[bouldercouncilhotline] Hotline: Building Code Standards for Energy Efficiency

[cmosupport at bouldercolorado.gov]

Sender: Cowles, Macon

I am grateful to Zane Selvans of the Transportation Advisory Board for providing me with information and references to the new Passive House design standard that was developed in Germany and is now being replicated in the United States. The Passive House standard is addressed at one metric: reducing energy use for heating and ventilation.

The design involves 1) sealing the building very tightly, 2) using 4-6 inches of insulation without thermal bridging, and 3) triple paned, argon filled windows.

Construction that follows these three criteria reduce energy use by 80-90% over code compliant buildings. Housing that is built following this standard achieves a HERS rating of 15-20. For comparison:

Boulder's current code, the 2006 IECC, results in a HERS rating of 100--the IECC 2006 baseline. Energy Star construction results in a HERS rating of 65-75. Compliance with the 2012 IECC achieves a HERS rating of 70. LEED homes typically result in HERS ratings of 70. Passive House Standards result in a HERS rating of 15-20.


Zane's email to me makes the following additional points on this subject:


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Passivhaus

The German Passivhaus building energy efficiency standard is a non-prescriptive, performance based standard that requires:
  - Minimal convective losses: less than 0.6 air changes per hour at 50 Pa of pressure.
  - Energy use for space heating: less than 15kWh per square meter per year.
  - Total *primary* energy use less than 120kWh per square meter per year.

In practice, this level of performance requires:
  - heat recovering ventilation systems
  - aggressive avoidance of thermal bridging (conductive heat loss)
  - triple paned high performance windows
  - insulated foundations

In many climates, this level of insulation means that internal heat loads (cooking, people, computers, lights, etc) can be sufficient to provide the overwhelming majority of the building's space heating.

Passive Passion is a decent short film narrative looking at efforts to popularize Passivhaus in the US, and do it cost effectively.
http://www.foursevenfive.com/index.php?main_page=page&id=30&chapter=1

The EU did a fairly large scale study of the cost effectiveness and applicability of the Passivhaus standard across N. Europe, and published the results in 2001:
http://www.passiv.de/old/07_eng/news/CEPHEUS_final_long.pdf

They concluded that the standard could be successfully and cost-effectively applied all across the EU, in a wide variety of building types.

There's been a lot of arguments in the high performance building community in the last year over whether the PH standard should be directly migrated to the US, given that much of the midwest has much
 harsher winters than central Europe, where the standard was developed.  These are fair criticisms, but they often revolve around whether or not the additional insulation is cheaper or more expensive than a PV array that would generate the same amount of power
 the insulation saves.  I think this stems from a misunderstanding of what's necessary to address climate change.  It is not practical to simply swap out renewable power for our existing energy sources.  We must also dramatically reduce overall energy consumption,
 or supplying that energy from renewable sources ends up being both expensive and very space intensive.  If you're not familiar with this argument, I highly recommend the following resources, which are very accessible to anyone with a modest amount of quantitative
 background:

Climate Change Recalculated, a good 90 minute talk by MacArthur Fellow, physicist and entrepreneur Saul Griffith:
http://fora.tv/2009/01/16/Saul_Griffith_Climate_Change_Recalculated

Sustainable Energy Without the Hot Air, a book by David JC MacKay, a Cambridge physicist and chief science advisor to the UK climate and Environment Ministry:
http://www.withouthotair.com/

They both do a good job of detailing where our energy comes from and what it gets used for, by sector and within the context of daily life.  Then they look at what it would take to get all that energy
 from renewable sources.

There's a Passivhaus certified designer working at RMI.  He had a good post related to the changing building energy efficiency standards last year:
<a href="http://blog.rmi.org/blog_nice_house_but_is_it_legal" title="http://blog.rmi.org/blog_nice_house_but_is_it_legal
Cmd+Click to follow link" style="font-family: Helvetica; font-size: medium; ">http://blog.rmi.org/blog_nice_house_but_is_it_legal

I think it's clear that, long term, our buildings will all need to meet a standard that looks very much like Passivhaus if we're going to get to climate neutrality.  If that's true, then any building
 we don't build that way right now is going to have to be replaced or subject to a costly retrofit in the future.  We might as well just take the steps necessary to migrate to the end point as quickly as possible.  Developing a local industry around high performance
 building components (windows, HRVs, SIPs, pre-fabricated buildings, etc), spurred by extremely high building energy efficiency standards in Boulder, ought to put us in a good position to supply other parts of the country when they come around.  


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Macon Cowles
Boulder City Councilor



Macon Cowles
Boulder City Councilor