Rather than using electricity directly for heating the water, heat pumps use electricity to move heat from one place to another. By alternating cycles of compression and expansion (evaporation) in a closed loop, a heat-pump water heater is able to extract heat from the surrounding air and deliver it to an insulated tank of water even though the stored water is at a higher temperature than the surrounding air.

While a storage-type electric water heater has a theoretical maximum energy factor (a measure of efficiency) of 1.0, a heat-pump water heater can achieve an energy factor of 2.0 or higher. The performance of some products is measured using

Invelope is a unique steel and foam panel installed behind brick veneer or terra cotta in metal-framed commercial buildings. The panel serves as a moisture and vapor barrier, drainage plane, and insulation while also providing a mounting system for brick veneer or terra-cotta cladding. Manufactured by Centria, Invelope is certified Cradle-to-Cradle Silver by MBDC (see EBN Feb. 2007), using the same steel-wrapped polyisocyanurate foam construction as the company’s Formawall panels. As a backup wall, this one-piece design offers some distinct advantages over traditional assemblies.

One of the most common ways to create a commercial backup wall for steel-stud construction combines exterior drywall; an air, water, and vapor barrier; and rigid or semi-rigid insulation board. This system creates a thermal break between insulation and studs as well as a rainscreen with air space and a drainage plane that allows moisture driven behind the cladding to escape. After the backup wall is complete, masons secure anchors into the studs to support the bricks, penetrating through the insulation, barriers, and gypsum. Maintaining a weather-tight seal during installation of all the components by different trades can be a significant challenge, and once the brick is installed, air, moisture, and thermal problems are difficult to assess and remediate.

The Villa composting toilet from Separett is the most widely available urine-separating model, while the Eco-Flush from Wostman Ecology is a low-flush option designed to work with septic systems and sewers. Both the Villa and the Eco-Flush are made in Sweden and molded with a compartment in front to gather urine and a larger compartment in back for fecal matter. The Villa uses a plastic view guard to cover the composting solid matter below; the guard moves back when the user sits down. The Eco-Flush holds water in the bowl (waterspot), more like a conventional toilet.

Generally, users find that a urine-separating toilet takes some time to master. Peter Harper wrote of his experiences with two models of urine-separating toilets in 1998 in Clean Slate, the magazine of the U.K.-based Centre for Alternative Technology, noting that his male guests didn’t want to sit down to use the toilet (an issue solved by putting a can in the corner for them to use before pouring urine down the toilet). Of his female guests, he wrote, “The difficulty of cleanly separating urine and feces made many female users feel uncomfortable, not knowing quite where to sit to achieve the best results.” Designs of the toilet bowls have generally improved since Harper wrote his article, but most models still require a learning curve.

Atlantic Concrete Washout of Orlando, Florida, offers a more environmentally responsible disposal option that not only removes the washout from the jobsite but also ensures proper disposal. The company delivers an empty, sealable container to construction sites in the state. When the container is full, the company sends a truck to pump out the water and replace or remove the container. The washout water is transported to the company’s facility, where it is dumped into holding tanks to separate the remaining solids, which are taken to a concrete crusher for recycling. The washout water is pumped into a 4,000-gallon (15,000 l) tank and taken to the state’s industrial wastewater treatment facility in Tampa for disposal.

The U.S. Environmental Protection Agency (EPA) regulates most concrete washout through the Clean Water Act and the National Pollution Discharge Elimination System (NPDES), which requires permitting for stormwater discharge at point sources such as construction sites. Regulation and enforcement vary from state to state, but Storm Water Pollution Prevention Plans (SWPPPs) are required for construction sites larger than one acre. Penalties for violating local, state, and federal ordinances can be severe. “In Orlando we’ve seen EPA give fines of up to $40,000 per site due to improper washout,” said Kat Wheeler, green building coordinator for Atlantic Concrete Washout.

Power for the system is supplied under raised floors via movable wiring components called whips, which can be moved as building use changes. (A simpler, more flexible overhead version of the system is also available through Herman Miller.) Modular sensor interfaces and fully dimmable switches simplify the installation and programming of occupancy and lighting sensors and other “plug-and-play” devices.

Each device has an address that is recognized by the system’s software, so they can be controlled individually or linked together to form zones, such as an array of lights. The zones can be connected to mechanical systems, daylighting, or other controls to form “scenes,” in which lighting and temperature are preprogrammed depending on the needs of the space. This allows a single switch to control the entire environment of a conference room, entryway, or office floor.

Achieving necessary reductions in greenhouse gas emissions will require almost every home in colder climates of the U.S. to undergo a deep-energy retrofit, often increasing wall insulation to R-30 or more and attic insulation to R-50. Although these retrofits are not technically challenging, they are extraordinarily expensive, running $50,000–$100,000 per house (see EBN July 2007). A new product from Quad-Lock Building Systems, a Canadian manufacturer of insulated concrete forms (ICFs), can simplify the installation of exterior foam on existing houses. The R-etro System includes four components: 4¼"-thick (110 mm) panels (called Plus Panels), plastic clips (called R-etro Ties), galvanized steel starting track, and fasteners.

The company offers three basic models of its tankless water heaters: the 180, 210, and 240; these units generate 150,000, 175,000, and 199,000 Btu/hr (44, 51, and 58 kW-thermal), respectively, with an output of 4.94 gallons per minute (gpm; 18.7 lpm) for the 240 model based on a 77ºF (43°C) rise. These units have low minimum firing rates between 15,000 and 17,000 Btu/hr (4.4–5.0 kW-thermal), low minimum water flows, and thermostats that monitor outgoing water temperature, which combine to produce consistent hot water. The residential models (labeled “CR”) incorporate corrosion-resistant stainless steel heat exchangers and copper tubing and are factory-set to provide hot water at a maximum temperature of 120ºF (49°C). They can be adjusted to temperatures as high as 140ºF (60°C), but higher temps require a mixing valve. The commercial “CC” models contain stainless steel tubing throughout the units for added durability and can generate water temperatures as high as 185ºF (85°C).

Both the residential and commercial units can be ordered as “A” models with added circulation pumps and 0.5-gallon (1.9 l) buffer tanks. These units have some advantages over the company’s standard CC and CR models, which, like most tankless water heaters, require a minimum water flow of at least 0.5 gpm (1.9 lpm) to activate the burner. The A model can handle flow rates as low as 0.1 gpm (0.4 lpm). When set to internal recirculation mode, water in the 0.5-gallon buffer tank circulates within the units, maintaining a pre-set temperature to produce consistent hot water while minimizing the hot and cold water stacking in the pipes known as a “cold water sandwich.” The recirculation system also provides protection from freezing in cold climates (these units are for indoor installation only) and can speed delivery of hot water through the pipes. Running the unit in internal recirculation mode does not significantly impact the unit’s overall efficiency, according to the company, though there will likely be some standby energy loss. These units can also be configured for external recirculation to fixtures, though this is typically less efficient than recirculation to a buffer tank.

Under NSF-140, carpets earn points toward silver, gold, and platinum levels based on their performance in five categories: chemical emissions; renewable energy and energy efficiency; biobased content, recycled content, and environmentally preferable materials; social equity factors and life-cycle assessment of the manufacturing process; and end-of-life management and recycling programs.

As with any point-based system, there is concern that a manufacturer could manipulate the standard by gaining points in one section to the detriment of others. PVC, for instance, is easy to melt down into new backing and earns recycling points. But according to Jane Wilson, director of standards at NSF, “There are prerequisites, so companies cannot gain points without hitting each criterion.” The prerequisites not only ensure compliance with basic environmental standards but also with performance standards such as appearance, colorfastness, and flammability.

The Boston company Practical Solar has introduced the first ready-to-go, practical heliostat system for reflecting sunlight into buildings. This sunlight can be used for daylighting of spaces that previously did not have direct solar access and for providing solar heat through a window or skylight. “We harvest sunlight,” says inventor and company president Bruce Rohr. “We can deliver it where you want it.”

Rohr had originally intended his heliostat system to be used for indirect space heating and water heating. After failing to raise money to develop advanced components for those applications, however, he shifted to simpler lighting and direct heating applications. The rest will come later, he says. While the heliostat relies on sophisticated engineering and software to make it work, the end product is extremely simple in its function, he told EBN.

GreenSpec Directory of green building products for this list of the Top-10 Products for Affordable Green Retrofits.

1. Fluid-Applied RoofingFluid-applied roofing products can be applied over an existing roof to extend its life and increase reflectivity, reducing cooling loads. If you have the budget, however, you’ll get even more savings by replacing the roof membrane and adding several inches of rigid-foam insulation.