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Three Types of Eco-Friendly Insulation for a Green Home

Archetype House A and B, exterior

One of the key goals of green building is to significantly reduce the amount of energy consumed over the life of the building from fossil fuels. Buildings work as a system and the tighter the building envelope, the smaller the heating and cooling system you’ll need. Further, if the building is oriented so that it can make maximum use of the sun to help with winter heating and natural lighting during the day the heating and lighting costs will also be reduced.

Insulation:

Insulation is measured by how much heat it can resist per inch (depth), resulting in an “R value” for “resistance value.” The Ontario building code states that newly constructed homes must have minimum levels of insulation – R20 in the walls, R40 in an unused attic, R35 for cathedral ceilings and R12 in the basement.  Because the Archetype homes are demonstration models, several different insulation types were installed in the two homes. They will be monitored to see how they perform over time.

In House A, above grade walls were insulated with mineral wool insulation between studs (R22.5), and fire resistant batt fibre insulation (R21) while the exterior walls were clad with 3″ styrofoam (R12),  7/16″ plywood sheathing, Blueskin exterior expoxy air barrier for a total R value of R35.  There is a vapour barrier and 1/2″ drywall on the interior.

In House B, two types of spray foam were used for insulation: Heatlok Soya Polyurethane 2-pound spray foam plus 1/2″ drywall, and stucco finish on the second and third floors. Icycnene spray foam with 1/2″ drywall and stucco or wood siding on the outside.

Spray foam has several advantages over batt insulation:

• it minimizes air leakage,
• creates a healthier indoor environment, and
• offers greater design freedom

House A and B’s basement walls were insulated using  mineral fibre insulation (R21) with a 2″ extruded polystyrene core over Durisol block resulting in a total value of R22. The basement floor consists of 4″ of poured concrete over a 2″ extruded polystyrene insulation board for a value of R10.

House A unfinished attic. SIPs insulation panels

The cathedral ceilings in both homes were insulated with structural insulated panels (SIPs) for a total insulation value of R39 (the roofing material would account for the last thermal resistance point). The panels consist of “7/16″ oriented strand board on both sides of a 10.5″ expanded polystyene core,” (think of an insulation sandwich).  These panels allow for liveable space in the attic requiring no cross struts across the bottom of the attic space for support thereby making the attic useable space. While the panels are apparently fast and easy to install, you do need to use a crane to get them up to the roof. House A’s attic has been left unfinished while house B’s has been finished with two rooms and a bathroom.

Windows: If the building envelope is tight, the major heat or cooling loss will likely occur through and around the windows. House A’s windows are double-glazed, Argon-filled, low-E (emmissivity) with fibreglass frames. Fibreglass expands and contracts at the same rate as glass, thereby reducing air leakage. House B’s windows are triple glazed, with the low-E coating on layers 2 and 4 with a third layer of glass in the middle of the window.

For more information, or to book a tour of the Archetype homes, click here.

Related posts:

The Archetype Homes: Landscaping the Drought Resistant Way

The Archetype Homes: Construction Waste and Innovative Building Techniques

The Archetype Homes: Green Homes are a Model of Energy Efficiency

Posted by CathyR