This exclusive comes courtesy of CTG Energetics, Inc.
Now that the USGBC membership has approved LEED-NC v2.2 (Leadership in Energy and Environmental Design for New Construction), it’s time to look at some of the most important changes that will impact LEED projects. Some of these changes will make it easier to achieve a credit, some will make it more difficult, and others will affect the documentation. In this article, we’ve review all of the changes in 2.2 and extract those items that change how you approach the credit.
For TFM‘s coverage of LEED, see “LEED and LCA” from the archives.
SS CREDIT 6 – STORMWATER. You’ll see a lot of new language here, but the stormwater credits will function similarly to v2.1. The new language is more responsive to the intent of the credit and uses clear metrics for calculating compliance. There is also a new option in 6.1 for Greenfield projects that uses stream channel protection as the metric, as opposed to runoff rate and quantity.
SS CREDIT 7 – HEAT ISLANDS. Solar Reflectance Index (SRI) takes over for reflectance and emissivity in these credits. SRI values for a few typical pavement types and roof types will be provided, but if you are using a non-typical pavement, you will need to test the material in the field to achieve credit 7.1. Also, since SRI is a relatively new metric, it may take some time for manufacturers to integrate this reporting in their product literature.
SS CREDIT 8 – LIGHT POLLUTION. This credit has been reorganized into three major components: interior light spill, lighting power density, and light trespass. You will find more specific requirements for interior lighting, compared to 2.1, and the energy use of the exterior lighting is now regulated in this credit. A new series of zone definitions and light trespass criteria provided that greatly improve the clarity of those requirements compared to v2.1. The lighting power density criteria appear to be a major improvement over the previous limitations on average footcandles and max/min ratios, with respect to clarity and documentation.
EA PREREQUISITE 1 – COMMISSIONING. Similar to SS credit 6, you’ll see entirely new language here, but the resultant criteria are pretty close to v2.1. The major clarification is the definition of who is eligible to serve as the Commissioning Authority (CxA)for the prerequisite and EA credit 3. LEED will be more accessible to small projects in v2.2 because the new language includes a clause that, for projects less than 50,000 SF, the CxA may be a member of the design or construction team. The new language also clarifies which systems are to be included in the scope of LEED commissioning.
EA CREDIT 1 – ENERGY PERFORMANCE. We’re teaching entire seminars on the changes to this credit, but they can be boiled down into a few critical items. First, the reference standard is now the 2004 version of ASHRAE 90.1, which carries with it a revised energy modeling protocol and more stringent performance criteria. Second, process loads are now accounted for in the energy modeling process. Third, there are two prescriptive paths for projects that choose not to take on the energy modeling process. Finally, the thresholds for each point have been reduced to account for the introduction of process loads and increased stringency to keep the thresholds roughly in line with v2.1 performance levels.
EA CREDIT 4 – REFRIGERANTS. The result of an intensive research study by the LEED Technical & Scientific Advisory Committee, this revised credit now tracks both ozone depletion and global warming impacts. Don’t be scared by the imposing equation that dominates the Requirements section. The 2.2 Reference Guide contains example calculations, and many manufacturers have already prepared technical sheets to help project teams determine which equipment achieves the new credit.
MR CREDIT 4 – RECYCLED CONTENT. The thresholds have doubled. So, the 5% and 10% thresholds are now 10% and 20%.
MR CREDIT 5 – LOCAL MATERIALS. There is no longer a credit for materials that are only manufactured within 500 miles of the project. Both credits (5.1 and 5.2) now require materials to be manufactured AND extracted/harvested within 500 miles.
EQ CREDIT 1 – OUTDOOR AIR MONITORING. The focus of this credit has shifted from monitoring CO2 to monitoring outdoor air ventilation rates. The intent remains the same – to maintain healthy IAQ by delivering the appropriate amount of fresh air. In implementing this credit, you will be looking at airflow meters in addition to CO2 sensors.
EQ CREDIT 2 – INCREASED VENTILATION. Because this credit was substantially broken in v2.1, it has been revised for simplicity and measurability. The credit now requires a simple 30% increase in the outdoor air ventilation rate, compared to the minimum rate established in EQ prerequisite 1. Because an increase in the ventilation rate may drive up energy consumption, teams will need to approach this credit carefully to balance energy and IAQ needs.
EQ CREDIT 3 – CONSTRUCTION IAQ. The big news is that the MERV 13 filters have been moved from this credit to EQ credit 5. This is important because many buildings with smaller HVAC systems that don’t accommodate MERV 13 filters have avoided this credit, despite the benefits of clean construction practices. EQ credit 5 is a logical home for the MERV 13 filters because they work in tandem with the walk-off mats to remove particulate contamination from building interiors.
EQ CREDIT 6 – CONTROLLABILITY OF SYSTEMS. The previous structure, with one credit for perimeter spaces and another for non-perimeter spaces, has been abandoned in favor of one credit for lighting controls and a second for thermal comfort controls. Many of the same design features will be used, such as operable windows for thermal comfort and photocells to control lighting in daylit buildings.
EQ CREDIT 7 – THERMAL COMFORT. Credit 7.1 still requires the designer to comply with the ASHRAE 55 standard. However, the permanent monitoring systems previously stipulated in credit 7.2 have been replaced with a requirement to develop an occupant survey for thermal comfort. This should make credit 7.2 more accessible at lower cost to a variety of projects.
Overall, we find that v2.2 is a substantially improved rating system. Because there was no allowance for adding/deleting/reassigning credits in this version, there remain opportunities for further improvement and evolution. These issues have been referred to the new committees being formed to developed LEED-NC v3.0. Look for announcements and activities at GreenBuild related to this effort. Combined with the major refinements to the certification process that will be announced shortly, we expect you’ll like what you see with the new LEED.