Tuesday November 20, 2012

I attended the Greenbuild conference and related meetings in San Francisco last week. This is the largest conference and trade show in the green building field, and it is increasingly becoming the conference where large manufacturers roll out new building products.

Described below are a few product highlights from the trade show.

Vacuum insulation
moving into the main stream?

Vacuum insulation has been around for a while, but it has never made inroads into the market -- despite a major effort by Owens Corning to do so with its Aura panel way back in 1992. Dow Corning is going to give it a shot. After premiering its Vacuum Insulation Panel (VIP) at the Living Futures Conference in May of this year, the company made a bigger splash at Greenbuild.

Dow Corning’s VIP is sold in 24-by-36-inch panels in thicknesses from a quarter-inch to an inch-and-a-half. The panels have a fumed silica core that is 95 percent pre-consumer recycled content, wrapped with an aluminum skin, and 1-inch-thick panels provide an insulating value of R-39 (center-of-panel).

Dow Corning’s vacuum panels have been used in commercial building facades to insulate spandrel glass (in all-glass curtainwall buildings, the opaque glass that spans between glazing), but I believe the primary application for VIPs will be in appliance manufacturing where high insulation performance in thin layers is desired (refrigerators, freezers, and water heaters). For information visit www.dowcorning.com.

A high-R-value coating
with silica aerogel

Silica aerogel is a bizarre material. Aerogel the lowest density solid known, and it insulates extremely well, owing to its molecular structure. For the past decade, the Cabot Corporation has produced silica aerogel granules under the brand name Lumira (previously Nanogel) that are used in daylighting panels that provide diffused daylight even while offering remarkably high insulating value (about R-20 in a 2-1/2-inch panel), and the material is also incorporated into a felt-like mat that can be used in roofing fabrics.

At Greenbuild the company introduced a new formulation of silica aerogel, Enova, that can be added to paint to provide a thin, insulating coating. A very effective demonstration in the booth used a piece of aluminum that was half painted with this 2-mm-thick coating and half uncoated with a refrigerated space behind. You could feel the dramatic difference in temperature, since the aerogel coating significantly reduced heat flow through the material. A key benefit will be preventing condensation. For information, visit www.cabot-corp.com/Aerogel/Coatings.

Zehnder’s top-efficiency HRV now certified with the Home Ventilating Institute

Zehnder is a Swiss manufacturer of high-efficiency heat-recovery ventilators (HRVs) for whole-house ventilation. Represented in America by Zehnder America since 2010, the company is defining the future of high-performance ventilation. All of the company’s HRVs carry Passivhaus certification, and the company’s Novus 300 HRV recently earned certification with the Home Ventilating Institute (HVI).

Based on the HVI test methods, the Novus 300 achieves "apparent sensible effectiveness" of 94 percent to 96 percent and "sensible recovery efficiency" of 90 percent to 91 percent, significantly exceeding the performance of any other HRVs in the HVI Certified Products Directory. One of the company’s ComfoAir models also carries HVI certification, and others in the line will be certified. For information, visit www.zehnderamerica.com.

Wood-fiber insulation
from Germany

In Europe it is becoming increasingly common to use high-permeability wood fiber sheathing as an exterior insulation material, and at least one such material was on display at the conference. The Small Planet Workshop in Olympia, Washington, is now distributing the German product Agepan THD. These 2-inch-thick panels insulate to R-5.7 (R-2.3 per inch) and have a high perm rating of 18 -- meaning that water vapor can pass through it fairly easily.

It’s hard to say whether wood-fiber insulative sheathing will gain followers here, but there is growing interest in wall assemblies that won’t trap moisture, so products like these are worth keeping an eye on. The Small Planet Workshop also distributes the expanded-cork boardstock insulation that I’ve written about previously and that I’m planning to use on my own house in Dummerston. For information, visit www.smallplanetworkshopstore.com.

Alex Wilson is the founder of BuildingGreen, Inc. and the Resilient Design Institute (www.resilientdesign.org), both based in Brattleboro. Send comments or suggestions for future columns to alex@buildinggreen.com.