Insulated Concrete Forms for Residential and Commercial Applications
Concrete forms: Insulated vs. Uninsulated
Use insulated concrete forms (ICFs)--interlocking systems of formworks for reinforced concrete that stay in place as permanent interior and exterior substrates for walls, floors, and roofs.
Item ID: 530
Building Envelope--Walls, Roof, & Floors
Technical Advisory Group: 2014 Commercial Building TAG (#9)
Average TAG Rating: 2.53 out of 5
TAG Ranking Date: 03/17/2014
TAG Rating Commentary:
- I think there is potential for energy savings, but there needs to be significant work in reducing the human health and environmental impacts associated with foam insulation and associated flame retardants
- Would need more info to understand why it is not currently used in the commercial sector.
- These are good for cutting down heating/cooling loads.
Insulated concrete forms (ICFs) consist of interlocking modular units of rigid insulation that are filled with concrete. The forms permanently remain in place to provide insulation for the structure they enclose. The insulating value for a typical insulating concrete form is about R-20.
While insulated concrete products exist and, in fact, have become commonplace in low-rise construction, it is unclear how they would save energy over construction in accordance with existing building codes unless selection of this material would result in a "beyond code" construction. Otherwise, the insulated concrete form is one of many ways of constructing a building to meet or exceed current code prescriptive or performance requirements.
ICFs offer several properties that may prove beneficial to a building designer including thermal mass and leak tightness. Insulated concrete forms have been used in the construction of schools, residence halls, hotels, banks, movie theatres, houses of worship, and institutional buildings. Manufacturers can provide Installation Manuals, Specifications, and Technical Bulletins that contain guidance and hardware suggestions (brackets) for various applications including floors, ceilings, waterproof walls, T-joints, and radius walls.
Baseline Description: Electrically Heated Homes
Baseline Energy Use: 9485 kWh per year per household
The 2014 NEEA "Residential Building Stock Assessment: Metering Study" indicates that the EUI for the region's houses with electric resistance heating is 17.74 kBtu/sf-year. Electric forced air furnace heated houses use 23.37 kBtu/sf-year while heat pump houses (heating only) use 10.55 kBtu/sf-year (Table ES2, Page xiv). Given that baseboard heaters are used in 12.3% of the housing stock, electric forced air furnaces in 6.1%, and air source heat pumps in 11.4%, the weighted average electrical heating system electrical energy use is about 7.32 + 4.78 + 4.03 = 16.13 kBtu/sf-year. Given a typical house size of 2007 sf, this equates to about 9,485 kWh/year.
Manufacturer's Energy Savings Claims:
"Typical" Savings: 44%
According to the EPS-IA, houses built with ICF exterior walls require an estimated 44% less energy to heat and 32% less energy to cool than comparable frame houses. (Note: The energy savings estimates come from a study of single-family houses spread across the U.S. and Canada. Researchers gathered data on 58 houses in all. Half had exterior walls constructed with concrete using ICFs made of expanded polystyrene (EPS) or extruded polystyrene (XPS) foam. The other half were neighboring houses with walls constructed of wood frame. All houses were relatively new (less than 6 years old) and built with modern methods). 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 can be expected to cut the conduction losses through foundation and above-grade walls by about half. ICF walls are also tighter as they average about 1/2 as much infiltration (air leakage) as frame construction.
Best Estimate of Energy Savings:
"Typical" Savings: 44%
Energy Savings Reliability: 4 - Extensive Assessment
Energy Use of Emerging Technology:
5,311.6 kWh per household per year
Energy Use of an Emerging Technology is based upon the following algorithm.
Baseline Energy Use - (Baseline Energy Use * Best Estimate of Energy Savings (either Typical savings OR the high range of savings.))
This ET is not a retrofit technology. It is appropriate for new construction in the residential and small, low-rise commercial sectors.
Currently no data available.
Simple payback, new construction (years): N/A
Simple payback, retrofit (years): N/A
Cost Effectiveness is calculated using baseline energy use, best estimate of typical energy savings, and first cost. It does not account for factors such as impacts on O&M costs (which could be significant if product life is greatly extended) or savings of non-electric fuels such as natural gas. Actual overall cost effectiveness could be significantly different based on these other factors.
Reference and Citations: