Finally, Buildings Are Going Net- Zero Water With Composting Toilets


Images credit the Bertschi School

Water and sewage piping are the arteries and veins of our cities, requiring huge investment in infrastructure and maintenance. But have the technology both to collect and clean rainwater, and deal with human waste locally, to go "off-pipe" and it is beginning to happen.

At Bertschi School in Seattle, the new Science wing has been built to meet Living Building Challenge standards, and is net-zero water and net-zero energy.

The project is designed pro-bono by the Restorative Design Collective, " a group of Seattle-area design professionals (led by KMD Architects) who share the desire to push themselves and their firms to the forefront of the sustainable building movement."

According to the school's press release,

The
 new
building 
features
 an
 ethnobotanical
 garden 
to 
grow
 food; cisterns 
for 
rainwater
harvesting; 
a
 green 
moss mat 
roof; composting 
toilet; natural 
ventilation
 and 
radiant
 floor
heating; a living 
wall
 of
 tropical 
plants 
to 
treat
 grey
 water; 
and
 solar
 panels, which 
will
produce 
all 
of
 the 
building's
 energy.


The Living Building Challenge 2.0 is the toughest green standard anywhere, and water is a key component of it; it envisions a future where water is harvested, purified and reused entirely on site. Meeting it is difficult and in many locations, even illegal, as they note:

Currently, such practices are often illegal due to health, land use and building code regulations, or by the undemocratic ownership of water rights, which arose precisely because people were not properly safeguarding the quality of their water. Therefore, reaching the ideal for water use means challenging outdated attitudes and technology with decentralized site- or district-level solutions that are appropriately scaled and efficient.

The photo shows Envirolet VF Vacuum flush systems, where, I have noted in an earlier post, an electric pump is connected to a Dometic vacuum toilet, mascerates the waste and toilet paper, and sends it to the composter. For the user upstairs, it will be a perfectly normal experience, sitting on a porcelain bowl. However it is not a completely water free system; you can see a white plastic drain pipe leading down from the upper unit. This normally has to be treated in some form of septic system or sent to the sewer system. It is a small demonstration of the real difficulty in going "off-pipe" rather than going net-zero, where a building might still be tied into the distribution system.

There are problems coming and going. The Seattle Times writes about buildings that are "unplugging from the water grid" and discovers that the school is not allowed to give the students purified grey water.

The building is set up to treat grey water to drinking standards, but it is still drawing water from the city water supply because of public health regulations.

"The state gets really nervous about treating drinking water on site," said Joel Sisolak, Washington advocacy and outreach director for the Cascadia Green Building Council. "Public water supplies and treatment water systems have done a lot of good in promoting public health. The question is, is it still the best model?"

That is, of course, the biggest question of all. Our current system of flushing our waste away, often to the same place where we get our drinking water, is broken. It is gratifying to see this demonstration of how we can start to fix it.

More at Bertschi School
More on going off pipe with composting toilets
Vancouver Office Building Goes "Off-Pipe"
Thinking about Crap: Should Houses Have Composting Toilets?

Follow me on Twitter! @lloydalter and friend me on Facebook

Tags: Composting Toilets | Seattle