design: Massing
Design: Massing
Design: Massing
Design: Plans Long east to west approx 20 x 60, provides heat and light when the sun shines 2700 SF of finished space Open plan allows for flexibility as well as daylighting throughout Three bedrooms on the second level and a flexible room which serves as both a home office and guestroom Direct gain passive solar No heat source on second
Design: Bioclimatic section
Design: Envelope Above grade walls R 40 Closed cell foam and polyiso board Below grade walls R 26 Cellulose and EPS Basement slab R 16 EPS Basement ceiling R 21 Recycled Denim Roof R 60 Closed cell foam Windows R 6.0 Triple glazed fiberglass orientation specific Insulated Headers
Methods: Under slab Insulation
Methods: Minimize wood maximize insulation
Methods: Closed cell spray foam insulation
Methods: Insulating the rafters
Methods: Radiant tubing and thermal mass
Methods: The thermal box (the cooler)
Methods: Windows Triple glazed fiberglass Low E Argon filled U.15 U.17 Orientation specific glazing: South 322 LOF EA2 VT.63 SHGC.61 U.16 All other 322 AFG TiR VT.57 SHGC.37 U.12
Foaming and sealing
Methods: Blower door and thermal imaging Find and seal the leaks NACH.09 600 CFM @ 50 Pascals
Systems Design: Energy 10 results Begin at the schematic phase Analyze and quantify what the potential loads will be for different design scenarios Look at: massing square footage surface area insulation window u value air leakage thermal mass heating and hot water systems plug loads and appliances Need to get all loads down so the last thing to do is to
Systems Design: Mechanical system Open loop GSHP using domestic water well This was the most efficient way for us to produce our heat and DHW with electricity. Provides 75-100 water to radiant slab. When there is no demand all circulators are off. Actual COP between 2 and 3 including well pump and controls.
Systems Design: HRV and VFD
Systems Design: Drain heat recovery and Low flow supply Hot water usage Showers Dishes Clothes washing Baths Dishwasher Lavatories
Systems Design: Appliances and lighting
Renewable Energy: Wind turbine installation
Renewable Energy: Net metering
Monitoring Installation of: kwh meter for wind turbine BTU meter for GSHP kwh meter for GSHP,well pump, circulators and controls Meter on DHW use
Results: Actual energy consumption Jan 08 to Jan 09 Breakdown by end use Actual Energy 10 Heat incl. pump & controls 1870 kwh 2189 kwh DWH incl. pump & controls 862 kwh 1258 kwh Lighting, appliances & plug 3362 kwh 4332 kwh Total kwh usage kwh 6094 kwh 7779 Wind kwh produced 6286 kwh Total usage/gain Minimal wood use 192 kwh Net gain 175 kwh Total 17 kwh net gain 10000 9000 8000 7000 6000 5000 4000 3000 2000 1000 0 Use Wind Use 6269 kwh Wind 6286 kwh
Production and use Jan 08 to Jan 09 2000 1800 1600 1400 1200 1000 800 600 400 200 0 J F M A M J J A S O N D Use 6269 kwh Wind 6286 kwh
Annual energy use in kwh s 30000 25000 20000 15000 10000 Average code 29,000 kwh Pill ZEH 6269 kwh 5000 0 Heat DHW Light/Appl. Plug Total consumption
West elevation
South elevation
Interior north
Interior south
Homeowner behavior and awareness The efficient design of a home can only do so much. The rest is up to the homeowner. Just as you can adjust your driving habits to maximize the efficiency of a car, you must adjust your lifestyle to increase the efficiency of your house. The end user must be on board.
Homeowner behavior and awareness Keep your thermostat down Turn off the lights in unoccupied spaces Avoid the clothes dryer as much as possible Stop phantom loads with switched outlets Conserve your hot water - Take note how often you turn on the hot water side of the faucet. How long is your shower? Understand your energy use through monitoring
Conclusions Orientation Use the sun it is free!!! Keep the house form small and simple Super insulated and airtight building envelope with no thermal bridges Find the most efficient heating system Use the most efficient lighting and appliances Extras Such as a GFX and VFD Get electrical and loads down as feasibly possible Start with the most basic methods and work toward the more difficult. Apply a renewable energy supply to the lowest possible load you can. Behavior modification for conservation Zero net energy is possible in this climate!!
Dog-on-slab