Passive chilled beams operate through simple convection: as warm room air rises, it passes through the water-cooled heat exchanger fins inside the chilled beam, where it cools and settles back into the room. This pattern of rising and settling air circulates the cooling energy. Passive beams can provide an energy-efficient HVAC solution, especially in retrofits or modular office layouts where duct space is a problem, but they require the use of added ventilation—usually underfloor—to provide fresh air and humidity control, and they do not provide heating.

Active chilled beams (ACBs) account for most chilled beam sales and are the focus of this article. They use the same heat-exchanger technology as passive beams but can supply both cooling and heating, as well as ventilation air. ACBs contain an added compartment (plenum) that is connected to the ventilation air supply (see diagram). This primary ventilation air (dehumidified and filtered outdoor air) enters the beam’s plenum under pressure where it is forced through nozzles that direct the flow of the air along the outside of a second chamber and into the room. This action pulls secondary air (room air) into the unit from underneath via induction past the heat exchanger coils. The now-cooled/heated secondary air mixes with the primary air in this second chamber and is blown back into the room. Unlike passive beams, active beams do not rely solely on convection for air circulation, so they can force warm air down into the room, supplying heating as well as cooling. (Multi-service beams are custom ACBs that include lighting, sprinklers, security, sensors, or other features). There are no electrical connections or moving parts in the beams, minimizing maintenance and creating a quiet HVAC system.

Environmental Building News covered the first generation of high-speed hand dryers in 2002 with Excel Dryer’s 1500-watt XLerator model. Life-cycle assessment (LCA) calculations at that time showed that these units consume, per use, about a third of the energy of conventional 2,200-watt electric hand dryers and about one-sixth the energy of using recycled paper towels (see

EBN Jan. 2002). But the first version of the XLerator was loud, and the water that it didn’t vaporize ended up on the floor or surrounding surfaces.

Mobile PV generators use components similar to those found on stand-alone (non-grid-connected) PV systems, but are configured for the harsh demands placed on portable generators. The PV panels are designed to handle rough conditions on a jobsite and are mounted on a trailer to minimize travel damage. Mobile Solar Power (one of BuildingGreen’s Top-10 Green Building Products for 2009—see

EBN Dec. 2009), Mobile Green Power, and Energy Acumen make enclosed trailers that protect electronic components from the elements, while Pure Power Distribution and SolaRover opt for an open-trailer design.

Although it is not vitrified, the brick looks similar to clay brick, and third-party surface testing shows that the toxic metals found in fly ash—including arsenic, mercury, and lead—are successfully encapsulated by the manufacturing process and should not leach out, according to CalStar. Indoor air quality chamber tests have not been done, but company representatives told

EBN that they are looking into obtaining Greenguard certification for chemical emissions once the bricks are in production. If the toxin levels and mortar adherence are similar to clay and cement products, the company will have created a viable brick replacement with a significantly smaller environmental footprint.

Building a better house was always their goal: “We wanted to start by figuring out how to design a more efficient house, then form a company to sell it,” said Jupiter. The company has branded its product as a New Old Green Modular (NOGM) home, since it specializes in historically inspired designs with modern, green amenities. All NOGM homes meet LEED for Homes standards, and owners can choose whether to pursue certification in either program. The company’s homes are less expensive than many green modulars: between $105/ft2 and $185/ft2 ($1,100/m2 to $2,000/m2) including the foundation (but excluding design, land, site, and finishing costs, which can bring the total over $200/ft2 or $2,100/m2).

Unlike many modular companies, New World Home does not own a factory. Instead, the company works with existing manufacturers to build houses according to its specifications. According to construction director Howie Berman, finding manufacturers that can meet those specifications can be difficult, since the company’s homes use at least 50% less energy than those built to code and use green materials and techniques that may be unfamiliar. “It’s hard to teach an old dog new tricks,” he said. But manufacturers are coming around. “We do the research for them—all they have to do is build to our specs,” Berman noted, and that makes it easier for manufacturers to pursue green building.

Ethanol Producer magazine, California produces 1.35 million tons of rice straw annually from the 600,000 acres (240,000 ha) in rice production, and only 3%–4% of that straw is used commercially.

Stak Blocks are 12" x 12" x 24" (305 x 305 x 610 mm) and weigh 30 pounds (14 kg), with a density of 15 lbs/ft3 (240 kg/m3)—about twice that of typical straw bales. The straw fibers are held together with a polyurethane binder (MDI), used at a concentration of about 2% by weight, according to company president Jay Ruskey. The blocks have a high enough density to create load-bearing walls with simple stacking. (With strawbale construction, load-bearing applications require special measures to prevent cracking of plaster as bales compress over time.) Stak Blocks interlock with molded bumps and dimples (think Lego), leaving a channel that is used for a threaded rod to secure the top plate to the foundation. The cavities could also be filled with re-bar and concrete to create a sort of insulated concrete form, though the diameter of the concrete columns would be fairly small.

Flywheels are spinning disks that store kinetic energy for use as a short-duration power supply. These systems have been around since the 1960s, but older units used heavy steel discs weighing as much as 6,000 pounds (2,700 kg) that spun at relatively low speeds of less than 4,000 rpm. Newer steel flywheels are lighter and spin faster but still require special installation and regular maintenance, consume a lot of power, and generate a lot of heat. Pentadyne flywheel systems, however, store power using a lightweight hub and carbon-fiber flywheel weighing just 58 pounds (26 kg) and spinning at up to 52,000 rpm.

“Kinetic energy is equal to mass times velocity squared,” said Jeff Colton, senior vice-president of sales and marketing at Pentadyne, “so doubling the rotational speed quadruples energy storage.” Using high-speed rotation, the GTX can supply 200 kilowatts of continuous power for over 12 seconds and recharges in less than 15 seconds; the units can also be linked in parallel for larger kilowatt demands or run time. This may not seem like a useful amount of coverage, but 98% of all power anomalies last less than ten seconds, according to the Electric Power Research Institute.

DeepRoot Partners has created Silva Cell to address these problems by providing a framework for holding uncompacted subsurface soil that can support tree roots and manage the runoff from small storms. Each 48" x 24" x 16" (120 x 60 x 40 cm) fiberglass-reinforced polypropylene frame (there is no recycled content because of structural concerns) holds 10 cubic feet (0.3 m3) of soil and can support H-20 loading standards of 32,000 pounds (14,500 kg) per axle (the company does not recommend these under roadways).

Silva Cell uses six vertical posts, a base, and a top deck reinforced with galvanized steel tubes. The frames can be stacked up to three high before the top deck is attached and can be laid side-by-side to provide more soil volume. Root barriers and membranes are added to direct roots away from structures. The Silva Cell framework provides a space that protects soil and allows roots to grow naturally to support the tree’s overall health. “Depending on the site, trees need two cubic feet (0.06 m3) of soil per square foot (0.09 m2) of tree canopy,” said Graham Ray,executive vice president of Deep Root Partners. A typical 4' x 10' (1 x 3 m) streetscape contains about 20 cubic feet (0.6 m3) of soil, which limits a tree’s canopy to a 10–foot (3-m) diameter before it falls into decline. But a tree with a 20–foot (6-m) diameter canopy (see chart) actually requires 500 cubic feet (14 m3) of uncompacted soil, and finding that much quality soil in a crowded urban landscape can be a challenge.

Rather than simply accepting that rejection and moving on to a more promising client, Grasso looked at his company’s product and set out to reinvent it. Six years later he introduced Pozzotive Plus, a line of CMUs and concrete facing brick that breaks new ground in the use of recycled materials.

Grasso developed a pozzolan (a material, such as fly ash, that exhibits cementitious properties when combined with calcium hydroxide) from 100% recycled glass. The glass, which can be of any color or type (from beverage glass to window glass), is ground in a multi-step process to an extremely fine powder (10–15 microns). In this form, the material (with the trade name Pozzotive) can be substituted for 30% of the portland cement in the CMU and concrete brick formulas.

Mineral wool forms naturally when strong winds blow through molten lava to create the thin, gold-colored strands that volcanologists call Pele’s hair. Today’s mineral wool insulation is made in a less dramatic process using basalt and iron-ore slag that is melted, spun into fibers, and held together with a phenolic resin. Adjusting the density of the fibers and the resin mix produces different residential and commercial insulation products, including batts, blankets, and rigid and semi-rigid boards. All of these products provide excellent sound attenuation and flame resistance along with R-values of about 4 per inch.

Though the life-cycle impacts of mineral wool­ production—primarily energy consumption—are significant, some of these are mitigated through the use of pre-consumer recycled slag from iron manufacturing. Thermafiber, for instance, uses a minimum 70% recycled slag and offers products at 75% and 90% recycled content, including a darker colored board for curtain walls at 84%. According to Austin Hess, business development manager for Thermafiber, “the U.S. Government’s [EPA] Comprehensive Procurement Guidelines require 75% recycled content for mineral wool, and we are one of the only companies that can produce that product.“