# Energy Efficiency, LEED, and Regulations 

The differences between an empirical energy efficiency ranking, such as
the Energy Star label for buildings, and compliance with energy
standards and regulations is important to understand. LEED Green
Building Certification does document that a building design is "Green"
in certain areas, but energy efficiency is based on apparent efficiency
designed into a facility (which is inherently an expectation of
efficiency but no guarantee) using energy compliance standards.
Compliance with ASHRAE Std 90.1-1999, which is used in LEED for EE
points, or compliance with 10 CFR 435A will, unfortunately, not provide
any guarantee of an energy efficient building. This occurs for many
reasons, including:

-   The regs and standards do not distinguish between certain system
    designs that will lead to excessive energy consumption and others
    that will lead to much lower consumption and resulting higher
    efficiency. Why? Partly out of ignorance and partly out of the need
    to follow a "standards-based process" that does not allow certain
    comparisons. We have evidence continuing to mount on the detriment
    to EE caused by large fan systems and by many VAV designs, but we do
    not have enough evidence to produce solid statistics on the impact.
    So, again unfortunately, we must rely on suggesting to building
    owners and designers that small fan systems (and probably no VAV)
    are critical to achieving higher efficiency. We do have results from
    a preliminary analysis that indicates that, on average for the whole
    country, the EUI of a building will be 20-30 kBtu/sq-ft higher (on a
    source energy basis) if a building has a VAV system, but this number
    could change as the analysis is verified and refined.

-   The energy budget modeling process used as one option to comply with
    the standards and regs, and also used to gain LEED points, typically
    does not allow different types of HVAC systems to be compared
    against each other in many cases; so the standard VAV is not allowed
    to be compared against single-zone systems. This will push designers
    strongly to only use VAV, since the simulation programs are modeling
    idealized, perfectly-functioning VAV systems. The range of major
    malfunctions and inefficiencies present in many, if not most, VAV
    systems in the real world are not treated.

-   The important benefits of separating the "V" from "HVAC" to provide
    discrete heating / cooling system functions and ventilation / IAQ /
    exhaust / relief air system functions is also not recognized by the
    standards and regs. One major benefit is the increase in quality of
    thermal control achieved through the potential of one occupant per
    thermal zone.

-   One major benefit of separating the V from HVAC is the ability to
    use small, local heating / cooling systems that only need to run
    when heating or cooling is required. If the separate ventilation
    system provides continuous ventilation, the total volume of air to
    keep the space fresh and keep the perception of air movement is much
    less. The simulation programs that need to be used to estimate the
    energy impacts of this approach are not readily able to handle the
    diversity of occupancy patterns that would impact energy use for the
    small, local system option.

-   The controls malfunctions that typically cause a large amount of
    inefficiency in buildings are not modeled in the compliance or LEED
    certification process, as the simulation programs assume that all
    controls work perfectly all the time. A major means of attaining an
    Energy Star label is to have controls that actually work properly
    and efficiently, but the standards and regs do not deal directly
    with this issue (and indirectly only mention it in passing).

-   The malfunction of air economizers and the resulting energy
    penalties are assumed to be nonexistent by the standards and regs,
    since all systems function perfectly. In the real world, if quality
    of maintenance is a problem, significant benefit is obtained from
    systems that cannot cause major energy penalties when they
    malfunction. The standards and regs force use of economizers in many
    cases, although Std 90.1 has provided important exclusions based on
    climate. Use of air economizers is unwise in many cases, and if the
    design separates the V from HVAC, the function of an economizer
    should be replaced by energy recovery equipment, which is a more
    technologically sure approach.

-   Truly high efficiency lighting designs will use quite a bit less
    energy than the standards and regs require, but designers are often
    uncomfortable trying to push the limits here.

Compliance with Std. 90.1 is no guarantee of energy efficiency, and
indeed some of the requirements in 90.1 will detract from quality space
and systems. The same is true for 10 CFR 435A. Compliance with 10 CFR
435A or Std. 90.1 can often lead to an Energy Star rating of 50 to 70. A
rating of 75 or higher is needed for an Energy Star label, so we might
say the Standards may likely only give us mediocre to
better-than-average energy performance. This is not what is needed for
energy efficiency.

Download this document from:
<http://eber.ed.ornl.gov/commercialproducts/Design.htm>

This document is not necessarily definitive, and comments are
appreciated.

Email: <macdonaldjm@ornl.gov>