Lean Urbanism is the Next Big Thing

There are so many ridiculous rules governing what we build. You can't live in tiny houses in Texas, build in straw bale in Toronto, or narrow streets in San Francisco. Our cities are run by engineers and planners and politicians who write big fat restrictive zoning bylaws and building codes that really restrict what you can do and make it take forever. That's why so many frustrated people take to tactical urbanism, redesigning intersections in Hamilton or putting up twenty is plenty signs in New York.

Andres DuanyLloyd Alter/ Andres Duany at Lean Urbanism Workshop/CC BY 2.0

Andrés Duany isn't into yarn bombing, but is throwing a new bomb into the planning world with Lean Urbanism. The goal is to cut through the fat codes and the red tape and go lean and minimal. Duany told Next City:

The biggest problem, and the one that makes cities feel the most vulnerable, is the liability culture. They think ‘if we take any risk whatsoever — if there’s any slack in the interpretation of this code — we’ll get sued.’

There are seven platforms in the Lean Urbanism structure (Lean Building, Lean Development, Lean Business, Lean Green, Lean Regulation, Lean Infrastructure, and Lean Education) but this article will focus on Lean Green, because these guys are really on to something here.

Lean Green

Lean Green is the antithesis of LEED green. In fact, much time and effort was spent by Duany and Robert Orr to attack LEED. I actually got into a screaming match with Duany when I complained about their inclusion of an article in Forbes by Anastasia Swearingen of the so-called Environmental Policy Alliance, a "guest commentary" so risible that even Forbes had to add a disclaimer and change their description of the author. I was accused of making an ad hominem attack when I was simply pointing out that in this case, their evidence was based on a tissue of lies from a front group out to destroy green building of any kind, and that quoting it hurts their cause.

And yes, these Lean Urbanists even bash the bike racks, perhaps the leanest thing in LEED. It is all so unnecessary; LEED isn't perfect, and it certainly isn't lean. It's bloated, but it serves its function. Lean Green is a totally different approach that can be a strong influence on its own.

The Original Green is Lean

Origianl GreenSteve Mouzon/ The Original Green/Screen capture

Lean Green owes much to the work of Steve Mouzon's Original Green, much admired on TreeHugger for its four attributes of a great green building: that it be loveable, durable, flexible and frugal. He noted that "if our behaviour doesn't change, tech won't save us." In planning our communities, Steve writes that they should be nourishing, accessible, serviceable and secure. Steve Mouzon has been a profound influence on my thinking and writing, which is why I was there in the first place.

Lean Green Principles

Architect and teacher Doug Kelbaugh's position paper lays out a somewhat confused basis for lean, energy efficient buildings. It certainly gets off to a good start:

Downsizing buildings is always Lean. Urban buildings that share walls, floors and roofs require less heating and air conditioning per person, as well as less building material and maintenance. Even Leaner is renovating or retrofitting an existing building, rather than building a new one. Leanest of all is opting to neither renovate nor build, and to make do with existing buildings.

It then gets a bit confusing. He calls for the use of renewable sources of energy and passive design elements rather than active systems. He then loads the roof with tracking photovoltaics and solar water heaters. He wants simple metrics and then calls for computer simulations of larger buildings. He claims that "If energy consumption must be calculated, the best overall metric is BTUs/ sf/yr/person, which is roughly equivalent to carbon footprint per capita" which, like Anastasia Swearington's Energy Use Intensity, tells you nothing about what the use is, how a business is organized or really much useful information at all.

Then there are Seven Lean Green principles, which should be considered standard practice by any designer, lean or plump:

1. Be built with local, low-energy materials and methods, and designed no bigger than needed.

No argument here, although clay brick does have a pretty high embodied energy.
Building materials that are in their natural or near-natural state are preferable to processed ones that have additional energy and chemical inputs. Locally sourced wood, stone, brick and glass are preferable to aluminum, plastic, concrete and steel (unless they are reused or recycled). Materials that are salvaged, non-toxic, renewable and bio-degradable are preferable.

2. Have an envelope capable of isolating or buffering it from heat, cold and humidity, consistent with the climate zone.

Kelbaugh calls for lots of insulation in temperate and cold climates, and the use of old-fashioned tools like curtains and shutters for windows. He says "The metrics should also be Lean" but then gets awfully specific and prescriptive for my tastes, saying that "There should be a vapor barrier on the warm side of the insulation." A lot of building science types now say otherwise. Similarly he gets into detail such as "In hot, humid climates, wall cavities must breathe to the exterior to prevent the build up of mildew and mold." Really, why throw in a detail like that when there are 30 different ways to build a wall?

3. Face south with sufficient glazing to passively collect solar gain in the heating season, and have appropriate shading of south and west glass during the cooling season.

Again, the principle is good and the description is too prescriptive. "The south face(s) should be generously glazed, as each square foot of vertical double-glazing gains more heat than it loses over the course of most heating seasons. " Others would point out that overly generous double glazed walls are going to make for very uncomfortable spaces, and would make a case for minimizing glazing and maximizing thermal mass on all walls.

4. Have sufficient mass to store solar gain and to act as a thermal flywheel, radiating warmth in the heating season and absorbing it in the cooling season.

Where heating is needed, there should be enough thermal mass inside the thermal envelope to carry any excess heat gain from one day to the next. Heavy, dark-colored masonry with direct exposure to the sun is among the best thermal storage/flywheel devices, especially if it is also part of the building’s structural system (Trombe Wall).

Note that in Point 2, It says "Light colored roofs and walls reflect unwanted solar heat gain. " One size does not fit all, but we do celebrate thermal mass. But here we are being all lean and low tech, and then: "Water and phase change materials are useful for thermal storage, although they must be in secure containers." Phase change materials and types of containers? This is crazy detail for a lean concept.

5. Be open to and induce natural ventilation when cooling is needed.

Cross-ventilation and chimney-effect, vertical ventilation should be used as needed to cool building spaces and building mass, especially at night when outdoor air is cooler in hot, humid climates. Night sky radiation and evaporative cooling are effective in hot, dry climates.

YES! This is a forgotten art and should be required. The most overlooked design element gets high priority.
windcatcher houseWikipedia/ Traditional wind-catcher house in Persia/CC BY 2.0

Kelbaugh calls the 7 point list " irreducible" but really, the problem with points 3, 4 and 5 is that they are treated in isolation when in fact they are all of one point; design in a manner appropriate for climate, which is Point 2. In a really hot climate (like ancient Persia) the windows are minimized, the walls are thick and the ceilings are really high to promote ventilation. It is all a balance among the different aspects and you can't really have one without the other.

6. Be adaptable over time, with materials and components recycled or reused at the end of their useful lives.

The building foundation, structure and shell should be built to last a century or more in order to shelter different users and needs over time. Buildings should be constructed of materials that are reusable or recyclable. Movable, short-lived and personalized building components should be flexible on a daily and seasonal basis, as well as adaptable over the years. Buildings should recycle gray water for toilet flushing and irrigation of plants. Occupants should recycle inorganic and compost organic waste, as well as minimize water consumption.

This is what we described as open building, the recognition that different functions have different lifespans, and alludes to Mouzon's call for flexibility. What it has to do with recycling (which is not lean at all) is beyond me.

7. Employ the first six principles preferably in urban settings and in ways that are site-specific, context-sensitive and that do not conflict with common sense or prevent other buildings from employing them.

Last, but far from least, if the building is located in an area that has few amenities and services in easy walking/biking distance or is not well served by transit, automobile dependence can offset the energy and climate benefits promoted by these principles.

Bravo for that. A building shouldn't be thought of in isolation, but is part of a community, with party walls and neighbours who should be respected, and there is no point in building a lean green structure if all the green benefits are lost because you have to drive there. Good stuff. But then what does this mean? And why is it here in 7?

Buildings that are 100 percent solar or zero- energy are usually less cost-effective than an equivalent investment in multiple buildings that are 60 to 80 percent solar.

Really? Sez who?

This is a really good start to an important document, but it isn't lean at all, making specific prescriptions and pronouncements covering questionable vapor barriers and bizarre things like phase changing materials. It says keep it simple, and then tosses in geothermal and biomass. It calls for a " simpler, more local and holistic regulatory regime" and then starts counting BTUs per square foot per person per year, which ain't exactly holistic. It does not live up to the summary that teased us with:

Lean Buildings reduce energy flows by tapping basic natural heating and cooling techniques and renewable energy sources in ways that are region-specific and climate-sensitive.

Far from being irreducible, I count four principles really:

1. careful material selection;
2. appropriate envelope design;
3. prioritize passive;
4. proper siting.

It's a start of a grand idea, Lean Green. In our own way, I think we have been pitching it in TreeHugger for years (and today in the Guardian!). But There needs to be more Mouzon in the mix, less weird building science, and a dose of resilience and loveability. There is more to green building than just energy.

Tags: Green Building | LEED | Less Is More | Living With Less


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