Consider this proposed approach to evaluating the environmental and life-cycle costs of thermal insulation.

Specifiers of construction materials find themselves on the front line of today's environmental struggles. They need to know all the implications of their product selections, both short and long-term. While insulation materials constitute a relatively small part of the overall cost of a building or plant, they determine a disproportionately large share of a facility's long-term environmental impact.

For purposes of this discussion, the environmental impact of thermal insulation falls into two categories: indirect and direct. Indirect environmental impacts are those which reduce the amount of energy consumed or lost through poorly performing insulation. Reducing energy losses reduces the demand for energy, thereby conserving nonrenewable fuel supplies and reducing the amount of pollutants, such as carbon dioxide (CO2), sulfur dioxide (SO2) and nitrogen oxides (NOx), released into the atmosphere through the burning of fossil fuels.

Direct environmental impacts result from the insulation manufacturing process itself, like the release of hydrochlorofluorocarbon (HCFC) and other potential ozone-depleting foaming agents, as well as from the landfill disposal of spent insulation.

Environmental Problems

Many of the world's environmental problems, including pollution, ozone depletion, acid rain, global warming and waste disposal, can be tied in one form or another to energy consumption.

Pollution. Thermal insulation plays a significant role in both the consumption and conservation of energy. The reduction of energy demand through the use of energy-efficient construction practices and insulation ultimately will reduce pollution from the burning of fossil fuels for direct heating and generation of electricity.

Ozone Depletion. According to the U.S. Environmental Protection Agency (EPA), the use of HCFCs and other chemical foaming agents in the United States for the manufacture of plastic insulating foams is a contributor to ozone depletion.

Acid Rain. There are two ways to minimize acid rain formation: (1) burn less fossil fuels; and, (2) remove the SO2 and NOx from the combustion gases. Reducing energy demand - and therefore reducing the burning of fossil fuels by using energy-efficient building practices and efficient, long-life insulation - will also have a positive carry-over effect on the acid rain problem.

Global Warming. An effective means of reducing the production of greenhouse gases is the control and reduction of fossil fuel combustion through proper insulation practices.

Waste Disposal. When designing and constructing buildings and plants, careful attention must be paid to both the environmental and economic life cycles of the insulation system. Both the manufacture of building materials and the construction of buildings and plants consume considerable amounts of energy. Specifiers of building materials and construction practices need to ensure that they are selecting efficiently manufactured materials, which will provide optimal performance and maximum service life before needing to be replaced and disposed.

By specifying and using insulation with a long-life expectancy, companies save not only money on replacements and retrofits, but also ensure they are doing their part to reduce the waste stream.

Balancing Environmental Responsiblities

When selecting an environmentally responsible insulation, it is no longer sufficient merely to select the required K-value and temperature range. The insulation must also (1) provide constant thermal performance in the actual operating environment, (2) be environmentally benign during manufacturing, (3) have a service life that will ensure long-term performance and minimize replacement and disposal in landfills, and (4) pose no health risks to those handling or installing it.

Realistically, these concerns need to be balanced with concerns of cost-effectiveness. The energy cost-effectiveness of an insulation could be expressed in terms of cost savings. If the cost of the energy saved by using a particular insulation is less than the total energy used in its manufacturing, installation, planned use, plus the energy used to recycle it, then it is not cost-effective. Also, the amount or cost of pollution avoided by using a certain type of insulation throughout its service life should be greater than the cost of pollution resulting from its manufacture and use. By carefully weighing all the factors and costs involved in these two relationships, the overall environmental profile of an insulation, or its environmental balance can be determined.

A Proposed Evaluation Technique

The above relationships hold true only if the insulation is (1) used in the proper way, (2) used in the correct thickness, (3) is properly installed, and (4) it maintains its expected performance and physical properties throughout its entire service life.

Achieving Environmental Balance With Cellular Glass Insulation

In discussing how cellular glass insulation achieves environmental balance, three critical attributes of the product must be evaluated: (1) its environmental profile, (2) its service life and efficiency, and (3) its environmental cost-effectiveness.

The environmental profile of an insulation depends on the following four characteristics: (1) its raw materials; (2) its manufacturing process, including gray energy, or the energy expended during the extraction, processing and transportation of raw materials; (3) installation and related methods and materials; and, (4) its disposal.

Raw Materials & Their Processing

The Manufacturing Process. Cellular glass insulation consists exclusively of minute sealed glass cell, formed by reacting ground glass at a high temperature. All the raw materials used to make glass are naturally occurring substances, commonly found in nature. None constitute a danger to man or the environment.

The manufacturing of cellular glass insulation involves the production of glass and a foaming (cellulating) process. This process produces CO2, which becomes entrapped in the tiny glass cells of the material. No additional foaming agents, HCFCs, organic binders or potentially harmful substances are used that might contribute at atmospheric pollution. In the finishing stage, rough blocks of cellular glass are cut and trimmed to their desired dimensions. During finishing, a certain amount of crushed glass or glass dust is produced as well as quantities of cell gasses. The glass dust is relatively heavy, so it is classified as a nuisance dust. It is neither carcinogenic nor likely to cause silicosis. Almost all of the dust and glass scraps are collected and recycled in a melting furnace to make new glass.

Energy Use & Air Pollution. Manufacturing of cellular glass insulation is essentially a thermal process and uses considerable energy, from both electrical and natural gas heating, to melt and foam the glass. While heating with natural gas and generating electricity with fossil fuels mean releasing air pollutants, the pollution resulting from manufacturing is considerable less than that which would result from increased energy use if cellular glass insulation were not used.

Plant Energy Efficiency. The plant recovers energy from both of its most energy-intensive operation: glass melting and cellulating. In both operations, hot exhaust gases from the combustion of natural gas are used to preheat the air used in the combustion process.

Installation and Use. The cutting and fitting required during the installation of cellular glass insulation releases small quantities of entrapped cell gases that might otherwise be considered harmful to the environment. However, the quantities are too small even to be considered atmospheric pollutants.

Disposal. Because of the unique physical characteristics of cellular glass insulation, it has a long service life. Typically, the system on which the insulation is installed is replaced or repaired before the insulation reaches the end of its life, or the site where it is installed is demolished. When the insulation reaches the disposal stage, will it have a detrimental impact on the environment?

Although all of the physical insulating properties of cellular glass insulation are typically intact at the time of removal or building demolition, it is not feasible to reuse this material as an insulation. The time required to salvage, sort, and clean would be economically prohibitive. Crushed cellular glass, however, has been used as a fill material for roadways, as a soil conditioner/additive and as a supplement to asphalt paving.

In most instances, cellular glass insulation ends its product life in either a municipal landfill or in a construction-and-demolition landfill. Crushing the insulation prior to disposal reduces its volume by 5 to 7 times. Since it is inert and environmentally benign, there is no danger to the ground-water regime.

Service Life & Energy Efficiency

While it's possible to construct buildings to last 50 years or more, construction practices today are turning out structures with as little as a 15- to 20-year service life. Industrial plants typically have shorter service lives. The unusual composition of cellular glass insulation makes it uniquely resistant to all types of potential insulation damage, including moisture absorption, thermal expansion and contraction, fire, corrosion and vermin. Because of its long-lived insulating properties, cellular glass insulation may even extend the service life of a facility.

The environmental "bottom line" of any insulation is how much energy (and resulting pollution) it saves or avoids through its use. In calculating two scenarios using a particular brand of cellular glass, we find that (1) by installing 2-inch-thick insulation on a 12-inch steam line operating at 400°F, the energy (pollution) saved over a five-year period by using the insulation equals 1,900 times the energy (pollution) created during the manufacture of the insulation; and, (2) the energy saved by installing 4-inch-thick cellular glass roof insulation system over a 40-year life is 134 times the energy created during the manufacture of the insulation.

Selecting cellular glass insulation should involve three separate evaluation, each assigned its own weight or number of points: technical, economic and environmental. (See chart.)

Conclusion

In conclusion, the environmental crises we are confronting today should cause us to re-evaluate the building practices of the last several decades. No longer can we afford to be energy-inefficient or environmentally unwise. In order to make educated decisions about the environmental characteristics and performance of any insulation product, contact the manufacturer directly.

Building materials, including insulation, need to be environmentally safe during their manufacture, installation, service life and disposal. In addition, constructing buildings and facilities using energy-efficient materials and methods to provide an extended service life is the only way we can achieve a level of economic and environmental cost-effectiveness acceptable to businesses, consumers and the community at large.

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The information contained in this article is a condensed version of a comprehensive booklet titled "Evaluating the Environmental Costs and Energy Consumption of Thermal Insulations: A Proposed Approach," which was published in 1994 by Pittsburgh Corning Corporation, headquartered in Pittsburgh, Pa.

For more information on cellular glass insulation, contact David K. Goss at Pittsburgh Corning by mail at 800 Presque Isle Dr., Pittsburgh, PA 15239-2799, by phone at (800) 359-8433 or via fax at (724) 327-5890.

One proposed decision-making process, shown in the above chart, involves three separate evaluations, each assigned its own weight or number of points: technical, economic and environment. Consider this evaluation when deciding which insulation materials and systems are best for your purposes.

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