Group items tagged

Data gathered during low-altitude flights in and around the Los Angeles basin in May 2010 suggest that the region's 9.9 million autos generate about 62 metric tons of ammonia each day

ammonia emissions from dairy farms in the eastern portion of the basin—home to about 298,000 cattle—range between 33 and 176 metric tons per day

Ammonia emissions from the dairy farms are concentrated, boosting atmospheric levels of the gas to more than 100 times background levels, so efforts to curb the farms' emissions (perhaps by feeding the animals different diets) might reduce smog more than those targeting cars.

are constructed with dark materials

"Because dark pavements absorb almost all of the sun's energy, the pavement surface heats up, which in turn also warms the local air

Berkeley Lab scientists have been studying "cool pavement" technologies

Like cool roofs, which are lighter-colored roofs that keep the air both inside and outside the building cooler by reflecting more of the sun's energy

pavements reflect as much as 30 to 50 percent of the sun's energy, compared to only 5 percent for new asphalt (and 10 to 20 percent for aged asphalt)

Heat Island Group has converted a portion of a new temporary parking lot at Berkeley Lab into a cool pavement exhibit that will also allow them to evaluate the products over time

provides an opportunity to feature cool pavement coatings that are applied directly to existing paved surfaces

the exhibit features six coatings donated by two manufacturers

Emerald Cities Cool Pavement and StreetBond.

Cool pavements can either be made from traditional pavement materials that are lighter in color

such as cement concrete

or can consist of cool-colored coatings or surface treatments for asphalt surfaces

An ideal design goal would be a pavement with solar reflectance of at least 35 percent

Sealcoats are a common maintenance practice for parking lots and schoolyards since the asphalt pavement structure degrades over tim

asphalt

can be used in lieu of a sealcoat, and are a good strategy for cities looking to introduce cool pavement technologies

Cool pavements come in different hues, including green, blue and yellow, and their solar reflectance value depends on both color and material

some colors that look dark but are actually more reflective in the near infrared spectrum

scientists will be collecting data to see how the coatings fare over time

At some point they will reach an equilibrium at which the solar reflectance won't degrade much anymore

very interested to see what happens when it rains, which may help the coatings self-clean and restore higher reflectance

"Across an entire city, small changes in air temperature could be a huge benefit as it can slow the formation of smog

Just a couple of degrees can also reduce peak power demand, by reducing the energy load from air-conditioning

Chicago has reported energy savings from using solar-reflective pavements in its alleys

more reflective parking lots could allow building owners and cities to save on energy needed to illuminate streets and parking lots

field studies are needed to verify and quantify the results.

many of these benefits have been confirmed by scientific models

leading a study

will closely monitor the solar reflectance values and temperatures of 20 x 24 square-foot pavement sections of six different materials on a residential street on the UC Davis campu

scientists hope to better understand how changes in solar reflectance over time affect heat transfer throughout the pavement structure

may assist policymakers and pavement professionals in making informed decisions regarding cool pavement requirements for building codes and project specifications

may also help sell cool pavement coatings since they tend to be more expensive than traditional sealants

hurdle is that the benefits of cool pavements are more for the public rather than the building owner

benefits are less immediately tangible than for cool roofs

initial cost premium can potentially be offset over the lifespan of the product with increased durability and less need for ongoing maintenance

schoolyards are a particular target because of the negative health implications of hot blacktops for schoolchildren