Selecting Low-Maintenance Plants

Question:
Are you aware of a recognized standard that identifies "low-maintenance/indigenous" plantings for sustainable landscaping in different geographies?

Response:
I don’t know of any guide that identifies native / adapted vegetation (low-maintenance) for the entire US and was always at a loss when asked by a design team. Plant selection changes a lot based on region and even local microclimate. For the most part, anything local is always a safe bet. For adapted plants, you want something that doesn’t require much water, fertilizer, or maintenance and won’t get out of control. The general rule is also to avoid turf grass as much as possible and use lots of mulch. If you are putting the landscaping out to bid, you could include a performance requirement that says plants must be native to the area or require minimal maintenance, etc. The attached documents might help you define xeriscaping or a process each site should employ when selecting plants. For example, you could emphasize the 7 principles found here: http://www.energysavers.gov/your_home/landscaping/index.cfm/mytopic=11960

This site is supposed to let you select water efficient plants, but I can’t get it to work: http://www.h2ouse.org/gardensoft/index.aspx

There are a few good sites for specific regions. For example:
Missouri: http://extension.missouri.edu/explorepdf/agguides/hort/g06912.pdf
Austin, TX: http://xeriscape.sustainablesources.com/
Colorado: http://www.ext.colostate.edu/pubs/garden/07228.html

You might also want to check out one of these books:
“Landscape Plants for Western Regions: An Illustrated Guide to Plants for Water Conservation” http://www.amazon.com/exec/obidos/ASIN/0960598839/phoenixtropicalg/002-2301829-6294425
“Waterwise Landscaping with Trees, Shrubs, and Vines: A Xeriscape Guide for the Rocky Mountain Region, California, and the Desert Southwest” http://www.amazon.com/exec/obidos/ASIN/096704510X/qid%3D1010441830/ref%3Dsr_11_0_1/002-2301829-6294425
“Plants for Natural Gardens: Southwestern Native & Adaptive Trees, Shrubs, Wildflowers & Grasses” http://www.amazon.com/exec/obidos/tg/detail/-/089013281X/ref=pd_sim_b_4/002-3622213-9240020?%5Fencoding=UTF8&v=glance

A good landscaper should be able to help you define this for your site (as should a good nursery):

Association of Professional Landscape Designers: http://www.apld.com/

American Society of Landscape Architects: http://online.asla.org/scriptcontent/index_find_firm.cfm

I hope this helps and good luck,
Nathan

Roca Dual Flush Toilets

For the last month I've been traveling in Morocco and Spain. In both countries, I saw a number of dual flush toilets (though still less than half of the toilets I saw). The most common brand seemed to be Roca. All Roca toilets have been dual flush since 2001 and many are 5/3 liters (in addition to the more common 6/4 liters or 1.5/1 gallon). The company is ISO 14001 certified for having an environmental



management system. Haven't seen their products in the US, but they seemed to work well. The picture above is a typical floor mounted tank type toilet from a Tryp Hotel in Madrid, Spain. The one below is a wall mounted tank type with the tank recessed between the wall studs from an Isis Hotel in Essouira, Morocco.

Water Savings Calculations

Question sent by email:

I've heard you say you can save 40% of domestic water without any added cost. How do you do this? Is it use of gray water for flushing in addition to waterless urinals, low flow toilets, aerators on sinks, etc???

Response:

It was very easy to do in the past with fixture selection. The water efficient fixtures we use have no added cost compared to conventional fixtures. We could save a tiny bit more with gravity fed toilets (the kind with the tank like you have at home), but we usually use flushometer toilets (the more commercial kind with the silver pipes sticking out of the wall).

Lets look at the calculations assuming there are two people in the building, one man and one woman.

Base Case (code compliant)

Toilet = 1.6 gpf - 3 times/day for woman, 1 time for man

Urinal = 1.0 gpf - 0 times/day for woman, 2 times for man

Sink = 2.5 gpm @ 80 psi - 3 times/day for 25 seconds for everybody

Shower = 2.5 gpm @ 80 psi - 1 times/day for 5 minutes for 10% of people

Design Case (what we do)

Toilet = 1.6 / 1.1 gpf dual flush - 1 full 2 half times/day for woman, 1 full for man

Urinal = 0 gpf - 0 times/day for woman, 2 times for man

Sink = 0.5 gpm @ 80 psi - 3 times/day for 20 seconds (sensors) for everybody

Shower = 1.6 gpm @ 80 psi - 1 time/day for 5 minutes for 10% of people

The scenario above would save 48.1% of the water in an office setting based on a comparison to EPAct 1992 (calculation for LEED NC v2.2):

Now we usually get a little less credit for the same water usage because the base case for commercial sinks has been reduced to 0.5 gpm @ 60 psi.

Base Case (code compliant)

Toilet = 1.6 gpf - 3 times/day for woman, 1 time for man

Urinal = 1.0 gpf - 0 times/day for woman, 2 times for man

Sink = 0.5 gpm @ 60 psi - 3 times/day for 25 seconds for everybody

Shower = 2.5 gpm @ 80 psi - 1 times/day for 5 minutes for 10% of people

Design Case (what we do)

Toilet = 1.6 / 1.1 gpf dual flush - 1 full 2 half times/day for woman, 1 full for man

Urinal = 0 gpf - 0 times/day for woman, 2 times for man

Sink = 0.5 gpm @ 80 psi - 3 times/day for 20 seconds (sensors) for everybody

Shower = 1.6 gpm @ 80 psi - 1 time/day for 5 minutes for 10% of people

The scenario above would save 34.8% of the water in an office setting based on a comparison to EPAct 1992 and the new commercial fixture rules (calculation for LEED 2009). Of course there is no kitchen sink in this example (assuming a college dorm), but that would have to be added in if appropriate:

Residential buildings code still allows 2.5 gpm sinks, so we typically save 38.1% in old and new versions of LEED.

Base Case (code compliant)

Toilet = 1.6 gpf - 5 flushes/day for all

Sink = 0.5 gpm @ 60 psi - 5 times/day for 25 seconds

Shower = 2.5 gpm @ 80 psi - 1 time/day for 5 minutes

Design Case (what we do)

Toilet = 1.6 / 1.1 gpf dual flush - 1 full & 4 half flushes/day for all

Sink = 0.5 gpm @ 80 psi - 5 times/day for 25 seconds

Shower = 1.6 gpm @ 80 psi - 1 times/day for 5 minutes

Of course the calculations above are done for 2 people, but the percent reduction will remain the same regardless of the number of people as long as you assume a 50/50 split between men and women.

We have plans to use greywater in some buildings and one of my projects in South Carolina did this (see Half Moon Outfitters case study). Showers really drive the numbers in residential buildings and it is possible to go below 1.6 gpm. We usually use Delta H20 Kinetic showers, but many of the best low-flow showers aren't allowed in Massachusetts because they're not on the approved plumbing list. The toilet in the top right is a tank-type dual flush from Dubai. The urinal on the bottom left uses no water for flushing and has a trap that can be cleaned and refilled with oil (Kohler Steward).

Hope this helps.