ASHRAE Journal - May 2023 - 49

TECHNICAL FEATURE
¥ Clarity is added regarding alteration compliance
options with air leakage. As part of this, roof replacement
alterations have been defi ned and the compliance
scope clarifi ed.
Roof Replacements
Addendum bi clarifi es requirements surrounding the
addition of insulation when existing buildings undergo
roof replacement. The committee has long believed
the time of roof replacement is the lowest cost and best
opportunity for existing buildings to be brought up to
code or as close to code as possible. However, until now,
the standard offered no guidance on how to address
existing building roofs with obstacles to installing the
minimum insulation required, especially for roofs with
insulation entirely above deck. Addendum bi clarifi es
what must be done when existing roof conditions limit
full thickness insulation levels.
This new addendum recognizes that existing building
roof replacements can be challenging and requires roofing
professionals to provide an inspection report identifying
obstacles to installing the full thickness of insulation
and to describe on construction documents how the
Restructuring
of the Standard
and AlteratiWithin the standard, requirements for New Buildings, Additions
ons have also been organized across all the sections.
Each Section is organized as follows: X.1.2 outlines the scope for
new buildings, X.1.3 has requirements or directions for Additions,
and X.1.4 has requirements or directions for Alterations. (Note: this
maps to 9.1.1.2, 9.1.1.3, and 9.1.1.4 in the Lighting section).
The last structural change relates to the location of Inspection,
Verifi cation and Testing and Commissioning requirements.
Inspections have been moved to Section 4, as they are a
jurisdictional administrative function or requirement. Verifi cation
and Testing (or Functional Performance Testing) provisions have
all been located in an X.9.1 section, with the more involved
commissioning provisions located in an X.9.2 section within each
major section (Sections 5 - 10).
Finally, users should note that, with the introduction of Energy
Credits, the Energy Cost Budget Method has moved from Section
11 to Section 12.
proposed design intends to minimize deviation from the
insulation requirements.
It further clarifi es the defi nition of roof replacement as
an alteration that involves removing all existing materials
down to the roof deck and installing a new roof assembly
above the roof deck. And it reinforces the standard's
requirement that two layers of insulation with staggered
joints must be installed in roof replacement designs. This
requirement is the same for new roof construction.
Envelope Commissioning
While inspections, verifi cation and commissioning
provisions did not change with this edition, they
were moved and section numbering was aligned
between all sections. In Standard 90.1-2022, anything
related to inspections has been move to Section 4, the
Administration and Enforcement section; anything
related to verifi cation and/or testing has been moved to
a X.9.1 section within each section; everything related to
commissioning has been moved to a X.9.2 section.
Envelope Backstop
A new requirement was added into the performancebased
compliance pathways of both Section 12-Energy
Cost Budget and Appendix G that limits the trade-off of
prescriptive envelope performance. The trade-off limits
are based on the envelope performance factors calculated
in accordance with the building envelope performance
compliance option (Appendix C). For residential
building types the proposed envelope performance factor
cannot exceed the base envelope performance factor
by more than 15%. In nonresidential building types the
proposed envelope performance factor cannot exceed
the base envelope performance factor by more than 7%.
These new trade-off limits recognize the importance of
maintaining a robust, well insulated building envelope.
Summary
In summary, several changes were introduced to the
envelope requirements of Standard 90.1-2022. These
changes are intended to improve energy effi ciency, ease
compliance and improve the clarity of the standard. In
the next article, we will delve deeper into changes to the
thermal bridging requirements, which are completely
new in the 2022 edition. Other articles will cover changes
to the lighting, mechanical, service water heating, power
and other, and performance compliance sections.
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ASHRAE Journal - May 2023

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