Whenever a new development is proposed, be it six-story mixed-use residences in Dinkytown, an overhaul of Downtown East on the Star Tribune lots, or most recently, a proposal for the southwest corner of Franklin and Lyndale, resistance will most likely show its face.  There are many reasons people or organizations oppose development, and simply writing them off as NIMBY (+1 in Bill’s metrics) ignores the potentially valid, sane arguments they may have.  Let’s save the discussions of height, shadows, traffic, crime, and others for a different day.

Fighting for historic preservation has become a big part of the debate in many developments.  I have my own personal questions on the merits of preservation for preservation sake, whether it’s conservation districts or individual decisions to save buildings.  I’ll readily admit that the benefits just seem too fuzzy to me (outside some seriously significant buildings), and a private approach where organizations or people pony up the money always seem better than making private benefits public (go ahead, call me a curmudgeon who doesn’t appreciate history if you must).  However, a more targeted argument comes up every so often on whether preservation or construction is good for the environment.

To aid this debate, a report [pdf] written by the National Trust for Historic Preservation released in early 2012 goes a long way toward quantifying the benefit of preservation + renovation compared to demolition + construction.  It provides great data points beyond the qualitative “all the old-world craftsmanship with embodied energy will hit the dumps,” which I greatly appreciate, and the information should be a valuable part of the discussion.

The study uses examples from across the country to determine environmental and climate impacts, with much of the variance stemming from electricity sources, local climate effects on heating and cooling, and local construction materials.  Chicago may be the closest to the Twin Cities for comparison in these respects, and the study shows that, depending on structure type, it may take between 10 and (gulp) 80 years for new construction to break even on environmental impacts vs. renovating existing structures.

Not Quite There

That said, the study has some shortcomings regarding evaluating total environmental impact, like any report (especially one authored by an agency focused on preserving historic structures as a key mission statement).  Among them:

• I believe the study’s major flaw is its assumption that new construction will remain at roughly the same intensity, footprint, and/or height of what it replaces.  While it may be true that houses across the metro, particularly in first-ring suburbs and wealthy parts of Minneapolis, are being torn down for new single-family homes, the historic-as-green argument crops up for projects that  replace smaller structures with apartments, mixed-use buildings, or other.  Replacing two structures housing 4-10 people with a 45 unit apartment is hardly comparable.  This important because…

• Transportation Energy Costs are Excluded:  The chart (page 17) shows how the US spends its energy today, and a big factor we should all be concerned with: transportation emissions – 29%.   The study avoids calculating these environmental impacts, most likely because calculating number of trips by mode and distance for average projects would be difficult.  But that doesn’t mean that a project in a transit-supported, dense environment close to thousands of jobs in a downtown core isn’t likely to see many of the new residents walking to stores or work, or taking transit more often.  More people using these cleaner modes may engage a positive feedback loop for existing residents, or give Metro Transit the kick in the pants they need to upgrade service.
• Unintended Consequences of Restricting Growth: Assuming the population or business growth is retained in our metro area but halted on historic grounds.  New construction may happen at the fringe of the metro, potentially requiring new concrete, asphalt, energy transmission costs, or other potential impacts.  These avoided costs don’t seem to be calculated.
• Sub-Optimal Regulatory Environment: The study ignores government policies that force higher new construction energy costs – namely required parking.  Does this mean all new construction builds only what is required?  Surely not, but it happens (University of Minnesota adjacent construction a relevant example), and other regulations may have similar impacts.

• End of Life Process for Existing Structures.  The study assumes all embodied energy is more or less lost to landfills, ignoring major re-use potential.  This could include moving the existing structure (saving it entirely) to a location where a single-family/detached home is warranted by the market.  It could include re-using beams, trim, bricks, fireplaces, and beyond in new construction or renovations for existing structures (which a local TV star lambasted a property owner for doing prior to demolishing a property).  There should be targeted public and private initiatives aimed at reducing lost embodied energy, and hopefully as many people as possible can turn a profit doing so (jobs!).

A Pragmatic Path for Minneapolis and St Paul

Despite these objections, I do believe lovable places, great urban design, and historic structures do play a role in lowering energy impact.  It’s obvious that century-old passive design elements found in our housing stock and street design help keep houses cool during our oppressive summer months without significant energy draws.

What should our cities do to evaluate project proposals on their environmental merits (among other issues that inevitably arise)?  I’m a math guy, so I like equations.  Absent a federal (or global) tax on carbon and other harmful emissions that level the playing field for how people spend their money on transportation, housing, and food, cities have the potential to implement their own metrics.

If the study’s methodology were updated to include some of the missing links discussed above, proposals could get an expected lifetime environmental impact value.  Obviously, the city would need to make assumptions for future behaviors – travel mode, distance, and frequency would need to be tailored to individual neighborhoods and use demographic (and infrastructure) trends.  For example, an apartment that’s a 5 minute walk from the West Lake SWLRT station may have low transit use today, but 5 years from now the share may triple.  This tool may require some heavy lifting up front, but the data is all there.

This information could help city leaders reach their sustainability and affordability goals, while also encouraging dense, new growth at key nodes and corridors.  Cities could give incentives in the form of lower property tax rates (just spitballin’ here..) the more a proposal reduces total environmental impact.  It may also steer developers to target certain lots, avoiding excessive hurdles  or costs set by the city by replacing surface parking or under-utilized industrial sites in the near-term.   Preservationists get a tool in the city’s pocket that’s fair, transparent, and tilts the scale toward keeping high-utility historic structures difficult to demolish by virtue of their embodied energy.

So, returning to my titular question: is new construction here in the Twin Cities green?  Well… it really depends on a host of factors, so perhaps I’ll leave it unanswered. What other opportunities are there to evaluate the merits of new development proposals?