ASHRAE Journal - August 2011 - 66

emerging technologies

superinsulated homes
By Alissa cooperman; John Dieckmann, Member ASHRAE; and James Brodrick, Ph.D., Member ASHRAE

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uperinsulating uses conventional materials in a nonconventional way to accomplish significant energy savings achievable in any

Housing Component Walls Ceilings Floors Foundations

Minimum R-Value 32 50 20 10

climate. The concept of superinsulating emerged in the 1980s as the cost of heating began to skyrocket. Increased insulation and air sealing with a ventilation system and nonconventional means of heating comprise a superinsulated house. Such a dwelling can save up to 75% of the annual costs for heating and cooling.1 Also, superinsulating can be accomplished during construction or significant retrofit of a dwelling, independent of its type or design.
A superinsulated house minimizes heat loss by significantly increasing the thermal resistance between the interior and exterior of the house. This is accomplished by increasing insulation (raising the R-value) in the walls, ceilings, roofs, and floors, in addition to careful construction which ensures that the dwelling is airtight. Table 1 outlines the R-value requirements for a superinsulated home.2 Due to the high R-values, walls of superinsulated houses are thicker than those of conventional homes. This necessitates insetting or recessing and careful sealing of windows and doors as they span the layers of the wall.3 Also, superinsulated homes are designed with the window area being no more than 10% to 15% of the total floor space, with the majority of the windows concentrated on the south-facing walls to maximize the benefits of solar heat gain.2 Insulation used to create a superinsulated house can range from common insulating materials, such as fiberglass batts, polystyrene foams and other fossil fuel-based foams, to sheep’s wool or aerogel insulation.4 The R-values and costs for these types of insulation can be seen in Table 2.

table 1: Superinsulated home required R-values.2 rafters, and floor joists. It is most effective when installed without voids and uncompressed by the wall cavity. For use in basements, this type of insulation can be purchased with a flame-resistant facing.6 Loose-fill fiberglass insulation also is available. It is comprised of 20% to 30% recycled glass. Like other products on the market, it can also be blown-in to create a “blown-in-blanket.” For this type of construction the material is processed with an adhesive.13 Cellulose insulation provides 38% higher performance than glass wool in terms of conductive heat loss, and air infiltration. It requires 20 times less energy to manufacture than other fiber insulations. Since the materials used to
Thermal Conductivity Btu·in/°F·ft2·h (W/m·K) 0.31 (0.04) 0.22 (0.03) 0.23 (0.03) 0.13 (0.02) 0.28 (0.04) 0.27 (0.04) 0.1 (0.01) Cost ($/ft2) $0.12 – $0.60 (Batt)6 $0.60 – $1.207,8 $0.74 – $1.30 (XPS) $3.50 $0.73 (Loose Fill)8

common insulation types
The most common form of insulation on the market is the fiberglass blanket (batt or roll), which is sized to fit standard construction spacings for wall studs, roof
Type of Insulation Fiberglass5 Mineral Wool Polystyrene9,10 Polyurethane11 Sheep’s Wool12 Cellulose5 Aerogel R-Value °F·ft2·h/Btu·in 3.14 – 4.30 (Batt) 2.20 – 4.30 (Blown, Attic) 3.7 – 4.3 (Blown, Wall) 3.5 – 5.5 3.8 – 5.0 (Rigid) 7 – 9 (Rigid) 3.6 3.6 – 3.7 (Attic) 3.8 – 3.9 (Wall) +10

table 2: Common and alternative insulating materials’ properties.
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ASHRAE Journal - August 2011

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