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 modelled 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 is Guardian's clearest metered case: an estimated $8,000 monthly utility cost was the problem, and the reported result was an 81 percent reduction in the average monthly HVAC bill to $1,482, based on Energy Wise® certification.
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: average monthly HVAC bill reduced by 81 percent, or $6,511 per month, to $1,482 per month average.
Source · Federal Social Security Administration Facility case study
Go deeper
Written by Data Subsystems, for Guardian Structural Technologies. Last updated .
Drafted from Guardian Structural product literature and published building-science sources. Awaiting Guardian technical review. Confirm any figure against the current product documents or ask us before you rely on it in a design.