Zero net energy: the new normal?
By Dave Gowers
With energy efficiency increasingly becoming the focus of both commercial and residential construction, we must seriously consider ICF construction as being a realistic solution to this energy efficiency demand.
But what does Zero Net Energy mean? Simply put, any structure designed for zero net energy must generate as much energy as it consumes. How is that achieved? By starting with an energy efficient building envelope and augmenting it with an energy generation system.
Typical energy generation systems might be solar, wind generation or water generation. ICF construction, with a performance equivalent to R50 when the thermal mass effect is factored in, is an obvious choice for the energy-efficient building envelope.
The wall core through the wall footing is in constant contact with ground source, which we know typically maintains a year-round temperature of approximately 65 degrees F. Over time, the total concrete core will move towards a steady 65 degrees F temperature, and therefore acts as a buffer to heat transfer from either direction.
In January 2020, the California updated residential building code will mandate that all new residential construction in the state of California must meet zero net energy standard. This is huge and will demand that the building envelope be substantially more energy efficient than has previously been required. It is very likely that other states will follow California’s lead.
Under the California Energy Efficiency Strategic Plan, the state has ambitious goals for the development of zero net energy buildings. These include:
- All new residential construction will be zero net energy (ZNE) by 2020.
- All new commercial construction will be ZNE by 2030.
- 50 percent of commercial buildings will be retrofit to ZNE by 2030.
- 50 percent of new major renovations of state buildings will be ZNE by 2025, and 100 percent by 2025.
Common wisdom dictates that high-performance homes cost more, yet builders in California are already considering how to meet the standard as cost-effectively as possible. Alternate building solutions to ICF construction attempting to achieve this mandated higher energy saving performance are the following:
- Double framing construction
- Structural Insulated Panel (SIP) construction
Let’s compare these alternative building solutions with ICF construction:
Double Framing Construction
It is unlikely that traditional single framing will continue to be cost effective when added to the cost of the energy generation system. Therefore, double framing, complete with its increased price tag, is most likely to replace single framing.
However, with ICF construction currently being economically competitive with single framing, it is clear that ICF construction will prove to be less expensive than double framing and could well become the construction method of choice on a wide scale.
SIPs have great insulation properties but lack the thermal mass effect of concrete, and therefore do not perform as efficiently as ICF construction.
Furthermore, SIP construction frequently requires the use of craneage for installation, which adds a cost consideration to be budgeted into the project. And finally, SIP construction is planned in its entirety by the SIP manufacturer, which is then installed to extensive shop drawings with very little opportunity for site changes.
In conclusion, it is clear that ICF construction has begun to be widely embraced, as more owners demand superior energy efficiency and the peace of mind of a resilient, safer home.
Dave Gowers is the owner and senior partner at Dave Gowers Engineering LLC in the Medford, Oregon, area. He has 49 years’ experience in construction, mostly at project management level, employed by both design and construction companies; involvement in a diversity of projects including commercial structures, potable and wastewater treatment facilities, heavy and light industrial installations, roads, and bridges; involvement with projects up to $1-billion in value, located in 15 different countries worldwide.
Gowers’ current focus is structural design of ICF projects, both residential and commercial. Through his company Cascade ICF, he is a Nudura distributor. Gowers, a member of ASCE and AC, has active PE licenses in Oregon, California, Washington, Nevada, Arizona, Iowa, and Maryland. He can be contacted at firstname.lastname@example.org or email@example.com or through his websites cascadeicf.com and dgengineering.com