The LEED® (Leadership in Energy and Environmental Design) Green Building Rating System, published by the U.S. Green Building Council (USGBC), has become a major force for encouraging the integration of green building principles and techniques into building projects. This summary discusses ways in which the various LEED v4 (new construction) credits affect the HVAC industry and how to best respond to the opportunities presented by the use of the LEED system on projects.
The LEED rating system awards points in one overall category (new to v4) and eight categories: location and transportation (LT), sustainable sites (SS); water efficiency (WE); energy and atmosphere (EA); materials and resources (MR); indoor environmental quality (EQ); innovation and design (IN); and regional priority (RP). Energy and atmosphere (EA) and indoor environmental quality (IEQ) are the two categories with the highest number of points available, and these are the same categories that will correlate to the HVAC system, plus the overall category called Integrative Process. For the purpose of our discussion, we will focus on the specific credits most impacted by the HVAC system.
The new Integrative Process credit in LEED v4 asks design teams to explore energy- and water- related improvements early in design. Moreover, it asks teams to use energy modeling to explore synergies and impacts across building systems and document the results — to perform holistic investigations rather than the sort of targeted, credit-specific calculations that have come to characterize other LEED credits.
Energy-related investigations can include:
- Site conditions, such as assessing shading from surrounding buildings
- Massing and orientation, and their impacts on HVAC loads, energy use, and renewable energy
- Envelope attributes, such as insulation levels, glazing ratios, and shading
- Thermal comfort ranges, including expanding the comfort zone
- Plug and process load reductions
- Programmatic and operational settings, such as schedules, occupancy, and required square footage
Energy and Atmosphere
The Energy and Atmosphere (EA) section has four prerequisites and seven credits. Each prerequisite (with corresponding credits) influences or impacts the HVAC system. The first prerequisite, Fundamental Commissioning of Building Energy Systems, involves validating energy usage through commissioning energy-related systems (mechanical, electrical, plumbing, and renewable energy systems and assemblies) that are installed, and calibrated to perform according to the project requirements, based on the design and construction documents. They must be in accordance with ASHRAE Guideline 0-2005 and ASHRAE Guideline 1.1–2007 for HVAC&R Systems, as they relate to energy, water, indoor environmental quality, and durability.
This prerequisite also is directly associated with EA Enhanced Commissioning credit, which continues the building commissioning process well after the building is completed. Commissioning is useful for verifying that fundamental building systems and assemblies are performing as intended to meet current needs and sustainability goals. Without periodic commissioning, it can be difficult to identify components that are not working according to specifications of the building operation plan. This process of assessing building system performance will uncover problem areas and inform equipment maintenance and upgrade schedules.
The second EA prerequisite, Minimum Energy Performance, and its correlating credit, credit Optimize Energy Performance, establishes a minimum energy efficiency that the building must meet. To meet the threshold for the prerequisite the building must demonstrate a 5% improved energy efficiency rating from the determined baseline or comply with the mandatory and prescriptive provisions of ANSI/ASHRAE/IESNA Standard 90.1–2010, with errata (or a USGBC-approved equivalent standard for projects outside the U.S.). The baseline building performance according to ANSI/ASHRAE/IESNA Standard 90.1–2010, Appendix G, with errata (or a USGBC-approved equivalent standard for projects outside the U.S.), using a simulation model. In turn, the points awarded in the credit are 1-18 point numbered scale. If option 2 of the prerequisite was followed, then the correlating credit requirement is to implement and document compliance with the applicable recommendations and standards in Chapter 4, Design Strategies and Recommendations by Climate Zone, for the appropriate ASHRAE 50% Advanced Energy Design Guide and climate zone. Interestingly, if project teams are pursuing the Integrative Process credit discussed in the previous section, they must also complete the basic energy analysis for that credit before conducting the energy simulation.
The third prerequisite, Building-Level Energy Metering, and its correlating credit, Advanced Energy Metering, require the use of building-level energy meters, or submeters that can be aggregated to provide building-level data representing total building energy consumption (electricity, natural gas, chilled water, steam, fuel oil, propane, biomass, etc). The corresponding credit also requires a meter at individual energy end uses that represent 10% or more of the total annual consumption of the building.
The last prerequisite, Fundamental Refrigerant Management, requires zero use of CFC-based refrigerants in HVAC and refrigeration. This means HVAC equipment using HCFC-22 (R-22, Freon) cannot be used. Fortunately, most of the major HVAC equipment now available do not use CFC-based refrigerants, so it’s not difficult to meet this requirement. This is another prerequisite that directly corresponds with a credit: EA Credit 4, Enhanced Refrigerant Management, which calls for reducing ozone depletion and global warming potential.
It is important to note that HVAC changes alone will not earn all the points under this credit.
Indoor Environmental Quality
HVAC also plays a role under the Indoor Environmental Quality section, which has two prerequisites and eight credits. The prerequisites establish minimum indoor air quality (IAQ) performance to enhance indoor air quality in buildings, and prevent or minimize exposure of building occupants, indoor surfaces and ventilation air distribution systems to environmental tobacco smoke.
HVAC, however, gets its opportunity in the following credits:
Credit Thermal Comfort (Design) requires the building envelope to meet the requirements of ASHRAE Standard 55–2010, Thermal Comfort Conditions for Human Occupancy with errata or a local equivalent. And Credit Thermal Comfort (Control) calls for controllability of the HVAC system by providing individual comfort controls for 50% or greater of the occupants. Thermal comfort controls allow occupants, whether in individual spaces or shared multi-occupant spaces, to adjust at least one of the following in their local environment: air temperature, radiant temperature, air speed, and humidity.
The Acoustic Performance credit also has minimum HVAC background noise, sound isolation, reverberation time, and sound reinforcement and masking requirements. For example, the HVAC systems need to achieve maximum background noise levels per the 2011 ASHRAE Handbook, HVAC Applications, Chapter 48, Table 1; AHRI Standard 885-2008, Table 15; or a local equivalent.
ICE AIR and LEED
ICE AIR systems can help earn LEED points by meeting three prerequisites and contribute to earning EA and IEQ points based on the LEED v4 rating system.
ICE AIR units can provide each individual space (guest rooms, classrooms, lobby, spa, restaurants and retail) with its own zoned comfort system while realizing energy savings in the process. These systems cool and/or heat only the spaces occupied, thus saving valuable resources that would otherwise be wasted by conditioning air in unoccupied spaces. In addition, because ICE AIR systems use a sealed refrigerant, Puron® R410A, the LEED refrigerant criteria is an easy solution.
ICE AIR systems solve a number of design challenges, including retrofit applications with no room for ductwork; sustainable HVAC systems; simultaneous cooling and heating; maximum control over indoor comfort; allowing flexibility for future system changes and upgrades; overcoming space limitations and installation restrictions; and meeting or exceeding noise restriction requirements.
Just like conserving energy by turning off the light in a room when it’s not in use, ICE AIR systems only supply air conditioning to rooms that require it, which maximizes individual comfort while using energy effectively.