Working out what an efficient envelope saves
The saving comes from three places: less conduction, less air leakage and smaller equipment running closer to its sweet spot. Only the first is visible in an R-value.
The three components
Conduction through the assemblies scales with area, the temperature difference and the U-factor. It is the part an R-value calculation captures.
Air leakage scales with the leakage rate and the same temperature difference. Guardian notes that up to 40 percent of a home's heat loss is air leakage, so an envelope that fixes only conduction leaves a large fraction of the loss untouched.
Equipment efficiency is the third. Correctly sized equipment in a low-load building runs longer, gentler cycles at higher efficiency than oversized equipment short-cycling.
Why measured results beat modeled ones
A model tells you what the design should do. A metered building tells you what it did. Where both exist, quote the metered one.
The Federal Social Security Administration facility shows the difference. Its 81 percent reduction in the average monthly HVAC bill, to $1,482, is a projection based on Energy Wise® certification, not a metered year. It is a design figure; a year of the building's utility bills would make it a measured one.
What Guardian publishes
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Up to 40 percent of a home's heat loss is due to air leakage.
Source · Products page, lasting cost savings
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Guardian states Shield™ panels reduce heating and cooling costs by 70 to 80 percent over conventional construction methods on the products page, and that Shield™ panel homes use 75 to 85 percent less energy on the market page.
Source · Products page; Market page
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Federal Social Security Administration Facility: the average monthly HVAC bill will be reduced by 81 percent, or $6,511 per month, to $1,482 per month average, based on Energy Wise® certification.
Source · Federal Social Security Administration Facility case study
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Published by Guardian Structural Technologies. Last updated .
Drafted from our product literature and published building-science sources. Awaiting our technical review. Confirm any figure against the current product documents or ask us before you rely on it in a design.