By Dave Gowers, P.E. – DG Engineering
This excerpt is from an article written for ICF Builder Magazine
Introduction
Energy conservation is very prominent in all aspects of our culture today, as indeed it should be. For too long we have squandered natural resources as if they would continue to be available indefinitely, and that of course is just not the case. This article explores how we might build with energy conservation in mind, by giving greater consideration to our building methods and choices. The result will be conservation of natural resources.
Anatomy of an Insulation System
Current building codes typically require exterior walls to have R-21 insulation. This leads to the erroneous conclusion that the wall assembly has an R-value of R-21, but that is not the case. In wood frame construction, with studs typically at 16” on center, double studs either side of all openings, and a single sill plate, and a double top plate, the actual performance R-value will be less than R-21 for the wall assembly. Calculation will show that this performance R-value is closer to R-17. This is further exacerbated by the fact that batt insulation will actually sag over time, leaving uninsulated cavities at the top of each space between studs.
Compare this to an ICF wall assembly, where the polystyrene foam is continuous from opening to opening, and from bottom of sill plate to top of roof plate. The calculated R-value of the foam is typically in the range of R-23 to R-25, depending on the ICF system selected. Because of the foam continuity, this is a true performance R-value, which is significantly better than that of wood framed construction, as described above.
However, it has been shown by rigorous testing1 that the thermal mass of the concrete plays a significant part in the performance R-value of the wall assembly, so much so that it might be considered as high as R-40! This leads to a colossal difference in energy conservation!
Code Position on Energy Conservation
Building codes are being continually upgraded each three year code cycle to reflect the energy requirements and recommendations of the sister energy codes. The 2024 International Energy Code recognizes that discontinuous insulation should be bolstered with added continuous rigid foam insulation across the framing, to ensure that R-value ratings are truer to that expected. The USA throughout has adopted the International Code series as it’s base, but each state will select the parts of the I-codes that they will adopt. Also, it might take 2 – 3 code cycles before the I-code recommendations are adopted. In the meantime, we continue to build 80% of new residential construction with energy -inefficient wood frame systems, that clearly underperform when considering resource conservation.
Insurance Coverage and Risk Management
At the time of writing, it is my understanding that fire insurance is being denied by the major insurance carriers. Whilst this decision may be influenced, and even reversed, in the fullness of time, it is almost certain that new premiums will be higher, and the scope of coverage most likely reduced. The fire risk for an ICF building envelope is substantially lower than that of wood-framed construction. It may transpire that fire insurance coverage for ICF construction may be possible where it has been denied for a similar wood-framed construction.
Indoor Environmental Quality
Many of us spend up to 90 per cent of our lives indoors, which means the quality of indoor air is as important to our health as is the quality of outdoor air. ICF construction typically produces a much tighter building envelope when compared with woodframe construction. This in turn allows for a tighter control on the IEQ, with a reduced energy demand, thus conserving natural resources.
Building Costs, Labor & Material Resources
The recent colossal tragedy of the LA fires is still being evaluated with regard to rebuilding and how to make that happen in the most efficient manner possible. With the order of 12,000 structures destroyed, including residences, schools, retail premises, etc, the logistics of rebuilding is mind-boggling. I’ve recently learned that if a homeowner chooses to build a residence of the same size or no more than 10% increase on what previously existed, Los Angeles County has instigated a fast track process. Unfortunately, there are no less than 12 government agencies which have to be solicited to determine the extent of their respective involvement in the fast track process. On the premise that everything proceeds and complies with this process, new residential construction has to be EV car ready, and full electric ready. This means that Los Angeles County is preparing for all new construction to be electricity dependent.
It has never been more important that new construction should be the most energy efficient possible, and that points strongly in the direction of ICF construction.
Trueness of construction is also an issue – the quality of framing lumber continues to decline, whereas the quality of ICF products is consistent both with regard to material quality and dimensional trueness.
Another aspect of the massive LA rebuilding is the availability of resources, with regard to both material and labor. There is already a shortage of framers nationwide, so the labor demand for the LA County rebuild will be extreme. It is far easier, and quicker, to train ICF installers than it is to train framers.
Operating Expenses
One area where ICF construction excels is the lifetime operating costs. Quoting from the Thermal Performance of ICF Walls, reference 1, “it should be noted that ICF walls ……… perform better than cavity walls, maintain their R-value over time, and consistently resist temperature fluctuation because of stored energy. ICF structures require less overall energy to heat or cool ………. with less cost to the end user.”
Repairs and Maintenance
Once built, the ICF building envelope will be virtually maintenance free for many years to come. This is not the case with wood framed construction which is immediately susceptible to mold, rot and decay within a relatively short timeframe. In wet climates such as Oregon, it is not uncommon to see a fully framed wood frame structure, totally exposed to the elements. Even though the contractor might make much effort to dry the structure once it is weathered in, one might question whether mold has already started to form.
Disaster resistance
The rebuild cost incurred in the aftermath of a major disaster, whether it be earthquake, hurricane, tornado or flood, is colossal! In recent years we’ve seen the effect on communities of wildfires and hurricanes. Frequently the only structures left standing in these areas are those of ICF construction!! Imagine the monumental cost and hence energy saving that would be achieved if all structures were built with ICF!
Conclusion
In conclusion, ICF construction is an excellent choice for building with the emphasis on energy conservation. The construction process itself will be more energy efficient due to conservation of resources, but the operating cost savings will continue for the life of the structure, reaping the benefit of continually preserving resources that have a diminishing finite availability.
References:
1: Thermal Performance of ICF Walls, by Micah Garrett, Chairperson ICFMA Education Committee, ICF Builder Magazine, May/June 2020
