ASHRAE Journal - July 2023 - 48

TECHNICAL FEATURE
FIGURE 1 Compliance Map for Standard 90.1-2022 Mechanical.
Section 6 Heating, Ventilating, and Air Conditioning
Section 6.1 General
Section 6.2 Definition of Compliance Paths
Section 6.4 Mandatory Provisions
Section 6.3
Simplified
Approach
Section 6.5
Prescriptive
Path
Section 6.6
Alternate
Compliance
Section 12
Energy Cost
Budget
Appendix G
Performance
Rating
Exception to optimum start for residential
spaces. Residential spaces are now
exempt from the optimum start requirement
for systems with direct digital control
(DDC) defined in Section 6.4.3.3.3.
Garage exhaust ventilation. Requires
garages with multiple sections separated by
solid walls to have separate exhaust systems
and controls. This prevents vehicle activity
in one section from unnecessarily exhausting
to other sections and improves safety
by ensuring controls are provided in each
section.
Section 6.7 Submittals
Section 6.8 Equipment Efficiency Tables
Section 6.9 Commisioning
Other Mandatory and Prescriptive Changes to Section 6
HVAC&R Requirements
There were also a multitude of updates to the
Mandatory (Section 6.4) and Prescriptive (Section
6.5) portions of the Standard 90.1-2022 HVAC
requirements. As shown in Figure 1, Section 6.4 is
required for all Standard 90.1-compliant paths except
for the " Simplified Approach " outlined in Section 6.3.
Alternatives to prescriptive compliance (Section
6.6, Section 12, and Appendix G) will be the subject of
future articles, including the brand-new total system
performance path (TSPR) in Section 6.6 that enables
performance-based compliance without energy
modeling.
The following is a summary of the Section 6 changes
that appear in the 2022 edition of Standard 90.1:
Demand control ventilation. Table 6.4.3.8 defines
the floor area thresholds requiring the use of demand
control ventilation based on climate zone, ventilation,
and use of exhaust air energy recovery. This topic has
gained importance in recent years given the variable
occupancy now seen in office buildings as a result of
the COVID-19 pandemic.
Small unit setback controls. Section 6.4.3.3.2
was updated to require setback thermostats for
residential spaces as this type of control has become a
cost-effective and readily available option to achieve
energy savings.
48
ASHRAE JOURNAL ashrae.o rg
J U LY 2023
Shaft ventilation damper requirements.
Requires motorized dampers in shaft vents
used for temperature control with the
exception of warm climates zones 0, 1, 2,
and 3.
Simplified building updates. Specifies
that verification of equipment efficiency
(Section 6.4.1.5) is required for compliance with the
Simplified Path (Section 6.3).
Ceiling fan efficiency. The requirements for large
ceiling fans were modified to align with Section 1008
of the Energy Act of 2020. The Act requires large-diameter
ceiling fans to have a CFEI greater than or equal
to 1.00 at high speed and greater than or equal to 1.31
at 40% speed or the nearest speed that is not less than
40% speed.
Compressed air systems. Standard 90.1-2022 introduced
new requirements for compressed air systems in
Section 10.4.6. The following aspects of compressed air
systems are now addressed:
* Trim compressors and storage;
* Advanced controls;
* Leak testing;
* Monitoring;
* Pipe sizing.
Dehumidification control. ASHRAE Standard 62.12019
implemented an off-hour dewpoint control limit
of 60°F (16°C) to control mold issues. ASHRAE Standard
90.1-2022 includes revised language throughout the
standard to align with the updated humidity requirements
of Standard 62.1. The updates also address efficient
humidification and dehumidification, with the
goals of minimizing simultaneous heating and cooling
and encouraging use of site recovered energy.
http://ashrae.org
ASHRAE Journal - July 2023

Table of Contents for the Digital Edition of ASHRAE Journal - July 2023
