Superinsulation - AbsoluteAstronomy.com

Superinsulation is an approach to building design, construction, and retrofitting that dramatically reduces heat loss (and gain) by using much higher levels of insulation and airtightness than normal. Superinsulation is one of the ancestors of the passive house

Passive house

The term passive house refers to the rigorous, voluntary, Passivhaus standard for energy efficiency in a building, reducing its ecological footprint. It results in ultra-low energy buildings that require little energy for space heating or cooling. A similar standard, MINERGIE-P, is used in...

approach.

Definition

There is no set definition of superinsulation, but superinsulated buildings typically include:

Very high levels of insulation
Building insulation
building insulation refers broadly to any object in a building used as insulation for any purpose. While the majority of insulation in buildings is for thermal purposes, the term also applies to acoustic insulation, fire insulation, and impact insulation...

(typically R_ip40
R-value (insulation)
The R-value is a measure of thermal resistance used in the building and construction industry. Under uniform conditions it is the ratio of the temperature difference across an insulator and the heat flux through it or R = \Delta T/\dot Q_A.The R-value being discussed is the unit thermal resistance...

walls and R_ip60
R-value (insulation)
The R-value is a measure of thermal resistance used in the building and construction industry. Under uniform conditions it is the ratio of the temperature difference across an insulator and the heat flux through it or R = \Delta T/\dot Q_A.The R-value being discussed is the unit thermal resistance...

roof, corresponding to SI
International System of Units
The International System of Units is the modern form of the metric system and is generally a system of units of measurement devised around seven base units and the convenience of the number ten. The older metric system included several groups of units...

U-values of 0.15 and 0.1 W/(m²·K) respectively)
Details to ensure insulation continuity where walls meet roofs, foundations, and other walls
Airtight construction, especially around doors and windows
a Heat recovery ventilation
Heat recovery ventilation
Heat recovery ventilation, also known as HRV, mechanical ventilation heat recovery, or MVHR, is an energy recovery ventilation system using equipment known as a heat recovery ventilator, heat exchanger, air exchanger, or air-to-air heat exchanger which employs a counter-flow heat exchanger between...

to provide fresh air
No large windows facing any particular direction
Much smaller than conventional heating system, sometimes just a small backup heater

Nisson & Dutt (1985) suggest that a house might be described as "superinsulated" if the cost of space heating is lower than the cost of water heating.

Theory

A superinsulated house is intended to reduce heating needs very significantly and may even be heated predominantly by intrinsic heat sources (waste heat generated by appliances and the body heat

Body heat

Body Heat is a 1981 film by Lawrence Kasdan.Body Heat may also refer to:*Body heat or thermoregulation, the ability of an organism to keep its body temperature within certain boundaries*Body Heat...

of the occupants) with very small amounts of backup heat. This has been demonstrated to work even in very cold climates but requires close attention to construction details in addition to the insulation (see IEA Solar Heating & Cooling Implementing Agreement Task 13

IEA Solar Heating & Cooling Implementing Agreement Task 13

IEA Solar Heating & Cooling Implementing Agreement - Task 13 was an international effort organised by one of the International Energy Agency's Implementing Agreements to build several solar low-energy houses. This took place between 1989 and 1993...

History

The term "superinsulation" was coined by Wayne Schick at the University of Illinois at Urbana-Champaign

University of Illinois at Urbana-Champaign

The University of Illinois at Urbana–Champaign is a large public research-intensive university in the state of Illinois, United States. It is the flagship campus of the University of Illinois system...

. In 1976 he was part of a team that developed a design called the "Lo-Cal" house, using computer simulations based on the climate of Madison, Wisconsin

Madison, Wisconsin

Madison is the capital of the U.S. state of Wisconsin and the county seat of Dane County. It is also home to the University of Wisconsin–Madison....

. Several houses, duplexes and condos based on Lo-Cal principles were built in Champaign-Urbana, Illinois

Illinois

Illinois is the fifth-most populous state of the United States of America, and is often noted for being a microcosm of the entire country. With Chicago in the northeast, small industrial cities and great agricultural productivity in central and northern Illinois, and natural resources like coal,...

in the 1970s.

In 1978 the "Saskatchewan House" was built in Regina, Saskatchewan

Regina, Saskatchewan

Regina is the capital city of the Canadian province of Saskatchewan. The city is the second-largest in the province and a cultural and commercial centre for southern Saskatchewan. It is governed by Regina City Council. Regina is the cathedral city of the Roman Catholic and Romanian Orthodox...

by a group of several Canadian government agencies. It was the first house to publicly demonstrate the value of superinsulation and generated a lot of attention. It originally included some experimental evacuated-tube solar panels, but they were not needed and were later removed.

In 1979 the "Leger House" was built by Eugene Leger, in East Pepperell, Massachusetts

East Pepperell, Massachusetts

East Pepperell is a census-designated place in Middlesex County, Massachusetts, United States. The population was 2,034 at the 2000 census.-Geography:East Pepperell is located at ....

. It had a more conventional appearance than the "Saskatchewan House", and also received extensive publicity.

Publicity from the "Saskatchewan House" and the "Leger House" influenced other builders, and many superinsulated houses were built over the next few years. These houses also influenced Wolfgang Feist when he developed the Passivhaus standard

Passive house

Retrofits

It is possible, and increasingly desirable, to retrofit superinsulation to an existing older house or building. The easiest way is often to add layers of continuous rigid exterior insulation, and sometimes by building new exterior walls that allow more space for insulation. A vapor barrier

Vapor barrier

A vapor barrier is often used to refer to any material for damp proofing, typically a plastic or foil sheet, that resists diffusion of moisture through wall, ceiling and floor assemblies of buildings and of packaging...

can be installed on the outside of the original framing but may not be needed. An improved continuous air barrier is almost always worth adding, as older homes tend to be leaky, and such an air barrier can be important for energy savings and durability. Care should be exercised when adding a vapor barrier as it can reduce drying of incidental moisture, or even cause summer (in climates with humid summers) condensation

Condensation

Condensation is the change of the physical state of matter from gaseous phase into liquid phase, and is the reverse of vaporization. When the transition happens from the gaseous phase into the solid phase directly, the change is called deposition....

and consequent mold

Mold

Molds are fungi that grow in the form of multicellular filaments called hyphae. Molds are not considered to be microbes but microscopic fungi that grow as single cells called yeasts...

and mildew

Mildew

Mildew refers to certain kinds of molds or fungi.In Old English, it meant honeydew , and later came to mean mildew in the modern sense of mold or fungus....

. This may cause health problems for the occupants and damage the existing structure. Many builders in northern Canada use a simple 1/3 to 2/3 approach, placing the vapor barrier no further out than 1/3 of the R-value of the insulated portion of the wall. This method is generally valid for interior walls that have little or no vapor resistance (e.g. they use fibrous insulation) and controls air leakage condensation as well as vapor diffusion condensation. This approach will ensure that condensation does not occur on or to the inside of the vapor barrier during cold weather. The 1/3:2/3 rule will ensure that the vapor barrier temperature will not fall below the dew point temperature of the interior air, and will minimize the possibility of cold-weather condensation problems. For example, with an internal room temperature of 20°C (68°F), the vapor barrier will then only reach 7.3 °C (45 °F) when the outside temperatures is at −18°C (-1°F). Indoor air dewpoint temperatures are more likely to be in the order of around 0 °C (32 °F) when it is that cold outdoors, much lower than the predicted vapor barrier temperature, and hence the 1/3:2/3 rules is quite conservative. For climates that do not often experience -18°C, the 1/3:2/3 rule should be amended to 40:60% or 50:50. As the interior air dewpoint temperature is an important basis for such rules, buildings with high interior humidities during cold weather (e.g., museums, swimming pools, humdified or poorly ventilated airtight homes) may require different rules, as can buildings with drier interior environments (such as highly ventilated buildings, warehouses). The 2009 International Residential Code (IRC) embodies more sophisticated rules to guide the choice of insulation on the exterior of new homes, which can be applied when retrofitting older homes.

A vapor permeable building wrap on the outside of the original wall helps keep the wind out, yet allows the wall assembly to dry to the exterior. Asphalt felt and other products such as permeable polymer based products are available for this purpose, and usually double as the Water Resistant Barrier / drainage plane as well.

Interior retrofits are possible where the owner wants to preserve the old exterior siding, or where setback requirements don't leave space for an exterior retrofit. Sealing the air barrier is more difficult and the thermal insulation continuity compromised (because of the many partition, floor, and service penetrations), the original wall assembly is rendered colder in cold weather (and hence more prone to condensation and slower to dry), occupants are exposed t major disruptions, and the house is left with less interior space. Another approach is to use the 1/3 to 2/3 method mentioned above — that is, to install a vapor retarder on the inside of the existing wall (if there isn't one there already) and add insulation and support structure to the inside. This way, utilities (power, telephone, cable, and plumbing) can be added in this new wall space without penetrating the air barrier. Polyethylene vapor barriers are risky except in very cold climates, because they limit the wall's ability to dry to the interior. This approach also limits the amount of interior insulation that can be added to a rather small amount (e.g., only R6 can be added to a 2x4 R12 wall).

Costs and benefits

In new construction, the cost of the extra insulation and wall framing may be offset by not requiring a dedicated central heating system. In homes with numerous rooms, more than one floor, air conditioning or large sized, a central furnace is often justified or required to ensure sufficiently uniform thermal conditions. Small furnaces are not very expensive and some ductwork to every room is almost always required to provide ventilation air in any case. Because the peak demand and annual energy use is low, sophisticated and expensive central heating systems are not often required. Hence, even electric resistance heaters may be used. Electric heaters are typically only used on the coldest winter nights when overall demand for electricity is low. Other forms of backup heater are widely used, such as wood pellets, wood stoves, natural gas boilers or even furnaces. The cost of a superinsulation retrofit may need to be balanced against the future cost of heating fuel (which can be expected to fluctuate from year to year due to supply problems, natural disasters or geopolitical events), the desire to reduce pollution from heating a building, or the desire to provide exceptional thermal comfort.

A superinsulated house takes longer to cool in the event of an extended power failure during cold weather, for example after a severe ice storm disrupts electric transmission because heat loss is much less than normal buildings, but the thermal storage capacity of the structural materials and contents is the same. Adverse weather may hamper efforts to restore power, leading to outages lasting a week or more. When deprived of their continuous supply of electricity (either for heat directly, or to operate gas-fired furnaces), conventional houses cool more rapidly during cold weather, and may be at greater risk of costly damage due to freezing water pipes. Residents who use supplemental heating methods without proper care during such episodes, or at any other time, may subject themselves to risk of fire or carbon monoxide poisoning

Carbon monoxide poisoning

Carbon monoxide poisoning occurs after enough inhalation of carbon monoxide . Carbon monoxide is a toxic gas, but, being colorless, odorless, tasteless, and initially non-irritating, it is very difficult for people to detect...

External links