ASHRAE Journal - July 2013 - 23

plan review by the permitting agency and during construction
inspection.
Even developers who employ design teams with signiﬁcant
energy expertise may desire a simple compliance option. For
example, the developer may want to invest project resources in
energy-efﬁciency components, not in energy analyses. Further,
buildings with highly energy-efﬁcient designs can use the simplest compliance options because their designs easily comply.
Other users of energy codes are product manufacturers who
use energy code criteria for individual products as a guide for
deﬁning the market baseline. These criteria can inﬂuence how a
manufacturer re-tools and revises a product line. The more comprehensive the re-tooling, the more helpful it is to have a longer
lead time. ASHRAE/IES Standard 90.1 routinely provides future
effective dates for mechanical equipment efﬁciency upgrades.

Characterization of Compliance Options
Energy codes commonly contain one or more simple compliance options where requirements are speciﬁed by design
trade and product specialty such as architectural requirements
(building envelope), mechanical requirements (heating, cooling, and ventilation), plumbing requirements (service water
heating system), and electrical requirements (power and lighting system). A more complicated option allows the designer to
show compliance for the entire building and all of its systems
combined.
The design-specialty options are often called prescriptive and
the combined option called performance. However, this simpliﬁcation is misleading because the reality is more complex. Energy codes don’t have only two options. They have a continuum
of compliance options. Proceeding from most simple to most
complex, and generalizing slightly for this overview:
• A true prescriptive compliance option speciﬁes materials
to be used. This article uses “prescriptive” in this precise sense
only.
• A component performance compliance option often contains a rating for an assembly of materials.
• Beyond this, there are gradations of options for systems.
• A partial system performance compliance option addresses more than one component, but still less than a full building
system.
• A full system performance compliance option considers
the full building system for that individual system.
• A multiple system performance compliance option allows
consideration of multiple systems together, but does not address all the systems within a building.
• Finally, there is the total building performance option,
which includes all of the energy consumption for the overall
building.
Compliance options aren’t necessarily separated into different chapters (or even in different tables) in a code or standard.
For example, the building envelope table for each climate
zone in ASHRAE/IES Standard 90.1 contains both the true
prescriptive and the component performance compliance options for opaque assemblies.
July 2013

Table 1 and the following sections discusses each compliance option. Common examples are provided for six categories of building systems: building envelope, mechanical
systems, service water heating, power, lighting, and other
equipment. While not all state and local energy codes and
standards contain requirements for all six categories at this
time, the national trends eventually will push local and state
codes in this direction. These examples are generally drawn
from national energy codes and standards. However, state and
international energy codes are cited where they contain options not included in national energy codes and standards.

Prescriptive Compliance Options
A true prescriptive compliance option provides some speciﬁc details about materials to be used.
Building Envelope. Prescriptive compliance options are
common, particularly for opaque components. For example,
a common prescriptive compliance option speciﬁes some details about how the wall assembly is constructed (e.g., woodframing vs. metal-framing, the depth and/or spacing of the
studs) and what minimum R-value is required for the insulation and how that insulation is to be installed in the assembly
(e.g., allowed to be installed in the cavity between wood-framing vs. metal framing, or required to be continuous across the
framing to limit thermal-bridging). Comparable options usually exist for the opaque roof and ﬂoor.
For fenestration products (windows, skylights, and doors), prescriptive options are not often used because of their many different
components. To be complete, this must address the frame material,
number of glazing layers, gap width between glazing layers, lowemissivity coatings if any, gas ﬁll if other than air, and spacer type.
This information is usually included in a table of default U-factor
for fenestration products without National Fenestration Rating
Council (NFRC) ratings. This provides a simple compliance option for designers and contractors, but it is not an appealing option
as the values tend to be punitive. Consequently, it is to the beneﬁt of designers, contractors, and especially fenestration product
manufacturers, to obtain NFRC-rated values to show compliance
using the component performance compliance option.
Prescriptive requirements exist for reducing air leakage
through inﬁltration and exﬁltration, such as requirements for
caulking and sealing. However, it is generally recognized that
these speciﬁcations have not always proven effective in delivering a well-sealed building envelope.
Mechanical. A common example of a prescriptive compliance option is the requirement for pipe and duct insulation for
space heating, space cooling, and ventilation systems. Insulation is typically speciﬁed in terms of minimum insulation
R-value, or in terms of material conductivity and minimum
thickness. In this case, the insulation is continuous, so it is not
necessary to describe the pipe or duct assembly (in contrast to
the building envelope where the insulation is often installed
between framing members).
Service Water Heating. Similar to mechanical systems, a
common example of a true prescriptive compliance option
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ASHRAE Journal - July 2013

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