Omni Block Thermally Compared to ICF
R-Value is just one piece of the Energy Puzzle
ICF 10″ versions probably have a slightly higher R-Value than Omni Block’s 8″ model. So, if you are only looking at just one piece of the energy puzzle, ICF construction looks very good against Omni Block.
According to the United States Department of Energy, 11% of a building’s heat loss or gain is through the walls.
Most wall assemblies have a high enough R-Value to attain a performance level that stops the heat from moving through it.
How much R-Value is required?
R-Value is a measurement of “resistance to heat transfer”. As with most factors, there is a Law of Diminishing Returns. Basically, all this means is that there is a point where attempting to further the benefits are out-weighed by the costs. This is true of wall R-Values. At some point the R-Value will effectively stop heat from moving through the wall.
When a dam is built to stop a river, is there another dam built right next to it to stop the river more? No, one dam stops/controls the river. No more dams are required.
Another analogy would be when you head to the beach, what SPF is your suntan lotion? Most use SPF 30 or SPF 45, but no one uses SPF 500. Why, because SPF 30 or SPF 45 is plenty adequate (may need to re-apply after submerging in the ocean) because you have effectively stopped the sun’s harmful UV rays. Once you stop the UV rays, how much more do you need to stop them? The answer, you don’t.
Energy efficiency professionals have determined a wall R-Value of 19 is more than adequate to economically stop heat transfer.
Once you stop the heat from moving through the wall, how much more do you need to stop it?
Understanding heat
It must be understood that heat has energy and looks to expend itself. To illustrate, put your hand on a granite countertop. What you feel versus what is really happening can be very confusing. Your hand feels a cold sensation, but actually it is the heat escaping your hand and is being drawn into the much cooler granite.
Another confusing example would be in the wintertime when your house is warm and you open a window and feel a blast of cold air. Is it the cold outside trying to get into your home or is it the heat getting out being displaced by the cold air? The answer… it is the heat escaping!
Heat chases cool… it is a principle of physics
Thermal Mass is another invaluable piece of the Energy Puzzle
If the walls are only responsible for 11% of the total energy loss or gain, increasing the R-Value will only minimally contribute to lowering utility usage. Ceilings, doors and windows make up the remaining major areas of energy loss or gain.
Understanding Thermal Mass
If you have ever been in a cave in the summer time you have experienced the affects of thermal mass. Below the very top of the earth’s crust is a “freeze/thaw” depth that varies from climatic region to region. The colder the temperature gets in a given region the deeper the freeze/thaw depth is. Most of the USA is well below 36″ and the earth’s natural temperature of indigenous materials is around 56°F. Concrete block is entirely fabricated using these indigenous materials; therefore concrete block’s natural temperature is around 56°F as well.
For this discussion, assume that all wall assemblies effectively stop the heat from moving through their respective wall equally.
89% of all heat gain or loss is from other sources than exterior wall assemblies.
If we focus on the summer heat and just the windows, it is obvious to anyone standing in front of a window that solar heat gain through windows can be substantial. In an ICF constructed building this heat gain builds up until the thermostat registers the build up and turns on the air conditioning to cool down the hot air that has built up (not through the walls). Remember, ICF’s have a high R-Value due to the EPS foam, so ICF’s are going to actually resist any interior heat build up and do absolutely nothing to diminish the heat build up.
Omni Block’s exposed thermal mass absorbs heat
The same heat that enters an Omni Block constructed building naturally, passively, and unnoticeably moves to the cooler concrete block wall surface (exposed thermal mass). Heat always chases cool. This type of heat movement is considerably more comfortable than forced air conditioning blowing cold air into the room that in many cases blows directly upon those that are inside the building.
Omni Block is more comfortable
Just the opposite occurs in the winter time. A external heat source is required to heat the building and in doing so, the surface of Omni Block’s exposed thermal mass is evenly heated as well. As rooms begin to cool (generally at different rates) the stored heat will leave the block and chase (naturally, passively, and unnoticeably) the cooler ambient room temperatures.
Thermal Flywheel Affect
The diagram at left is the Department of Energy’s explanation of the Thermal Flywheel affect on a building’s shell, insulation and interior surface temperatures. Omni Block’s unique block design provides a more than adequate thermal path to delay the solar heat gain from entering into a building. As a brief summary, the block cools at night and as the sun rises solar heat gain starts to penetrate the block. By noon or so, the direct sun is no longer on the wall so the solar “drive” diminishes the solar heat and diffuses it so that it begins to retract back to the exterior surface. The insulation contained within Omni Block provides additional protection and completes the thermal flywheel. The interior surface remains cool and can absorb heat that enters the building from the primary culprits of ceilings, windows and doors.
It doesn’t matter where the heat is stopped in a wall as long as it is stopped before entering the building
Interestingly, in the 1950’s HVAC contractors would consult the industry accepted Manual J, which was their engineering reference manual to determine the proper tonnage of the HVAC equipment. At this time in our construction history, buildings were constructed with very little R-Values in their walls and ceilings, windows were primarily single pane glass and leaked air badly, doors were not properly insulated and were not very tight, and the HVAC equipment had SEER’s (Seasonal Energy Efficiency Rating) of 6. HVAC contractors, as a rule-of-thumb, would determine that every 400 square feet of livable space required one ton of heating, ventilation and air conditioning.
Skip to the 2010’s where construction techniques have improved mainly because of better products and a smarter buying public that understands the more energy efficient a building the lower the costs of heating and cooling will be. Buildings now have R-19 or more in their walls, ceilings have R-38, windows are double and triple paned glass and many times are tinted and even filled with a gas (Argon) that can help with their efficiency, doors are insulated and properly trimmed to prevent air leakage, and HVAC systems have improved in a variety of ways to use less energy and have SEER’s of 18 or higher. Great news except that the typical HVAC contractor now inputs all of this data into computer programs and still recommends one ton of heating, ventilation and air conditioning for every 400 square feet!
Due to Omni Block’s unique combination of R-Value, Thermal Mass and a Thermal Flywheel, the HVAC system of a building that utilizes Omni Block can be significantly downsized.
Omni Block building’s HVAC systems are downsized by 50%
Omni Block has 1000’s of buildings that are more than satisfactorily energy efficient and comfortable usually using about 50% of what is the standard HVAC contractor recommendation.
ICF construction does not have exposed thermal mass, nor does their product design allow for a thermal flywheel affect. They use R-Value and building tightness only so many HVAC contractors may see no justifiable reason to downsize an ICF constructed building.
Omni Block uses R-Value and building tightness, and then adds the use of exposed thermal mass and the flywheel affect, both major contributors to a building’s energy efficiency.