ICFs - Insulating Concrete Forms
The payback on your decision to use BuildBlock ICFs begins the day you move into your new home. It starts with the way things sound different. It is quieter. With your solid concrete core and 2-1/2" inner and outer layer of EPS insulation, your walls are sealed tight. When the wind is blowing hard or a heavy rain is pelting the exterior, the only noise you will hear is coming through your windows. You won't hear the creaking and groaning sounds of wood construction. You may also notice a difference in the way TV and music sounds when played in a room with an ICF exterior wall.
The second thing you will notice is the way the house feels. You don't have cold spots around the exterior walls. The cold spots typically found along the exterior walls of wood frame construction are not there because the concrete core absorbs energy (heat) from the sun and from the heating system, and radiates the heat back slowly.
The next thing you will notice is how tight the house is. There are no drafts. A conventionally built wood frame house can be fairly airtight the day it is completed. The problem is that wood moves, it shrinks, seals between the foundation top plate and floor and joints at floors, roof and corners develop small air gaps over time. A BuildBlock ICF home is solid concrete, reinforced with steel, from below the ground to the roof. There are no corners to separate; no seams to open up where the basement top plate meets the floor or where the floors meet the walls. There is also no outside air coming in through electrical receptacles and switches because of poorly installed insulation. That is because your switches and receptacles are separated from the outside by solid concrete and several inches of rigid foam insulation.
After your first month you will begin to see the financial payback of a BuildBlock ICF home when your first utility bill arrives. Because your home is so tight, and so well insulated and because it has thermal mass (concrete) in the walls it will cost substantially less to keep comfortable. The key to this unconventional comfort is the concrete mass sandwiched between layers of 2-1/2" EPS insulation. Concrete holds energy. What you end up with is a wall system with an R-Value of 21 that behaves like an R-35. See Footnote 1.
A massive building uses less energy than a similar low mass building due to the reduced heat transfer through the massive elements. There are fewer spikes in the heating and cooling requirements, since mass slows the response time and moderates indoor temperature fluctuations.
In the winter during the day the concrete absorbs the heat from the sun and from the mechanical heating system. As outside temperatures cool in the evening, the concrete cools down very slowly. In conventional wood frame construction, as soon as the temperature changes outside, the thermostat tells the heating system to compensate almost immediately causing the heating unit to run more often and for longer periods of time.
During the summer months, the concrete absorbs the cooler air from the air conditioning and the evening outside air, and slowly releases the cold during the day as it slowly absorbs the heat from the outside air.
Thermal mass can shift energy demand to off-peak time periods when utility rates are lower creating additional savings.
The final payback comes the day you sell your home. Because your home is steel reinforced concrete instead of wood frame, it will appraise at a higher value and you will be in a position to sell it for more than a comparably appointed wood frame home.
1.The ASHRAE Standard 90.1–Energy Standard for Buildings Except Low-Rise Residential Buildings, the International Energy Conservation Code, and most other energy codes recognize the benefits of thermal mass and require less insulation for mass walls.
Thermal resistance (R-values) and thermal transmittance (U-factors) do not take into account the effects of thermal mass, and by themselves, are inadequate in describing the heat transfer properties of construction assemblies with significant amounts of thermal mass. Only computer programs such as DOE-2 and EnergyPlus that take into account hourly heat transfer on an annual basis are adequate in determining energy loss in buildings with mass walls and roofs. The heat flow through the wall is dependent on the materials' unit weight (density), thermal conductivity, and specific heat.