History of Insulation

  • In medieval times, in northern climates the walls were stuffed with straw and mud plaster to try to keep out the cold.
  • Insulation evolved very slowly until 1932, when the process to create fiberglass was discovered by accident.
  • Over the next decade this material was made into blankets and began to be used widely to help make buildings more efficient and comfortable.
  • Originally spray-in polyurethane oams developed in the 1940’s and they have become continually more popular since the late 1970’s.
  • The greatest advances in the past 20-30 years in insulation have been in the area of spray foams.

Methods and Materials

  • Fiberglass: Fiberglass is the most common insulation used in modern times. It is used in a wide variety of applications because it slows the spread of heat, cold, and sound in structures, cars and aircraft, it keeps rooms warm in the winter and cool in the summer and thereby serves as a convenient method to increase energy efficiency
  • Cellulose:
  • Blown cellulose can be installed in new or existing structures because it is a great option for an attic floor or enclosed wall cavity.
  • Damp-sprayed cellulose provides an effective solution for open wall cavities in new construction.
  • Mineral Wool: When its pressed into rolls and sheets, its ability to partition air makes them excellent insulators and sound absorbers.
  • Spray Foam: Its is a chemical product created by two materials, isocyanate and polyol resin, which react when mixed with each other and produce a high thermal insulating value with no air infiltration.
  • Reflective or Radiant Barrier: Usually installed in attics to reduce summer heat and insulate against winter cold. Radiant and reflective barriers reduce radiant heat gain instead of slowing it like in other materials.


  • Fiberglass: The average cost per square foot is between $0.64 - $1.19
  • Spray Foam: Professional application of spray polyurethane is typically calculated by the board foot.
  • Open-cell spray foam is generally 35 to 55 cents per board foot
  • Closed-cell spray foam is generally $1.00 - $2.00 per board foot
  • Reflective or Radiant Barrier: To cover a typical 500 square foot attic, you'll likely spend $175 to $325

New Technology

  • Newest types of eco-friendly insulation are:
  • Recycled Denim: From denim clothing. This insulation is suitable for residential and commercial use in the same places as fiberglass
  • Icynene: It delivers up to 50% greater energy savings when compared to other home insulation products.
  • Nanogel: It provides a superior combination of thermal and sound insulation.

Heat Transfer

  • Heat transfer is the exchange of thermal energy between physical systems.
  • The rate of heat transfer depends on the temperatures of the material and the properties of the materials through which the heat is transferred.
  • The three fundamental modes of heat transfer are conduction, convection and radiation.


Created with images by jmrodri - "Living room insulated"

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