© 2014 Jonathan Ochshorn.
Following is my summary and critique of the USGBC's LEED Building Design & Construction Reference Guide, v4. Commentary on the Reference Guide can be found in these red boxes, sometimes within each of the chapter links immediately above, but also in my summary and critique of the prior versions: Version 2.2 NC and Version 3.0.
Energy is a "problem" because (a) fossil fuels (gas, coal, oil), when burned, release CO2 into the atmosphere, a global warming gas; and (b) these same fuels are nonrenewable and therefore, by definition, unsustainable.
The LEED overview also discusses other negative impacts of continued fossil fuel use: polluting or otherwise "destructive" extraction processes (which become more risky as the fuel sources themselves become harder to find or to reach); uncertainty of supply; the possibility of higher prices as supply diminishes and/or demand increases; and something that LEED characterizes as "national security vulnerability." Buildings, according to this overview, use 40% of these fuels (up from 39% in the previous version).
The LEED overarching strategy has two major components: be more energy-efficient through passive building design strategies and through high-tech energy-efficient product design and selection; and use more "renewable" energy sources, either produced on or off site.
Commissioning is included in this section, since it applies most importantly to energy-using building systems, especially those controlling heating/ventilation/air-conditioning (HVAC) and hot-water systems.
Intent: Make sure that goals for 4 parameters (energy, water, IEQ, and durability) are incorporated into the building design and construction according to the "owner's project requirements" (OPR) as defined in the "basis of design" (BOD).
Requirements: Commissioning is abbreviated as Cx in LEED documents. It refers to a process that includes the review and testing of building systems to verify that they are performing as intended.
It seems remarkable that a process called "commissioning" has become an important part of this green building guide, but such verification and fine-tuning of desired building performance parameters is apparently not the default and expected outcome of the conventional construction process in the U.S.
The following items must be commissioned:
Mechanical, electrical, plumbing, and renewable energy systems are commissioned per ASHRAE 0-2005 and ASHRAE 1.1-2007 for HVAC&R Systems, insofar as they apply to the 4 parameters listed in the "Intent" section (energy, water, IEQ, and durability).
General requirements for the exterior enclosure system are included in the OPR and BOD, but full commissioning of the system is not required by this prerequisite (an optional credit elsewhere in this section covers the enclosure system).
This is what the Cx needs to do: review the OPR and BOD as well as the actual design of the project; make and implement a plan for commissioning; review the construction documents for conformance with the commissioning plan; make various checklists and figure out how to test the various systems; verify that the systems work as intended; and so on. Make a final Cx report.
The Commissioning authority (CxA) is engaged no later than the end of the design development phase of the project, and must have experience with at least 2 similar projects.
The CxA prepares a "users' manual" for the building, or, in LEED terminology, "a current facilities requirements and operations and maintenance plan" that tells the owner how to operate his or her building efficiently.
Intent: Reduce energy use.
Requirements: There are 3 options.
OPTION 1 (Whole building energy simulation): 5% improvement over baseline (or 3% for major renovations). Baseline is per Appendix G, ASHRAE Standard 90.1-2010 (with errata).
The prior LEED version required a 10% improvement based on ASHRAE 90.1-2007, while this version requires only a 5% improvement over ASHRAE 90.1-2010. However, the new 2010 ASHRAE baseline is, according to the LEED commentary, 18% more energy-efficient than the 2007 baseline, so LEED has apparently reduced the mandatory improvement percentage to compensate for this increased baseline performance. If we call the amount of energy used per the 2007 baseline e, then the energy used per the 2010 baseline is 18% less, or 0.82e. A 10% improvement over the 2007 baseline energy use is therefore 0.90e, and a 5% improvement over the 2010 baseline is 0.95 x 0.82e = 0.78e. In other words, if the 2010 baseline is really 18% more energy-efficient than the 2007 version, then a building designed according to the new LEED prerequisite would be about 13% more energy-efficient than one built under the previous LEED Guide.
But, of course, all such speculations about "energy efficiency" are pretty much meaningless. As I wrote in my prior LEED critique (2009 version): What is striking here is the lack of interest in designing a building that actually makes sense. The only thing measured is the difference between the proposed design and a modified "minimum" proposal, rather than considering alternate proposals that might work even better. That is, if one starts with a bad design, it can still appear "good" when compared to an even less energy-efficient ["baseline"] version of the bad design.
OPTION 2 (Prescriptive compliance): satisfy appropriate requirements in ASHRAE 90.1-2010 as well as various provisions in the appropriate ASHRAE 50% Advanced Energy Design Guide. This Guide series, according to ASHRAE, "provides a sensible approach to easily achieve advanced levels of energy savings without having to resort to detailed calculations or analysis." They include "recommendations for practical products and off-the-shelf technology, needed for achieving a 50% energy savings compared to buildings that meet the minimum requirements of ANSI/ASHRAE/IESNA Standard 90.1-2004."
OPTION 3 (Prescriptive compliance, Advanced Buildings Core Performance Guide, but only for projects less than 100,000 square feet in size): Various sections of ASHRAE 90.1-2010 (with errata) need to be followed, including Section 1 (design process strategies), Section 2 (core performance requirements), and 3 strategies from Section 3 to the extent that they apply to the project. According to the Advanced Building (NBI) website linked above, the Core Performance Guide, "the cornerstone of the Advanced Buildings suite of technical tools and resources, is a direct, simplified approach to achieve predictable energy savings in small- to medium-sized buildings without the need for modeling."
Intent: Gather information about energy use, providing feedback that could influence maintenance and management, as well as — somehow — identifying "opportunities for additional energy savings."
Requirements: Provide meters, or use those supplied by utilities, to measure the energy consumed by the building for all of its energy-consuming functions. Share the data with USGBC for 5 years or until the building is sold, whichever comes first.
Intent: Reduce stratospheric ozone depletion.
Requirements: Do not use CFCs (chlorofluorocarbons) in HVAC&R equipment, or phase out use in existing equipment either before project completion or — if LEED accepts your reasoning — at some future time.
If substitute refrigerants are used, try to find a good alternative (there are none) that not only has low ozone depletion potential (ODP), but also low global warming potential (GWP), and short environmental lifetimes. The following values are excerpted from Table 1 (EA Credit 4) listing "100-year values":
Intent: Like Prerequisite 1, but starting earlier and ending later; with additional requirements to verify that systems are working properly, as intended and designed.
Requirements: There are two non-exclusive options, the first worth up to 4 points and the second worth 2 points. However, because Option 1 has two "paths," with Path 2 requiring the satisfaction of Path 1, there really are 3 options, as follows:
First: This is called "Option 1, Path 1" by LEED, and includes a list of things that the CxA must do, for 3 points:
Second: This is called "Option 1, Path 2" by LEED, and can only be counted if Path 1 has already been satisfied, for 1 extra point. It requires that the actual performance of energy- and water-consuming systems be monitored and evaluated.
Third: This is called "Option 2" by LEED, and can be satisfied (for 2 points) either instead of, or in addition to, the first two "paths." To get these 2 points, one must actually implement that part of the EA prerequisite dealing with the building's envelope. The commissioning of the building envelope has its own abbreviation within the language of LEED: BECx. Using ASHRAE Guideline 0-2005 and the National Institute of Building Sciences (NIBS) Guideline 3-2012, Exterior Enclosure Technical Requirements for the Commissioning Process, the CxA must do the same things itemized under "Path 1": e.g., review submittals, and so on.
Intent: Lower use of energy for all the economic/environmental reasons cited in the overview.
Requirements: There are 2 options, using the same standards as in the first two options in the EA prerequisite. If compliant, then the prerequisite is satisfied by default. Note that the big points are only available through Option 1.
OPTION 1 Whole building energy simulation: Remember that the prerequisite required an energy savings (compared to the "baseline" building) of 5%. Therefore, points for this credit are only gained for additional energy savings, compared to the baseline building: 1 point for 6% savings, with an additional point for every 2% increment of savings up to 26% (and 11 points); after that, each additional point requires a 3% incremental increase up to 38% (and 15 points); after that, each additional point requires a 4% incremental increase up to 50% (and the maximum of 18 points). A savings greater or equal to 54% qualifies for "exemplary performance" points.
In this latest version of the LEED guidelines, the EA section pretends to be interested in actual energy use by requiring that an "energy performance target" measured in kBtu per square foot-year be established. This requirement is completely specious, however, since the "target" is something that each project can make up, and is not constrained by any default values for particular building types in particular climates. Along the same lines, the LEED fiction writers pretend that energy use is actually being evaluated by eliminating the phrase "energy cost savings" from the v4 "Intent" and "Requirements" and by substituting the ambiguous and misleading phrase, "energy savings." One must dig a bit deeper into the guide's "further explanation" section before encountering the actual requirements for measuring, not energy, but energy costs.
[From Version 2.2 critique] Here, cost is explicitly made the basis of the design's sustainable "value": if it costs less, it must be more sustainable (and we'll give you more points). The LEED commentary states: "The intent is to encourage simulations that provide owners value, and help them minimize their energy costs." Of course, the idea of making environmental decisions based on cost rather than on actual environmental impact is what contributed to environmental damage in the first place. The history of energy use, and consequent environmental damage, from the abuse of timber to coal to oil, is set in motion by the same calculation of cost and profitability advocated in the LEED guidelines.
OPTION 2 Prescriptive compliance path (for 1-6 points): Satisfy the requirements of the appropriate ASHRAE 50% Advanced Energy Design Guide, same as in EA Prerequisite 2 (which must be followed as a prerequisite if this option is used here).
For each of the various guides, 1 point can be obtained by following the requirements for each of these enclosure or other building elements: building envelope opaque surfaces; building envelope glazing; interior lighting; exterior lighting; and plug loads.
Intent: Provide information on energy use in order to find opportunities for energy savings and in order to facilitate ("support") energy management.
Requirements: Install meters to record energy use for the whole building (at 1 hour intervals or less) and also for any particular energy "end use" that constitutes 10% or more of the building's total energy use. The meters must record both consumption and demand, consumption being the total energy consumed during a particular time period (measured, e.g., in watt-hours or kWh) and demand being the "instantaneous" power requirement (measured, e.g., in watts or kW).
Intent: Encourage building owners to participate in demand response (DR) programs and therefore to "make energy generation and distribution systems more efficient, increase grid reliability, and reduce greenhouse gas emissions."
Requirements: Since participating in a demand response program presupposes the existence of a demand response program where the project is located, LEED provides two "cases" for compliance with this credit, the first for projects that can participate in demand response programs and the second for projects that can't.
Case 1: Where demand response programs are available, sign up for the program for at least a year (with "the intention of multiyear renewal") for not less than 10% of the estimated peak demand.
Case 2: Where demand response programs are not available, prepare the electric/metering system to do essentially the same things as in Option 1, and contact the "local utility representatives to discuss participation in future DR programs."
Demand response is a strategy whereby utilities provide monetary incentives to customers to reduce their demand during peak usage time periods. Such a strategy has no impact on the total amount of electricity needed or generated (i.e., it has no impact on the total amount of fossil fuels burned or global warming gases produced by electric utilities); rather, it spreads out the generation of electricity over a 24-hour day or 7-day week, so that the size and capacity of the utilities' generators can be reduced — this saves the utilities money but otherwise does nothing to reduce electric use or the pollution and global warming gases associated with such use.
LEED claims that DR reduces greenhouse gas emissions, but provides no explanation of why this should be the case. Obviously, reducing demand will reduce the need for electric generation (using fossil fuels), but DR only redistributes demand to non-peak hours, leaving the total demand unchanged. There are unsubstantiated claims by the Demand Response Smart Grid Coalition (DRSG) that DR reduces total electric consumption by 4% because "the amount that is reduced on peak is not replaced in the off-peak period." This makes no sense, since if I use my dishwasher timer to avoid peak charges, I'm still running the dishwasher and using the same amount of power, except using it during off-peak periods. If people become more conscious of energy conservation measures while participating in DR programs, then this is a result of energy conservation rather than DR.
Aside from this, the LEED credit requires only that 10% of the peak demand be spread out. As can be seen from the diagram below, this is hardly a significant peak reduction.
Intent: Lower use of fossil fuel based energy to "reduce the environmental and economic harms" associated with fossil fuel use.
Requirements: Use renewable energy, calculating the percentage used by dividing the yearly "equivalent cost" of the renewable energy by the total yearly energy cost for the building.
LEED's equation has two errors. First, it equates a percentage with a mere fraction, forgetting to multiply the fraction by 100. Second, it omits a unit of time from the numerator of the fraction, which must be 1 year to be consistent with the "annual" time unit in the denominator.
Points are achieved as follows: 1 point for 1% renewable energy; 2 points for 5% renewable energy; and 3 points for 10% renewable energy.
It is more than a bit puzzling that one can only get 3 points under this credit, based on 10% use of renewable energy. In contrast, LEED grants up to 18 points for energy cost savings of 50% based on a comparison with a fictitious "baseline" building. To be clear: if your building uses an ordinary quantity of energy (i.e., it has no major energy reductions compared to a baseline building, except for the mandatory 5% to satisfy the prerequisite) but if it generates enough on-site renewable energy to cover all annual energy needs — making it a net zero energy building — only 3 points are awarded (plus 1 more for exemplary performance). On the other hand, if the same building is redesigned with no renewable energy but uses only 50% of the energy computed for a hypothetical baseline building, it gets 18 points. This latter design is still burning significant quantities of fossil fuels for its heating, cooling, and plug loads and yet it gets 18 points; whereas the former design burns no fossil fuels and is entirely self-sufficient from an energy standpoint, yet it only gets 3 (or 4) points.
Perhaps in response to this strange treatment of on-site renewable energy, LEED has slipped in an additional two points for net zero energy buildings within the "grid-source" renewable energy credit for "Green Power and Carbon Offsets." There is no explanation given for why these extra two points are buried within a credit that has nothing to do with on-site renewables. In any case, the anomalous point spread between net zero buildings (4 + 2 = 6 points) and buildings which, though efficient, still use energy derived from fossil fuels (18 points or more) remains.
Intent: Reduce ozone depletion and minimize global warming gases.
Requirements: There are two options (in either case, exclude small HVAC units and other small refrigeration units): Either do not use refrigerants at all — or use refrigerants with virtually no impact, i.e., with ozone depletion potential (ODP) of zero and global warming potential (GWP) less than 50 for Option 1 — or...
OPTION 2. Use refrigerants with a low combined ODP and GWP; specifically, such that LCGWP + LCODP × 100,000 ≤ 100; where
LCODP = Lifecycle ozone depletion potential (lb CFC 11/Ton-Year) = [ODPr × (Lr × Life + Mr) × Rc] / Life
LCGWP = Lifecycle global warming potential (lb CO2/Ton-Year) = [GWPr × (Lr × Life + Mr) × Rc] / Life
ODPr = ozone depletion potential of refrigerant (0 to 0.2 lb CFC 11/lbr)
GWPr = global warming potential of refrigerant (0 to 12,000 lb CO2/lbr)
Lr = refrigerant [annual] leakage rate (0.5% to 2.0% with 2% default)
Mr = end-of-life refrigerant loss (2% to 10% with 10% default)
Rc = refrigerant charge (0.5 to 5.0 lbs of refrigerant per ton of gross ARI rated cooling capacity)
Life = equipment life (default 10 years).
Refrigerant charge (Rc) is the "ratio of total refrigerant used in a piece of equipment to the total cooling capacity of that equipment, expressed in pounds per ton or kilograms per kW." Low values correspond to more efficient equipment using less refrigerant and therefore having less impact on the atmosphere.
"Table 1" lists "100-year values" for various refrigerants; a few are excepted here (and I've also shown these excerpted values in Prerequisite 4):
The "Behind the Intent" section points out some of the dilemmas in selecting refrigerants — that those with low ODP may have high GWP; or that those with low GWP may be more inefficient than other refrigerants, thereby requiring more energy (and more global warming gases released as a result of this additional energy use). In any case, LEED doesn't seem particularly interested in actually measuring the impact on global warming, given these nuances in the selection of appropriate refrigerants.
The "natural" refrigerants" (i.e., water, ammonia, hydro-carbons, and carbon dioxide) potentially offer options, but are not problem-free (according to the Natural Refrigerants Fund: "The main barriers to the use of ammonia are its toxicity and flammability in particular concentrations in the air. For hydro-carbons the concern is their high flammability. CO2 has low energy efficiency and very high working pressures in cycles with transcritical parameters. Systems with water require turbocompressors that can pass the large volume flows. Air systems have a very good energy efficiency only at large temperature lift making them suitable for heat pumps and very low temperature refrigeration applications. The safety barrier can be surpassed using technical standards and regulations, coupled with proper maintenance and training of personnel.") The LEED commentary offers no solutions to this dilemma, only the acknowledgment that "careful consideration" is required.
The United States Environmental Protection Agency (published June 27, 2014) suggests that new refrigerants have been developed (and are being accepted by the EPA) that reduce global warming potential while still having low ozone depletion potential: "After receiving input from industry, environmental groups, and others, EPA is proposing to list additional low GWP hydrocarbon refrigerants in six refrigeration and air conditioning applications."
Intent: Encourage grid-source reduction of greenhouse gases and carbon mitigation.
Requirements: Sign a 5-year or longer contract for the provision of "green power," carbon offsets, or renewable energy certificates (RECs). For 1 point, the contract must provide at least 50% of the project's energy; for 2 points, 100%. It is also possible to achieve 2 points without signing any contracts for green power, without purchasing any RECs, and without buying any carbon offsets, as long as the building is anticipated to produce enough on-site renewable power to compensate for its entire energy use (i.e., for net zero energy buildings).
Green power and RECs must be certified by Green-e. Other restrictions apply. For example, "RECs can only be used to mitigate the effects of Scope 2, electricity use" whereas carbon offsets "may be used to mitigate Scope 1 or Scope 2 emissions." The EPA defines Scope 1 and 2 emissions as follows:
Scope 1 emissions are direct GHG emissions from sources that are owned or controlled by the entity. Scope 1 can include emissions from fossil fuels burned on site, emissions from entity-owned or entity-leased vehicles, and other direct sources.
Scope 2 emissions are indirect GHG emissions resulting from the generation of electricity, heating and cooling, or steam generated off site but purchased by the entity, and the transmission and distribution (T&D) losses associated with some purchased utilities (e.g., chilled water, steam, and high temperature hot water).
It is puzzling that 2 points are awarded under this credit for net zero energy buildings with no requirement to satisfy any of the credit's goals. It is also puzzling that this "market-driven" guide asks its corporate clients to spend more money on electricity (by buying green power or RECs) than is necessary within the actual marketplace for electric power, and to purchase "carbon offsets" — these are expenditures for which nothing is gained for the corporate buyer other than LEED points (and the corresponding public relations benefits). Welcome to the new face of corporate cynicism, aka "greenwashing."
First posted 8 July 2014; last updated 8 July 2014