Image Credit: Chris Green/Fine Homebuilding 161 Structural insulated panels (SIPs) make a tight shell and go up quickly.
Image Credit: Chris Green/Fine Homebuilding 161 The lofty spaces let in lots of light. All interior materials and finishes were chosen for their low-VOC and formaldehyde content.
Image Credit: Chris Green/Fine Homebuilding 161 Al Rossetto builds all of his homes with a tight shell of structural insulated panels (SIPs), and insulated concrete forms (ICFs). He also uses what he calls a "solar flywheel" where water from solar panels warms a large bed of sand under the home during the day. This heat is then slowly released through the night.
Image Credit: Rob Wotzak AN ATYPICAL LITTLE HOME: 51.4 MMBtu/year. Builder Al Rossetto swears by his list of 5 essential energy efficient features: an ICF foundation, SIP walls, high-efficiency windows, low temperature radiant heat, and a balanced ventialtion system. Based on his repeated success, it seems like he's on to something.
#Modest House Built to Scandinavian Green Standards
This modest home may not seem out of the ordinary, but energy efficiency specialist Efficiency Vermont calls it extraordinary — “Best of the Best” and “the most energy efficient home in the state,” to be specific. With a HERS score of 95.3 out of 100, and four years of energy bills to document its performance, the building deserves the accolades. Builder Al Rossetto leaves nothing to chance: he has used the same construction details to lock in five-star Energy Star ratings for every home he has built since.
Is Vermont the new Scandinavia?
The shallow, frost-protected footing is possibly this home’s most unusual detail. Northern Vermont’s deep frost line and rocky soil make building conventional foundations a challenge. A shallow bed of gravel surrounded by a horizontal apron of rigid foam insulation — a system used in Scandinavia for decades — worked well here.
When paired with an insulated concrete form (ICF) foundation, this system ended up saving energy and materials. The walls and roof are all structural insulated panels (SIPs), which go up quickly and provide a tight shell. Energy efficient windows with triple glazing and multiple low-e layers (also standard equipment in Scandinavia) complete the package.
A healthy indoor space was the top priority
Even though Al put a lot of effort into energy-efficient construction, his first priority was to build healthy home. He started by reviewing material-safety data sheets and scratching unhealthy products off of his list. The tile and solid wood used on the floors of the kitchen, bathrooms, and remainder of the house are easy to clean and don’t off-gas harmful chemicals. A heat recovery ventilator circulates fresh air from outside without letting precious heat escape.
Flat-plate solar collectors provide 75 percent of the domestic hot water and boost the radiant heat system by preheating a 16-in. bed of sand under the ground floor. Mounting the solar panels on the ground instead of on the roof allowed Al to locate the house for accessibility and beautiful views rather than solar orientation. Only three trees had to be cut down to accommodate construction, and most of the wood was used as finished railings, flooring, and stairs. In the end, only six yards of construction waste was hauled away. Everything else was recycled.
It was four years before another home grabbed the title of most energy efficient home in Vermont. Al has no hard feelings. “I’d like to shake their hand” he says about anyone who works as hard as he does to build better, more-efficient homes.
Don't let all the fancy acronyms scare you. Green building isn't only about using exotic materials and high-tech HVAC components. Building an energy efficient home is often just a matter of doing a good job. The SIPs came with an installation manual. "We read it, followed the directions and were conscientious during our work," Al explained. Paying attention to details by filling voids and cracks with spray foam and caulk isn't hard work, but it can make all the difference when it's time to turn on the heat.
General Specs and Team
Builder: Al Rossetto, A. Rosetto Construction
Architect/designer: Al Rossetto
Foundation: shallow frost-protected footing, gravel in perforated PVC forms/drains, 2 in. XPS (R-10) buried and extending horizontally distance of frost depth; 6-in. ICF walls (Amvic, R-22)
Walls: 6.5-in. SIPs (Insulspan, R-22)
Roof:12.25-in. SIPs (Insulspan, R-50)
Windows: triple-pane, low-e, argon-filled; SHGC, .24, U-factor, .2 (Kohltech, R-5)
- Concrete slab over 16-in. sand bed for significant thermal mass
- Extremely tight building envelope
- Solar hot water and radiant heat
- Daylighting facilitated by open floor plan and window layout
- All lighting is CFL or LED
Heating/cooling: radiant heating system fed by solar and gas hot-water heater, 4 flat-plate solar collectors with 120-gallon storage tank and solar heat exchanger
Water heating: shared with radiant heating system
HERS score: 95.3 (old system)
Annual energy use: 51.4 MMBtu
Indoor Air Quality
- Interior portion of Form-A-Drain footing system (under slab) is part of a natural-draft radon-venting system
- Solid wood cabinets and flooring
- Central vacuum system
Green Materials and Resource Efficiency
- Fiber-cement siding
- Trees cut down on site milled into stair parts and loft flooring
- Almost all construction waste recycled
EnergyStar score: 5+ stars