Taming Your Asphalt Energy Monster with Trees

Your asphalt parking lot is an energy monster.

tree powerAnyone who has stood in the church parking lot at noon after worship during the summer knows that black asphalt slabs are energy monsters They store massive amounts of heat, and raise the temperature of the air around your church as much as 20 degrees above what a grassy area would. In conservation and meteorological studies, they are referred to as “heat islands.” On a micro scale -they hold heat near your building –fighting with your air-conditioning, raising your energy bills, and drying out grass and gardens.

Parking lots STORE heat and dissipate it right into your building -even after the sun goes down.  And the closer the lot is to your building, the great the heat transfer. It’s made even worse by the typical brick and stone materials which many churches are made out of. In one church I used to go to, the asphalt parking lot was just six feet from the brick wall of the church …and this proximity ran for 200 feet down the building without a single tree shading the area. (Yet the church had dozens of mature trees on the opposite side of the building where there was no parking lot). 

This all costs you money because the AC inside the church has to work overtime battling your asphalt slab. Money in energy, and money in the eventual wear and tear on the equipment.

Two fixes are regularly touted by conservation groups, city planners and landscape architects:

1. Plant trees!
2. Consider alternative materials to black asphalt.

For most churches, TREES are a very good answer.

“The net cooling effect of a young, healthy tree is equivalent to ten room-size air conditioners operating 20 hours a day.”

 – U.S. Department of Agriculture

“Trees properly placed around buildings can reduce air conditioning needs by 30 percent and can save 20 – 50 percent in energy used for heating.” 

–  USDA Forest Service

We all know that planting trees improves the environment. Trees suck carbon dioxide and provide habitat. But they can also shade your parking lot, which in turn reduces the amount of heated air next to your buildling. that means your air conditioning bills and the ac mechanicals get a break. It will also require less water for your church gardens and grass.

For more technical help, consult the Federal Urban Foresty website design recommendations at http://www.na.fs.fed.us/spfo/pubs/uf/techguide/toc.htm  Or visit numerous “Urban Forestry” websites for advice, including http://www.milliontrees.slco.org/html/rightTree/TreesForEnergyWind.html


== Don’t put parking lots right next to your building. Keep your heat island away from the building.

== Plant the CORRECT KIND of trees in islands in the parking lot. You don’t want the kind that will bust up the pavement. Pick local varieties that grow slow, have deep roots (typically that means non-flowering, but ask an arborist), and grow upwards rather than horizontally.

== Border your parking lot with heat tolerant grassy strips, native grass plants, and TALL shade producing trees.

== Do not “plant” air conditioning units near the asphalt. Put them in a cool shady spot. This will improve their efficiency. (work easier = more $ savings, plus fewer repairs, and better cooling when it’s really hot)

== Ornamental trees are nice to look at, but they don’t produce as much shade as a taller tree. They also require more maintenance, are more prone to bugs and fungus (and thus need chemicals), and don’t last as long in the landscape. Oak trees, by contrast, live to be 100, don’t bust up pavement (they send their roots deep) and are a better symbol of your contribution to the FUTURE.

== Plant drought resistant native grasses and perennials plants and native perennial flowers near your parking lot (anywhere for that matter), RATHER THAN ANNUALS which require water (and money every year).  Save your “good looking” floral budget for the front door area.

== Pour cool concrete near the doors, and shade the entry. The main church door is a major point of loss for your expensive energy dollars.   If you’re remodeling, install a set of double doors (an airlock) to conserve energy.

== Change your “Door Use Strategy.” Doors that get constant use allow heating and cooling (money) to escape. Most churches have several doors which members use to enter and exit to the parking lot. During the summer and winter months talk to your members, and put a sign on your doors CLOSEST the parking lot asking members not to use them, or not to leave them open. Stop the transfer of money out of your building. 

== Look at the windows facing the parking lot or exposed to the sun. An inexpensive reflective film on those windows will dramatically reduce the radiant energy coming in from the asphalt and sunlight. “Films” have come a long way and aren’t just the ‘mirrored’ type you might be thinking of.

== Place Evergreens on the windward side of your building to block winter wind chills from raising your heating bills.

BTW: Where does your church parking lot drain to? 
While not the subject of this particular thread, it’s worth looking into. Water runoff is a problem in most cities. Contact your local water/sewer or environmental department about what you can do to plant a retainment area into your property. Such retainment areas can not only help reduce flooding, they can help CLEAN the water running off the lot -which usually had a higher degree of petroleum biproducts from all the cars.

Additionally, there are several new pourous asphalt technologies being used across the country which allow water to percolate through the parking lot and replenish the surrounding aquifer rather than being carried off. For more info, visit http://www.pavegreen.com/

Other suggestons welcome!

<>< Neil

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