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22. ENERGY & ATMOSPHERE
Fundamental Commissioning of the Building Energy Systems
Prerequisite 1. It is not enough to specify energy-conserving equipment and to design energy-efficient buildings: one must also make sure that such designs and equipment are actually installed and operating as intended. That a properly functioning building is not necessarily the outcome of an ordinary design process is itself a remarkable admission; in any case, this prerequisite requires that at least some "commissioning," involving the main energy-using building systems (i.e., HVAC&R, lighting and daylighting controls, domestic hot water, and renewable energy systems, if any) are included in the project. The building envelope— including Milstein Hall's stone veneer, floor-to-ceiling glass, stamped aluminum soffit panels, and so on—is excluded, although the LEED commentary suggests that "significant financial savings and reduced risk of poor indoor air quality" can be achieved by voluntarily including it within this prerequisite. And there is a commissioning credit which goes beyond the requirements in this prerequisite.
This prerequisite describes two documents identifying project objectives that the so-called commissioning authority (CxA) must review: the "Owner's Project Requirements" (OPR) and the "Basis of Design" (BOD), the latter of which is prepared by the design team.
Minimum Energy Performance
Prerequisite 2. This prerequisite prevents projects from obtaining LEED certification without at least meeting minimum guidelines for energy efficiency established by ASHRAE/IESNA Standard 90.1-2004. Included are requirements for the building envelope, HVAC, service water heating, power, lighting, and other equipment that are adjusted according to climate zone. Because these minimum requirements are already requirements of many state building codes, this prerequisite doesn't really force LEED-certified projects to meet energy-conservation goals that they wouldn't be compelled to meet in any case.
Even so, Milstein Hall apparently only barely satisfies this energy performance prerequisite. As discussed previously with respect to Table 5, Milstein Hall is projected to be two percent more efficient than current Code-mandated energy standards. However, it achieves this dubious energy distinction only by leaning up against two existing buildings, Sibley and Rand Halls, along parts of its southern, eastern, and western facades: both heating and cooling loads are reduced for Milstein Hall since approximately 3,000 square feet (279 square meters) of its "exterior" wall area does not actually face the exterior. As a free-standing building without the benefit of such shared wall surfaces, Milstein Hall would experience greater heat loss and heat gain, and would have difficulty meeting even the minimum standards of ASHRAE 90.1-2004.
Fundamental Refrigerant Management
Prerequisite 3. This prerequisite is, like No. 2, difficult not to meet for new construction, as chlorofluorocarbon (CFC) based refrigerants are no longer used in new HVAC&R equipment. Milstein Hall is connected to Cornell's campus-wide lake-source cooling system, so that refrigeration equipment has been already eliminated in any case.
Optimize Energy Performance
Credit 1. While there are three "compliance paths" for this credit, there is only one way to get up to 10 points for energy-efficiency: one must create an energy simulation (a computer model) for the proposed building and compare it to what is called a "baseline" condition. This is immediately very strange: how can a baseline design be created when every building—especially an idiosyncratic structure like Milstein Hall—is unique? Before describing what such a baseline building is under the LEED guidelines, a simpler and more rational basis for judging energy efficiency can easily be imagined: one could simply assign energy points based on a project's projected energy use, e.g., the number of BTUs consumed per hour per square feet (Watts per square meter) for a particular building type in a particular climate zone. Projects that used less energy per unit area would get more points. Adjustments would be made for building type (lab vs. hotel vs. office building, etc.) and climate zone.
Rather than judging energy use in this straightforward way, LEED's Credit 1 method compares the proposed building, not to objective metrics based on the rate of energy consumption, but to an imaginary baseline building that is designed just like the proposed building, but even more thoughtlessly. Using standard light framing and insulation, with ordinary windows equally distributed on all four sides, and the orientation arbitrarily varied, an average baseline energy value can be computed. If the original design fundamentally made no sense from an energy standpoint, then the baseline design will almost certainly make even less sense. In this way, even foolish design strategies can be labeled "energy-efficient," to the extent that their thoughtless original proposals perform better than their even-more-thoughtless baseline brothers.1
There is one additional aspect to this LEED energy-efficiency credit that makes no sense from an environmental standpoint. Energy use, or efficiency, is not measured within the LEED system by computing how much energy is used. Nor is it measured by evaluating the negative environmental impacts of such energy use. Instead, it is measured by cost. This means that proposals that cost more to heat and cool than their standard baseline variations will not be rewarded with LEED points, even if costlier approaches have environmental benefits compared to the baseline. The market-driven ideology that defines the LEED system makes cost the ultimate arbiter of virtually all environmental questions (with a few exceptions within the LEED guidelines), notwithstanding the almost embarrassingly obvious fact that it is precisely this market-driven thirst for profit that is responsible for most of the planet's environmental problems in the first place.
Milstein Hall will get six "Credit 1" points based on energy-cost savings of 28.58 percent over its baseline design—the maximum 10 points for this credit requires energy-cost savings of 42 percent. These points are based on the energy efficiency of the thermal envelope (including its high-efficiency glazing), reduced interior and exterior lighting power density (including occupancy sensors, but no illumination sensors), passive chilled beams, radiant floor heating, heat recovery, and VAV air handlers. The envelope model presumably does not account for substantial thermal bridging along the entire length of seismic expansion joints separating Milstein Hall from the existing buildings it connects to, nor substantial thermal bridging due to the continuity of uninsulated steel columns originating on the building's exterior, nor substantial thermal bridging due to shelf angles supporting stone veneer panels that cut into rigid insulation panels, nor substantial thermal bridging due to metal bollards above underground spaces that interrupt rigid insulation, nor numerous discontinuities in the building's air barrier that permit substantial air leakage. Thermal bridging in Milstein Hall was discussed earlier in the section on thermal control.
Onsite Renewable Energy
Credit 2. One to three LEED points can be awarded by obtaining 2.5 percent, 7.5 percent, or 12.5 percent of the building's energy (again measured in units of cost rather than in units of energy) onsite, e.g., from solar, wind, geothermal, biomass, bio-gas, or low-impact hydro sources. Systems can be either electrical (e.g., wind, hydro, photo-voltaic, etc.); geo-thermal (deep-earth water or steam generating either thermal or electrical energy); or solar-thermal (active solar). In other words, sustainability is measured by the cost of renewable energy, rather than by its environmental sustainability. For example, as photovoltaics get cheaper, LEED gives you fewer points for using them, since a given amount will "save" less money. Here's a hypothetical comparison:
Case 1: Proposed building uses $875 for fossil fuels (95 percent energy used) + $125 renewable energy (5 percent energy used). Total energy cost = $1,000, of which 12.5 percent of the cost is for renewable energy, resulting in three LEED points, the maximum possible. The actual percentage of renewable energy used is 5 percent of the total.
Case 2: Proposed building uses $975 for fossil fuels (90 percent energy used) + $25 renewable energy (10 percent energy used). Total energy cost = $1,000, of which 2.5 percent of the cost is for renewable energy, resulting in one LEED point. The actual percentage of renewable energy used is 10 percent of the total.
In these hypothetical scenarios, the cost of renewable energy relative to the cost of fossil fuels has gone down in Case 2, compared to Case 1. Twice the energy is derived from renewable sources in Case 2, compared to Case 1. Which case is more sustainable? According to LEED, Case 1—with only 5 percent of energy use derived from renewables—is much better than Case 2, for which 10 percent of energy is derived from renewables. Not only that, but the Case 1 building receives the maximum number of points possible for this credit (3 points) while the superior Case 2 building barely gets 1 point—and wouldn't get any points if the cost of its renewable energy dropped from $25 to $24.
Related to the use of an energy-cost metric to measure energy sustainability is the repeated insistence that market forces (costs and profitability) are consistent with energy-efficient green design. Pat Murphy wonders why "the USGBC and other LEED advocates continue to insist that green buildings with significant energy savings do not 'have to cost more?'" His answer is that "if energy-efficient green buildings do cost more (and maybe significantly more), then fewer owners and builders would take the financial risk, being unsure of the market."2 This then leads to the conclusion, supported by the historic record, that only governmental intervention in the form of more stringent building code requirements—leveling the playing field for all developers—would lead to significant changes.
Milstein Hall has none of the conventional symbols of "green building" design, not only because its architects eschew such trite forms of expression, but also because they had—at least as manifested in this design—no serious interest in sustainable design to begin with. In spite of having an enormous amount of roof area with an ideal orientation to the southern sun, Milstein Hall employs neither photovoltaics nor any other type of renewable energy system. Is this rational from a cost standpoint? Probably. Does this demonstrate a serious interest—even if only an academic-research interest within an architecture department situated within a university with a stated commitment to sustainability—in sustainable (renewable) energy sources? Probably not.
Enhanced Commissioning
Credit 3. This credit, earned by Milstein Hall, is an extension of Prerequisite 1 (Fundamental Commissioning of the Building Energy Systems), adding the following commissioning steps:
- The commissioning authority (CxA) must be hired prior to the construction documents phase, must be independent of the design/construction teams, and experienced in at least two building projects.
- The CxA must review the owner's project requirements (OPR), the basis of design (BOD), and the design documents no later than the mid-point of the construction documents phase, rechecking later.
- The CxA must review contractor submittals.
- A "systems manual" must be produced, and a process for training building occupants and operating staff must be created.
- The CxA must review building operations 8–10 months after substantial completion (handover) of the project, and a plan must be developed to resolve anything within the commissioning scope that is unsatisfactory.
Like Prerequisite 1, the real puzzle with this LEED point is the implicit acknowledgment that buildings are not ordinarily checked out in this way. What is also striking is the fact that no further commissioning is required after 10 months of operation. The building can fall apart and its energy systems can degrade into serious states of inefficiency, but the LEED rating remains intact forever.
A more serious criticism is that such commissioning does not guarantee that LEED-rated buildings actually perform well. In late 2007, the USGBC released the results of a study it had commissioned to analyze the actual performance of LEED buildings.3 The claim that their results "show average LEED energy use 25–30 percent better than the national average" was famously challenged by Henry Gifford, who wrote that "what the data actually indicate is that the 22 percent of LEED buildings whose owners participated in the study and reported their energy data used an average of 29 percent more energy than the most similar buildings in the dataset that the study authors chose to use as a comparison! Going to so much trouble and expense to end up with buildings that use more energy than comparable buildings is not only a tragedy, it is also a fraud perpetuated on US consumers trying their best to achieve true environmental friendliness."4
Enhanced Refrigerant Management
Credit 4. This credit is an extension of Prerequisite 3, to support "early compliance" with the Montreal Protocol (1989 with subsequent revisions) which was developed to protect and heal the ozone layer. It basically adds a concern about global warming potential (GWP) to the concern about ozone depletion potential (ODP) found in Prerequisite 3. To do this, the weighted average annual "life cycle" potentials of the proposed refrigerant in terms of both global warming and ozone depletion, accounting for expected annual leakage, end-of-life loss, and refrigerant charge, are considered. Small units like window air conditioners or small refrigerators are excluded. Not using refrigerants at all is another option for compliance. Milstein Hall gets this credit because Cornell's lake-source cooling eliminates refrigerants, not because of any particular design decision related specifically to the building.
Measurement and Verification
Credit 5. This credit is earned by making a plan to measure and verify energy use for at least one year, post-occupancy, using simulation or analysis methods. In other words, it is something that one would probably do anyway in earning the Credit 3 point for "enhanced commissioning." Like Credit 3, it raises questions about why such feedback is not ordinarily gathered, and why a building's LEED rating survives forever even though this measurement exercise may terminate after one year of occupancy. Most importantly, the credit, while useful in as much as it encourages owners to actually measure and examine their energy use, does nothing to actually create an energy-efficient building: the LEED point is awarded just for making the plan, not for actually meeting any energy standard. Milstein Hall earns this point, in any case.
Green Power
Credit 6. This credit requires that at least 35 percent of "grid-source" electricity—electricity not produced onsite—is from renewable sources and is produced on a "net zero pollution" basis, for a period of two years. The "green-ness" of the energy is measured per the Center for Resource Solutions (CRS) "Green-e" certification, and includes solar, wind, geothermal, bio-mass, and low-impact hydro.
The actual power purchased need not be "green," if one uses renewable energy certificates (RECs), tradable renewable certificates (TRCs), or other similar things. This credit is really designed for projects that need to buy LEED points in order to become certified, or for projects that wish to move up a notch in the LEED rating hierarchy—e.g., from certified to silver, from silver to gold, or from gold to platinum.
Notes
1 There is another big problem with comparing a baseline building to the building as designed: "…many dissimilarities exist, such as size and heating characteristics of the glazing, heating characteristics of other envelope elements, lighting density, and type of HVAC system. However, these are not the main differences between the buildings. The real difference is that the design building almost certainly will be built, and the base building is just an imaginary building." Inevitable variations in the actual vs. "designed" elements comprising the real building "can cause the energy modeling to be off by up to 15% from the deterministic modeling output… Energy modeling software that compares design and base buildings needs to be revised so that it can allocate uncertainties to the inputs of the design building and present a probabilistic output." See Khazaii, "Rethinking Energy Modeling," 79 (my italics).
2 Murphy, The Green Tragedy.
3 For the final report released in 2008, see: Cathy Turner and Mark Frankel, "Energy Performance of LEED for New Construction Buildings," New Buildings Institute, March 4, 2008, here.
4 Henry Gifford, "A Better Way to Rate Green Buildings," undated (but probably from about Spring 2009), here.
contact | contents | bibliography | illustration credits | ⇦ chapter 21 |