Monday, December 17, 2012

A Tale of Two Roofs (part 2 of 3)

or, Lessons in Resource Conservation from a Post-Disaster, Developing-Nation Context
…And How to Reconcile them with One’s Experience in Design, Energy-Efficiency, Urban Agriculture, and Living Systems



Earthquake vs. Envelope: Keeping the Baby with the Bathwater

A kindergarten in the Delmas 32 neighborhood under repair/construction, 2011.

In Haiti after the earthquake, the loss of life was something I had never experienced, and the immediacy of need in the built environment was daunting.

Over time, things were improving, but were still hardly adequate.
For example, internally displaced persons (are we afraid of the term 'homeless'?) figures:
  • 1.5 million after the January 12, 2010 quake (Source: OCHA)
  • 810,000 by January 2011:  (Source: IOM DTM / OCHA)
  • 515,000 by January 2012:  (Source: IOM DTM)
  • 357,785 by October 2012 (Source: IOM DTM)

Further, 28% of surveyed buildings were collapsed, with 33% requiring repairs, and 80% of schools destroyed following the quake (Source: Architecture for Humanity).

The numbers vary depending on the sources, as you'll no doubt notice, but bottom line: people needed homes, schools, social services, and places to do business. Given this, pursuits other than ‘building back better’, safely and quickly, seemed frivolous. I needed to turn entire parts of my brain - or recent training and experience -off.

Or did I?

The obvious example was in the design of earthquake-resistant buildings.

A proposed Passive House, in section. The red line indicating the building envelope, and an attempt to divide interior from exterior to eliminate thermal bridges.

In Chicago, I used my Passive House training to plan, design, and implement buildings with very energy-efficient envelopes, or those surfaces of a building that touch the exterior. The goal was to try as best one could to separate interior from exterior – like the Styrofoam lining inside the hard outer shell of a cooler or Thermos – and minimize (or eliminate) energy-wasting thermal bridges. This was critical in a climate such as Chicago, which as many know, experiences both many months of severe winter and hot, humid summers.

In the Caribbean, temperature (and humidity) swings are less severe, and whether energy is lost by conduction, convection, or radiation through a building’s envelope, an earthquake really couldn’t give a shit.

Energy conservation – in the form of good building envelopes – didn’t really matter in Haiti, right?

An example of an existing primary school in the Delmas 32 neighborhood of Port-au-Prince. Owners often did the best they could with available funds, but roofs like these were not unusual.

The answer came when standing beneath a lost battle: a school classroom addition recently completed, the roof of which was the most prominent – and important – element.
Comprised of one single thickness of corrugated aluminum sheeting, just like thousands of other crappy school roofs in Haiti, I stood under it, alongside students as the heat beat down mercilessly on our heads on a modest (for Port-au-Prince) 85 degree F day.
I had argued, unsuccessfully, to add a tiny amount to the budget for a roof that would helped cool the classroom passively, using the following multiple layers:
  • the aforementioned aluminum sheeting, atop
  • wood battens, which would create a void space to allow heat to escape from behind the metal sheets by convection, atop
  • foil-faced radiant barrier plywood sheathing, to deflect UV rays up and away, reducing transference of heat energy through the roof

But budget decisions trumped this design.

While I could go on extensively about the many decisions involved in earthquake-resistant design and envelope/energy-conscious design, the point is that the two are not mutually exclusive, and if the goal were truly ‘sustainable’ development, both must be considered.

Consider also that:
  • Schools in Haiti are traditionally little more than a few concrete block walls and a roof. If the main element that makes for a comfortable, humane learning environment is ‘cheaped-out’, everybody loses.
  • Haiti is blessed with no snow, so those structural loading considerations we worried about in Chicago roofs was not an issue. What Haiti has – in spades – is hot, humid, sunny days. So… design for it.
  • Wealthier building owners in Haiti do – and will continue to – air-condition their buildings. If building envelope is an afterthought, valuable conditioned air goes out the window (almost literally), and with it go the lessons of resource conservation to current and future generations.

If we take the opportunity and expense to satisfy the minimum requirements of withstanding earthquakes – which is challenging enough in making good design, detailing, materials, and construction oversight all work together to produce a correctly built building, why wouldn’t we do the easy stuff with passive design and good building envelopes?

Too many decision-makers in post-disaster, developing-nation contexts like Haiti let expediency get in the way of making truly sound, informed decisions to allow people and their environments to work great together.

(more to come soon...) 

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