Article No: 245

2008-09-29 10:44:57
Cool, Quiet, and Green

 Photography by John Riddle, Greenblock
Rafiki Foundation Home Office Complex in Eustis, Florida
With the summer sunshine in the morning and the downpours of the afternoon rains, the Central Florida weather provides a tough working environment for those completing the structures at the Rafiki Foundation Home Office Complex in Eustis, Florida.

With roofs, windows, and doors installed, the indoor working environment is much more bearable, even preferred by the dozens of trades and installers on the project. Could the insulated concrete form walls already provide a benefit?
The answer is a resounding, “yes.”

In fact, walking the jobsite in the Central Florida heat can be almost exhausting, let alone assembling the standing seam metal roof structures. However, the temperature change entering into any of the 13 structures is immediate and you might think the ventilation system is already in place, if it were not for the electricians busily running hundreds of feet of Romex wiring into the carved runs of channels in the ICF walls. 

It is this “cooling effect” in a building just barely past the “dry-in” that generates excitement from the Rafiki Foundation team on just how efficient and Green their new home office complex will be with completion and move-in only a few short months away.

“The coolness of the interiors hits you immediately as you walk into the buildings,” comments Steve Kranz, director of home operations for Rafiki Foundation. “As the interiors begin to come together, we are quickly realizing that ICF walls will be a major benefit in keeping our cooling costs low.”

Insulating concrete form (ICF) wall systems keep interior temperatures more constant and help to prevent fluctuating heat increases/decreases due to the continuous insulation, lack of air infiltration, and the thermal mass of the concrete wall. The Greenblock ICF walls at Rafiki are constructed with four inches of high density expanded polystyrene foam panels (two inches on both the inside and outside of the walls). Within the foam panels lies four inches of steel reinforced solid poured concrete. The concrete used on this project is 3000 psi and is placed into the ICF wall cavities in one continuous pour at a four-foot lift rate.

“Concrete placed in an ICF wall cavity takes longer to cure. This longer cure time results in a stronger wall,” says Steve Reiter, vice president of marketing for Greenblock. “The concrete is kept at a consistent temperature, maintains its moisture, and reduces air exposure which creates the perfect curing environment and, if core tested after 180 days, could approach the 5000 psi level.”

So how does the Rafiki Village ICF wall system contribute to the Green building effort? Green building is literally sweeping the nation and Florida is no exception. With several certification rating systems in place, Florida places a high value on efforts to reduce the impact of the environmental footprint of a structure.

For commercial buildings, probably the most recognizable system is the United States Green Building Council’s LEED for New Construction rating system. LEED-NC promotes a “whole building” approach with performance criteria in five areas: sustainable site development, water efficiency, energy efficiency, materials selection, and indoor environmental quality.

It is within the LEED-NC “Energy Efficiency” section where Greenblock ICFs make the most impact. And, should Rafiki Foundation choose to have their structures certified using the LEED-NC rating system, it is where they would achieve the most impact; up to 10 points toward the 26 required to certify.

According to the Insulating Concrete Form Association,, this strong focus on energy savings is appropriate considering the bulk of a building’s environmental footprint is caused by the energy consumed in the heating and cooling of a structure over the course of its lifetime, (in fact, the construction and operation of buildings generate half of all greenhouse gas emissions in North America*).

Keeping with the Green theme, it is not only the energy efficiency of the Greenblock walls at Rafiki that are contributing to its possible certification. The ICF walls also contribute potential points toward several other LEED-NC rating system categories—all benefiting the Rafiki Foundation through efficiency, occupancy, and budget.

Earning potential “Sustainable Site Development” credits, the ICF wall construction caused minimal disturbance to the site as the wall alignment systems were erected on the interior of the ICF wall structure. This limited the activity of the installation team on the exterior of the buildings and helped to reduce the amount of site disturbance otherwise commonly found with conventional framing or CMU construction.

Another opportunity for Rafiki to gain LEED points is within the “Materials and Resource” credit sections. Construction waste reduction is an ongoing effort at the Rafiki Home Office Complex jobsite and was initiated during the ICF wall construction.

“We brought in dedicated waste containers during the ICF wall construction,” says Kranz.  “There were containers for concrete, wood and EPS foam. Greenblock ICFs are 100% recyclable, so it required minimal effort from the ICW installation team to separate out their portion. And, since ICF wall construction produces less waste than typical CMU construction; the collection was easier than expected. Once the EPS foam was separated from the polypropylene web ties, they were taken to local recycling facilities,” continued Kranz.

Regionally, the construction of the Greenblock ICF walls would earn credit points as the ICFs used on this project were manufactured at Greenblock’s two Florida facilities (within a 500 mile radius of the project) and the aggregate in the concrete mix would qualify as it is also locally produced.

Even though the HVAC systems have yet to be installed, it is safe to project that the indoor air quality will be superior due to the airtight nature of the ICF walls. This lack of air infiltration earns points in several areas within the “Indoor Environmental Quality” section including increased ventilation effectiveness and thermal comfort. 

Also contributing to indoor air quality is the reduction or prevention of outside air containments and pollutants from entering the structures. Once inside, Greenblock’s EPS foam emits no VOCs or formaldehyde. It will not generate any off-gassing, as the material is inorganic and inert and the concrete mass within the ICFs is equally non-toxic. Plus, the manufacturing of Greenblock EPS panels does not produce any CFCs or HCFCs.

With insulated concrete form walls on this project, it is conceivable that a LEED-NC rating could earn as much as 20 of the 26 points needed for certification—that is only considering the ICF walls in the design. Other factors on this, and just about any other project, would easily surpass the minimum certification standards needed to be considered Green.
The Rafiki Foundation’s intent was not to just be “certified” Green, but to create a sustainable complex with the structures continuing their operating benefits for decades to come. It is with this sustainable goal in mind that ICF construction “scores” points beyond a Green rating scale. 

As the project continues to move forward to completion, it is evident that insulated concrete form walls play a major role in the sustainability and Green construction efforts as the buildings are made ready for occupancy—including providing some advance benefits for the construction teams. 

*Data provided by US Energy Information Administration