CSA S500:21

Preface

This is the second edition of CSA S500, Thermosyphon foundations for buildings in permafrost regions. It replaces the previous edition published in 2014.

Previous to this Standard, there have been no guidelines or standards for the design, construction, and maintenance for thermosyphon supported foundations.

The following are the major changes to this edition:

a) updated the climate change discussion to provide current references;

b) clarified the thermal analysis discussion; and

c) clarified the distinctions and engineering considerations between various types of thermosyphons.

CSA Group received funding for the development of this Standard from Standards Council of Canada, as part of the Northern Infrastructure Standardization Initiative, supported by the Government of Canada’s Clean Air Agenda.

This Standard has been developed in compliance with Standards Council of Canada requirements for National Standards of Canada. It has been published as a National Standard of Canada by CSA Group.

Scope, objectives, and application

1.1 Scope

This Standard provides requirements for all life cycle phases of

thermosyphon foundations for new buildings on permafrost, including site characterization, design, installation, and commissioning phases as well as for monitoring and maintenance phases. This Standard is meant to ensure the long-term performance of thermosyphon-supported foundation systems under changing environmental conditions.

1.2 Objectives

The objectives of this Standard are to

a) foster an awareness and understanding of application technology, with a focus on factors that could compromise the functionality of foundation systems reliant on thermosyphons;

b) describe the typical phases of the life cycle of thermosyphon foundations for buildings on permafrost, including design, installation, commissioning, monitoring, and maintenance;

c) describe performance expectations for thermosyphon foundations together with monitoring requirements necessary to support an appropriate maintenance program;

d) provide guidance to maximize the long-term viability of thermosyphon-supported foundation systems under changing environmental conditions; and

e) specify the materials to be used in thermosyphon foundations.

1.3 Application

This Standard is intended to be used by designers, contractors, building owners, and operators. For owners, it provides an understanding of the design and construction processes necessary to verify that adequate measures are taken during these phases. The Standard also provides monitoring and maintenance expectations for building operators.

This Standard is applicable to new buildings on permafrost sites, particularly those with thaw sensitive materials. It provides guidance on the necessary aspects and deliverables from a geotechnical investigation, provides advice on foundation conditions that support or counter the use of thermosyphons as a foundation system. Preservation of the permafrost for support of the building has been identified as a design objective before this Standard is implemented.

1.4 Exclusions

This Standard does not cover

a) abandonment/demolition of buildings with thermosyphon foundations;

b) thermosyphons in areas of non-permafrost or retrofitting thermosyphons to existing buildings; and

c) thermosyphons used for infrastructure other than buildings.

1.5 Terminology

In this Standard, shall is used to express a requirement, i.e., a provision that the user is obliged to satisfy in order to comply with the standard; should is used to express a recommendation or that which is advised but not required; and may is used to express an option or that which is permissible within the limits of the standard.

Notes accompanying clauses do not include requirements or alternative requirements; the purpose of a note accompanying a clause is to separate normative clauses from explanatory or informative material.

Notes to tables and figures are considered part of the table or figure and may be written as requirements.

Annexes are designated normative (mandatory) or informative (non-mandatory) to define their application.

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