Division 7 Ebook Page 83 Enclosure Solutions FAQ

ENCLOSURE SOLUTIONS FAQs 4 14. What is "optimum insulation"? A: Optimum insulation is that amount of insulation that has the lowest life cycle cost. Insulation is an investment. Like other investments, it is expected to provide a return, or, an economic benefit. Otherwise, why buy insulation? The obvious economic benefit of insulation is that it saves on heating & cooling costs. The question is, "How much insulation is enough?" "What is the optimum amount of insulation?" "Optimum insulation" is the amount of insulation that has the lowest life cycle cost (LCC). LCC can be expressed as: LCC = FC+M+R+E -RV LCC = Life Cycle Cost ($) FC = First Cost ($) M = Maintenance and repair cost ($) R = Replacement Cost ($) E = Energy Cost ($) RV = Resale value or salvage ($) The concept of determining lowest life cycle cost is illustrated in Figure 1. It shows first cost increasing as R-value increases. Install more insulation, and the first cost of insulation increases. It shows energy cost decreasing as R-value increases. Add more insulation and energy consumption and cost decreases. The lowest life cycle cost (LCC) is the lowest sum of first cost and energy cost at a given level of R-value. In this hypothetical example, R-20 is the lowest LCC, and, is therefore the optimum insulation level. This example only demonstrates the concept of "optimum insulation". Actual optimum levels must be calculated for specific climates, specific building construction types, specific building usage patterns and specific economic assumptions. The concept of Life Cycle Cost Analysis and Optimum Insulation are utilized by ASHRAE in the development of the energy standard 90.1. 15. Is FOAMULAR Extruded Polystyrene and Thermafiber RainBarrier continuous insulation compatible with air/weather barriers, sealants, waterproofing, other insulations, claddings, substrates, etc? A: Continuous insulation is often necessary to meet any one of several compliance paths available in energy codes. Because there are alternative paths to compliance, continuous insulation is not "required". Instead energy codes "prescribe" or "recommend" CI R-value amounts that are often based on "optimum insulation levels". Most energy codes have a "prescriptive path" to compliance. In that case, if the prescribed details, including CI are followed, the final design is "deemed to comply". Regardless of the compliance path utilized continuous insulation is a major contributor to compliance, energy efficiency and sustainability. To determine the amount of continuous insulation that is "prescribed" for a particular project always consult local energy codes, and, see the family of Enclosure Solutions Wall Systems guides to prescribed CI R-values.

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