We have started to explore larger projects with our development company in Philadelphia that include shared off-street parking lots with a common driveway. This provides a new opportunity to explore more sustainable pavement options than the traditional blacktop used in most projects. Part of our research, as always, is devoted to finding the best mix of sustainability and cost so that we, and others like us, can actually have a chance of implementing something new on a for-profit project.

First, a bit of quick background on how Philadelaphia’s Water Department is actually encouraging projects to use permeable pavement in larger projects. In Philly, the city requires projects that exceed 15,000 square feet of area to develop an approved Stormwater Management Plan. Typically this involves large underground detention basins and extensive piping. There is also a lengthy design process typically associated with the Philadelphia Water Department.

Fortunately, the PWD provides incentives to builders to fast track their design and approval process for stormwater management if they can satisfy the needs via “green” methods. This typically always includes some type of pervious paving surface where impermeable would typically be installed and a method of delaying roof runoff from entering the city sewers (think green roofs or giant rain barrels).  Yea Philly!

OK, now on to the different options available in pervious surfaces that you can drive a car or even a large truck over. We’ll cover the main types that we have run across and you can tell us what we’ve missed in the comments. All of these systems are installed in a similar fashion. There is often a bit more excavation and up to a foot of crushed stone or gravel installed prior to the paving surface in order to help facilitate collection and storage of large rainfalls without the surface experiencing flooding. Simple, smart and effective. Read on and enjoy my rating system.

Porous Asphalt (Blacktop)

That's a fancy stream of water!

Porous Asphalt, or Blacktop as the kids say, is one of the more popular options out there as it seems to be the most cost effective and widely accepted. After all, it looks pretty much like normal blacktop and asphalt is king for most of our roads and parking lots.

Cost – $
Maintenance – Lots
Porosity – ~176″/hour
Ability to Grow “Green Things” – 0 out of 5
Overall Sustainaearthgreenfriendliness – D+

The Asphalt starts out strong with low cost and effective porosity, but quickly loses points for requiring a lot of maintenance, zero ability to grow anything, being nasty and a strong contributor to the urban heat island effect. Don’t get us wrong, it’s much better than standard asphalt. We’d just prefer one of the other alternatives a bit more for smaller projects that don’t include thousands of miles of roadways.

The maintenance we are talking about is a biannual cleaning with a giant commercial vacuum type device to keep the voids in the blacktop from getting clogged over time. Sweeping or pressure washing won’t do and may only contribute further to premature clogging. Check out the National Asphalt Pavement Association for more info.

Pervious Concrete

Oooooooooh!

Pervious Concrete is the same concept as porous asphalt, except it’s concrete. It’s very easy to order and have installed by a skilled flatwork contractor, even if they have never used it before as it is basically normal concrete with no “fines” in it. This is how it remains open to water infiltration. A benefit over asphalt is that is will result in a much lighter color that will not contribute to the urban heat island effect as much. It is still concrete though and comes with the carbon footprint associated with concrete if you’re counting carbon points on your project. A bit costlier to have installed than porous asphalt, it is a choice we prefer if options are limited.

Cost – $$
Maintenance – Lots
Porosity – ~480″/hour
Ability to Grow “Green Things” – 0 out of 5
Overall Sustainaearthgreenfriendliness – C

One way to reduce your carbon footprint with any concrete order is to insist on local or even reclaimed aggregates and push for the highest amount of Fly Ash and/or Slag which are both reclaimed waste products. Pervious Concrete also requires the same biannual sucking that porous asphalt recommends. Check out PerviousPavement.org for more info on Pervious Concrete.

Pervious Block Pavers

Most commonly seen permeable concrete paver

There are many different types of Pervious Block Pavers popping up on the market now that the concept of saving the earth is gaining popularity again. The most commonly seen permeable paver is shown to the left and creates a hexagonal shape of concrete around a central pocket where grasses can be planted or simple gravel can be filled in.

Cost – $$$
Maintenance – Some
Porosity – Varies
Ability to Grow “Green Things” – 3 out of 5
Overall Sustainaearthgreenfriendliness – B+

That tire is really working up a sweat.

Since the popularity of this interlocking concrete paver had increase, more varieties have hit the market that look more like traditional pavers. An example is shown to the right. These pavers have less open area that is usually created either at the corners or by spacing the pavers on all sides to allow for infiltration. This type of paver can not grow anything in the voids, but is typically filled with gravel. It’s a nice option for those that want the traditional paver look with boosted functionality.

Tbe biggest deterrent to these types of pavers is the cost. Not only are the pavers themselves pricey, but the cost of install is typically much higher than the other varieties of permeable paving due to having to lay individual, small blocks by hand. There can be some maintenance with these pavers as they may individually settle or become misplaced after some use. They may also be damaged easier than a uniform pavement by snow removal in the winter. There are too many suppliers of these products for me to point to one source, but Google can help you out if interested in more info.

Drivable Grass

Drivable Grass with grass, sand, gravel & mulch filler

Drivable Grass is a specific product manufactured by the Soil Retention company. It’s kind of a unique product that we recently stumbled across at Greenbuild that I felt deserved it’s own category. The product melds a bit of the benefits of the other products into one system.

For starters, is comes in 2′ x 2′ mats that are much more affordable to have installed than the individual pavers. It also has a much larger exposed area (61%) for greater infiltration and more room to grow grass or ground cover in if desired. Also, unlike the traditional hexagon turf pavers, this system does not isolate the plant material into individual pockets. This allows the plantings to remain cooler and receive more uniform watering. These benefits result in a greener parking surface than most of the alternative plantable systems.

Cost – $$
Maintenance – Very Little
Porosity – I couldn’t find a spec. Sorry.
Ability to Grow “Green Things” – 4 out of 5
Overall Sustainaearthgreenfriendliness – A

Currently, this is our top choice to use in a few of the sites we are looking to develop in Philly that have shared parking areas. It looks like the cost will be less than permeable concrete and we will get the added benefit of creating a green space in the parking lot that requires much less maintenance than other systems which will reduce the HOA fees for the home owners. All good things so far.

Plastic Grid Systems

Yes, you can drive on these plastic cup things

Cost – $$
Maintenance – Very Little
Porosity – Lots
Ability to Grow “Green Things” – 5 out of 5
Overall Sustainaearthgreenfriendliness – A

Last but not least are the plastic grid varieties of permeable paving systems. Some of these get extra points for being made of recycled plastic and being fully recyclable themselves. We have done the least research on these systems, but the install seems straightforward and it can result in a fully sodded surface if desired. The main issue we saw was that it is recommended for light or occasional use parking lots if you want to maintain the grass on the site. If anyone has any experience with this type of product, please speak up in the comments.

Conclusion. That’s all I have. Contribute below.

With silver bells and cockle shells? Hopefully not if you live in Philadelphia. First of all ‘silver bells’ is now classified as an invasive species and cockle shells are poisonous if ingested. So, Mary had things kind of wrong.

It’s important to know what you’re planting and to understand the conditions of where it is being planted. Many of us, in our naiveté, are encouraged to go to Home Depot, buy the prettiest plant we can find, and plant it wherever we want. However, then, of course, we realize the soil we planted it in is acidic so we buy fertilizer for it, then it’s growth rate is more than we could have imagined so we prune it, and then when we find unexpected mildew on it we apply heaps of fungicide to it. We’ve all been there. And the moral of the story is if you want to grow something badly enough you probably can, but at what cost? Louis XIV ordered that blooming flowers should always line the beds of Versailles, even in winter. So what did his staff do? They replaced every single flower, every single night, with countless stocks preserved in their greenhouses. At one point Versailles was using more water than all of Paris. For many Postgreen readers this is a harrowing prospect. We can no longer build vast greenhouses, apply heaps of inorganic fertilizer, water our annuals twice a day, and constantly mow our lawns. Water, money, and time are limited resources for us, and looking back on it they probably were for Louis XIV as well.

There are three methods I have come across so far for limiting the use of resources in the garden, all of which can be used in tandem. Using as many native plants as possible is the first and most important rule of gardening. Now, I’m not arguing that all your plants should be native. Please, don’t read this post and go rip out all of your epimedium and thyme. However, it is a good idea to have a majority of native plants. Native plants have an innate affinity with the particular way that soil conserves and stores water in a given community and a natural harmony with the conditions already there, whether they be acidic or loamy. So constant water and fertilizer becomes less necessary. Furthermore, they are also more likely to be free of the pests and disease that plague plants of non-native origin.

Another method for reducing resources is matrix planting. Matrix planting is based on the idea that in nature plants form self-sustaining communities which exclude outsiders, like weeds, while nourishing and protecting those within the community. Matrix planting seeks to replicate these communities in the garden and, in the process, eliminate the need for hoes, weeding, shovels, and watering cans. The driving force of matrix planting is matching the right plant to the right community in the right soil. Matrices take a few years to becomes established, but, in the end, greatly reduce the amount of resources put into your garden. Peter Thompson says it best: “The harder gardeners work, the more the problems seem to multiply…….If we let them, plants could do much of the hard work of gardening for us.”.

Lastly, use xeriscape. Xeriscaping is the use of drought tolerant plants. Pick plants that prefer the reasonably moist soil of Philadelphia, but can survive long periods of drought. No more watering, no more overuse of groundwater, no more dead and wilted plants. To start with some of my favorite water-wise plants in Philadelphia are:

Sedum ‘Autumn Joy’

Creeping Juniper

Black Eyed Susans

Purple Coneflowers

Creeping Thyme

Yarrow

Epimedium

Pennsylvania Sedge

Blue Fescue

Maiden Grass

These are just a few of my favorites, but please comment with your favorite drought tolerant plants and your experiences with them!

Now, here are some resources for those of you who are hungry for knowledge:

Fairmount Park publishes a great list of Natives for the Philadelphia region, usually they even list which ones are drought resistant/tolerant.

The University of Massachusetts has published an awe-inspiring list of drought tolerant plants.

The Self-Sustaining Garden: The Guide to Matrix Planting by Peter Thompson – By far the best resource on matrix planting. Buy this book, love it, leave it on your neighbors doorsteps when they decide they want to grow Mediterranean fig trees in a zone 5 hardiness garden.

What other resources have you found for local drought tolerant plants and sustainable gardening? Share them in the comments.

A couple weeks ago the team at Postgreen decided to officially hire local landscape architecture and urban design firm Studio Bryan Hanes to develop back yard landscaping options for our future Postgreen Homes clients.

Bryan came highly recommended from Brian Phillips of ISA and we couldn’t be happier that we took his advice. The illustrations you see below are some of the initial concepts that Bryan’s studio has come up with in the past few weeks. These are the options we are leaning towards for the new Postgreen Homes site launching at our July 30th party. Let’s get into these bad boys. All titles are courtesy of Nic, the Creative Content Master.

Entertainment

Built-in bench and table for entertaining. Ample open gravel space for many guests during your fancy parties.

What’s up with the suit here?

The Easiest Maze

Visual interest. Ample planting beds with easy access ideal for food or flowers. Intimate enough to relax. Flexible enough to entertain. Fun for kids.

Urban Farming

This has been our largest request to date. People want as large an area as possible to plant food things. This layout solves that with a modern layout that is easy to reach all plants. It also provides a nice sitting and entertaining area for your guests that may not want to help you garden.

Welcome to the Jungle

For those not interested in food plantings as much as simply being surrounded by as much greenery as possible. Ideal for singles and couples and small dinner parties.

Play Time

For those of us with children that require space to run and play. Also great for grown up yard games of skill. Think bocce or cornhole, not lawn darts.

Options

We plan to offer a bunch of customization options or upgrades on each of these layouts as well. For instance, we would have a base material for the decking, but if you wanted to upgrade to something like Ipe, you could do that on the new site. Other options could include gravel types, groundcover, planting packages and plater box materials.

We also talk quite a bit late last night about how to illustrate different size lots. The images above represent a 17′ wide by 17′ deep yard which is pretty common for a Philadelphia rowhome. This will obviously not be the case for every home. Some will be 12′ deep and other might be 25′. In the end we decided it is best to simply keep the layouts as shown to illustrate the concept for the back yard. The actual decking square footage or # of planters and such may change, but the overall concept of the layout will remain intact.

Let us know what you think of the proposed layouts. There is a limited time to make changes to them and this may be your last chance to influence our direction.

We imagine a way of life where waste is significantly decreased by our Extreme Green Kitchen, backyard garden, and composter working together in a self-sustaining cycle. Many of you have probably heard of the concept “waste equals food.” William McDonough, architect, designer and author of the esteemed book Cradle to Cradle, developed the idea. Working alongside his colleague and co-author Michael Braungart, McDonough calls for “the transformation of human industry through ecologically intelligent design.” “Waste equals food” is a system of “true recycling”—a system designed with the Life Cycle in mind. By applying this concept to our kitchen we hope to revise the current relationship between food culture and production so that they connect more closely to the home.

I recently met with Alison Hastings from the Delaware Valley Regional Planning Commission to discuss a current project she is involved with entitled the Greater Philadelphia Food System Study. They are researching ways to redesign the food system so that it is healthier, more efficient and able to exist in a world without oil. She gave me the contact information for Roxanne Christenson, co-founder and President of the Institute for Innovations in Local Farming. The Institute operates Somerton Tanks Farm, an urban farm acting as a prototype for Small Plot Intensive (SPIN) farming. I will be contacting her to discuss her work and thoughts on backyard farming kits, which could be sold with Postgreen homes. We also currently have our eyes on the Nature Mill composter because it is fully automatic, able to break down meat and dairy, and Energy Star approved. And don’t be worried about odor because it includes an odor-absorbing air filter that lasts up to five years.

So, our general idea is that owners of Postgreen homes could use these kits to plant their own backyard garden, which, using the SPIN method of farming, could produce a large amount of their fresh produce. The food is then cooked and stored efficiently in their Extreme Green Kitchen. The food scraps would then be transferred to the included composting system located under the kitchen sink. Food that would have been wasted, instead becomes nutrient rich soil that is added to the backyard garden to “feed” the existing soil, and continue the cycle of growth.

If you have any other product ideas, methods or even words of warning, share them with us in the comments.

As we near the completion of the 100K House project, we need to start thinking about our landscape design. As always we have to consider LEED reqs and points, modern design and budget. We are talking to a few local landscape designers in the area interested in the project. Due to budget and time constraints, we may not be able to go all out on design this time, but hope to make continual improvements going forward.

To keep things simple, I’ve compiled one list of only the points we are going after in the Sustainable Sites section of the LEED for Homes rating system. The fact that our site is so small makes a lot of these items pretty easy to accomplish. At the same time, the erosion controls are a bit out of place and possibly the only thing on the entire LEED checklist that we might not do if it weren’t for LEED.

LEED Landscaping Goals

Prerequisite: No Invasive Plants

1. Add mulch or soil amendments as appropriate.
2. All compacted soil must be tilled to at least 6 inches.
3. Do not use any conventional turf (technically less than 20%).
4. All plants must be drought tolerant.
5. If sidewalks are replaced, use white or gray concrete or any material with a solar reflectance index (SRI) of at least 29.
6. Design lot to be 100% permeable (no hardscaping). This includes permeable paving and even hardscaping that is designed to direct all runoff toward a permanent infiltration feature (on-site rain garden or rainwater cistern).
7. Plant one tree or four f-gallon shrubs to reduce erosion.
8. Install rainwater cistern to manage runoff from the roof.

Again, these are only the goals for our project. There are other ways to get points in this section of LEED that I did not go into here.

As far as the design, we will most likely have a very simple layout that contains a lot of decorative gravel rather than traditional turf. We are using our favorite residential landscape designer in the US as inspiration – rosenlof/lucas. We spoke to them a few times, but the distance makes it difficult for us to work with them both logistically and philosophically. The image above is from their site. It’s well work the visit to their site to get inspiration for modern and affordable landscape design.

A lot of the sidewalk around the 100K House lots is badly damaged and broken up. While it’s not required, we had planned to replace the damaged sections and plant as many trees as possible while we were at it. A couple months ago I looked into green alternatives to standard concrete sidewalks and found two main options – Pervious Concrete and Recycled Rubber Sidewalks.

While both are pretty cool products, I wanted to try and use something that the city of Philadelphia was already considering so I place a quick call to a contact at our local CDC, NKCDC.org, and they told me that there were rumors of rubber sidewalks and tree barriers being implemented in the city in the near future. As great as pervious concrete’s tagline is, after a bit of research I also sided with the city on rubber sidewalks for a number of reasons.

Why Recycled Rubber Sidewalks Make Sense

First, rubber sidewalk material is made entirely of recycled tires which we seem to have plenty of in our country. The material is more expensive than concrete by about 30% or so, but it lasts three times longer and does not have the carbon footprint that the production of concrete is notorious for.

Another big selling point for rubber sidewalks is the fact that they are much kinder to tree roots that are planted in or near sidewalks. The rubber tiles that often make up the sidewalk can also be removed to trim roots and service any utility lines running beneath them. Urban trees are often cut down after they reach maturity due to the fact that they have invaded the concrete sidewalks around them and with rubber, we can save most if not all of these trees from an early demise.

Rubber also makes a much friendlier surface to walk and play on, and it deadens sound as well. Lastly, it also reduces the heat island effect by staying much cooler than concrete in the sun.

OK, back to our use of rubber sidewalks. After a bit of research, I found that even though many in Philly were pushing for the use of rubber sidewalks, not test cases had been done that I could find. The corner that we are building on is a relatively high foot traffic area in between neighborhood so why not make it a case study for the city? We had the opportunity to meet with one of Philadelphia’s Councilmen this week, James Kenney, and it turns out he has been pushing for. It turns out that Kenney also has a soft spot for the environment and is also pushing for green roof incentives and converting Philly’s fleet of vehicles to hybrids. He was excited about the possibility of a test case of rubber sidewalks in Philly and gave us the contact to a local material vendor that could help us out with a quote. We contacted them today and see no reason why we shouldn’t be able to use this material over traditional concrete. Should be fun.

For more on both pervious concrete and rubber sidewalks, check out the links below:

http://www.perviouspavement.org

http://www.rubbersidewalk.com

http://www.rubbersidewalks.com