Insulation can cut heating and cooling costs significantly, especially in homes built to today’s energy efficiency standards. It also protects drywall, plumbing, and other structural elements of the home from constant ambient temperature shifts that can cause them to warp or break down over time.
Exterior wall insulation is a key strategy for saving energy and improving indoor thermal comfort in various climate zones. However, different types of insulation require various thicknesses and materials to be effective.
Temperate Climates
Insulation is vital for regulating the temperature of buildings and creating a comfortable living environment. It also contributes to energy efficiency, cost savings and noise reduction. The level of insulation required in different climate zones varies according to temperature patterns and humidity levels.
The primary aim of insulation in cold climates is to reduce heat loss through the surface of the building envelope or air gaps, as well as through fluid flow (convection) and electromagnetic waves (radiative transfer). Insulation for these climates needs to be made up of bulk, thermal or reflective insulation.
In temperate climates, such as those in Sydney and Darwin, the challenge is to prevent both too much heat from entering the home during the hot weather and too much heat from escaping during the cool period. It is important to select a combination type of insulation, such as foil backed boards or blown in cellulose that is vapor permeable and has a high R-value. Foil backed products should be installed with the foil facing inwards unless advised otherwise by the manufacturer.
Cavity fill insulation is a good choice in double brick walls as long as it is treated to be moisture resistant and the total R value achieved is adequate for the climate zone. Fiberglass batts or rolls and blown-in cellulose are a good option for both hot and cold climate zones and should be installed as per the manufacturer’s requirements.
Hot Climates
The same principles of thermal insulation that keep a building warm during cold climates also protect buildings from overheating in hot climatic conditions. However, in this case the goal is to prevent the transfer of moisture and humidity as well. Spray foam insulation is excellent for this purpose as it forms a firm boundary preventing the transfer of heat and moisture and limiting the amount of air movement within a space.
Adding effective insulation to a building in a hot climate helps to reduce the burden on an air conditioning system and significantly cut down energy costs. This makes it much more affordable to live or work in a building and creates a comfortable environment for residents.
Hot climates also need vapor retarders to minimize condensation in walls and ceiling cavities. These are typically placed at the exterior wall where air can most easily penetrate into a building, such as where water pipes are located. They also help to control moisture migration through a building envelope, even on materials such as concrete masonry and brick that were once thought to be impermeable.
Insulation is a good investment no matter the climate, but in hot climates it is particularly valuable and can be used to save a great deal of money on energy bills. However, it is important to remember that insulation only slows down the flow of heat. It doesn’t stop it altogether, so a good combination of shading techniques and high solar reflectance roofing materials will help to maximize energy savings.
Cold Climates
The need for insulation in cold climates is critical. The walls, floors and attics should be well insulated to help prevent energy losses through conduction and convection. It is also important to reduce thermal transmission through the walls of the house (radiative heat transfer) because that is where most heat escapes.
In these climates, high R-value wall insulation is a good option. Energy Star recommends a minimum of R-49 in the attic and R-34 in the walls. Fiberglass and blown-in cellulose are excellent choices. This type of insulation is also great for retrofitting older homes.
It is important to select an insulation material that performs well in the summer as well, because of the large differences between indoor and outdoor temperatures. Natural materials such as wood fiber, cellulose and cork have high thermal capacity and can do this, but they are more expensive than synthetic materials.
A hybrid solution of both exterior insulating sheathing and insulated drywall inside the stud cavity may be appropriate for some climate zones. This combination can improve the overall R-value of the wall assembly to over 16 / RSI2.8 and provide improved moisture resistance. This type of insulation is more effective in cold climates because the higher R-value reduces the interior sheathing temperature to below 35°F, which will limit condensation.
Dry Climates
Insulation is an important element in a home. It reduces the transfer of heat to and from a building, decreasing its energy usage. It is vital for keeping homes warm in winter and cool in summer. The insulation material you choose depends on your climate zone, as well as other factors such as R-value and moisture resistance.
If you live in a dry climate, it is best to use natural and sustainable insulation materials over petrochemical-based ones. For instance, rock wool and glass wool are ideal for exterior walls in temperate and cold climate regions. These materials are made of cellulose fibres, shattered glass, dolomite, and oxides such as aluminium and silicon. They have a low thermal conductivity, which makes them effective in reducing a building’s energy consumption.
Besides being eco-friendly, these materials are fire-retardant and water-resistant, making them perfect for dry climates. If you want to further decrease your building’s energy consumption, consider using a combination of recycled plastics and foam boards. These materials have superior hydrophilicity, fire resistance, and stability compared to regenerated bio-insulation.
In air-conditioned buildings in hot and humid climate zones, it is recommended to use a reflective layer under bulk insulation to increase resistance to radiant heat. It is crucial to install the reflective insulation properly, as it only works when it’s facing downwards and should be kept away from contact with other elements such as ceiling linings.