Category Archives: Zero Energy Buildings

Zoning and Certification Standards for Small Wind Turbines

Until recently, wind turbine manufacturers and operators were challenged by the tasks of keeping machines operating reliably and improving energy capture. Although dramatic improvements have been made in both areas, there have been occasions when acoustic emissions proved so vexing they overshadowed performance and reliability issues. For example, some wind turbines suffer an unfavorable reputation for noise problems associated with high tip speeds, furling, or blade flutter. Because of the potential for installation near residences, noise may be even more important for small turbines than for large turbines installed in wind power plants. – 2004 NREL Report

Complaints (from customers or others) about sound characteristics are rare, but are usually related to turbines with flexible blades and side furling mechanisms. – Canadian Wind Energy Association, Small Wind Purchasing Guide

The market for small residential and rural wind turbines (up to 10KW) has been growing at double digit rates for several years and is now entering its young adult stage as venture capital enters the market and certification standards are being introduced in both the U.S. and U.K. markets.  Wind energy is roughly on par with PV in return on investment, but faces much tougher zoning issues due to the visual impact of towers and the lack of reliable and easy to use acoustic criteria for use by zoning officials.  As a result, the greatest market challenge for small wind turbine manufacturer’s and early adopters that want to take advantage of the technology, is getting zoning approval in the more 25,000 different zoning districts within the U.S.

In my view, zoning ordinances should focus on easing height restrictions to recognize the physics of wind power, building permits to assure adequate tower foundations and anchoring, and on protecting consumers from unwarranted sound pollution.  Setbacks should be a function of both tower heights and the need for acoustic buffers.  I’ve attached my version of a model ordinance based on a review of what I think are best practices from the U.S., the U.K., and Canada including a method of assuring that no unwarranted sound disturbance crosses a property line.  The balance of this post will focus on the sound issue.

The American Wind Energy Association [AWEA] recommends the following noise provision in it’s model small wind ordinance:

For wind speeds in the range of 0-25 mph, small wind turbines shall not cause a sound pressure level in excess of 60 dB[A],  or in excess of 5 dB[A] above background noise, whichever is greater, as measured at the closest neighboring inhabited dwelling.  This level, however, may be exceeded during short-term events such as utility outages and severe wind storms.

In the sense that most small wind turbines operate below ambient noise levels under most conditions, this provision seems reasonable.  However, it is filled with loopholes that serve the small wind industry, but fail to protect the public from unwarranted sound pollution.  For example:

  1. Sound restrictions end at 25mph (presumably the definition of a “severe wind storm”) prior to the acoustic problems of furling and blade flutter start starting to become objectionable.
  2. When there is a blackout or “utility outage” and therefore no load on a grid-tied wind system, some turbine designs “free wheel” or spin a much higher rpm’s causing spikes in the acoustic emission.  This may also be true of off-grid systems whose batteries reach a full charge.
  3. 1)According to British Standard 4142 a “noise rating level” (i.e. the noise level once corrected for the presence of tones or other noise characteristics) of 10 dB above the background noise is likely to give rise to complaint, [and] one only 5 dB above background would be marginal…”. The proposed “5 dB[A] above background noise” is therefore right on the edge of being complaint worthy.  In addition, the “measured at the closest neighboring inhabited dwelling” takes the sound provision over the property line and does not account for future adjacent construction (i.e. the rights of future property owners).

In short, the AWEA model noise ordinance provision seems designed to protect legacy designs that have not been optimized for sound emission and to create the smallest possible acoustic buffer in an effort to open the market to smaller lot sizes.  However, the concept of a provision based on some level of emission in excess of background noise is a step in the right direction.  What that provision might be and how it might reasonably be enforced is another matter.  Before I tackle that topic, I think it’s important to review the new Small Wind Safety and Performance Standards sponsored by the American Wind Energy Association [AWEA] and the British Wind Energy Association [BWEA].

The BWEA standard was released in February 2008 and the AWEA standard is in process and currently available as a “Draft Document”.  Both standards will require a much needed third party verification of energy conversion performance and assure that minimum safety and quality standards are met.  This will allow consumers to easily compare the performance of competing designs and trade that performance off against cost, warranties, and other features.  It will also provide government incentive programs and zoning officials with an reasonable and acceptable list of “approved designs”.  Both standards are virtually identical relative to the provisions for energy conversion, safety, and quality.  However, language and requirements of the two standards diverge significantly relative to “Acoustic Sound Testing”.

The current AWEA “Rated Sound Level” states that:

The sound level that will not be exceeded 95% of the time, assuming an average wind speed of 5 m/s (11.2 mph), a Rayleigh wind speed distribution, 100% availability, and an observer location 60 m (~ 200 ft.) from the rotor center1, calculated from IEC 61400-11 test results, except as modified in Section III of this Standard.

In contrast, the BWEA “Rated Sound Level” provides for two conditions at higher wind speeds.  One appropriate for larger turbines and one for smaller residential zone turbines:

BWEA Reference 60m Sound Level, Lp,60m. The sound pressure level in dB(A) re 20 μPa rounded up to the nearest dB, at an observer distance of 60 m [~197 ft] from the rotor centre (i.e. a slant distance) and calculated from the Declared Apparent Emission Sound Power Level when the turbine is subjected to a wind speed of 8 m/s [17.9 mph] at its rotor centre. The 60 m distance is representative of the closest observer distance expected for a turbine toward the larger size of small wind turbines.

BWEA Reference 25m Sound Level, Lp,25m. The sound pressure level in dB(A) re 20 μPa rounded up to the nearest dB, at an observer distance of 25 m [~82 ft] from the rotor centre (i.e. a slant distance) and calculated from the Declared Apparent Emission Sound Power Level when the turbine is subjected to a wind speed of 8 m/s [17.9 mph] at its rotor centre. The 25 m distance is representative of the closest observer distance expected for a micro or domestic size turbine.

Both standards provide for a method of determining sound levels at X distance from a turbine relative  to ambient(background) sound levels.  However, as currently written the AWEA standard only provides information to make this calculation at the 5 m/s [11.2 mph] rated wind speed which bypasses the issues of furling, blade flutter, high wind speeds, free wheeling, and power outages.

In contrast, the BWEA standard includes the provision for an Emission Noise Map in their labeling requirement which maps the sound emission of the turbine relative to the distance from the turbine hub and the wind speed.  The map starts at the turbine cut-in speed and ends at the cut-out speed.  However, for turbines that do not “cut-out”(i.e. stop operating), “but achieve protection to high winds by various mechanisms such as furling their blades or yawing the turbine to cross-wind. In these cases the red and orange zones of the Noise Map will continue up to the wind scale maximum”.   This still doesn’t address free-wheeling and power outages, but I’ll get to that in a moment.  It should also be noted that the BWEA standard assesses a noise penalty of 5dB[A] if the turbine emits any specific tones that may be objectionable to the human ear.

BWEA Wind MapIn the appendix, the BWEA standard provides a method of  using the noise map to assess site suitability for U.K. zoning purposes based on the red, amber, and green zones.  In addition, using the Sound Power, Noise Slope, and Noise Penalty the standard provides equations for calculating the noise level at any wind speed and any distance from the turbine.  It also provides a conservative formula for estimating the ambient noise level in a “country field” as a function of wind speed.  According to the BWEA standard, the values from this background noise formula “can be taken as a worst-case scenario (i.e. the lowest ambient noise) for a rural background.”

In all fairness, the AWEA standard is still in draft form and may end up addressing small wind turbine acoustic issues in a better way, however from a consumer viewpoint the BWEA standard is currently far superior.  That said, how should zoning officials protect the public interest regarding small wind turbine sound emissions?  I’ll start with a list of basic premises:

  1. What’s at issue is not so much the sound emitted by the turbine, but the sound emitted in excess of the ambient noise conditions, especially night time noise conditions.
  2. The noise or sound limitations should be established at the property line.
  3. The sound emission criteria should include all conditions including high winds (furling, yawing, and flutter) and power outages (free wheeling).
  4. For some turbine designs, the effect of the above will be to increase the effective setback (and indirectly the minimum lot size) by creating an acoustic buffer in excess of any setback based on tower height.

Under most conditions wind turbine sound emissions disappear into the background offering only a faint whoosing sound to the human ear.  However, for zoning purposes an acoustic buffer should be required to encompass all operating conditions and to protect residents from turbine designs that have not been optimized for acoustic performance.  The best way to achieve that is to establish a property line sound level based on ambient noise levels plus some standard.

European noise standards tend to be more developed, so I’ll use those as a baseline.  In the U.K. the guideline is:

  • Daytime: A background noise + 5 dB[A] or 43dB[A] whichever is greater
  • Nighttime: A background noise + 5dB[A] or 35 to 40 dB[A] whichever is greater
  • Plus a 2 to 5dB(A) penalty for tones

In France the guideline is:

  • Background noise + 5dB[A] during the day
  • Background noise + 3 dB[A] at night

Since 3 dB[A] over background noise is barely discernible outside of the lab, and sleep disturbance should be the key criteria for a small wind turbine sound provision, I believe that 3dB[A] over background noise should be the property line limit for a zoning ordinance.  This is conservative in that any habitable building on an adjacent property will be setback an additional distance which provides additional acoustic buffer.

Language for the sound provision of my model Small Wind Turbine zoning would look something like this:

Acoustic Setback Requirement – The acoustic emission sound level of the Small Wind Turbine as measured at the property line, shall not be more than 3dB[A] over the background noise level under any operating conditions, including high winds, yawing, furling, and power outages.  Background noise may be calculated using Equation A.1 of the British Wind Energy Association [BWEA], Small Wind Turbine Performance and Safety Standard (February 2008) as plotted in Figure 1 below.

BWEA Background Noise Graph

Measured site specific background noise levels may also be used provided that they are verified via a survey and report prepared by a qualified engineer.  The acoustic setback from the property line required to meet the 3dB[A] over background noise level requirement can be satisfied/calculated in two ways:

  1. For Small Wind Turbines that are certified to the BWEA Small Wind Turbine Performance and Safety Standard (February 2008),  the wind turbine manufacturer shall provide calculations that use BWEA Equation A.2 to quantify the required acoustic setback.
  2. For Small Wind Turbines not certified to the BWEA standard, the wind turbine manufacturer shall provide certified data and calculations prepared by a qualified engineer that quantify the required acoustic setback.  These calculations must include a 5dB[A] penalty for any tonality according to ISO 1996-2:2007 Annex D based only on 1/3rd octave band data as follows:

The turbine is declared tonal if any 1/3rd octave band (in any of the spectra from section 3.4.16) is higher than its adjacent bands by

15 dB in the low frequency bands (50 to 125 Hz)

8 dB in the mid-frequency bands (160 to 400 Hz)

5 dB in the high frequency bands (500 to 10000 Hz)

The maximum wind speed used for the submitted calculations shall be the cut-out speed or for wind turbines that do not have a cut-out speed no less than 50 mph.

A proposed model small wind turbine ordinance is attached below in pdf format which includes provisions for height limitations based on physics, turbine size limitations based on turbine blade size and lot size ( consideration of scale),  requirements for building permits, and the acoustic provisions outlined in this post.

A Model Small Wind Zoning Ordinance

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Three Letters to Obama

The Obama administration has recently received three letters or petitions regarding energy policy.  As with any policy position they are shaped by the world views of the men and women who authored them.

Dr. James Hansen is head of the NASA Goddard Institute for Space Studies and a leading global climate change researcher.  It is not surprising that his proposal revolves around a tax policy aimed at decarbonizing the American economy and reducing greenhouse gases.

Edward Mazria is an architect and creator of the 2030 Challenge, a voluntary pledge that all new buildings and major building renovation be constructed to a carbon-neutral (using no fossil fuel GHG emitting energy to operate) standard by 2030. Mazria’s proposal is centered on achieving building energy efficiency goals rewarded with lower mortgage rates in the case of residential construction and by accelerated depreciation in the case of commercial construction.  If enacted, it claims to both create millions of jobs and reduce carbon emissions.

Richard Heinberg is senior fellow at the Post Carbon Institute and the author of The Party’s Over – Oil, War and the Fate of Industrial Societies,  Powerdown – Options and Actions for a Post – Carbon World, and the Oil Depletion Protocol.   Heinberg and the other authors of Post Carbon Institute’s “Real New Deal” marry the imperatives of climate change and the peaking and ultimate depletion of our fossil fuel resources into a comprehensive plan to transition the U.S. to a new energy economy.

All three proposals are valid and merit serious review, but only the Post Carbon Institute’s proposal offers a comprehensive view of the challenges we must face.  As such, the Hansen and Mazria proposals are important subsets of what needs to be a much larger solution.

Hansen sent an open letter to Barack and Michelle Obama.  Here are some relevant excerpts from the letter:

A rising carbon price is essential to “decarbonize” the economy, i.e., to move the nation toward the era beyond fossil fuels. The most effective way to achieve this is a carbon tax (on oil, gas, and coal) at the well-head or port of entry.  The tax will then appropriately affect all products and activities that use fossil fuels.

The public will support the tax if it is returned to them, equal shares on a per capita basis (half shares for children up to a maximum of two child-shares per family), deposited monthly in bank accounts.  No large bureaucracy is needed.  A person reducing his carbon footprint more than average makes money.   A person with large cars and a big house will pay a tax much higher than the dividend.  Not one cent goes to Washington.  No lobbyists will be supported.  Unlike cap-and-trade, no millionaires would be made at the expense of the public.

A carbon tax is honest, clear and effective.  It will increase energy prices, but low and middle income people, especially, will find ways to reduce carbon emissions so as to come out ahead.  The rate of infrastructure replacement, thus economic activity, can be modulated by how fast the carbon tax rate increases.  Effects will permeate society.  Food requiring lots of carbon emissions to produce and transport will become more expensive and vice versa, encouraging support of nearby farms as opposed to imports from half way around the world.

A Two-Year, Nine-Million-Job Investment Proposal

The road to energy independence, economic recovery and reductions in greenhouse gas emissions runs through the Building Sector.” – Edward Mazria

The 2030 Challenge Stimulus plan is a two year investment commitment to create 9 million jobs overall and 4-million jobs in the construction sector.  It is a jobs growth and carbon reduction plan rolled into one.  In the residential sector it trades low interest rate loans off against investments to increase building energy efficiency.  For an existing home, the interest rate provided would be a function of renovating that home to some level below the existing energy code requirements in exchange for a lower mortgage rate.

Mortgage Interest Rate (subject to market conditions)  2030 Challenge Energy Reduction

4.0%    30% below code
3.5%    50% below code
2.5%    75% below code
2.0%    Carbon neutral

For example, a homeowner with a    current $272,300    mortgage with equity of $12,000, would have a mortgage balance of $260,300. At an interest rate of 6%, the current monthly mortgage payment would be $1633. If this homeowner wants to qualify for the 2.5% interest rate, they will need to renovate their home to use 75% less energy than that required by code, immediately creating jobs and putting construction teams back to work.

The cost of renovation would be approximately $51,250, which includes a solar system, which would qualify for a $7000 tax credit. The cost of the renovation, minus the tax credit, would be added to the mortgage balance, so that the new mortgage is now $304,550.    However, because of the significantly lower 2.5%    interest rate, the new mortgage payment is just $1203, a savings of $430 per month. With the additional monthly savings on energy bills of approximately $145, this homeowner would save a total of $575 per month.

Because building construction historically represents about 10% of GDP, Mazria thinks that the private building sector may be the key to reviving the U.S. economy.  He proposes that $96-billion be invested annually for the next two years in mortgage interest rate buy-downs and accelerated depreciation for commercial buildings.  As a result, Mazria claims that with a participation of only 5.8% of homes and 3.1% of commercial buildings the program would generate 9-million jobs and $1-trillion in private sector spending, and pay for itself in the form of increased tax revenue.

In addition to the economic claims, Mazria calculates that over the five year period, the proposal would reduce CO2 emissions by 504 million metric tons and energy consumption by 6.47 Quadrillion Btu.

Even at a participation of only 5.8% (over 4-million) of homes, Mazria’s proposal may have a scaling problem, as the country finds itself lacking the architectural, engineering, and code verification talent to transform that many homes in the proposed time-frame.  Conceptually however, this is a beautifully conceived plan and deserves serious attention.

The Real New Deal
Energy Scarcity and the Path to Energy, Economic, and  Environmental Recovery

The energy transition cannot be accomplished in four years or eight…  What can and must be accomplished in a single administration is the essential change of direction.

The Post Carbon Institute [PCI] argues that the current economic crisis provides the opportunity and potentially the political will to make a significant down payment on the transition to a renewable energy economy that would otherwise be inconceivable.  In fact if we don’t act now, the current crisis may just merge with “peak oil” and the effects of climate change to create a decades long global state of emergency.

PCI outlines a comprehensive program comprising five different solution sets.

  1. A massive and immediate shift to renewable energy (Hansen’s proposal fits here)
  2. The electrification of our transportation system
  3. The transformation to a “smart” electrical grid
  4. The de-carbonization and localization of our food production and delivery system
  5. The retrofit of our building stock for energy efficiency and distributed power generation. (Mazria’s proposal fits here)

Since the cost of such a transition spread over 20 years would be in the order of $4.5-trillion the authors admit that given the current financial meltdown, private capital will not be forthcoming and deficit spending by the government along with significant policy changes will be required to launch the transition.  To direct policy, the authors recommend creating “an Energy Transition Office, tied to no existing agency, specifically tasked with tracking and managing the transition and with helping existing agencies work together toward the common goal”.

The authors do not underestimate the enormous and unprecedented scope of their proposal.  Aside from avoiding or mitigating the devastating impacts of peak oil and climate change the potential  benefits are enormous and would include:

  • eliminating the need to police oil exporting areas of the world, saving billions of dollars a year in military expenditures
  • saving billions per year by creating a food system that substantially reduces obesity, cancer, and asthma
  • helping to create and foster skilled, self-reliant and resilient communities

Although the plan as presented merely serves to outline the possible solutions and the scope of the problems we face, what sets it apart is it all-embracing view of the resource depletion and environmental  perils we must resolve to survive.

Thoughts About a New Energy Economy
Calls for the transition to a new energy economy typically come from three main quarters.  All three are valid, but only one sees the forest for trees.

The national security quarter recognizes that we depend too much on imports from countries and regions that are either unstable and/or hostile to our national interests.  This argument for action plays well with the right, but does not recognize the environmental threat of global warming or greater economic peril of peak oil.  Although it forms the basis of an argument for an energy transition, it can equally be used to justify a more robust military policy.

The climate change quarter is currently dominant in the minds of the public and with policy makers.  It sees great peril and human suffering in the coming decades but doesn’t recognize that the peak oil is imminent and will soon take center stage.  The economic devastation of peak oil will likely be additive to the current debt crisis and put global warming on the back burner.  Ironically, the advent of peak oil will greatly reduce carbon emissions and mitigate the effects of global warming but the decline in oil supply alone will not be sufficient to drive atmospheric CO2 levels back to 350 PPM.

Peak oil is lesser known.  There is a peak oil caucus in congress, but there is little political will to take action in a county where nearly half the population believes in the battle cry of “drill baby drill”.  Unlike the effects of global warming which will be slow and indirect in coming, the effects of peak oil will be as sudden as the collapse of the World Trade Center and Lehman Brothers.  More shock and awe than a slow rising of the tides.  It will touch every corner of our economy with a combination of price shocks and shortages.  It will leave us with one chance and one chance only to transform our energy infrastructure to solar, wind, and geothermal using what remains of our rapidly depleting fossil fuel resources.

As I look to the future, I see three possible courses of action:

Option one is that we recognize the problem of resource depletion and take action well in advance of  the anticipated world wide peak in oil production.  Since peaking is imminent and the transition will take approximately two decades, unfortunately the ship has already sailed on option one. Looking back we will someday wish we had paid much more attention to Jimmy Carter.

With the election of Obama, option two is already in play, and we have begin to take some action based on fears of climate change and for reasons of national security.  However, our current actions are no where near sufficient to avoid extreme hardship.  The ship of state is on a collision course with the iceberg and we have only just given the order to reduce speed.  Our collision with destiny is now unavoidable and the question now is whether there will be a sufficient number of life boats.  In addition, just as we need it the most, we lack sufficient capital to make the transition in the face of the global financial meltdown.  This is not just another severe business cycle, this is the beginning of the  realignment of the the post WWII global financial system and the end of American economic dominance.  It is likely that peak oil will become evident just as the dollar loses its status as the world’s reserve currency and as a nation we may then be unable to fund the energy transition with either public or private funds.  Essentially bankrupt and losing our grip on global influence and power the country may lurch to the right in a desperate attempt to reclaim global dominance.

Option three is to maintain a posture of “drill baby drill denial” in spite of reality.  At this point the country may resort to engaging in “resource wars” to claim the world’s remaining oil reserves and to protect the American “way of life”.   This would be a policy doomed to failure and assured of increasing human misery.  It would also be a policy that will put us at risk of missing our only window to transition away from fossil fuels.  Call this the Mad Max policy.

My hope is that we’ll stick with option two and muddle through to a new and sustainable energy economy.  It promises to be extremely painful and disruptive decade or two of transition, but in the end we will find ourselves in a much healthier relationship with our environment and possibly with each other.

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The Obama Energy Plan and our Homes

How will Obama’s energy polices affect our homes?  We won’t really know until his proposals are debated and enacted by congress, but we can get a sense of what might happen from his campaign’s position statements.  From his campaign website’s fact sheet his stated position on building energy efficiency is as follows:

“Obama…will establish a goal of making all new buildings carbon neutral, or produce zero emissions, by 2030.  [He] will also establish a national goal of improving new building efficiency by 50 percent and existing building efficiency by 25 percent over the next decade to help us meet the 2030 goal.”

This is straight from the playbook of Ed Mazra’s Architecture 2030 Challenge.  As evidenced by the following quote from the 2030 website, the 2030 Challenge is predicated on climate change and the reduction of green house gas emissions associated with the Building Sector.

“Rapidly accelerating climate change (global warming), which is caused by greenhouse gas (GHG) emissions, is now fueling dangerous regional and global environmental events. Data from the U.S. Energy Information Administration illustrates that buildings are responsible for almost half (48%) of all GHG emissions annually. Seventy-six percent of all electricity generated by US power plants goes to supply the Building Sector. Therefore, immediate action in the Building Sector is essential if we are to avoid hazardous climate change.”

I have two issues with the 2030 Challenge.

One is that the 48% responsibility for GHG emissions attributed to buildings is overstated.  The emissions assigned to the building sector are primarily the indirect result of drawing on electrical power generated from coal and natural gas fired power plants, so the question becomes whether to focus our resources on the building “demand” side, or the power plant “supply” side, or some combination of both.  In that broader context, we may find that it is much easier to deal with a few hundred power plants than to transform 150 million residential and commerical buildings.  From a public policy perspective, both the demand and supply side should be considered as a synergistic whole.

My second issue is more fundamental.  Architecture 2030 asks and answers the wrong question.  The question that Architecture 2030 asks is what actions should we take to mitigate the effect of the building sector on climate change.  However, the greater question is what actions should we take to render the building sector sustainable.  Once sustainability is on the table then we have to consider carrying capacity and carrying capacity overshoot at which point climate change is just another canary in the coal mine.

Carrying capacity is all about the ecological limits (capacity) of our planet’s resources and sinks.  By considering GHG emissions as the primary driver for building energy improvements, policy makers are overlooking the much more immediate and serious resource issues of peak oil and gas.  Since both of these peak events will be evident as early as 2010, all buildings should be built or retrofitted to a net zero energy and carbon standard NOW, not 22 years from now.

However, I digress.  Since it will take the actual emergency of these peaking events to mobilize the political will to enact a national zero energy standard, the question is what can we expect when Obama takes office next year.

The first likely step will be to start the process of improving building efficiency by 50% through our building codes.  A significant improvement is already in the works for the residential sector with the IECC 2009. However, at this time, the 30% improvement authored by the Energy Efficient Codes Coalition, will only be a voluntary appendix to the next release of the code.  In addition, once the new code is released, it has to be reviewed and adopted by hundreds of city, county, and state authorities.  In the process, these authorities often dumb down new energy code provisions in response to local politics.  We can also expect a major push back from a decimated housing sector deeply concerned about adding any new code mandated building costs.

My best guess is that under Obama, the voluntary 30% improvement provision authored by Energy Efficient Codes Coalition will be supported by Obama’s Grant Program for Early Adopters policy proposal.  This proposal creates a competitive grant program for states and localities that “take the first steps in implementing new building codes that prioritize energy efficiency, and provides a federal match for those states with leading-edge public benefits funds that support energy efficiency retrofits of existing buildings.”

The grant proposal creates a policy that respects local politics and helps to support those areas of country that have the political will to move forward with improving building energy efficiency.

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Conduction, Insulation, and Zero Energy Homes

The concept of conduction is how we normally think of heat loss/gain in a home.  When you put your cold hands around a hot cup of coffee, you’re using the principle of conduction to warm your hands.  The transfer of energy via conduction takes place directly through a material from molecule to molecule.  The resistance to this heat flow is measured by the R-value in the insulation and other materials that we use to construct the ceiling, walls, and floors of our homes.  The higher the combined R-value of the materials we use, the better the resistance to heat gain and loss.

That sounds straight forward and simple at face value, but it can be misleading when we are comparing different construction systems and choices.  First of all the ASTM tests used to rate a material’s published R-value are not real world.   The tests used tend to favor permeable insulations such as fiberglass over rigid insulation systems, because they DO NOT take into account the real world issues of air and moisture infiltration into the wall and ceiling cavities which can seriously degrade the published “laboratory” R-values of permeable insulation products.

The other misconception about R-values is that they only provide information about the “insulation cavity” and do not take into account the “whole wall”.   For example, about 20 to 25% of the area of a typical framed “stick-built” wall is comprised of wood studs (~ R1 per inch) that have no where near the R-value of the actual “insulation”.  In addition, the insulation has to fit around pipes and wires and be custom cut where the stud spacing varies from the standard 16” or 24” on center framing.  This is why it is difficult to compare a house framed with 2×6’s and R-19 fiberglass insulation to a house “framed” with Structurally Insulated Panels (SIP) with 3.5-inches of R-14.9 expanded polystyrene (EPS) rigid insulation.  If we just consider the R-value of the insulation the two systems the 2×6 wall appears to be better.  However if we look at the true “whole wall” performance as tested by the Oak Ridge National Laboratory [ORNL], the R-value of the 2×6 system is only 11, and R-value of the SIP system is 13.95.

When we’re talking about conduction in the exterior envelop of a home, we’re basically talking about insulation.  And the purpose of insulation is to trap and confine “dead” air.  To do that effectively an insulation has to be sufficiently dense and completely fill the insulation cavity or space it is designed to insulate.  For illustration purposes the the attached pdf file compares various insulation choices and their strengths and weaknesses.  The insulation types described are typically used in stick built construction (which is used in about 80% of homes built in the U.S.) and provides a good decision matrix for that type of construction.

Fiberglass and the other (air) permeable insulation materials dominate stick built construction, but construction is no different than other disciplines and professions and we tend to do a lot of things because “we’ve always done them that way.”  So I think it would be helpful if I listed all the things we’ve added over the years that add cost and complication, just to work around the weaknesses of permeable insulation materials:

  • Added a plastic moisture barrier on the warm side of the envelope to help keep moisture from getting into the insulation cavity that would cause mold and/or rot
  • Added a house wrap like Tyvek on the outside of wall to partially mitigate air infiltration and intrusion.  Note: The primary purpose of a house wrap is to provide a moisture barrier, they only reduce air infiltration by a little over 10%.
  • Purposely over sized framing members in the wall and ceiling to provide sufficient thickness for code mandated R-values.
  • Added vented soffits and roof vents to bleed moisture out of ceilings and attics, again to prevent mold and rot.
  • Added rubberized membranes on the roof deck from the eave to beyond 24” of the exterior wall to mitigate the effects and damage of ice dams.  Why? Because of the inherently poor insulation at the intersection of the wall and the ceiling provided by fiberglass and other permeable insulations.
  • Routinely install larger than necessary heating and cooling systems to make up for poor envelop performance

If you want to build a net zero energy home with a “tight” envelop, avoid permeable insulation materials and use a foam-in-place, closed cell polyurethane insulation with a “green” blowing agent.

Download Residential Insulation Comparison Table [pdf file]

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The LEED Narrative – Going Beyond

I received an email this morning from Scot Horst , who chairs the LEED Steering Committee. He describes the behind the scenes narrative that has been going on since work began on LEED 2009.

Person A: “Global warming doesn’t give us much time.”
Person B: “But we can’t address much of anything, let alone global warming, if we’re only dealing with a small fraction of the entire built environment. We need to get everyone involved.”

Person A: “Yes, but why get them involved in a system that doesn’t take them far enough to save us from ourselves? We need our buildings to be restorative.”
Person B: “LEED can’t save us from ourselves. LEED, as a tool, can engage the market in transformation. That transformation is about people. It is not about LEED credits.”

Person A: “You’re missing the point. We have to be tougher. We have to go beyond.”
Person B: “No, you’re missing the point. We have to find ways to engage a market that has never thought about these issues before.”

Persons A and B: “Let’s find a way to do both.

”This is an engaging and very important narrative and perhaps the most important point for me is that LEED is a “tool” that helps to raise consciousness and “engage the market in transformation.” My personal view is that we must “go beyond” and that much of what we currently do in the green building movement, however well intentioned, is nothing more than rearranging the deck chairs on the titanic. The global warming mentioned in Horst’s narrative has provided the catalyst for both LEED and Architecture 2030, but focusing solely on warming misses the point. Warming is a symptom and not a cause. It has prompted us to take some action, but not to “go beyond”. As a premise for action it has been useful, but is easily attacked on it’s “scientific validity”. It is one of the canaries in the coal mine, but there has been is very little discussion of the coal mine. We need to expand the narrative and take a broader view.

Taking a page out of ecological economics, once you picture the built environment as a mere subset of our closed ecosystem, then your conceptual framework regarding sustainable building is forever changed. It means you have to accept that there are limits, and that we are not going to be able to grow forever. It implies the built environment must have some optimal size and level of consumption relative to the larger ecosystem. It means you cannot grow beyond that optimum without threatening man’s survival within that ecosystem. Out of this stream of thought flows a list of very troubling questions?

  • How do we stop growing?
  • What are the limits? What is optimal?
  • Does climate change tell us they have already been exceeded?
  • Do we face a kind of built environment armageddon when fossil fuel production peaks and begins to decline?
  • Is a zero energy standard imperative now?
  • What do we do? How do we do it?

Our very survival depends on how and when these questions are answered. LEED does not provide the answers, but it does help us to prepare.

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“One Last Chance” for a Sustainable Future?

“It has often been said that, if the human species fails to make a go of it here on the Earth, some other species will take over the running. In the sense of developing intelligence this is not correct. We have or soon will have, exhausted the necessary physical prerequisites so far as this planet is concerned. With coal gone, oil gone, high-grade metallic ores gone, no species however competent can make the long climb from primitive conditions to high-level technology.
This is a one-shot affair. If we fail, this planetary system fails so far as intelligence is concerned. The same will be true of other planetary systems.On each of them there will be one chance, and one chance only.”
Sir Frederic Hoyle, British Astronomer, 1964

Hoyle’s “necessary physical prerequisites” are not yet gone, but the extraction of our most critical non-renewable energy resources will soon reach a geological milestone, and production will peak and then decline. This will set a two to three decade clock on our last and only chance to achieve a sustainable society.

  • The consensus is that the production of oil has already peaked (2006) or will peak shortly and that serious shortages will occur by about 2010
  • Natural gas production in N. America will peak between 2010 and 2015
  • Uranium extraction will peak in 2025 and shortages are possible as early as 2013 when we can no longer depend on the recycling of Russian nuclear warheads to meet demand.
  • Coal will peak around 2025 at about 30% above the present production

“…we don’t have to run out of oil to start having severe problems with industrial civilization and its dependent systems. We only have to slip over the all-time production peak and begin a slide down the arc of steady depletion.”
Howard Kunster ,The Long Emergency, 2005

We are left with the choice of only two future paths of development. The “business as usual” path will lead us to tragically overshoot the earth’s carrying capacity, resulting in economic collapse, and a dramatic reduction in the earth’s population as we return to a pre-industrial revolution standard of living. The second path represents Hoyle’s “last and only chance” to wisely use our remaining fossil fuel resources to build a sustainable and renewable energy foundation for a new steady-state world economy. An economy and society with a stable population that falls within the limits of our planet’s carrying capacity. I fear that the greater probability lies with the first path, but know we have both the knowledge and means to forge the second

On the supply side, the second path requires that we rapidly replace our current extractive, non-renewable energy model with renewable sources like geothermal, solar, wind, and wave power. It will be a future dominated by electrical power as liquid fuels become increasingly scarce. However, it will not be enough to reach a stable, sustainable future without major changes to the demand side of the energy equation,

As we enter this period of sustained crisis and begin the journey down the path of ecological stability, it will quickly become evident that the only reasonable standard for building design will be a standard of net zero energy consumption. Because we lack information, initially this will be part science and part intuition based on passive heating and cooling lessons from the past. Eventually we will come to know the embodied energy of every building material and component and make many decisions based on the EROIE (energy return on investment of the energy embodied) of building products like insulation, low-e glazing, PV panels, and wind turbines. Houses will become smaller and change shape as energy trumps fashion and becomes the primary design factor. A whole new industry will emerge to help homeowners convert over 100-million thinly insulated, poorly constructed homes into some semblance of energy efficiency. Pattern’s of development and zoning laws will change as the age of the automobile comes to a close. Populations will shift and migrate as the end of cheap air-conditioning makes living in many parts of the country less desirable. Home landscaping will change from ornamental to edible, and gray water irrigation will become commonplace as the energy costs to move and purify water change our attitudes about this precious natural resource. Local materials will dominate construction and the age of imported Italian granite countertops will come to an end

The longer policy makers wait to take action the lower the probability of success. When shortages become evident we may still fall into denial. Demagogues and special interests will deny the limits of geology and blame OPEC, Islam, environmentalists, or speculators. If allowed, they will cloud the issue and cost us precious time.

Our “last chance” will be a battle. It will not be an easy time.

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Fantasy Economics and the Sustainable Society Revolution

“Macroeconomic theory in our text books conveniently behaves as if the ecosystem does not exist all the while consuming products and services from the ecosystem which fuels economic growth.”
Mark Anielski

“Despite evidence that the ecology does in fact exhibit constraints in accordance with the laws of physics, we continue down a ruinous path too afraid, paralysed, or unable to acknowledge the truth since such a revelation would put in question all we have pursued since the Industrial
Revolution. This would mean that the pursuit of increased wealth and prosperity by current generations will impose a high price on future generations.”

Mark Anielski

In a perfect Adam Smith world, markets are supposed to efficiently set prices based on relative supply and demand. In the real world, a host of other factors can effect price. Federal and local governments add sales and other taxes. Governments impose tariffs and import duties. Cartels increase and decrease supply to achieve political or financial objectives. Central banks increase the money supply, improving “liquidity” while fostering monetary and price inflation

However, prices for many goods also reflect a fantasy economics that assumes an infinite supply of non-renewable raw materials and zero costs associated with the consumption and disposal of goods. For example, the economic activity associated with an asbestos plant and economic activity to clean up the resulting super-fund site are both counted as positive contributions to our GNP

Crude oil is another great example. Non renewable resources like oil follow a bell shaped supply curve. During the easy to find and extract “up” side of bell curve, supply out-strips demand and prices are low. In most minds supply and reserves are thought to infinite and no thought is given to conservation. Think of Hummers, NASCAR, and SUV’s as the symbols for this side of bell curve. Indirect costs like pollution, suburban sprawl, energy insecurity, and climate change are NOT factored into the price, but are paid none the less through higher healthcare costs, lower productivity, taxes, military adventures, and “natural” disasters

As we reach the top of the bell curve as in the case of oil today, demand is approaching the limits of supply and prices have increased rapidly. According to the IEA, supply reached an all time production in May of 2006 of 86.11-million barrels per day in July 2006 and in 2007 the price of crude oil has increased by about 70% to over $95 per barrel as we draw down the developed world’s stockpiles. And yet even these prices do not reflect the true costs of depleting this non-renewable resource

As we roll over the top of the oil production bell curve sometime around 2010, supply will decline and at some point after conservation and replacement technologies fail to close the gap, a painful path of “demand destruction” will become our only option to balance the supply-demand equation. The economic recession caused by this demand destruction will be just another hidden cost of the economic fantasy of “unlimited” non-renewable resources

What does all this have to do with “The Sustainable Home Blog”? Is this just a self-indulgent rant, rambling for the sake rambling? The reason I keep returning to the topics of economic theory and peak oil is that they have everything to do with limits and reason for sustainable building

The green building movement is already big business and we may have reached a tipping point in 2007, where more than 50% of the key decision makers in the business world of building have reached the conclusion that the movement has legs and that a decades long bull market for all things green is an opportunity worth pursuing. What is the source of this apparent demand for these new green products and buildings? Is it global warming, rising energy costs, insurance claims from sick building syndrome, or the urge to “do good”? I think it’s all of these reasons and more, but “going green” is still more fashion than necessity, and collectively, it has not entered our consciousness that there are limits to growth in a closed ecosystem and that our current path of “development” threatens our very survival

That’s all about to change. The ecosystem has been sending us warning signals (the effects of air and water pollution, species loss, climate change, fisheries collapse, etc.) for decades, but because these signals didn’t have a direct individual impact on the majority of world’s inhabitants, we have continued on a path of unsustainable global development modeled after the American standard of living and consumption. As we push up against the geological limits of peak oil(~2010), peak natural gas(~2015), peak coal(~2025), and peak uranium(~2025), the cheap energy that’s been driving development since the beginning of the industrial revolution will will no longer be either cheap or abundant and we will come face to face with our own unsustainable reality. No combination of known technologies will even come close to filling the gap left by these declining non-renewable energy sources and it will take decades for us to recognize the natural limits to growth of our ecosystem and transition to a steady-state and sustainable economy.

As we enter this period of sustained crisis, it will quickly become evident that the only reasonable standard for building design will be a standard of net zero energy consumption. Because we lack information, initially this will be part science and part intuition based on on passive heating and cooling lessons from the past. Eventually we will come to know the embodied energy of every building material and make many decisions based on the EROIE (energy return on investment of the energy embodied) of building products like insulation, low-e glazing, PV panels, and wind turbines. Houses will become smaller and change shape as energy trumps fashion and becomes the primary design factor. A whole new industry will emerge to help homeowners convert over 100-million thinly insulated, poorly constructed homes into some semblance of energy efficiency. Pattern’s of development and zoning laws will change as the age of automobile comes to a close. Populations will shift and migrate as the end of cheap air-conditioning makes living in many parts of the country less desirable. Home landscaping will change from ornamental to edible, and gray water irrigation will become commonplace as the energy costs to move and purify water change our attitudes about this precious natural resource. Local materials will dominate construction and the age of imported Italian granite countertops will come to an end.

We might look back and call this the sustainable society revolution. A revolution where in we deconstruct, modify, and replace much of what we thought and built during the industrial revolution. In a very real sense, its already started and we’re just seeing the first signs.

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