ASHRAE 55-2017

ASHRAE 55-2017

Standard 55-2017 — Thermal Environmental Conditions for Human Occupancy (ANSI/ASHRAE Approved)

Full Description

Standard 55 specifies conditions for acceptable thermal environments and is intended for use in design, operation, and commissioning of buildings and other occupied spaces. The 2017 edition of ANSI/ASHRAE Standard 55 incorporates seven published addenda to the 2013 edition, and provides three compliance methods: a graphic method for simple situations, an analytical method for more general cases and a method that uses elevated air speed to provide comfort. The standard has a separate method for determining acceptable thermal conditions in occupant-controlled naturally conditioned spaces. Given the widespread and easy accessibility of computing power and third-party implementations of the analytical method, it is expected that more users will favor the comprehensive analytical methods over the graphical method.

Since 2013, Standard 55 has been rewritten with a renewed focus on application of the standard by practitioners and use of clear, enforceable language. Requirements are now clearly stated and calculation procedures appear sequentially. For example, during design, a « representative occupant » must be defined, and the air speed and temperature they experience must be an average across the human body at three typical measurement heights. All informative background information has been moved to informative appendices.

Other noteworthy additions to the standard include clarification of the three comfort calculation approaches in the elevated air speed section; simplification of Appendix A to a single procedure for calculating operative temperature; an update to the scope to ensure the standard isn’t used to override health, safety, and critical process requirements; a new requirement for calculating change to thermal comfort resulting from direct solar radiation; and removal of permissive language throughout the standard.

Documentation requirements to show that a design complies with Standard 55 are contained in Section 6, and a sample compliance form is provided in Appendix K. Both of these sections are clarified and streamlined for use by owners and third-party rating systems.

ASHRAE 62.2-2016

Standard 62.2-2016 — Ventilation and Acceptable Indoor Air Quality in Residential Buildings (ANSI Approved)

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Major Scope Changes and More in Standard 62.2-2016

The 2016 edition of ANSI/ASHRE Standard 62.2 makes two major changes to scope by including unvented space heaters as a potential contaminant source and by expanding « covered dwellings » to include all multifamily dwelling units. A number of other significant changes are also incorporated. A minimal calculated mechanical ventilation rate is provided for existing buildings, below which installation of whole-house ventilation is not required; a distinction is now made between range hoods and other kitchen ventilation options; new methods are provided for determining an infiltration credit for horizontally attached multifamily dwelling units and for determining requirements for a variety of noncontinuous ventilation strategies; and a maximum short-term relative exposure limit is implemented for the first time.

Standard 62.2 defines the roles of and minimum requirements for mechanical and natural ventilation systems and the building envelope intended to provide acceptable indoor air quality in low-rise residential buildings. As in the previous editions of this standard, there are three primary sets of requirements and a number of secondary ones. The three primary sets involve whole-building ventilation, local demand-controlled exhaust, and source control. The secondary requirements focus on properties of specific items needed to achieve the main objectives of the standard. Standard 62.2 applies to spaces intended for human occupancy within single-family houses and multifamily structures, including manufactured and modular houses. This standard does not apply to transient housing such as hotels, motels, nursing homes, dormitories, or jails.

The standard considers chemical, physical, and biological contaminants that can affect air quality. It does not address thermal comfort requirements, specific pollutant concentration levels, or certain potential pollutant sources such as unvented combustion space heaters and contamination from outdoor sources or from episodic occupant-controlled events such as painting, smoking, cleaning, or other high-polluting events.