The United States Green Building Council’s
Leadership in Energy and Environmental Design
Technical Resources Department
June 24, 2005
This document provides an overview of a green building program’s rating system and
how it may affect HVAC contractors. Since the green building guidelines and
requirements are changing often and evolving rapidly, this document should only be
considered a briefing. Note: Contractors considering involvement in a green building
project should obtain and thoroughly review the specific requirements for that project.
Historically, green building efforts never achieved broad market acceptance or critical
mass until the advent of the United States Green Building Council (USGBC). It now
appears that the USGBC’s Leadership in Energy and Environmental Design (LEED)
Green Building Rating System may have developed enough support and sufficient
traction in the market to catapult green building onto everyone’s “radar screen” involved
in building construction.
Early evidence of a fundamental shift influenced by the LEED green building rating
program came during late 2003 as a trend developed with large cities and the federal
government requiring that certain types of public buildings attain some level of LEED
rating. The following year additional support came from larger cities to the point that, at
least for the foreseeable future, LEED has become the de facto rating system for green
buildings. As of the writing of this technical brief, the state of Washington had become
the first to adopt state-wide requirements that publicly-funded buildings must meet a
national environmental standard—such as LEED.
The LEED Rating System
A major key to the success of LEED is the simplicity of the rating system. To reach the
pinnacle of LEED’s recognition in the New Construction (NC) rating system—
Platinum—requires a building to “win” a total of 52 out of a possible 69 points. Points
are awarded in six categories:
• Sustainable sites
• Water efficiency
• Energy and atmosphere
• Materials and resources
• Indoor environmental quality
• Innovation and design
The other recognition levels “below” Platinum are Certified, Silver, and Gold and in the
LEED-NC rating system the minimum number of points required are 26, 33, and 39,
LEED rating systems are revised and updated via a process that is open for public
comment—similar to the process by which building codes are continually updated. Any
individual or company can submit comments on proposed rating system changes.
The USGBC currently has six LEED Green Building Rating Systems. Of those, three are
potentially of business interest to HVAC contractors.
• LEED-NC New Construction and Major Renovations. This is a set of
performance standards for new commercial construction and is the “oldest”
USGBC rating system.
• LEED-EB Existing Buildings. This is a set of performance standards for the
sustainable renovation and operation of existing buildings. The LEED-EB criteria
cover building operations and systems upgrades in existing buildings where the
majority of interior or exterior surfaces remain unchanged.
• LEED – H Homes. This program is currently in the pilot stage, under
development at USGBC.
Contractors interested in LEED ratings can stay abreast by visiting the USGBC website
Unless otherwise noted, this Background Paper focuses on and is specific to LEED-NC,
the new commercial construction rating system.
On energy efficiency, LEED and ASHRAE are working jointly on energy performance
goals and ratings. ASHRAE standards are used as benchmarks from which LEED
standards are measured—typically some fixed percentage above ASHRAE is required to
obtain additional LEED points. Examples of ASHRAE standards referenced by LEED
• 90-1 Energy Standard for Buildings Except Low-Rise Residential Buildings—
Establishes insulation levels by geographic zones
• 62-1-2004 Ventilation for Acceptable Indoor Air Quality—Determines
building ventilation requirements.
• 55-1992 Thermal Comfort—Provides industry-accepted methods to
measure and evaluate occupant comfort levels.
LEED AND HVAC BUSINESS
LEED’s Potential Impact on HVAC Contractors
Overall, the growing governmental agency adoption of LEED has the potential to provide
opportunities to HVAC contractors—if contractors are willing to adapt to new
procedures, technologies, and system designs. LEED certifications require so much
upfront coordination between owners, designers, and construction trades that conflicts
that normally “cost” HVAC contractors may potentially be resolved prior to the start of
construction. The following “performance standards” have been pulled out of the overall
LEED program rating systems in an effort to focus on the HVAC-specific business
• Optimize Energy Performance – The most important LEED credits to HVAC
contractors are for energy reductions/improvements. Up to 10 points can be
obtained by improving energy performance—5 to 15 percent and 50 to 60 percent
improvements represent the endpoints for 1 to 10 points for existing buildings
(LEED-EB) and new construction (LEED-NC), respectively. In order to
significantly improve the energy efficiency of buildings, building insulation
envelopes will have to be improved above code and, as a result, HVAC system
capacities are likely to be downsized from historical tons/square foot ratios. In
order to achieve maximum energy efficiency, which equates to maximum LEED
points, duct system air velocities will almost certainly have to be reduced.
Note: This lower duct air velocity strategy is consistent with ASHRAE’s
preliminary “green” standards to significantly reduce energy use in office
buildings. As one approach to achieve higher HVAC efficiencies, ASHRAE has
recognized the need to reduce HVAC fan horsepower—which is a typically
operated 8760 hours per year. In addition to lowering main duct velocities,
limiting flexible duct length to five-foot sections or less has been recommended.
All this represents an effort to reduce total HVAC fan horsepower by reducing
duct friction losses.
• Ventilation Effectiveness – More extensive and complex ventilation systems will
be needed to maintain LEED’s high IAQ levels. It is also possible that more of the
open plenum return sections might to be ducted to better control and improve
IAQ. While not yet part of the LEED requirement, it is worth noting that new
Federal guidelines for certain building types require a totally-separate ventilation
system for mail rooms. This relates to LEED because so many of the building
types required to be LEED-certified by cities and the government are likely to fall
within the affected Federal building type. Other Federal-building-specific
guidelines will likely also come into play for the same reason in many LEED-
Note: In many geographic areas, higher ventilation rates and control strategies
can be employed to take more advantage of “free” cooling from intervals when
outdoor temperatures are lower—such as at night or in the early morning.
Typically, the lowest daily Spring and Fall temperatures occur around 6:00
a.m.—providing an opportunity to exchange the air in the building prior to the
arrival of the workers and provide pre-cooling; this is especially applicable to
heating-dominated climates. Energy efficiency points and innovative design
points may be available to “free cooling” design strategies. It is worth noting that
“free cooling” and temperature setbacks work with conventionally-ducted HVAC.
Its effectiveness is questionable with under floor air distribution—the “thermal
inertia” in the floor slabs “fights” attempts to save HVAC energy via free cooling
or temperature setbacks.
• Indoor Air Quality – In all LEED rating systems, there is an emphasis on IAQ—
both during construction and after occupancy. LEED credits can even be earned
during the course of construction when careful, documented attention to IAQ is
provided for the health benefit of construction workers. LEED references
SMACNA’s IAQ Guidelines for Occupied Buildings Under Construction for both
new and existing buildings if a portion of the building is occupied during
renovation and construction. For existing buildings—LEED EB—there is a
prerequisite to meet ASHRAE 62-1 standards and to verify all building exhaust
systems—codes simply require that the mechanical capability to meet ventilation
requirements be present, not that it be demonstrated and verified. Also, LEED
points are given for outdoor air delivery monitoring and increased ventilation
rates (30% above ASHRAE 62-1 for LEED EB). LEED NC uses a more obscure
ASHRAE standard, 129-1997 – Measuring Air Change Effectiveness, that uses
tracer gases to determine the “age” of the air. More effective air filtration systems
can be expected and an emphasis on maintenance—filter changing, system
performance verification, balancing, etc.—which will provide service business
opportunities for HVAC contractors that already offer or are considering those
services. This greater emphasis on cleaner air should also help to reduce or even
eliminate the practice of using a building’s permanent HVAC system for
temporary heat during construction.
• Building Systems Monitoring – Temperature, humidity, and CO2 monitoring are
worth a LEED point. Either the installation of the system, the monitoring service
or a combination of both may be services that offer potential to HVAC
contractors as part of an on-going maintenance contract. This would certainly be a
worthwhile strategy to “bond” customers to an HVAC contractor offering such
services. In a related area, LEED provides points (up to three) for enhanced
metering of individual loads. The intent is to provide for the ongoing
accountability and optimization of building energy performance and water
consumption reduction, over time. In addition, building maintenance staff training
can be used to earn LEED points and may be an opportunity for HVAC
contractors to include as a new high-value adder to maintenance contracts.
• Recycled Content – LEED points can be earned for recycled content. While
HVAC metal duct easily qualifies for this point, a minimum overall project
materials percentage—five percent of the total value of the materials in the
project—must be “reached” with recycled content to garner a point. So, a
combination of a metal roof and metal duct would contribute heavily to the
minimum required percentage of the total required materials that contain recycled
content. This may give other metal uses and applications, such as metal framing
versus wood, a market boost.
• LEED Accredited Professional (AP) – Finally, a LEED point can be earned if one
member of the design team is a LEED AP—something that HVAC contractors
might consider. If the HVAC contractor is LEED AP, that may improve the
likelihood that they will have a seat at the project management table. At a
minimum, it puts the HVAC contractor on an equal footing with other LEED APs
on the project. LEED certification testing is offered in a manner that makes it
widely available and fairly convenient to take the AP test.
• Minimum Energy Performance – Computer simulation is required to assess that
the building’s energy performance meets or exceeds ASHRAE 90.1 and any other
energy-use related “claims” that will be used to garner LEED points. While
energy simulations are often done in larger buildings, this is a very burdensome
cost to smaller buildings for which a LEED rating is being sought. The cost to
“run” an energy simulation is nearly the same regardless of building size.
Specific Technologies and Procedures
Volatile Organic Compounds (VOCs) – LEED points may also be earned through the use
of low emitting paints, sealants, and adhesives. While many manufacturers are beginning
to develop low-VOC products, some research may be required to obtain HVAC-related
and –approved products that both comply with LEED requirements and UL, as required
by the codes.
Geothermal – Geothermal HVAC—variously called ground-source, water source, or
ground-coupled—is likely to achieve greater market penetration in LEED projects than it
currently has realized in the general market. This is due to three forces—the much higher
energy efficiencies inherent in geothermal, the long-standing commitment from both
EPA and DOE to provide market support for geothermal, and the classification of
geothermal as renewable. At least with geothermal, it is also likely that the HVAC system
design trend will move more towards unitary system designs and away from large central
plants. Because of the energy saving potential, it is also likely that in-the-floor hydronic
heating will be used more in areas such as large bathrooms and heating-only areas with
high ceilings—garages, warehouses—and perimeter areas for local occupant control,
especially in heating-dominated climates.
Non-CFC Refrigerants – In all LEED ratings, zero use of CFC-based refrigerants is a
prerequisite. Since the CFC phase out is in the final stages and HVAC contractors often
do not specify equipment this will have a limited impact.
Renewable Energy – Renewable energy to offset various portions of the building’s
energy use garners increasing points for 5, 10, and 20 percent energy offsets with one
point for the first level and additional points for a higher percentage of energy offset.
LEED defines renewable to include solar, wind, geothermal, low-impact hydro, and
biomass and bio-gas strategies. Geothermal would typically present the greatest
opportunity to HVAC contractors; 20 percent operational savings above air-cooled
equipment is easily obtainable, especially if heat pumps are used. It also appears that
“additional” points can be captured from the energy use reduction improvements above
and beyond ASHRAE 90-1, the Optimize Energy Performance credits category. The use
of the more efficient geothermal heat pumps might be worth as many as seven points on
the combined value of the Renewable Energy and Optimize Energy Performance credits
categories with the possibility of as many as four additional points if the HVAC system
can be classified as “innovative” in its design approach.
Commissioning – Commissioning is a prerequisite for all LEED ratings. This should
provide new business for HVAC contractors already providing this service and
commissioning should reduce change orders through better upfront planning and design.
Be aware, though, that LEED commissioning can only be provided by a team that does
not include individuals directly responsible for project design or construction
management. There is also an additional point for “additional commissioning” which is
the process ASHRAE generally considers as “total” building commissioning—from
design all the way through OEM procedures.
Architectural Sheet Metal – To date, many LEED certified buildings have used metal
roofs. Many use roof and drainage system designs to capture runoff for use in landscape
watering and toilet flushing. Both these trends should provide more business to sheet
metal architectural contractors as more complex roof/drainage designs are created and
require higher skill levels to fabricate and install.
Cool Roofs –Currently, the requirement is to meet the less stringent EPA Energy Star
Cool Roof rating over at least 75 percent of the building’s total roof area—which is worth
a LEED point. Beginning at the end of October 2005, “cool” roofs will be codified into
the California energy code. Because no bare, primary metal comes close to meeting the
program requirements of California’s or EPA’s Energy Star Cool Roof requirements,
metals will have to be coated with a special-purpose coating—usually a ceramic coating.
Note: Green Roofs are a vegetated roof which typically uses non-metallic underlying
construction materials and qualifies for LEED credit with only 50 percent of the total
The Future “Reach” of LEED
The USGBC not only creates sustainable building construction “standards” it also
functions as a think tank to develop long-term strategies to move the market—inside the
Beltway the buzzword is “market transformation.” An example of a long-term, strategic
approach is USGBC's Emerging Green Builders. This effort seeks to involve a coalition
of students and young professionals into the green building movement; this effort is
likely further endue future building construction leaders with a fondness for sustainable
building practices. An annual USGBC green building design competition engages this
“next” generation with incentives which are more sustainable than simple recognition—
jobs and internships await some of the brightest of these young “green” professionals.