ICF Energy Efficiency Provides Many Benefits
The high thermal mass and minimal air infiltration of insulating concrete form walls create a more uniform and stable temperature throughout your home. You won’t find hot spots or cold drafts.
This graph shows how much energy is required to overcome heat from different parts of the home.
Where does my home lose efficiency the most?
Every home is different based on the materials and techniques used to build it. But in general the areas that affect energy loss the most are: Walls, Windows, Doors, Ceilings, Floors, Ducts, Infiltration, and Internal Gain.
Exterior walls change the most based on the weather outside. ICF walls because of their insulation on both sides as well as the concrete sandwiched in the middle do not rapidly change back and forth with the heating and cooling day and night. The concrete is referred to as “thermal mass.” Basically because of the thickness and density of the ICF wall it takes so long to change the temperature one direction or the other, the temperature instead stays fairly constant.
Windows don’t have the same thickness, insulation, or thermal mass of ICF or even wood walls. New technology such as multiple panes of glass, sealed gas filled panes, and thermal sheeting make newer windows highly efficient. The natural heating and cooling cycle does affect windows more than walls and is one area where any structure will lose or gain heat.
Keeping the door as much as possible is a great defense against heating or cooling the outdoors. As we enter and leave the home heating or cooling is lost.
The ceiling borders non-climate controlled space, otherwise known as the attic. Insulated attics still heat and cool based on the weather outside and conduct those changes through to the interior of your home. Using an insulated roof or decking system can shield your ceilings from the heat loss or gain. Also you can use spray foam insulation to further insulate the space and provide more protection from changes in temperature.
You can lose as much as 15% of the heat or cooling in your home through your floors. Many homes are built on crawlspace or concrete slab foundations. Energy can leech from the ground and into your home.
Whether overhead or in the ground, air ducts in the attic or in the walls can be a source of energy loss. Make sure your ducts are well sealed, clear of debris and dust, and insulated. Keeping ducts well maintained will aid in energy efficiency.
Air infiltration is also referred to as drafts. Electrical plugs, doors, poorly sealed windows and plumbing can all lead to drafts. ICFs eliminate most of these because the electrical chases and plumbing are just cut into the foam and are not exposed to the outside.
Usually, the largest sources of internal heat gain come from appliances. Eliminating these can not only directly reduce energy usage (if the appliances aren’t running, they are not using energy), but indirectly they keep the temperature of the building, lower thus reducing the energy used by the air conditioner. Stoves/Ovens, Incandescent lighting, dishwashers, clothes dryers, showers, computers, and television all give off heat. This heat can be a great addition in the winter, but during the summer it adds to our cooling bills. ICFs are far superior because you’re maintaining such a standard temperature, the internal gains are fairly constant.
How much can a homebuyer save?
Houses built with ICF exterior walls require an estimated 44% less energy to heat and 32% less energy to cool than comparable frame houses. The bigger the house, the bigger the savings. In hotter areas, heating savings will be less and cooling savings more.
The smaller heating and cooling equipment needed for such an energy-efficient house can cut construction costs by an estimated $500 to $2,000. The biggest equipment savings come with the houses that have the most energy savings.
Where do the savings come from?
Insulating values for ICF walls using polystyrene foam are R-17 to R-26, compared to wood frame’s R-9 to R-15. ICF walls are expected to cut conduction losses through foundation and above-grade walls in half. And ICF walls are tighter. In tests, they averaged about half as much infiltration (air leakage) as wood-frame homes.
The energy efficiency of ICF houses has been independently verified by other agencies. They compared the energy use of single-family houses with various exterior walls including ICF, concrete masonry, and wood framing. The results show that in almost all climates across the US and Canada, concrete homes use less energy for heating and cooling.
But ICF walls do more than cut down on energy loss. Concrete gives them the heat-absorbing property, “thermal mass,” the ability to smooth out large temperature swings. It keeps the walls warmer when the outdoor temperature hits its coldest extreme and cooler when the outdoor temperature is hottest. The walls “add back” heat or cooling, which contributes about 6% of the energy needed for free.
Since the energy needed is less, furnaces and compressors that heat and cool can be smaller. And the more the energy savings, the greater the possible reduction in equipment size —and cost.