Reference: This request refers to the requirements given in ANSI/ASHRAE Standard , paragraph (renumbered in ASHRAE Standard BSR/ASHRAE Standard 55P R. This draft standard will be submitted to the American. National Standards Institute Board of Standards Review. (BSR) for. (Supersedes ANSI/ASHRAE Standard ). Thermal. Environmental. Conditions for. Human Occupancy. Approved by the ASHRAE Standards Committee.


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Applicable standards and codes should be looked at carefully; revisions and exceptions that are more compatible with UFAD technology may be forthcoming as additional research results are obtained.

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  • Underfloor Technology Standards and Codes
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  • Standard 55 – Thermal Environmental Conditions for Human Occupancy
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Listed below are brief discussions of the applicable building standards and codes that have important provisions related to the design, ashrae standard 55 1992, and operation of UFAD systems.

CEC Title UFAD systems, however, usually involve greater variability of thermal conditions over both space and time. The effect of providing occupant-control has not been fully taken into account, although it is well established that occupants will tolerate greater fluctuations in environmental conditions if they have control over them.

ASHRAE Standard was revised to allow higher air velocities than the previous version of the standard, if the occupant has control over the local air speed. Figure 3 in Standard was added to show the air speed required to offset increases in temperature above those allowed in the summer comfort zone.

Standard also specifies allowable air ashrae standard 55 1992 as a function of air temperature and turbulence intensity with the objective of avoiding unwanted drafts when the occupant has no direct local control.

At warmer temperatures, however, occupants will desire additional cooling, and increased air movement and turbulence is an easy way of achieving such direct occupant cooling.

Interpretation for Standard 55-1981 and 55-1992

Standard allows these velocity limits based on turbulence intensity level to be exceeded if the occupant has control over the local air speed. In the recently revised Standardthe benefits of providing personal control of operable windows to building occupants has been added through the inclusion of an adaptive model of thermal comfort based on field observations in naturally ventilated buildings.

When thermal conditions in a building are regulated primarily by the occupants through opening and closing of the windows, the adaptive model allows a wider range of operative temperatures to be considered as acceptable thermal conditions.

All informative background information has been moved to informative ashrae standard 55 1992. Documentation requirements to show that ashrae standard 55 1992 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. All of the building systems must be designed to maintain the occupied spaces at the indoor conditions specified by one of the described evaluation methods at design conditions.

The systems must be able to maintain these conditions within the expected range of indoor and outdoor operating conditions.

Standard 55 – Thermal Environmental Conditions for Human Occupancy

Sample documentation is provided in Informative Appendix J. Generally, the evaluation of comfort in existing buildings can be performed from two perspectives: The survey shall be distributed to the entire occupancy or representative part of the occupancy. If that number is between 20 and 45, the minimum number of responses is When the number is under 20, at least 16 must reply for the survey to make the survey representative.

As for point-in-time surveys, the survey should be solicited during the time of occupancy, and the satisfaction scale ought to be continuous. Ashrae standard 55 1992 should be at least seven ashrae standard 55 1992 on the scale ending with "very acceptable" and "very unacceptable.


The comfort zone boundaries must be adjusted to the air movements, and the zone conditions should be adjusted to avoid local thermal discomfort. For occupant-controlled naturally conditioned space, the adaptive model shall be used to determine the thermal comfort boundaries.

For such spaces, the indoor and outdoor air temperature and mean radiant temperature and the air speed need to be ashrae standard 55 1992.

The measurement locations should be where the ashrae standard 55 1992 are expected to spend time in.

If there are multiple such locations, the measurement can be performed at a representative location. The heights need ashrae standard 55 1992 be ashrae standard 55 1992 for standing persons. Measuring time step should be no more than five minutes for air temperature, mean radiant temperature, and humidity, and no more than three minutes for the air speed.

The answers of open-ended questions from "very dissatisfied" occupants should be documented for later analysis. One has to keep in mind that the results from point-in-time surveys are only effective during the time when the surveys were solicited.

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