How does asphalt contribute to heat island effect?
We all know the saying: "It's so hot you could fry an egg on the sidewalk!". But is it possible? Research shows that a concrete sidewalk can heat up to 145*F. So you might actually be able to cook an egg on the sidewalk.
Our summers are reaching high temperatures and we increasingly see the need to find solutions for climate change. This especially applies to reducing heat in urban area surfaces. As specialists in lumber, we are also looking for ways of how we can contribute to lowering temperatures for communities.
Why do conventional pavements get so hot?
You will come across several causes and impacts of summertime urban heat islands. Simply put: asphalt pavements get hot because they absorb about 80-95% of the sunlight. Not only do they absorb heat, but they also radiate heat and contribute to global warming.
To understand new pavement solutions to climate change, we first have to understand how solar energy works. How does the sun heat pavements? And how does the heat affect the air above? There are three main properties that have a big effect on pavement temperatures: solar reflectance, thermal emittance, and permeability.
Solar reflectance
Solar reflectance is the percentage of solar energy reflected by a surface. Conventional paving materials such as asphalt and concrete have solar reflectances of 5 to 40 percent. This means they absorb 95 to 60 percent of the energy reaching them instead of reflecting it into the atmosphere.
Thermal emittance
A material’s thermal emittance determines how readily a surface lets off heat. When exposed to sunlight, a surface with high emittance will reach thermal equilibrium at a lower temperature than a surface with low emittance. The reason behind this is that high-emittance surfaces give off heat more readily.
ProFlow™ Permeable Pavers at ADOHI Residence | University of Arkansas.
Designed for storm-water control, permeable pavements are emerging as a cool pavement and thus a solution for climate change. The first mass timber building ever erected in the USA with this technology that has a LEED Silver rating by the U.S Green Building Council.
Permeability
Although they were originally designed for storm-water control, permeable pavements are emerging as a cool pavement and thus a solution for climate change. These pavements allow air, water, and water vapor into the voids of the pavement.
ProFlow™ Permeable Pavers can be made of sustainable wood materials such as Black Locust. Black Locust Lumber is becoming more and more popular for exteriors. Due to its beauty, durability of 50+ years, and certifiable sustainability Black Locust is a perfect wood material choice.
When wet, these pavements can lower temperatures through evaporative cooling. The water passes into the soil or supporting materials below. Moisture within the pavement structure evaporates as the surface heats, thus creating a cooling effect.
What are the benefits of permeable pavement solutions for climate change?
Installing cool pavements can be part of an overall strategy to reduce air temperatures. You can maximize the benefits of permeable pavement solutions for climate change by using a sustainable wood material such as Black Locust.
As lumber experts, our solution to climate change in our field was born 8 years ago and grew into the environmental product of ProFlow™ Permeable Pavers. It is a solution to climate change that has the benefits of reduced energy use, stormwater management, and also several quality of life benefits: it reduces heat stress on the body.
Alternative pavement material can be Black Locust Lumber that has natural durability of 50+ years and several quaility of life benefits compared to concrete pavements.
Reduced energy use
ProFlow™ Permeable Pavers evaporate water and contribute to lower air temperatures. They also provide other energy benefits. ProFlow™ Permeable Pavers allow stormwater to flow into the ground, which lowers stormwater runoff. With reduced runoff, communities may realize energy savings with regards to pumping stormwater and maintaining conveyance structures.
Flooding in cities is becoming a real issue due to climate change. Concrete and asphalt are not able to absorb stormwater.
Stormwater management
ProFlow™ Permeable pavements allow water to soak into the pavement and soil. While this reduces stormwater runoff, it also recharges soil moisture. Another benefit is that it improves water quality by filtering out dust and dirt.
Quality of Life Benefits
Using ProFlow™ Permeable pavements in urban green spaces or where children play can provide comfort benefits. Lower surface air temperatures are more pleasant to spend time around. By using Black Locust hardwood pavers instead of concrete and asphalt, the surface is also softer on the feet.
When selecting the right material for your next pavement project keep sustainability in mind. Stick to your frying pan when you are up for some eggs for breakfast and find a more sustainable permeable paving solution.
