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Insulation for Energy Efficiency

Materials with a High Thermal Mass

While lining the roof, walls, and floor with insulation can reduce heat loss in winter and heat gain in summer, choosing building materials with a high thermal mass is important, especially in areas where there is a marked difference between day and night temperatures.  Thermal mass refers to the ability of a material to absorb heat energy.  A lot of heat energy is required to change the temperature of high density materials.  Materials with a high thermal mass include:

• stone 
  
• brick
  
• rammed earth
  
• concrete
  
• tiles

Using thermal mass correctly moderates the internal temperature of the home by averaging the day/night temperature of the home.  These materials work best when they are exposed to the winter sun for prolonged periods of time, allowing the material to store the heat.  However, in summer, it is important that these same materials remain shaded in order to stop them retaining heat and actually make the home hotter.

Dark, matte, or textured surfaces absorb and re-radiate more energy than light, smooth, reflective surfaces.

Glass and Insulating Factors

Glass is actually a very poor insulator and the sun’s rays easily pass through a normal window.  This can provide extra heat in winter but often makes it uncomfortable in summer.  Double-glazed windows are an option as they reduce conducted heat transfer.  However, they don’t significantly reduce radiant heat transfer so they do need to be used with external shading in summer.   Double-glazed windows are good at slowing heat losses to the outside, making them popular in cold climates.

In an energy efficient home, think about the size, location, and glazing type of your window, as well as the window coverings.  Windows that face north should be full length.  Use minimum glass on the western and eastern sides of your home, and place small areas of glass on the southern side.  The total window area should be less than 25 percent of the total floor area of the home.  Ensure that your windows are well-sealed to reduce heat loss through tiny gaps.  Triple sealing them is the best.