R-Value: Effective 100!
An acknowledgement
We acknowledge that when using standard calculations for R-value the Monolithic Dome does not exceed 27 to 30. By standard computations, we mean the summation of the Airform, concrete, rebar and polyurethane foam. It will not exceed 30 in anyone’s book, be it the ASHAE Guide or an other insulation guide.
Actual calculations
So, why do we claim an effective R-value of 100?
We have had our buildings checked by professional engineers to calculate the actual heat loss through the structure. This is done by having a measurement of the amount of heating and/or cooling inputs into the building, matching the inputs with the degree days from local weather conditions, and calculating the R-value that must be in place to make the equation balance. In every case, we got an R-value in excess of 80 generally 100.
We use 100
We find it very defensible in all conditions. Over the years, we have checked structure after structure, Monolithic Dome after Monolithic Dome and have always found the R-value an effective 80 plus and often over 100.
The California Handbook for Solar Energy is the only government publication we have found that takes into account the thermal mass of the concrete, when measuring heat loss. Simply stated, the concrete acts as a heat sink that slows the passage of heat, back and forth through the wall or roof assembly.
Therefore, we claim an effective R-value of 100. We can defend that by actual practice. Our customers who have monitored their heating and cooling costs tell us that we are probably too low, that the R-value is actually higher. Obviously with an effective R-value of 100, the structure is losing very little heat from conductance. Monolithic Domes lose very little air due to air leakage.
The function and purpose of the building makes the greatest difference in heating or cooling a building. For example, a church with large crowds for two hours, one day a week, will have dramatically different cooling/heating needs and costs than a warehouse facility with many employees that is used every day.
HEED Program
UCLA engineers have come up with a program they have named HEED. It is the first program we have found that takes into account the position of the insulation and the thermal items in a wall or ceiling. It calculates the Monolithic Dome tremendously high because of the super insulation on the exterior of the thermal mass.
updated 11/11/2013
The California Energy Commission also illustrates the same thing in their Passive Solar Handbook
Read the article titled High Occupancy Design Criteria for HVAC in the Monolithic Dome.
