RMI Report Suggests Zero-Energy Homes are Now More Feasible, Thanks In Part to Cheaper Glass

October 3rd, 2018 by Drew Vass, Executive Editor

The Rocky Mountain Institute (RMI), an independent, nonprofit organization, recently released a report detailing how the costs to build zero-energy (ZE) or zero-energy ready (ZER) homes are now less than consumers—and builders—may think. “The Economics of Zero-Energy Homes: Single Family Insights” report, by Jacob Corvidae, Michael Gartman and Alisa Petersen, highlights methods builders can utilize to achieve zero-energy in their projects, while also pointing out that those suggestions should generate cost increases of only 6-8 percent.

“It’s now clear that zero-energy ready homes make sense economically today, even as they provide multiple benefits over standard construction,” says Corvidae, RMI’s principal and coauthor of the report. And for this reason, “It looks like zero-energy homes will become the norm sooner than most people realize,” he suggests. “Building anything else today runs a risk of creating homes that will be seen as out-of-date in only five years.”

In its research, RMI found more affordable triple-pane windows to be one of the cost-lowering energy features making ZE and ZER homes more feasible these days. In interviews with numerous builders, researchers found that by packaging those windows with alternative systems of framing and other measures, many are achieving air leakage rates of as little as 0.12 air changes per hour. At the same time, researchers discovered demands for thin glass in television screens have helped to lower material costs for some of the glass used in triple-pane windows by approximately 80 percent, making them a more affordable and cost effective option.

“For builders, there may be long-term advantages to over-engineering a super-efficient home’s envelope design,” the report suggests. “Thicker walls and windows can reduce noise penetration, potentially increase a home’s longevity, and improve indoor comfort in colder climates.”

Meanwhile, the institute suggests those benefits may be stretched even farther in the near future, as scientists at Lawrence Berkeley National Laboratory are now working to bring R-5 to R-7 performance to windows at a cost that’s expected to be close to or equivalent to double-pane windows.

RMI’s cost-optimized recommendations for builders include windows varying in cost by climate zones, with zone two averaging $360 and zone five averaging $2,840 per unit. But even at those rates, researchers suggest higher-performing windows will save money in the long run.

The full report is available here.

This article is from Door and Window Market [DWM] magazine's free e-newsletter that covers the latest door and window industry news. Click HERE to sign up—there is no charge. Interested in a deeper dive? Free subscriptions to [DWM] magazine in print or digital format are available. Subscribe at no charge HERE.

Tags: , ,

Leave Comment