Boulder’s Passive Aggressive Building Standards

Usually when people say that “better is the enemy of good enough”, they’re pointing out that striving for perfection can be a distraction from just getting the job at hand done.  There are other dynamics that involve these concepts too.  As social animals, we tend to judge ourselves against those around us.  Once our basic needs have been satisfied, our relative wealth or deprivation often becomes more important to us than our absolute level of well being.  We have little concept of how much is enough.  This can lead to the familiar runaway acquisitiveness (keeping up with the Joneses) when there is a well established (or constructed…) social norm favoring consumption.  Less obviously, it can also lead to an inappropriate lack of ambition when faced with an objective task that is not supported by widespread social norms.

Over the last couple of years Boulder has upped its building energy efficiency standards.  The new permitting regime requires buildings to perform better — net of on-site generation like photovoltaics — than the 2006 international building codes (IBC).  Smaller dwellings (< 3000 square feet) have to use 30% less energy than the baseline.  Medium homes (3000-5000 sq ft) need to do 50% better, and large ones (> 5000 sq ft) have to beat it by 75%.  Obviously this is an improvement over the previous situation, but in comparison to what is possible, and what is necessary to combat climate change, it’s actually pretty unimpressive.  Homes of all sizes built to the Passive House standard use 80-90% less energy than the baseline code, and they do it without counting any on-site power generation against the building’s energy consumption, whereas the HERS index that is used in the Boulder code does count on-site generation.  This is an important distinction, because the atmosphere doesn’t cancel out your nighttime coal-fired emissions with the solar electricity that you sell onto the grid during the day.  All it cares about is the total amount of CO2 released.

Passive House buildings achieve this energy savings by enveloping the living space in an unbroken, nearly airtight sheath of insulating material.  The entire building envelope has to be free of thermal bridges, and essentially all infiltration and exfiltration of air is done via an energy recovering ventilation system, often using a ground-coupled heat exchanger to pre-heat or pre-cool incoming air (depending on the season).  All windows are highly insulating. Equator-facing windows are appropriately shaded to avoid solar gain in the summer and promote it in the winter, and pole-facing windows are minimized, while east and west facing windows (which can’t be effectively shaded in summer) use special thermally opaque coatings to minimize unwanted solar gain.

All this extra insulation, sealing, fancy windows, etc. costs more of course, but it’s financially worthwhile because it means you don’t need to buy a furnace and ducting or a boiler, hydronic plumbing, and radiators.  You also end up having virtually non-existent heating and cooling bills down the road.  In Germany it cost less than 5% more on average to build a Passive House vs. a comparable dwelling meeting the 2006 IBC, and some builders have been able to push their construction costs down to where there’s no longer a premium to be paid at all.  Often this is done by manufacturing components of the buildings off-site, in a large workshop, allowing much better quality control, more efficient use of building materials, and more predictable construction phasing.  Here’s a great time-lapse of a partially pre-fabricated Passive House going up over a couple of days in Slovenia:

In contrast, building passive in the US generally costs much more than traditional construction.  Partly this is because the US market is small, so builders are less familiar with the techniques.  Also, high performance windows, heat recovering ventilation systems and highly efficient household appliances often have to be imported.  Local planning boards are unfamiliar with passive buildings, and often make the permitting process very difficult, despite the fact that there are tens of thousands of these dwellings functioning just fine in northern Europe.  Often they make it impossible for passive buildings to be cost effective by requiring heating systems which are grossly over sized.  Instead we should be doing the opposite, effectively prohibiting — or at least rendering economically nonsensical — the installation of active heating and cooling systems in new buildings.

Doing so would stimulate the creation of a local high performance building industry, lowering construction costs and creating a cadre of local architects, builders, and regulators familiar with the techniques the standard requires.  Serious Materials already manufactures windows compatible with passive houses nearby.  We could play the same role in North America that the 1999-2001 CEPHEUS (Cost Efficient Passive Houses as European Standards) project played in the EU — demonstrating that the buildings work, and are cost effective at scale — and we already know the result, so there’s no risk involved in doing so.  Today, a decade after that test run, there are more than 25,000 Passive House certified buildings across Europe.  In the US, there are less than two dozen.

Disturbingly, it’s also possible that the particular variety of “better” that we’ve chosen (beating the 2006 IBC by 30-75% depending on the size of the building) may actually end up being worse in some ways, because it pushes buildings into an economic dead-zone for energy efficiency.  Up to a certain point, adding additional insulation makes sense, but then it starts to cost more than the energy it saves is worth — until you’ve added so much additional insulation and such a tight building envelope that you avoid the expense of the furnace altogether.  Thus a 50% or 75% improvement in energy efficiency can actually end up costing more than a 90% improvement!  Because of this financial “valley of death”, many people will likely end up choosing to install solar panels rather than investing in efficiency.  Boulder County already requires larger houses outside the city limits have very low HERS scores, all the way down to being “net zero energy” for the biggest ones, but because it’s the building’s net energy usage that’s being counted, they usually end up being only modestly more efficient than normal, and having enormous PV arrays.

So we may end up doing better than before, and better than most US jurisdictions, and we’ll feel good about it, but we aren’t doing what the atmosphere silently demands, which is that we reduce our fossil energy use by 80-90%.  In this case better isn’t good enough, and good enough is already technically and economically feasible, so we have no excuse for failing.

Boulder, and all the other places claim to care about climate change, must aspire to more than simply failing less spectacularly than the rest of the world.  We should try to succeed.  We should demonstrate that success is both possible and pleasant.  Scientists can describe the broad constraints, the shape and the size of the space we have to work within — we can say what good enough is.  Good engineers and designers can create solutions that meet the challenge.  Designing within difficult constraints often leads to much better solutions.  It requires re-thinking problems and more clearly defining what the fundamental goals actually are.  It makes you find new regions in the solution space, that you never knew were there.

As a scientist and an engineer it’s easy to feel like once the conditions for a solution have been laid out, and it has been demonstrated that a viable solution exists, that the actual grunge work of implementation is best left as an exercise for the reader.  But at the end of the day, just knowing what we have to do, and how we can go about doing it isn’t enough.  We have to actually do it.  In this case the reader is citizens and policymakers and entrepreneurs.  We can play those roles too.  If we do, then fifty years from now any building that still needs a furnace, boiler or fireplace will hopefully be considered either defective or rustic.

Published by

Zane Selvans

A former space explorer, now marooned on a beautiful, dying world.

Leave a Reply