When building a net zero energy green home, it’s best to begin with a list of design priorities…that is, a list of attributes, materials, design features, whatever, that you want to communicate with your architect and builder. If you are new to building, you may need to assemble a design team that meets to suggest ideas in lots of different areas: solar heating, insulation levels, building materials, water systems, solar hot water, solar electricity, finishes, and others. Here’s the list I prepared for my architect, James Plagmann of HumaNature Architecture, a gentleman I’ve worked with for quite a few years. I am including it here so others can benefit from my experience in energy efficiency, solar energy, green building, etc.
Design Priority – Chiras/Stuart Residence
Revised 5/16/2011
Footprint
Original dimensions 34.5 x 45 OD, or 1552 square feet
New dimensions (single story) : about 26 x 50 or 1300 square feet
Preference – more rectangular so all rooms have access to the sun for passive solar
Heating and Cooling
Passive Solar heating and cooling, net zero energy
Heat passively with backup 1,000-watt heater in energy recovery ventilator (ERV)
Materials
All recycled and natural materials
Nontoxic building materials – no VOCs
Minimize waste by designing in 2-foot increments and to dimensions of Tech Block
Framing – advanced framing to minimize wood use
Roof
Metal roof for durability and rain catchment
Gutters and downspout for rainwater catchment – water preferably diverted to buried tank for garden watering
Ensure plenty of south-facing roof for solar hot water system and possible PVs – don’t compromise solar gain with dormers or other features on south side
Foundation
Poured concrete with R-25 exterior insulation
Surface diversion system to reduce water against foundation – two feet down, 10-foot apron of polyethylene (two layers) to divert water away from house to minimize mold
French drain below perimeter of the apron to remove water
Slab
Concrete with fly ash, if possible
R-25
Please pay attention to all penetrations, including floor drains, if any, to avoid air infiltration
Walls
R-60 plus
Materials: Double 2 x 4 wall, outside wall load bearing.
Stud spacing: 24 inches oc.
Insulation: Two inches high density Icynene — R-13.6
14 inches dry blown cellulose insulation at 3.2 per inch – R-44.8
R-value = R 58.4
Ceiling
Insulation – R-90 to R-100
How do we achieve this?
One solution:
Four inches of high density Icynene (6.8 per inch) between ceiling joists to create airtight seal – R 27.2
20 inches of dry blown cellulose (3.2 per inch) – R-64
Energy heel trusses
Total insulation = R=91
Limit or eliminate ceiling cans – all ceiling cans should be airtight insulation contact recessed cans
LED and CFL lighting throughout – we need to include as much LED as possible
Floor
Top cord bearing trusses – approximately 24 inches
Insulate for sound proofing and possibly thermal performance
Windows
All windows – low-E
Wood frame with metal cladding
U factor — 0.10 to 0.14 (R 7 to 10)
Wood frame with metal cladding. No vinyl or fiberglass windows
Warm edge spacers
South-facing windows – Solar Heat Gain coefficient 0.6 or higher
East and West windows – SHGC 0.35
Visual Transmittance – 0.6 or higher
Air infiltration – 0.3 or less
High condensation resistance
Would like to install thermo shutters on interior of all windows – so please leave room beside windows for attachment and “storage” of thermoshutters
Finishes
Interior – Hopefully, earthen plaster with earthen plaster finish coat or drywall with earthen or lime plaster finish coat
Exterior – Hardiboard
All nontoxic paints, stains, and finishes
Contributing editorDan Chirasis a renewable energy and green homes expert who has spent a lifetime learning life’s lessons, which he shares in his popular blog,Dan Chiras on Loving Life. He’s the founder and director of The Evergreen Institute and president of Sustainable Systems Design. Contact him by visitinghis websiteor finding him onGoogle+.
