ICF Energy Savings
Concrete Homes Save Energy
Building a concrete home with insulating concrete forms (ICFs) saves energy and money. The greater insulation, tighter construction and temperature-moderating mass of the walls conserve heating and cooling energy much better than conventional wood-frame walls. This reduces monthly fuel bills. It also allows the use of smaller heating and cooling equipment, saving money in construction.
Home Energy Savings Comparison
|Location||Oklahoma City, OK|
|Square Footage||4,000 SF|
|Yearly Energy Cost:||$3,656.25|
|Yearly Energy Cost PSF:||$.91 sq.ft.|
|Construction Method:||Traditional wood construction (2×6 framing)|
Air barrier behind sheetrock
|R-19 batt insulation with seal gaps over studs.|
|The entire home was also covered in 1×8 decking, and 1” EPS sheets were added for additional insulation over exterior sheeting.|
|The entire frame was wrapped in tar paper as an air barrier.|
|It also utilized a dual heat & air system with a heat pump and weather-clad double pane vinyl windows.|
|Another energy saving feature was the absence of windows on the west side of the home to minimize solar heat gain through window openings.|
|Location||Oklahoma City, OK|
|Square Footage||5,000 SF|
|Yearly Energy Ccost:||$1,886.63 (1,000 SF Larger Home)|
|Annual Savings:||$1,769 (58%)|
|Yearly Energy Cost PSF:||$.38 sq.ft.|
|Construction Method:||Insulating Concrete Form (ICF)|
|Efficiency Features:||R-30 Icynene insulation to seal the attic rafters for a controlled attic.|
|Dual speed geothermal heat pump.|
|Low-E Argon, double pane vinyl windows.|
How much will I 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 colder areas of the U.S. and Canada, heating savings will be more and cooling savings less. 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.
How do we know all this?
- The energy savings estimates are from a study of 58 single-family houses across the US and Canada. Half had exterior walls constructed of concrete using ICFs made of expanded polystyrene (EPS) or extruded polystyrene (XPS) foam.
- The other half were neighboring houses with wood-frame walls. All houses were less than 6 years old.
- The researchers compared the energy bill of each concrete house to its frame counterpart, carefully correcting for important differences to get an “apples-to-apples” comparison.
- Estimates of equipment savings are actual numbers reported by contractors who build ICF houses.
Residential Energy Savings
Max Daughtrey wanted to build a home for himself that performed exceptionally well but looked like “a normal house”. To accomplish this goal, he chose to build with ICFs. Daughtrey was familiar with the many benefits of building with ICFs and after extensive research, he decided that BuildBlock was the best block to meet his needs.
Daughtrey got exactly what he wanted out of the home. The design of the house fits in nicely in the neighborhood but performs like nothing else in the area. The ICFs provide incredible insulation and are paired with geothermal heating and cooling. According to a report by CenterPoint Energy (see below) the home uses 89% less energy than a select few homes in the area that are ranked as “energy efficient”. It is hands down the most efficient home in the area. The owners are spending an average of $25 a month to heat the home in the winter and $30 a month to cool it in the summer. Daughtrey received a $1,400 rebate on their city utility bill because of the homes incredible efficiency.
Stone Creek Home
Located in Canton Ohio, this Stone Creek ICF house earned first runner up in the small residential category, which includes houses that are 3,000 square feet or less. The home was selected by the ICF Builder Award Committee based on it’s success despite weather challenges during construction, its added industry exposure, and the exceptional results when completed. Built by one of the leaders in energy efficient homes in Ohio, Charis Homes, this 2,570 square foot house offers incredible savings as well as an environment that is so healthy, it literally changed the lives of the homeowners.
Stone Creek maximizes the benefits of ICFs. The insulated concrete wall provides exceptional sound mitigation, low air infiltration, resistance to strong winds, and an interior temperature that’s easy to keep stable. Adding to the homes efficiency are Energy Star windows, a Pex Manifold plumbing system, Navien hot water tank, and a 97% efficient Carrier Infinity Furnace with zoned controls. Utility bills for similar homes in the area typically average around $3,600 a year but the owners of Stone Creek are paying, on average, $120 a month. That’s nearly 60% in energy savings in an area of the country that sees some extremely cold winters.
Commercial ICF Energy Savings
Valencia Heights was designed to be beautiful as well as functional. The building is comprised of a total of 33 apartments and is close to downtown George Town. Each plan features a spacious and contemporary design. Open and inviting rooms finished with the best quality craftsmanship. The first floor is at least 12ft above sea level. BuildBlock ICFs were used for all exterior walls and placed on an engineered pier and beam foundation system. The second floor has an Epicore flooring system. This is an engineered steel and concrete system that adds greatly to the strength of the structure. The exterior walls are finished using a synthetic wall finish sealed with mold inhibitor paint for long durability.
Energy efficiency is a major marketing point for the condos since energy [costs] related to air-conditioning has been reduced from $400 to $80 per unit. [Based on estimates comparing the energy use of a similar CMU structure on the island.] The Cayman Islands have a mean temperature of 80F – 90F almost year round. It is humid at times and the heat index reaches up to 115F. Electricity is diesel generated and very expensive. ICFs are a perfect fit when trying to build with energy efficiency in mind.
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 the 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. Thewalls “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.
Estimating the size of heating and cooling equipment for concrete homes is complicated because the effect of thermal mass must be simulated in a computer program. But the software tool “HVAC Sizing for Concrete Homes” takes care of the difficult calculations. All you have to do is enter information about the house, like location, house size, and wall construction.